import os from "os"
import path from "path"
import fs from "fs/promises"
import { spawn } from "child_process"
import { Decimal } from "decimal.js"
import { z, ZodSchema } from "zod"
import {
  generateText,
  LoadAPIKeyError,
  streamText,
  tool,
  wrapLanguageModel,
  type Tool as AITool,
  type LanguageModelUsage,
  type ProviderMetadata,
  type ModelMessage,
  type StreamTextResult,
} from "ai"

import PROMPT_INITIALIZE from "../session/prompt/initialize.txt"
import PROMPT_PLAN from "../session/prompt/plan.txt"
import BUILD_SWITCH from "../session/prompt/build-switch.txt"

import { Bus } from "../bus"
import { Config } from "../config/config"
import { Flag } from "../flag/flag"
import { Identifier } from "../id/id"
import { Installation } from "../installation"
import { MCP } from "../mcp"
import { Provider } from "../provider/provider"
import { ProviderTransform } from "../provider/transform"
import type { ModelsDev } from "../provider/models"
import { Share } from "../share/share"
import { Snapshot } from "../snapshot"
import { Storage } from "../storage/storage"
import { Log } from "../util/log"
import { NamedError } from "../util/error"
import { SystemPrompt } from "./system"
import { FileTime } from "../file/time"
import { MessageV2 } from "./message-v2"
import { LSP } from "../lsp"
import { ReadTool } from "../tool/read"
import { mergeDeep, pipe, splitWhen } from "remeda"
import { ToolRegistry } from "../tool/registry"
import { Plugin } from "../plugin"
import { Project } from "../project/project"
import { Instance } from "../project/instance"
import { Agent } from "../agent/agent"
import { Permission } from "../permission"
import { Wildcard } from "../util/wildcard"
import { ulid } from "ulid"
import { defer } from "../util/defer"
import { Command } from "../command"
import { $ } from "bun"

export namespace Session {
  const log = Log.create({ service: "session" })

  const OUTPUT_TOKEN_MAX = 32_000

  const parentSessionTitlePrefix = "New session - "
  const childSessionTitlePrefix = "Child session - "

  function createDefaultTitle(isChild = false) {
    return (isChild ? childSessionTitlePrefix : parentSessionTitlePrefix) + new Date().toISOString()
  }

  function isDefaultTitle(title: string) {
    return title.startsWith(parentSessionTitlePrefix)
  }

  export const Info = z
    .object({
      id: Identifier.schema("session"),
      projectID: z.string(),
      directory: z.string(),
      parentID: Identifier.schema("session").optional(),
      share: z
        .object({
          url: z.string(),
        })
        .optional(),
      title: z.string(),
      version: z.string(),
      time: z.object({
        created: z.number(),
        updated: z.number(),
      }),
      revert: z
        .object({
          messageID: z.string(),
          partID: z.string().optional(),
          snapshot: z.string().optional(),
          diff: z.string().optional(),
        })
        .optional(),
    })
    .openapi({
      ref: "Session",
    })
  export type Info = z.output<typeof Info>

  export const ShareInfo = z
    .object({
      secret: z.string(),
      url: z.string(),
    })
    .openapi({
      ref: "SessionShare",
    })
  export type ShareInfo = z.output<typeof ShareInfo>

  export const Event = {
    Updated: Bus.event(
      "session.updated",
      z.object({
        info: Info,
      }),
    ),
    Deleted: Bus.event(
      "session.deleted",
      z.object({
        info: Info,
      }),
    ),
    Idle: Bus.event(
      "session.idle",
      z.object({
        sessionID: z.string(),
      }),
    ),
    Error: Bus.event(
      "session.error",
      z.object({
        sessionID: z.string().optional(),
        error: MessageV2.Assistant.shape.error,
      }),
    ),
  }

  const state = Instance.state(
    () => {
      const pending = new Map<string, AbortController>()
      const autoCompacting = new Map<string, boolean>()
      const queued = new Map<
        string,
        {
          input: ChatInput
          message: MessageV2.User
          parts: MessageV2.Part[]
          processed: boolean
          callback: (input: { info: MessageV2.Assistant; parts: MessageV2.Part[] }) => void
        }[]
      >()

      return {
        pending,
        autoCompacting,
        queued,
      }
    },
    async (state) => {
      for (const [_, controller] of state.pending) {
        controller.abort()
      }
    },
  )

  export async function create(parentID?: string, title?: string) {
    return createNext({
      parentID,
      directory: Instance.directory,
      title,
    })
  }

  export async function createNext(input: { id?: string; title?: string; parentID?: string; directory: string }) {
    const result: Info = {
      id: Identifier.descending("session", input.id),
      version: Installation.VERSION,
      projectID: Instance.project.id,
      directory: input.directory,
      parentID: input.parentID,
      title: input.title ?? createDefaultTitle(!!input.parentID),
      time: {
        created: Date.now(),
        updated: Date.now(),
      },
    }
    log.info("created", result)
    await Storage.write(["session", Instance.project.id, result.id], result)
    const cfg = await Config.get()
    if (!result.parentID && (Flag.OPENCODE_AUTO_SHARE || cfg.share === "auto"))
      share(result.id)
        .then((share) => {
          update(result.id, (draft) => {
            draft.share = share
          })
        })
        .catch(() => {
          // Silently ignore sharing errors during session creation
        })
    Bus.publish(Event.Updated, {
      info: result,
    })
    return result
  }

  export async function get(id: string) {
    const read = await Storage.read<Info>(["session", Instance.project.id, id])
    return read as Info
  }

  export async function getShare(id: string) {
    return Storage.read<ShareInfo>(["share", id])
  }

  export async function share(id: string) {
    const cfg = await Config.get()
    if (cfg.share === "disabled") {
      throw new Error("Sharing is disabled in configuration")
    }

    const session = await get(id)
    if (session.share) return session.share
    const share = await Share.create(id)
    await update(id, (draft) => {
      draft.share = {
        url: share.url,
      }
    })
    await Storage.write(["share", id], share)
    await Share.sync("session/info/" + id, session)
    for (const msg of await messages(id)) {
      await Share.sync("session/message/" + id + "/" + msg.info.id, msg.info)
      for (const part of msg.parts) {
        await Share.sync("session/part/" + id + "/" + msg.info.id + "/" + part.id, part)
      }
    }
    return share
  }

  export async function unshare(id: string) {
    const share = await getShare(id)
    if (!share) return
    await Storage.remove(["share", id])
    await update(id, (draft) => {
      draft.share = undefined
    })
    await Share.remove(id, share.secret)
  }

  export async function update(id: string, editor: (session: Info) => void) {
    const project = Instance.project
    const result = await Storage.update<Info>(["session", project.id, id], (draft) => {
      editor(draft)
      draft.time.updated = Date.now()
    })
    Bus.publish(Event.Updated, {
      info: result,
    })
    return result
  }

  export async function messages(sessionID: string) {
    const result = [] as {
      info: MessageV2.Info
      parts: MessageV2.Part[]
    }[]
    for (const p of await Storage.list(["message", sessionID])) {
      const read = await Storage.read<MessageV2.Info>(p)
      result.push({
        info: read,
        parts: await getParts(read.id),
      })
    }
    result.sort((a, b) => (a.info.id > b.info.id ? 1 : -1))
    return result
  }

  export async function getMessage(sessionID: string, messageID: string) {
    return {
      info: await Storage.read<MessageV2.Info>(["message", sessionID, messageID]),
      parts: await getParts(messageID),
    }
  }

  export async function getParts(messageID: string) {
    const result = [] as MessageV2.Part[]
    for (const item of await Storage.list(["part", messageID])) {
      const read = await Storage.read<MessageV2.Part>(item)
      result.push(read)
    }
    result.sort((a, b) => (a.id > b.id ? 1 : -1))
    return result
  }

  export async function* list() {
    const project = Instance.project
    for (const item of await Storage.list(["session", project.id])) {
      yield Storage.read<Info>(item)
    }
  }

  export async function children(parentID: string) {
    const project = Instance.project
    const result = [] as Session.Info[]
    for (const item of await Storage.list(["session", project.id])) {
      const session = await Storage.read<Info>(item)
      if (session.parentID !== parentID) continue
      result.push(session)
    }
    return result
  }

  export function abort(sessionID: string) {
    const controller = state().pending.get(sessionID)
    if (!controller) return false
    log.info("aborting", {
      sessionID,
    })
    controller.abort()
    state().pending.delete(sessionID)
    return true
  }

  export async function remove(sessionID: string, emitEvent = true) {
    const project = Instance.project
    try {
      abort(sessionID)
      const session = await get(sessionID)
      for (const child of await children(sessionID)) {
        await remove(child.id, false)
      }
      await unshare(sessionID).catch(() => {})
      for (const msg of await Storage.list(["message", sessionID])) {
        for (const part of await Storage.list(["part", msg.at(-1)!])) {
          await Storage.remove(part)
        }
        await Storage.remove(msg)
      }
      await Storage.remove(["session", project.id, sessionID])
      if (emitEvent) {
        Bus.publish(Event.Deleted, {
          info: session,
        })
      }
    } catch (e) {
      log.error(e)
    }
  }

  async function updateMessage(msg: MessageV2.Info) {
    await Storage.write(["message", msg.sessionID, msg.id], msg)
    Bus.publish(MessageV2.Event.Updated, {
      info: msg,
    })
  }

  async function updatePart(part: MessageV2.Part) {
    await Storage.write(["part", part.messageID, part.id], part)
    Bus.publish(MessageV2.Event.PartUpdated, {
      part,
    })
    return part
  }

  async function cleanupRevert(session: Info) {
    if (!session.revert) return
    const sessionID = session.id
    let msgs = await messages(sessionID)
    const messageID = session.revert.messageID
    const [preserve, remove] = splitWhen(msgs, (x) => x.info.id === messageID)
    msgs = preserve
    for (const msg of remove) {
      await Storage.remove(["message", sessionID, msg.info.id])
      await Bus.publish(MessageV2.Event.Removed, { sessionID: sessionID, messageID: msg.info.id })
    }
    const last = preserve.at(-1)
    if (session.revert.partID && last) {
      const partID = session.revert.partID
      const [preserveParts, removeParts] = splitWhen(last.parts, (x) => x.id === partID)
      last.parts = preserveParts
      for (const part of removeParts) {
        await Storage.remove(["part", last.info.id, part.id])
        await Bus.publish(MessageV2.Event.PartRemoved, {
          sessionID: sessionID,
          messageID: last.info.id,
          partID: part.id,
        })
      }
    }
    await update(sessionID, (draft) => {
      draft.revert = undefined
    })
  }

  export const PromptInput = z.object({
    sessionID: Identifier.schema("session"),
    messageID: Identifier.schema("message").optional(),
    model: z
      .object({
        providerID: z.string(),
        modelID: z.string(),
      })
      .optional(),
    agent: z.string().optional(),
    system: z.string().optional(),
    tools: z.record(z.boolean()).optional(),
    parts: z.array(
      z.discriminatedUnion("type", [
        MessageV2.TextPart.omit({
          messageID: true,
          sessionID: true,
        })
          .partial({
            id: true,
          })
          .openapi({
            ref: "TextPartInput",
          }),
        MessageV2.FilePart.omit({
          messageID: true,
          sessionID: true,
        })
          .partial({
            id: true,
          })
          .openapi({
            ref: "FilePartInput",
          }),
        MessageV2.AgentPart.omit({
          messageID: true,
          sessionID: true,
        })
          .partial({
            id: true,
          })
          .openapi({
            ref: "AgentPartInput",
          }),
      ]),
    ),
  })
  export type ChatInput = z.infer<typeof PromptInput>

  export async function prompt(
    input: z.infer<typeof PromptInput>,
  ): Promise<{ info: MessageV2.Assistant; parts: MessageV2.Part[] }> {
    const l = log.clone().tag("session", input.sessionID)
    l.info("chatting")

    const inputAgent = input.agent ?? "build"

    // Process revert cleanup first, before creating new messages
    const session = await get(input.sessionID)
    if (session.revert) {
      cleanupRevert(session)
    }
    const userMsg: MessageV2.Info = {
      id: input.messageID ?? Identifier.ascending("message"),
      role: "user",
      sessionID: input.sessionID,
      time: {
        created: Date.now(),
      },
    }

    const userParts = await Promise.all(
      input.parts.map(async (part): Promise<MessageV2.Part[]> => {
        if (part.type === "file") {
          const url = new URL(part.url)
          switch (url.protocol) {
            case "data:":
              if (part.mime === "text/plain") {
                return [
                  {
                    id: Identifier.ascending("part"),
                    messageID: userMsg.id,
                    sessionID: input.sessionID,
                    type: "text",
                    synthetic: true,
                    text: `Called the Read tool with the following input: ${JSON.stringify({ filePath: part.filename })}`,
                  },
                  {
                    id: Identifier.ascending("part"),
                    messageID: userMsg.id,
                    sessionID: input.sessionID,
                    type: "text",
                    synthetic: true,
                    text: Buffer.from(part.url, "base64url").toString(),
                  },
                  {
                    ...part,
                    id: part.id ?? Identifier.ascending("part"),
                    messageID: userMsg.id,
                    sessionID: input.sessionID,
                  },
                ]
              }
              break
            case "file:":
              // have to normalize, symbol search returns absolute paths
              // Decode the pathname since URL constructor doesn't automatically decode it
              const filePath = decodeURIComponent(url.pathname)

              if (part.mime === "text/plain") {
                let offset: number | undefined = undefined
                let limit: number | undefined = undefined
                const range = {
                  start: url.searchParams.get("start"),
                  end: url.searchParams.get("end"),
                }
                if (range.start != null) {
                  const filePath = part.url.split("?")[0]
                  let start = parseInt(range.start)
                  let end = range.end ? parseInt(range.end) : undefined
                  // some LSP servers (eg, gopls) don't give full range in
                  // workspace/symbol searches, so we'll try to find the
                  // symbol in the document to get the full range
                  if (start === end) {
                    const symbols = await LSP.documentSymbol(filePath)
                    for (const symbol of symbols) {
                      let range: LSP.Range | undefined
                      if ("range" in symbol) {
                        range = symbol.range
                      } else if ("location" in symbol) {
                        range = symbol.location.range
                      }
                      if (range?.start?.line && range?.start?.line === start) {
                        start = range.start.line
                        end = range?.end?.line ?? start
                        break
                      }
                    }
                  }
                  offset = Math.max(start - 1, 0)
                  if (end) {
                    limit = end - offset
                  }
                }
                const args = { filePath, offset, limit }
                const result = await ReadTool.init().then((t) =>
                  t.execute(args, {
                    sessionID: input.sessionID,
                    abort: new AbortController().signal,
                    agent: input.agent!,
                    messageID: userMsg.id,
                    extra: { bypassCwdCheck: true },
                    metadata: async () => {},
                  }),
                )
                return [
                  {
                    id: Identifier.ascending("part"),
                    messageID: userMsg.id,
                    sessionID: input.sessionID,
                    type: "text",
                    synthetic: true,
                    text: `Called the Read tool with the following input: ${JSON.stringify(args)}`,
                  },
                  {
                    id: Identifier.ascending("part"),
                    messageID: userMsg.id,
                    sessionID: input.sessionID,
                    type: "text",
                    synthetic: true,
                    text: result.output,
                  },
                  {
                    ...part,
                    id: part.id ?? Identifier.ascending("part"),
                    messageID: userMsg.id,
                    sessionID: input.sessionID,
                  },
                ]
              }

              let file = Bun.file(filePath)
              FileTime.read(input.sessionID, filePath)
              return [
                {
                  id: Identifier.ascending("part"),
                  messageID: userMsg.id,
                  sessionID: input.sessionID,
                  type: "text",
                  text: `Called the Read tool with the following input: {\"filePath\":\"${filePath}\"}`,
                  synthetic: true,
                },
                {
                  id: part.id ?? Identifier.ascending("part"),
                  messageID: userMsg.id,
                  sessionID: input.sessionID,
                  type: "file",
                  url: `data:${part.mime};base64,` + Buffer.from(await file.bytes()).toString("base64"),
                  mime: part.mime,
                  filename: part.filename!,
                  source: part.source,
                },
              ]
          }
        }

        if (part.type === "agent") {
          return [
            {
              id: Identifier.ascending("part"),
              ...part,
              messageID: userMsg.id,
              sessionID: input.sessionID,
            },
            {
              id: Identifier.ascending("part"),
              messageID: userMsg.id,
              sessionID: input.sessionID,
              type: "text",
              synthetic: true,
              text:
                "Use the above message and context to generate a prompt and call the task tool with subagent: " +
                part.name,
            },
          ]
        }

        return [
          {
            id: Identifier.ascending("part"),
            ...part,
            messageID: userMsg.id,
            sessionID: input.sessionID,
          },
        ]
      }),
    ).then((x) => x.flat())
    await Plugin.trigger(
      "chat.message",
      {},
      {
        message: userMsg,
        parts: userParts,
      },
    )
    await updateMessage(userMsg)
    for (const part of userParts) {
      await updatePart(part)
    }

    // mark session as updated
    // used for session list sorting (indicates when session was most recently interacted with)
    await update(input.sessionID, (_draft) => {})

    if (isLocked(input.sessionID)) {
      return new Promise((resolve) => {
        const queue = state().queued.get(input.sessionID) ?? []
        queue.push({
          input: input,
          message: userMsg,
          parts: userParts,
          processed: false,
          callback: resolve,
        })
        state().queued.set(input.sessionID, queue)
      })
    }

    const agent = await Agent.get(inputAgent)
    const model = await (async () => {
      if (input.model) {
        return input.model
      }
      if (agent.model) {
        return agent.model
      }
      return Provider.defaultModel()
    })().then((x) => Provider.getModel(x.providerID, x.modelID))
    let msgs = await messages(input.sessionID)

    const previous = msgs.filter((x) => x.info.role === "assistant").at(-1)?.info as MessageV2.Assistant
    const outputLimit = Math.min(model.info.limit.output, OUTPUT_TOKEN_MAX) || OUTPUT_TOKEN_MAX

    // auto summarize if too long
    if (previous && previous.tokens) {
      const tokens =
        previous.tokens.input + previous.tokens.cache.read + previous.tokens.cache.write + previous.tokens.output
      if (model.info.limit.context && tokens > Math.max((model.info.limit.context - outputLimit) * 0.9, 0)) {
        state().autoCompacting.set(input.sessionID, true)

        await summarize({
          sessionID: input.sessionID,
          providerID: model.providerID,
          modelID: model.info.id,
        })
        return prompt(input)
      }
    }
    using abort = lock(input.sessionID)

    const lastSummary = msgs.findLast((msg) => msg.info.role === "assistant" && msg.info.summary === true)
    if (lastSummary) msgs = msgs.filter((msg) => msg.info.id >= lastSummary.info.id)
    const numRealUserMsgs = msgs.filter(
      (m) => m.info.role === "user" && !m.parts.every((p) => "synthetic" in p && p.synthetic),
    ).length
    if (numRealUserMsgs === 1 && !session.parentID && isDefaultTitle(session.title)) {
      const small = (await Provider.getSmallModel(model.providerID)) ?? model
      const options = {
        ...ProviderTransform.options(small.providerID, small.modelID, input.sessionID),
        ...small.info.options,
      }
      if (small.providerID === "openai") {
        options["reasoningEffort"] = "minimal"
      }
      if (small.providerID === "google") {
        options["thinkingConfig"] = {
          thinkingBudget: 0,
        }
      }
      generateText({
        maxOutputTokens: small.info.reasoning ? 1500 : 20,
        providerOptions: {
          [model.providerID]: options,
        },
        messages: [
          ...SystemPrompt.title(model.providerID).map(
            (x): ModelMessage => ({
              role: "system",
              content: x,
            }),
          ),
          ...MessageV2.toModelMessage([
            {
              info: {
                id: Identifier.ascending("message"),
                role: "user",
                sessionID: input.sessionID,
                time: {
                  created: Date.now(),
                },
              },
              parts: userParts,
            },
          ]),
        ],
        model: small.language,
      })
        .then((result) => {
          if (result.text)
            return Session.update(input.sessionID, (draft) => {
              const cleaned = result.text.replace(/<think>[\s\S]*?<\/think>\s*/g, "")
              const title = cleaned.length > 100 ? cleaned.substring(0, 97) + "..." : cleaned
              draft.title = title.trim()
            })
        })
        .catch((error) => {
          log.error("failed to generate title", { error, model: small.info.id })
        })
    }

    if (agent.name === "plan") {
      msgs.at(-1)?.parts.push({
        id: Identifier.ascending("part"),
        messageID: userMsg.id,
        sessionID: input.sessionID,
        type: "text",
        text: PROMPT_PLAN,
        synthetic: true,
      })
    }

    const lastAssistantMsg = msgs.filter((x) => x.info.role === "assistant").at(-1)?.info as MessageV2.Assistant
    if (lastAssistantMsg?.mode === "plan" && agent.name === "build") {
      msgs.at(-1)?.parts.push({
        id: Identifier.ascending("part"),
        messageID: userMsg.id,
        sessionID: input.sessionID,
        type: "text",
        text: BUILD_SWITCH,
        synthetic: true,
      })
    }
    let system = SystemPrompt.header(model.providerID)
    system.push(
      ...(() => {
        if (input.system) return [input.system]
        if (agent.prompt) return [agent.prompt]
        return SystemPrompt.provider(model.modelID)
      })(),
    )
    system.push(...(await SystemPrompt.environment()))
    system.push(...(await SystemPrompt.custom()))
    // max 2 system prompt messages for caching purposes
    const [first, ...rest] = system
    system = [first, rest.join("\n")]

    const assistantMsg: MessageV2.Info = {
      id: Identifier.ascending("message"),
      role: "assistant",
      system,
      mode: inputAgent,
      path: {
        cwd: Instance.directory,
        root: Instance.worktree,
      },
      cost: 0,
      tokens: {
        input: 0,
        output: 0,
        reasoning: 0,
        cache: { read: 0, write: 0 },
      },
      modelID: model.modelID,
      providerID: model.providerID,
      time: {
        created: Date.now(),
      },
      sessionID: input.sessionID,
    }
    await updateMessage(assistantMsg)
    await using _ = defer(async () => {
      if (assistantMsg.time.completed) return
      await Storage.remove(["session", "message", input.sessionID, assistantMsg.id])
      await Bus.publish(MessageV2.Event.Removed, { sessionID: input.sessionID, messageID: assistantMsg.id })
    })
    const tools: Record<string, AITool> = {}

    const processor = createProcessor(assistantMsg, model.info)

    const enabledTools = pipe(
      agent.tools,
      mergeDeep(await ToolRegistry.enabled(model.providerID, model.modelID, agent)),
      mergeDeep(input.tools ?? {}),
    )
    for (const item of await ToolRegistry.tools(model.providerID, model.modelID)) {
      if (Wildcard.all(item.id, enabledTools) === false) continue
      tools[item.id] = tool({
        id: item.id as any,
        description: item.description,
        inputSchema: item.parameters as ZodSchema,
        async execute(args, options) {
          await Plugin.trigger(
            "tool.execute.before",
            {
              tool: item.id,
              sessionID: input.sessionID,
              callID: options.toolCallId,
            },
            {
              args,
            },
          )
          const result = await item.execute(args, {
            sessionID: input.sessionID,
            abort: options.abortSignal!,
            messageID: assistantMsg.id,
            callID: options.toolCallId,
            agent: agent.name,
            metadata: async (val) => {
              const match = processor.partFromToolCall(options.toolCallId)
              if (match && match.state.status === "running") {
                await updatePart({
                  ...match,
                  state: {
                    title: val.title,
                    metadata: val.metadata,
                    status: "running",
                    input: args,
                    time: {
                      start: Date.now(),
                    },
                  },
                })
              }
            },
          })
          await Plugin.trigger(
            "tool.execute.after",
            {
              tool: item.id,
              sessionID: input.sessionID,
              callID: options.toolCallId,
            },
            result,
          )
          return result
        },
        toModelOutput(result) {
          return {
            type: "text",
            value: result.output,
          }
        },
      })
    }

    for (const [key, item] of Object.entries(await MCP.tools())) {
      if (Wildcard.all(key, enabledTools) === false) continue
      const execute = item.execute
      if (!execute) continue
      item.execute = async (args, opts) => {
        await Plugin.trigger(
          "tool.execute.before",
          {
            tool: key,
            sessionID: input.sessionID,
            callID: opts.toolCallId,
          },
          {
            args,
          },
        )
        const result = await execute(args, opts)
        const output = result.content
          .filter((x: any) => x.type === "text")
          .map((x: any) => x.text)
          .join("\n\n")
        await Plugin.trigger(
          "tool.execute.after",
          {
            tool: key,
            sessionID: input.sessionID,
            callID: opts.toolCallId,
          },
          result,
        )

        return {
          output,
        }
      }
      item.toModelOutput = (result) => {
        return {
          type: "text",
          value: result.output,
        }
      }
      tools[key] = item
    }

    const params = await Plugin.trigger(
      "chat.params",
      {
        model: model.info,
        provider: await Provider.getProvider(model.providerID),
        message: userMsg,
      },
      {
        temperature: model.info.temperature
          ? (agent.temperature ?? ProviderTransform.temperature(model.providerID, model.modelID))
          : undefined,
        topP: agent.topP ?? ProviderTransform.topP(model.providerID, model.modelID),
        options: {
          ...ProviderTransform.options(model.providerID, model.modelID, input.sessionID),
          ...model.info.options,
          ...agent.options,
        },
      },
    )
    const stream = streamText({
      onError(e) {
        log.error("streamText error", {
          error: e,
        })
      },
      async prepareStep({ messages }) {
        const queue = (state().queued.get(input.sessionID) ?? []).filter((x) => !x.processed)
        if (queue.length) {
          for (const item of queue) {
            if (item.processed) continue
            messages.push(
              ...MessageV2.toModelMessage([
                {
                  info: item.message,
                  parts: item.parts,
                },
              ]),
            )
            item.processed = true
          }
          assistantMsg.time.completed = Date.now()
          await updateMessage(assistantMsg)
          Object.assign(assistantMsg, {
            id: Identifier.ascending("message"),
            role: "assistant",
            system,
            path: {
              cwd: Instance.directory,
              root: Instance.worktree,
            },
            cost: 0,
            tokens: {
              input: 0,
              output: 0,
              reasoning: 0,
              cache: { read: 0, write: 0 },
            },
            modelID: model.modelID,
            providerID: model.providerID,
            mode: inputAgent,
            time: {
              created: Date.now(),
            },
            sessionID: input.sessionID,
          })
          await updateMessage(assistantMsg)
        }
        return {
          messages,
        }
      },
      async experimental_repairToolCall(input) {
        return {
          ...input.toolCall,
          input: JSON.stringify({
            tool: input.toolCall.toolName,
            error: input.error.message,
          }),
          toolName: "invalid",
        }
      },
      headers:
        model.providerID === "opencode"
          ? {
              "x-opencode-session": input.sessionID,
              "x-opencode-request": userMsg.id,
            }
          : undefined,
      maxRetries: 3,
      activeTools: Object.keys(tools).filter((x) => x !== "invalid"),
      maxOutputTokens: ProviderTransform.maxOutputTokens(model.providerID, outputLimit, params.options),
      abortSignal: abort.signal,
      stopWhen: async ({ steps }) => {
        if (steps.length >= 1000) {
          return true
        }

        // Check if processor flagged that we should stop
        if (processor.getShouldStop()) {
          return true
        }

        return false
      },
      providerOptions: {
        [model.providerID]: params.options,
      },
      temperature: params.temperature,
      topP: params.topP,
      messages: [
        ...system.map(
          (x): ModelMessage => ({
            role: "system",
            content: x,
          }),
        ),
        ...MessageV2.toModelMessage(msgs.filter((m) => !(m.info.role === "assistant" && m.info.error))),
      ],
      tools: model.info.tool_call === false ? undefined : tools,
      model: wrapLanguageModel({
        model: model.language,
        middleware: [
          {
            async transformParams(args) {
              if (args.type === "stream") {
                // @ts-expect-error
                args.params.prompt = ProviderTransform.message(args.params.prompt, model.providerID, model.modelID)
              }
              return args.params
            },
          },
        ],
      }),
    })
    const result = await processor.process(stream)
    const queued = state().queued.get(input.sessionID) ?? []
    const unprocessed = queued.find((x) => !x.processed)
    if (unprocessed) {
      unprocessed.processed = true
      return prompt(unprocessed.input)
    }
    for (const item of queued) {
      item.callback(result)
    }
    state().queued.delete(input.sessionID)
    return result
  }

  export const ShellInput = z.object({
    sessionID: Identifier.schema("session"),
    agent: z.string(),
    command: z.string(),
  })
  export type ShellInput = z.infer<typeof ShellInput>
  export async function shell(input: ShellInput) {
    using abort = lock(input.sessionID)
    const session = await get(input.sessionID)
    if (session.revert) {
      cleanupRevert(session)
    }
    const userMsg: MessageV2.User = {
      id: Identifier.ascending("message"),
      sessionID: input.sessionID,
      time: {
        created: Date.now(),
      },
      role: "user",
    }
    await updateMessage(userMsg)
    const userPart: MessageV2.Part = {
      type: "text",
      id: Identifier.ascending("part"),
      messageID: userMsg.id,
      sessionID: input.sessionID,
      text: "The following tool was executed by the user",
      synthetic: true,
    }
    await updatePart(userPart)

    const msg: MessageV2.Assistant = {
      id: Identifier.ascending("message"),
      sessionID: input.sessionID,
      system: [],
      mode: input.agent,
      cost: 0,
      path: {
        cwd: Instance.directory,
        root: Instance.worktree,
      },
      time: {
        created: Date.now(),
      },
      role: "assistant",
      tokens: {
        input: 0,
        output: 0,
        reasoning: 0,
        cache: { read: 0, write: 0 },
      },
      modelID: "",
      providerID: "",
    }
    await updateMessage(msg)
    const part: MessageV2.Part = {
      type: "tool",
      id: Identifier.ascending("part"),
      messageID: msg.id,
      sessionID: input.sessionID,
      tool: "bash",
      callID: ulid(),
      state: {
        status: "running",
        time: {
          start: Date.now(),
        },
        input: {
          command: input.command,
        },
      },
    }
    await updatePart(part)
    const shell = process.env["SHELL"] ?? "bash"
    const shellName = path.basename(shell)

    const scripts: Record<string, string> = {
      nu: input.command,
      fish: `eval "${input.command}"`,
    }

    const script =
      scripts[shellName] ??
      `[[ -f ~/.zshenv ]] && source ~/.zshenv >/dev/null 2>&1 || true
       [[ -f "\${ZDOTDIR:-$HOME}/.zshrc" ]] && source "\${ZDOTDIR:-$HOME}/.zshrc" >/dev/null 2>&1 || true
       [[ -f ~/.bashrc ]] && source ~/.bashrc >/dev/null 2>&1 || true
       eval "${input.command}"`

    const isFishOrNu = shellName === "fish" || shellName === "nu"
    const args = isFishOrNu ? ["-c", script] : ["-c", "-l", script]

    const proc = spawn(shell, args, {
      cwd: Instance.directory,
      signal: abort.signal,
      detached: true,
      stdio: ["ignore", "pipe", "pipe"],
      env: {
        ...process.env,
        TERM: "dumb",
      },
    })

    abort.signal.addEventListener("abort", () => {
      if (!proc.pid) return
      process.kill(-proc.pid)
    })

    let output = ""

    proc.stdout?.on("data", (chunk) => {
      output += chunk.toString()
      if (part.state.status === "running") {
        part.state.metadata = {
          output: output,
          description: "",
        }
        updatePart(part)
      }
    })

    proc.stderr?.on("data", (chunk) => {
      output += chunk.toString()
      if (part.state.status === "running") {
        part.state.metadata = {
          output: output,
          description: "",
        }
        updatePart(part)
      }
    })

    await new Promise<void>((resolve) => {
      proc.on("close", () => {
        resolve()
      })
    })
    msg.time.completed = Date.now()
    await updateMessage(msg)
    if (part.state.status === "running") {
      part.state = {
        status: "completed",
        time: {
          ...part.state.time,
          end: Date.now(),
        },
        input: part.state.input,
        title: "",
        metadata: {
          output,
          description: "",
        },
        output,
      }
      await updatePart(part)
    }
    return { info: msg, parts: [part] }
  }

  export const CommandInput = z.object({
    messageID: Identifier.schema("message").optional(),
    sessionID: Identifier.schema("session"),
    agent: z.string().optional(),
    model: z.string().optional(),
    arguments: z.string(),
    command: z.string(),
  })
  export type CommandInput = z.infer<typeof CommandInput>
  const bashRegex = /!`([^`]+)`/g
  /**
   * Regular expression to match @ file references in text
   * Matches @ followed by file paths, excluding commas, periods at end of sentences, and backticks
   * Does not match when preceded by word characters or backticks (to avoid email addresses and quoted references)
   */
  export const fileRegex = /(?<![\w`])@(\.?[^\s`,.]*(?:\.[^\s`,.]+)*)/g

  export async function command(input: CommandInput) {
    log.info("command", input)
    const command = await Command.get(input.command)
    const agent = command.agent ?? input.agent ?? "build"

    let template = command.template.replace("$ARGUMENTS", input.arguments)

    const bash = Array.from(template.matchAll(bashRegex))
    if (bash.length > 0) {
      const results = await Promise.all(
        bash.map(async ([, cmd]) => {
          try {
            return await $`${{ raw: cmd }}`.nothrow().text()
          } catch (error) {
            return `Error executing command: ${error instanceof Error ? error.message : String(error)}`
          }
        }),
      )
      let index = 0
      template = template.replace(bashRegex, () => results[index++])
    }

    const parts = [
      {
        type: "text",
        text: template,
      },
    ] as ChatInput["parts"]

    const matches = Array.from(template.matchAll(fileRegex))
    await Promise.all(
      matches.map(async (match) => {
        const name = match[1]
        const filepath = name.startsWith("~/")
          ? path.join(os.homedir(), name.slice(2))
          : path.resolve(Instance.worktree, name)

        const stats = await fs.stat(filepath).catch(() => undefined)
        if (!stats) {
          const agent = await Agent.get(name)
          if (agent) {
            parts.push({
              type: "agent",
              name: agent.name,
            })
          }
          return
        }

        if (stats.isDirectory()) return

        parts.push({
          type: "file",
          url: `file://${filepath}`,
          filename: name,
          mime: "text/plain",
        })
      }),
    )

    const model = await (async () => {
      if (command.model) {
        return Provider.parseModel(command.model)
      }
      if (command.agent) {
        const agent = await Agent.get(command.agent)
        if (agent.model) {
          return agent.model
        }
      }
      if (input.model) {
        return Provider.parseModel(input.model)
      }
      return undefined
    })()

    return prompt({
      sessionID: input.sessionID,
      messageID: input.messageID,
      model,
      agent,
      parts,
    })
  }

  function createProcessor(assistantMsg: MessageV2.Assistant, model: ModelsDev.Model) {
    const toolcalls: Record<string, MessageV2.ToolPart> = {}
    let snapshot: string | undefined
    let shouldStop = false
    return {
      partFromToolCall(toolCallID: string) {
        return toolcalls[toolCallID]
      },
      getShouldStop() {
        return shouldStop
      },
      async process(stream: StreamTextResult<Record<string, AITool>, never>) {
        try {
          let currentText: MessageV2.TextPart | undefined
          let reasoningMap: Record<string, MessageV2.ReasoningPart> = {}

          for await (const value of stream.fullStream) {
            log.info("part", {
              type: value.type,
            })
            switch (value.type) {
              case "start":
                break

              case "reasoning-start":
                if (value.id in reasoningMap) {
                  continue
                }
                reasoningMap[value.id] = {
                  id: Identifier.ascending("part"),
                  messageID: assistantMsg.id,
                  sessionID: assistantMsg.sessionID,
                  type: "reasoning",
                  text: "",
                  time: {
                    start: Date.now(),
                  },
                }
                break

              case "reasoning-delta":
                if (value.id in reasoningMap) {
                  const part = reasoningMap[value.id]
                  part.text += value.text
                  if (part.text) await updatePart(part)
                }
                break

              case "reasoning-end":
                if (value.id in reasoningMap) {
                  const part = reasoningMap[value.id]
                  part.text = part.text.trimEnd()
                  part.metadata = value.providerMetadata
                  part.time = {
                    ...part.time,
                    end: Date.now(),
                  }
                  await updatePart(part)
                  delete reasoningMap[value.id]
                }
                break

              case "tool-input-start":
                const part = await updatePart({
                  id: toolcalls[value.id]?.id ?? Identifier.ascending("part"),
                  messageID: assistantMsg.id,
                  sessionID: assistantMsg.sessionID,
                  type: "tool",
                  tool: value.toolName,
                  callID: value.id,
                  state: {
                    status: "pending",
                  },
                })
                toolcalls[value.id] = part as MessageV2.ToolPart
                break

              case "tool-input-delta":
                break

              case "tool-input-end":
                break

              case "tool-call": {
                const match = toolcalls[value.toolCallId]
                if (match) {
                  const part = await updatePart({
                    ...match,
                    tool: value.toolName,
                    state: {
                      status: "running",
                      input: value.input,
                      time: {
                        start: Date.now(),
                      },
                    },
                  })
                  toolcalls[value.toolCallId] = part as MessageV2.ToolPart
                }
                break
              }
              case "tool-result": {
                const match = toolcalls[value.toolCallId]
                if (match && match.state.status === "running") {
                  await updatePart({
                    ...match,
                    state: {
                      status: "completed",
                      input: value.input,
                      output: value.output.output,
                      metadata: value.output.metadata,
                      title: value.output.title,
                      time: {
                        start: match.state.time.start,
                        end: Date.now(),
                      },
                    },
                  })
                  delete toolcalls[value.toolCallId]
                }
                break
              }

              case "tool-error": {
                const match = toolcalls[value.toolCallId]
                if (match && match.state.status === "running") {
                  if (value.error instanceof Permission.RejectedError) {
                    shouldStop = true
                  }
                  await updatePart({
                    ...match,
                    state: {
                      status: "error",
                      input: value.input,
                      error: (value.error as any).toString(),
                      metadata: value.error instanceof Permission.RejectedError ? value.error.metadata : undefined,
                      time: {
                        start: match.state.time.start,
                        end: Date.now(),
                      },
                    },
                  })
                  delete toolcalls[value.toolCallId]
                }
                break
              }
              case "error":
                throw value.error

              case "start-step":
                await updatePart({
                  id: Identifier.ascending("part"),
                  messageID: assistantMsg.id,
                  sessionID: assistantMsg.sessionID,
                  type: "step-start",
                })
                snapshot = await Snapshot.track()
                break

              case "finish-step":
                const usage = getUsage(model, value.usage, value.providerMetadata)
                assistantMsg.cost += usage.cost
                assistantMsg.tokens = usage.tokens
                await updatePart({
                  id: Identifier.ascending("part"),
                  messageID: assistantMsg.id,
                  sessionID: assistantMsg.sessionID,
                  type: "step-finish",
                  tokens: usage.tokens,
                  cost: usage.cost,
                })
                await updateMessage(assistantMsg)
                if (snapshot) {
                  const patch = await Snapshot.patch(snapshot)
                  if (patch.files.length) {
                    await updatePart({
                      id: Identifier.ascending("part"),
                      messageID: assistantMsg.id,
                      sessionID: assistantMsg.sessionID,
                      type: "patch",
                      hash: patch.hash,
                      files: patch.files,
                    })
                  }
                  snapshot = undefined
                }
                break

              case "text-start":
                currentText = {
                  id: Identifier.ascending("part"),
                  messageID: assistantMsg.id,
                  sessionID: assistantMsg.sessionID,
                  type: "text",
                  text: "",
                  time: {
                    start: Date.now(),
                  },
                }
                break

              case "text-delta":
                if (currentText) {
                  currentText.text += value.text
                  if (currentText.text) await updatePart(currentText)
                }
                break

              case "text-end":
                if (currentText) {
                  currentText.text = currentText.text.trimEnd()
                  currentText.time = {
                    start: Date.now(),
                    end: Date.now(),
                  }
                  await updatePart(currentText)
                }
                currentText = undefined
                break

              case "finish":
                assistantMsg.time.completed = Date.now()
                await updateMessage(assistantMsg)
                break

              default:
                log.info("unhandled", {
                  ...value,
                })
                continue
            }
          }
        } catch (e) {
          log.error("", {
            error: e,
          })
          switch (true) {
            case e instanceof DOMException && e.name === "AbortError":
              assistantMsg.error = new MessageV2.AbortedError(
                { message: e.message },
                {
                  cause: e,
                },
              ).toObject()
              break
            case MessageV2.OutputLengthError.isInstance(e):
              assistantMsg.error = e
              break
            case LoadAPIKeyError.isInstance(e):
              assistantMsg.error = new MessageV2.AuthError(
                {
                  providerID: model.id,
                  message: e.message,
                },
                { cause: e },
              ).toObject()
              break
            case e instanceof Error:
              assistantMsg.error = new NamedError.Unknown({ message: e.toString() }, { cause: e }).toObject()
              break
            default:
              assistantMsg.error = new NamedError.Unknown({ message: JSON.stringify(e) }, { cause: e })
          }
          Bus.publish(Event.Error, {
            sessionID: assistantMsg.sessionID,
            error: assistantMsg.error,
          })
        }
        const p = await getParts(assistantMsg.id)
        for (const part of p) {
          if (part.type === "tool" && part.state.status !== "completed" && part.state.status !== "error") {
            updatePart({
              ...part,
              state: {
                status: "error",
                error: "Tool execution aborted",
                time: {
                  start: Date.now(),
                  end: Date.now(),
                },
                input: {},
              },
            })
          }
        }
        assistantMsg.time.completed = Date.now()
        await updateMessage(assistantMsg)
        return { info: assistantMsg, parts: p }
      },
    }
  }

  export const RevertInput = z.object({
    sessionID: Identifier.schema("session"),
    messageID: Identifier.schema("message"),
    partID: Identifier.schema("part").optional(),
  })
  export type RevertInput = z.infer<typeof RevertInput>

  export async function revert(input: RevertInput) {
    const all = await messages(input.sessionID)
    let lastUser: MessageV2.User | undefined
    const session = await get(input.sessionID)

    let revert: Info["revert"]
    const patches: Snapshot.Patch[] = []
    for (const msg of all) {
      if (msg.info.role === "user") lastUser = msg.info
      const remaining = []
      for (const part of msg.parts) {
        if (revert) {
          if (part.type === "patch") {
            patches.push(part)
          }
          continue
        }

        if (!revert) {
          if ((msg.info.id === input.messageID && !input.partID) || part.id === input.partID) {
            // if no useful parts left in message, same as reverting whole message
            const partID = remaining.some((item) => ["text", "tool"].includes(item.type)) ? input.partID : undefined
            revert = {
              messageID: !partID && lastUser ? lastUser.id : msg.info.id,
              partID,
            }
          }
          remaining.push(part)
        }
      }
    }

    if (revert) {
      const session = await get(input.sessionID)
      revert.snapshot = session.revert?.snapshot ?? (await Snapshot.track())
      await Snapshot.revert(patches)
      if (revert.snapshot) revert.diff = await Snapshot.diff(revert.snapshot)
      return update(input.sessionID, (draft) => {
        draft.revert = revert
      })
    }
    return session
  }

  export async function unrevert(input: { sessionID: string }) {
    log.info("unreverting", input)
    const session = await get(input.sessionID)
    if (!session.revert) return session
    if (session.revert.snapshot) await Snapshot.restore(session.revert.snapshot)
    const next = await update(input.sessionID, (draft) => {
      draft.revert = undefined
    })
    return next
  }

  export async function summarize(input: { sessionID: string; providerID: string; modelID: string }) {
    using abort = lock(input.sessionID)
    const msgs = await messages(input.sessionID)
    const lastSummary = msgs.findLast((msg) => msg.info.role === "assistant" && msg.info.summary === true)
    const filtered = msgs.filter((msg) => !lastSummary || msg.info.id >= lastSummary.info.id)
    const model = await Provider.getModel(input.providerID, input.modelID)
    const system = [
      ...SystemPrompt.summarize(model.providerID),
      ...(await SystemPrompt.environment()),
      ...(await SystemPrompt.custom()),
    ]

    const next: MessageV2.Info = {
      id: Identifier.ascending("message"),
      role: "assistant",
      sessionID: input.sessionID,
      system,
      mode: "build",
      path: {
        cwd: Instance.directory,
        root: Instance.worktree,
      },
      summary: true,
      cost: 0,
      modelID: input.modelID,
      providerID: model.providerID,
      tokens: {
        input: 0,
        output: 0,
        reasoning: 0,
        cache: { read: 0, write: 0 },
      },
      time: {
        created: Date.now(),
      },
    }
    await updateMessage(next)

    const processor = createProcessor(next, model.info)
    const stream = streamText({
      maxRetries: 10,
      abortSignal: abort.signal,
      model: model.language,
      messages: [
        ...system.map(
          (x): ModelMessage => ({
            role: "system",
            content: x,
          }),
        ),
        ...MessageV2.toModelMessage(filtered),
        {
          role: "user",
          content: [
            {
              type: "text",
              text: "Provide a detailed but concise summary of our conversation above. Focus on information that would be helpful for continuing the conversation, including what we did, what we're doing, which files we're working on, and what we're going to do next.",
            },
          ],
        },
      ],
    })

    const result = await processor.process(stream)
    return result
  }

  function isLocked(sessionID: string) {
    return state().pending.has(sessionID)
  }

  function lock(sessionID: string) {
    log.info("locking", { sessionID })
    if (state().pending.has(sessionID)) throw new BusyError(sessionID)
    const controller = new AbortController()
    state().pending.set(sessionID, controller)
    return {
      signal: controller.signal,
      async [Symbol.dispose]() {
        log.info("unlocking", { sessionID })
        state().pending.delete(sessionID)

        const isAutoCompacting = state().autoCompacting.get(sessionID) ?? false
        if (isAutoCompacting) {
          state().autoCompacting.delete(sessionID)
          return
        }

        const session = await get(sessionID)
        if (session.parentID) return

        Bus.publish(Event.Idle, {
          sessionID,
        })
      },
    }
  }

  function getUsage(model: ModelsDev.Model, usage: LanguageModelUsage, metadata?: ProviderMetadata) {
    const tokens = {
      input: usage.inputTokens ?? 0,
      output: usage.outputTokens ?? 0,
      reasoning: usage?.reasoningTokens ?? 0,
      cache: {
        write: (metadata?.["anthropic"]?.["cacheCreationInputTokens"] ??
          // @ts-expect-error
          metadata?.["bedrock"]?.["usage"]?.["cacheWriteInputTokens"] ??
          0) as number,
        read: usage.cachedInputTokens ?? 0,
      },
    }
    return {
      cost: new Decimal(0)
        .add(new Decimal(tokens.input).mul(model.cost?.input ?? 0).div(1_000_000))
        .add(new Decimal(tokens.output).mul(model.cost?.output ?? 0).div(1_000_000))
        .add(new Decimal(tokens.cache.read).mul(model.cost?.cache_read ?? 0).div(1_000_000))
        .add(new Decimal(tokens.cache.write).mul(model.cost?.cache_write ?? 0).div(1_000_000))
        .toNumber(),
      tokens,
    }
  }

  export class BusyError extends Error {
    constructor(public readonly sessionID: string) {
      super(`Session ${sessionID} is busy`)
    }
  }

  export async function initialize(input: {
    sessionID: string
    modelID: string
    providerID: string
    messageID: string
  }) {
    await Session.prompt({
      sessionID: input.sessionID,
      messageID: input.messageID,
      model: {
        providerID: input.providerID,
        modelID: input.modelID,
      },
      parts: [
        {
          id: Identifier.ascending("part"),
          type: "text",
          text: PROMPT_INITIALIZE.replace("${path}", Instance.worktree),
        },
      ],
    })
    await Project.setInitialized(Instance.project.id)
  }
}
