import path from "path"
import { fileURLToPath } from "url"

import { Flag } from "@/flag/flag"
import { Global } from "@/global"
import { Filesystem } from "@/util/filesystem"
import { Flock } from "@/util/flock"

import { parsePluginSpecifier, pluginSource } from "./shared"

export namespace PluginMeta {
  type Source = "file" | "npm"

  export type Theme = {
    src: string
    dest: string
    mtime?: number
    size?: number
  }

  export type Entry = {
    id: string
    source: Source
    spec: string
    target: string
    requested?: string
    version?: string
    modified?: number
    first_time: number
    last_time: number
    time_changed: number
    load_count: number
    fingerprint: string
    themes?: Record<string, Theme>
  }

  export type State = "first" | "updated" | "same"

  export type Touch = {
    spec: string
    target: string
    id: string
  }

  type Store = Record<string, Entry>
  type Core = Omit<Entry, "first_time" | "last_time" | "time_changed" | "load_count" | "fingerprint" | "themes">
  type Row = Touch & { core: Core }

  function storePath() {
    return Flag.OPENCODE_PLUGIN_META_FILE ?? path.join(Global.Path.state, "plugin-meta.json")
  }

  function lock(file: string) {
    return `plugin-meta:${file}`
  }

  function fileTarget(spec: string, target: string) {
    if (spec.startsWith("file://")) return fileURLToPath(spec)
    if (target.startsWith("file://")) return fileURLToPath(target)
    return
  }

  async function modifiedAt(file: string) {
    const stat = await Filesystem.statAsync(file)
    if (!stat) return
    const mtime = stat.mtimeMs
    return Math.floor(typeof mtime === "bigint" ? Number(mtime) : mtime)
  }

  function resolvedTarget(target: string) {
    if (target.startsWith("file://")) return fileURLToPath(target)
    return target
  }

  async function npmVersion(target: string) {
    const resolved = resolvedTarget(target)
    const stat = await Filesystem.statAsync(resolved)
    const dir = stat?.isDirectory() ? resolved : path.dirname(resolved)
    return Filesystem.readJson<{ version?: string }>(path.join(dir, "package.json"))
      .then((item) => item.version)
      .catch(() => undefined)
  }

  async function entryCore(item: Touch): Promise<Core> {
    const spec = item.spec
    const target = item.target
    const source = pluginSource(spec)
    if (source === "file") {
      const file = fileTarget(spec, target)
      return {
        id: item.id,
        source,
        spec,
        target,
        modified: file ? await modifiedAt(file) : undefined,
      }
    }

    return {
      id: item.id,
      source,
      spec,
      target,
      requested: parsePluginSpecifier(spec).version,
      version: await npmVersion(target),
    }
  }

  function fingerprint(value: Core) {
    if (value.source === "file") return [value.target, value.modified ?? ""].join("|")
    return [value.target, value.requested ?? "", value.version ?? ""].join("|")
  }

  async function read(file: string): Promise<Store> {
    return Filesystem.readJson<Store>(file).catch(() => ({}) as Store)
  }

  async function row(item: Touch): Promise<Row> {
    return {
      ...item,
      core: await entryCore(item),
    }
  }

  function next(prev: Entry | undefined, core: Core, now: number): { state: State; entry: Entry } {
    const entry: Entry = {
      ...core,
      first_time: prev?.first_time ?? now,
      last_time: now,
      time_changed: prev?.time_changed ?? now,
      load_count: (prev?.load_count ?? 0) + 1,
      fingerprint: fingerprint(core),
      themes: prev?.themes,
    }
    const state: State = !prev ? "first" : prev.fingerprint === entry.fingerprint ? "same" : "updated"
    if (state === "updated") entry.time_changed = now
    return {
      state,
      entry,
    }
  }

  export async function touchMany(items: Touch[]): Promise<Array<{ state: State; entry: Entry }>> {
    if (!items.length) return []
    const file = storePath()
    const rows = await Promise.all(items.map((item) => row(item)))

    return Flock.withLock(lock(file), async () => {
      const store = await read(file)
      const now = Date.now()
      const out: Array<{ state: State; entry: Entry }> = []
      for (const item of rows) {
        const hit = next(store[item.id], item.core, now)
        store[item.id] = hit.entry
        out.push(hit)
      }
      await Filesystem.writeJson(file, store)
      return out
    })
  }

  export async function touch(spec: string, target: string, id: string): Promise<{ state: State; entry: Entry }> {
    return touchMany([{ spec, target, id }]).then((item) => {
      const hit = item[0]
      if (hit) return hit
      throw new Error("Failed to touch plugin metadata.")
    })
  }

  export async function setTheme(id: string, name: string, theme: Theme): Promise<void> {
    const file = storePath()
    await Flock.withLock(lock(file), async () => {
      const store = await read(file)
      const entry = store[id]
      if (!entry) return
      entry.themes = {
        ...(entry.themes ?? {}),
        [name]: theme,
      }
      await Filesystem.writeJson(file, store)
    })
  }

  export async function list(): Promise<Store> {
    const file = storePath()
    return Flock.withLock(lock(file), async () => read(file))
  }
}