wip(app): line selection

1 files changed, 281 insertions, 4 deletions

diff --git a/packages/ui/src/components/diff.tsx b/packages/ui/src/components/diff.tsx
index 46b6709b6..20dd5c440 100644
--- a/packages/ui/src/components/diff.tsx
+++ b/packages/ui/src/components/diff.tsx
@@ -1,16 +1,70 @@
 import { checksum } from "@opencode-ai/util/encode"
-import { FileDiff } from "@pierre/diffs"
+import { FileDiff, type SelectedLineRange } from "@pierre/diffs"
 import { createMediaQuery } from "@solid-primitives/media"
-import { createEffect, createMemo, onCleanup, splitProps } from "solid-js"
+import { createEffect, createMemo, createSignal, onCleanup, splitProps } from "solid-js"
 import { createDefaultOptions, type DiffProps, styleVariables } from "../pierre"
 import { getWorkerPool } from "../pierre/worker"
 
+type SelectionSide = "additions" | "deletions"
+
+function findElement(node: Node | null): HTMLElement | undefined {
+  if (!node) return
+  if (node instanceof HTMLElement) return node
+  return node.parentElement ?? undefined
+}
+
+function findLineNumber(node: Node | null): number | undefined {
+  const element = findElement(node)
+  if (!element) return
+
+  const line = element.closest("[data-line], [data-alt-line]")
+  if (!(line instanceof HTMLElement)) return
+
+  const value = (() => {
+    const primary = parseInt(line.dataset.line ?? "", 10)
+    if (!Number.isNaN(primary)) return primary
+
+    const alt = parseInt(line.dataset.altLine ?? "", 10)
+    if (!Number.isNaN(alt)) return alt
+  })()
+
+  return value
+}
+
+function findSide(node: Node | null): SelectionSide | undefined {
+  const element = findElement(node)
+  if (!element) return
+
+  const code = element.closest("[data-code]")
+  if (!(code instanceof HTMLElement)) return
+
+  if (code.hasAttribute("data-deletions")) return "deletions"
+  return "additions"
+}
+
 export function Diff<T>(props: DiffProps<T>) {
   let container!: HTMLDivElement
   let observer: MutationObserver | undefined
   let renderToken = 0
-
-  const [local, others] = splitProps(props, ["before", "after", "class", "classList", "annotations", "onRendered"])
+  let selectionFrame: number | undefined
+  let dragFrame: number | undefined
+  let dragStart: number | undefined
+  let dragEnd: number | undefined
+  let dragSide: SelectionSide | undefined
+  let dragEndSide: SelectionSide | undefined
+  let dragMoved = false
+  let lastSelection: SelectedLineRange | null = null
+  let pendingSelectionEnd = false
+
+  const [local, others] = splitProps(props, [
+    "before",
+    "after",
+    "class",
+    "classList",
+    "annotations",
+    "selectedLines",
+    "onRendered",
+  ])
 
   const mobile = createMediaQuery("(max-width: 640px)")
 
@@ -27,6 +81,7 @@ export function Diff<T>(props: DiffProps<T>) {
   })
 
   let instance: FileDiff<T> | undefined
+  const [current, setCurrent] = createSignal<FileDiff<T> | undefined>(undefined)
 
   const getRoot = () => {
     const host = container.querySelector("diffs-container")
@@ -117,6 +172,186 @@ export function Diff<T>(props: DiffProps<T>) {
     observer.observe(container, { childList: true, subtree: true })
   }
 
+  const setSelectedLines = (range: SelectedLineRange | null) => {
+    const active = current()
+    if (!active) return
+    lastSelection = range
+    active.setSelectedLines(range)
+  }
+
+  const updateSelection = () => {
+    const root = getRoot()
+    if (!root) return
+
+    const selection =
+      (root as unknown as { getSelection?: () => Selection | null }).getSelection?.() ?? window.getSelection()
+    if (!selection || selection.isCollapsed) return
+
+    const domRange =
+      (
+        selection as unknown as {
+          getComposedRanges?: (options?: { shadowRoots?: ShadowRoot[] }) => Range[]
+        }
+      ).getComposedRanges?.({ shadowRoots: [root] })?.[0] ??
+      (selection.rangeCount > 0 ? selection.getRangeAt(0) : undefined)
+
+    const startNode = domRange?.startContainer ?? selection.anchorNode
+    const endNode = domRange?.endContainer ?? selection.focusNode
+    if (!startNode || !endNode) return
+
+    if (!root.contains(startNode) || !root.contains(endNode)) return
+
+    const start = findLineNumber(startNode)
+    const end = findLineNumber(endNode)
+    if (start === undefined || end === undefined) return
+
+    const startSide = findSide(startNode)
+    const endSide = findSide(endNode)
+    const side = startSide ?? endSide
+
+    const selected: SelectedLineRange = {
+      start,
+      end,
+    }
+
+    if (side) selected.side = side
+    if (endSide && side && endSide !== side) selected.endSide = endSide
+
+    setSelectedLines(selected)
+  }
+
+  const scheduleSelectionUpdate = () => {
+    if (selectionFrame !== undefined) return
+
+    selectionFrame = requestAnimationFrame(() => {
+      selectionFrame = undefined
+      updateSelection()
+
+      if (!pendingSelectionEnd) return
+      pendingSelectionEnd = false
+      props.onLineSelectionEnd?.(lastSelection)
+    })
+  }
+
+  const updateDragSelection = () => {
+    if (dragStart === undefined || dragEnd === undefined) return
+
+    const selected: SelectedLineRange = {
+      start: dragStart,
+      end: dragEnd,
+    }
+
+    if (dragSide) selected.side = dragSide
+    if (dragEndSide && dragSide && dragEndSide !== dragSide) selected.endSide = dragEndSide
+
+    setSelectedLines(selected)
+  }
+
+  const scheduleDragUpdate = () => {
+    if (dragFrame !== undefined) return
+
+    dragFrame = requestAnimationFrame(() => {
+      dragFrame = undefined
+      updateDragSelection()
+    })
+  }
+
+  const lineFromMouseEvent = (event: MouseEvent) => {
+    const path = event.composedPath()
+
+    let numberColumn = false
+    let line: number | undefined
+    let side: SelectionSide | undefined
+
+    for (const item of path) {
+      if (!(item instanceof HTMLElement)) continue
+
+      numberColumn = numberColumn || item.dataset.columnNumber != null
+
+      if (side === undefined && item.dataset.code != null) {
+        side = item.hasAttribute("data-deletions") ? "deletions" : "additions"
+      }
+
+      if (line === undefined) {
+        const primary = item.dataset.line ? parseInt(item.dataset.line, 10) : Number.NaN
+        if (!Number.isNaN(primary)) {
+          line = primary
+        } else {
+          const alt = item.dataset.altLine ? parseInt(item.dataset.altLine, 10) : Number.NaN
+          if (!Number.isNaN(alt)) line = alt
+        }
+      }
+
+      if (numberColumn && line !== undefined && side !== undefined) break
+    }
+
+    return { line, numberColumn, side }
+  }
+
+  const handleMouseDown = (event: MouseEvent) => {
+    if (props.enableLineSelection !== true) return
+    if (event.button !== 0) return
+
+    const { line, numberColumn, side } = lineFromMouseEvent(event)
+    if (numberColumn) return
+    if (line === undefined) return
+
+    dragStart = line
+    dragEnd = line
+    dragSide = side
+    dragEndSide = side
+    dragMoved = false
+  }
+
+  const handleMouseMove = (event: MouseEvent) => {
+    if (props.enableLineSelection !== true) return
+    if (dragStart === undefined) return
+
+    if ((event.buttons & 1) === 0) {
+      dragStart = undefined
+      dragEnd = undefined
+      dragSide = undefined
+      dragEndSide = undefined
+      dragMoved = false
+      return
+    }
+
+    const { line, side } = lineFromMouseEvent(event)
+    if (line === undefined) return
+
+    dragEnd = line
+    dragEndSide = side
+    dragMoved = true
+    scheduleDragUpdate()
+  }
+
+  const handleMouseUp = () => {
+    if (props.enableLineSelection !== true) return
+    if (dragStart === undefined) return
+
+    if (dragMoved) {
+      pendingSelectionEnd = true
+      scheduleDragUpdate()
+      scheduleSelectionUpdate()
+    }
+
+    dragStart = undefined
+    dragEnd = undefined
+    dragSide = undefined
+    dragEndSide = undefined
+    dragMoved = false
+  }
+
+  const handleSelectionChange = () => {
+    if (props.enableLineSelection !== true) return
+    if (dragStart === undefined) return
+
+    const selection = window.getSelection()
+    if (!selection || selection.isCollapsed) return
+
+    scheduleSelectionUpdate()
+  }
+
   createEffect(() => {
     const opts = options()
     const workerPool = getWorkerPool(props.diffStyle)
@@ -126,6 +361,7 @@ export function Diff<T>(props: DiffProps<T>) {
 
     instance?.cleanUp()
     instance = new FileDiff<T>(opts, workerPool)
+    setCurrent(instance)
 
     container.innerHTML = ""
     instance.render({
@@ -146,9 +382,50 @@ export function Diff<T>(props: DiffProps<T>) {
     notifyRendered()
   })
 
+  createEffect(() => {
+    const selected = local.selectedLines ?? null
+    setSelectedLines(selected)
+  })
+
+  createEffect(() => {
+    if (props.enableLineSelection !== true) return
+
+    container.addEventListener("mousedown", handleMouseDown)
+    container.addEventListener("mousemove", handleMouseMove)
+    window.addEventListener("mouseup", handleMouseUp)
+    document.addEventListener("selectionchange", handleSelectionChange)
+
+    onCleanup(() => {
+      container.removeEventListener("mousedown", handleMouseDown)
+      container.removeEventListener("mousemove", handleMouseMove)
+      window.removeEventListener("mouseup", handleMouseUp)
+      document.removeEventListener("selectionchange", handleSelectionChange)
+    })
+  })
+
   onCleanup(() => {
     observer?.disconnect()
+
+    if (selectionFrame !== undefined) {
+      cancelAnimationFrame(selectionFrame)
+      selectionFrame = undefined
+    }
+
+    if (dragFrame !== undefined) {
+      cancelAnimationFrame(dragFrame)
+      dragFrame = undefined
+    }
+
+    dragStart = undefined
+    dragEnd = undefined
+    dragSide = undefined
+    dragEndSide = undefined
+    dragMoved = false
+    lastSelection = null
+    pendingSelectionEnd = false
+
     instance?.cleanUp()
+    setCurrent(undefined)
   })
 
   return <div data-component="diff" style={styleVariables} ref={container} />