Function applySelection

packages/session-ui/src/components/file.tsx:746–787

(range: SelectedLineRange | null)

  const lineFromMouseEvent = (event: MouseEvent): MouseHit => mouseHit(event, parseLine)

  const applySelection = (range: SelectedLineRange | null) => {
    const current = instance
    if (!current) return false

    if (virtual()) {
      current.setSelectedLines(range)
      return true
    }

    const root = viewer.getRoot()
    if (!root) return false

    const total = lineCount()
    if (root.querySelectorAll("[data-line]").length < total) return false

    if (!range) {
      current.setSelectedLines(null)
      return true
    }

    const start = Math.min(range.start, range.end)
    const end = Math.max(range.start, range.end)
    if (start < 1 || end > total) {
      current.setSelectedLines(null)
      return true
    }

    if (!root.querySelector(`[data-line="${start}"]`) || !root.querySelector(`[data-line="${end}"]`)) {
      current.setSelectedLines(null)
      return true
    }

    const normalized = (() => {
      if (range.endSide != null) return { start: range.start, end: range.end }
      if (range.side !== "deletions") return range
      if (root.querySelector("[data-deletions]") != null) return range
      return { start: range.start, end: range.end }
    })()

    current.setSelectedLines(normalized)
    return true
  }

  const setSelectedLines = (range: SelectedLineRange | null) => {
    viewer.lastSelection = range