import { watch } from "node:fs"
import type { WorkflowDef } from "./types"

export class FileWatcher {
  private watchers: Map<string, ReturnType<typeof watch>> = new Map()
  private timers: Map<string, ReturnType<typeof setTimeout>> = new Map()

  watch(def: WorkflowDef, worktree: string, onTrigger: () => void): void {
    if (def.trigger !== "file_change" || !def.paths) return
    const key = def.name
    this.unwatch(key)

    const patterns = def.paths.map((p) => {
      let escaped = p
        .replace(/[.+^${}()|[\]\\]/g, "\\$&") // escape regex metachars
        .replace(/\*\*/g, "\x00")               // globstar placeholder
        .replace(/\*/g, "[^/]*")                 // * → any non-slash
        .replace(/\x00/g, ".*")                  // globstar placeholder → .*
        .replace(/\?/g, "[^/]")                  // ? → single char
      return new RegExp("^" + escaped + "$")
    })

    const debounceMs = (def.debounce ?? 60) * 1000

    const watcher = watch(worktree, { recursive: true, persistent: false }, (_event, filename) => {
      if (!filename) return
      if (patterns.some((r) => r.test(filename))) {
        const existing = this.timers.get(key)
        if (existing) clearTimeout(existing)
        this.timers.set(key, setTimeout(onTrigger, debounceMs))
      }
    })

    this.watchers.set(key, watcher)
  }

  unwatch(key: string): void {
    const w = this.watchers.get(key)
    if (w) { w.close(); this.watchers.delete(key) }
    const t = this.timers.get(key)
    if (t) { clearTimeout(t); this.timers.delete(key) }
  }

  stopAll(): void {
    for (const [k] of this.watchers) this.unwatch(k)
  }
}