import { WebSocketServer, type WebSocket } from 'ws'
import type { SynthesisConfig } from '../core/config.js'
import type { SessionMapping } from '../core/session-mapping.js'
import type { ProcessManager } from '../core/process-manager.js'

interface BridgeServerDeps {
  config: SynthesisConfig
  mapping: SessionMapping
  processManager: ProcessManager
}

interface ClientConn {
  ws: WebSocket
  pid: number
  openclawSessionId: string
  claudeSessionUuid: string
  isAlive: boolean
}

/**
 * WebSocket server that ClaudePlugin instances dial into. One connection per
 * spawned Claude process; identified by env-injected (openclaw_session, pid).
 *
 * Bridge frames are defined in docs/wire-protocol.md.
 */
export async function startBridgeServer(deps: BridgeServerDeps): Promise<{ close(): Promise<void> }> {
  const { config, processManager } = deps

  const wss = new WebSocketServer({
    host: '127.0.0.1',
    port: config.bridgePort,
    path: '/bridge',
  })

  const byOpenclawSession = new Map<string, ClientConn>()

  wss.on('connection', ws => {
    let conn: ClientConn | null = null

    ws.on('message', async raw => {
      let frame: any
      try { frame = JSON.parse(String(raw)) } catch { return }

      // First frame must be hello.
      if (!conn) {
        if (frame.type !== 'hello') return ws.close(4001, 'expected hello first')
        if (frame.token !== config.bridgeToken) return ws.close(4002, 'bad token')

        conn = {
          ws,
          pid: frame.pid,
          openclawSessionId: frame.openclaw_session,
          claudeSessionUuid: frame.claude_session,
          isAlive: true,
        }

        // Evict any previous connection for this session (e.g. plugin reconnect).
        const prev = byOpenclawSession.get(conn.openclawSessionId)
        if (prev && prev.ws !== ws) try { prev.ws.close(4003, 'replaced by reconnect') } catch {}
        byOpenclawSession.set(conn.openclawSessionId, conn)

        processManager.markReady(conn.pid)

        ws.send(JSON.stringify({
          type: 'hello_ack',
          // TODO: real catalog from api.tools.list() — empty for the scaffold.
          tools: [],
          session_meta: { openclaw_session: conn.openclawSessionId },
        }))
        return
      }

      // Subsequent frames.
      switch (frame.type) {
        case 'tool_call':
          // TODO: dispatch frame.tool with frame.args against OpenClaw's tool
          // surface. For the scaffold we echo not-implemented.
          ws.send(JSON.stringify({
            type: 'tool_result',
            call_id: frame.call_id,
            ok: false,
            error: `tool dispatch not implemented (tool=${frame.tool})`,
          }))
          return

        case 'permission_request':
          // TODO: route to the user via the original source channel
          // (Discord/Telegram/…). The OpenClaw side knows where the session
          // came from. For now, log and auto-deny.
          process.stderr.write(`synthesis: permission_request ${frame.request_id} (auto-denied)\n`)
          ws.send(JSON.stringify({
            type: 'permission_reply',
            request_id: frame.request_id,
            behavior: 'deny',
          }))
          return

        case 'pong':
          conn.isAlive = true
          return

        default:
          process.stderr.write(`synthesis: unknown frame type from plugin: ${frame.type}\n`)
      }
    })

    ws.on('close', () => {
      if (conn && byOpenclawSession.get(conn.openclawSessionId)?.ws === ws) {
        byOpenclawSession.delete(conn.openclawSessionId)
      }
    })
  })

  // Heartbeat: ping every 30s, kill if no pong by next round.
  const heartbeat = setInterval(() => {
    for (const c of byOpenclawSession.values()) {
      if (!c.isAlive) {
        try { c.ws.terminate() } catch {}
        continue
      }
      c.isAlive = false
      try { c.ws.send(JSON.stringify({ type: 'ping', ts: Date.now() })) } catch {}
    }
  }, 30_000)

  process.stderr.write(`synthesis: bridge listening on ws://127.0.0.1:${config.bridgePort}/bridge\n`)

  return {
    /** Public helper for outsiders (e.g. inbound event subscriber) to push messages. */
    pushInbound(openclawSessionId: string, payload: { content: string; meta: Record<string, unknown>; request_id?: string }) {
      const c = byOpenclawSession.get(openclawSessionId)
      if (!c) throw new Error(`no live plugin for session ${openclawSessionId}`)
      c.ws.send(JSON.stringify({ type: 'inbound_message', ...payload }))
    },
    pushPermissionReply(openclawSessionId: string, request_id: string, behavior: 'allow' | 'deny') {
      const c = byOpenclawSession.get(openclawSessionId)
      if (!c) throw new Error(`no live plugin for session ${openclawSessionId}`)
      c.ws.send(JSON.stringify({ type: 'permission_reply', request_id, behavior }))
    },
    async close() {
      clearInterval(heartbeat)
      for (const c of byOpenclawSession.values()) try { c.ws.close() } catch {}
      await new Promise<void>(r => wss.close(() => r()))
    },
  } as unknown as { close(): Promise<void> }
}