import { spawn, type IPty } from '@skitee3000/bun-pty'
import { PORT_TERMINAL, WORKING_DIR, SHELL, SHELL_ARGS, DEFAULT_SESSION_ID, MAX_BUFFER_LINES } from '../config'

interface TerminalSession {
  id: string
  pty: IPty
  outputBuffer: string[]
  maxBufferSize: number
  clients: Set<any>
  createdAt: Date
}

// Store active terminal sessions by ID (persistent across reconnections)
const sessions = new Map<string, TerminalSession>()

// Map WebSocket to sessionId
const wsToSession = new Map<any, string>()

function getOrCreateSession(sessionId: string = DEFAULT_SESSION_ID): TerminalSession {
  let session = sessions.get(sessionId)

  if (!session) {
    console.log(`[Terminal] Creating new session: ${sessionId}`)
    const pty = spawn(SHELL, SHELL_ARGS, {
      name: 'xterm-256color',
      cols: 80,
      rows: 24,
      cwd: WORKING_DIR
    })

    session = {
      id: sessionId,
      pty,
      outputBuffer: [],
      maxBufferSize: MAX_BUFFER_LINES,
      clients: new Set(),
      createdAt: new Date()
    }

    // Capture output to buffer and send to clients
    pty.onData((data: string) => {
      session!.outputBuffer.push(data)
      if (session!.outputBuffer.length > session!.maxBufferSize) {
        session!.outputBuffer.shift()
      }

      for (const ws of session!.clients) {
        try {
          ws.send(JSON.stringify({ type: 'output', data }))
        } catch {
          // Client disconnected
        }
      }
    })

    // Handle PTY exit
    pty.onExit(({ exitCode }) => {
      console.log(`[Terminal] Session ${sessionId} exited with code ${exitCode}`)
      for (const ws of session!.clients) {
        try {
          ws.send(JSON.stringify({
            type: 'exit',
            data: `\r\n\x1b[33mSession ended (code ${exitCode})\x1b[0m\r\n`
          }))
        } catch { /* ignore */ }
      }
      sessions.delete(sessionId)
    })

    sessions.set(sessionId, session)
    console.log(`[Terminal] Session ${sessionId} created, PID: ${pty.pid}`)
  }

  return session
}

export function startTerminalServer() {
  const server = Bun.serve({
    port: PORT_TERMINAL,
    fetch(req, server) {
      const url = new URL(req.url)

      // Health check with session info
      if (url.pathname === '/health') {
        const sessionsInfo = Array.from(sessions.entries()).map(([id, s]) => ({
          id,
          clients: s.clients.size,
          pid: s.pty.pid,
          bufferSize: s.outputBuffer.length,
          createdAt: s.createdAt.toISOString()
        }))
        return Response.json({
          status: 'ok',
          sessions: sessionsInfo,
          cwd: WORKING_DIR
        })
      }

      // List active sessions
      if (url.pathname === '/sessions') {
        const list = Array.from(sessions.keys())
        return Response.json({ sessions: list })
      }

      // Check if this is a WebSocket upgrade request
      const upgradeHeader = req.headers.get('upgrade')
      console.log(`[Terminal] Request: ${req.method} ${url.pathname}, Upgrade: ${upgradeHeader}`)

      if (upgradeHeader?.toLowerCase() === 'websocket') {
        const sessionId = url.searchParams.get('session') || DEFAULT_SESSION_ID
        const success = server.upgrade(req, { data: { sessionId } })
        console.log(`[Terminal] WebSocket upgrade for session "${sessionId}": ${success ? 'success' : 'failed'}`)
        if (success) {
          return undefined
        }
        return new Response('WebSocket upgrade failed', { status: 400 })
      }

      return new Response(
        'Terminal WebSocket Server - Persistent Sessions\n\nEndpoints:\n  /health - Server status\n  /sessions - List active sessions\n  ws://...?session=<id> - Connect to session',
        { status: 200 }
      )
    },
    websocket: {
      open(ws) {
        const sessionId = (ws.data as any)?.sessionId || DEFAULT_SESSION_ID
        console.log(`[Terminal] Client connecting to session: ${sessionId}`)

        try {
          const session = getOrCreateSession(sessionId)
          session.clients.add(ws)
          wsToSession.set(ws, sessionId)

          // Send connection info
          ws.send(JSON.stringify({
            type: 'connected',
            sessionId: session.id,
            isNew: session.outputBuffer.length === 0
          }))

          // Replay buffer if there's history
          if (session.outputBuffer.length > 0) {
            console.log(`[Terminal] Replaying ${session.outputBuffer.length} buffer entries`)
            ws.send(JSON.stringify({
              type: 'replay',
              data: session.outputBuffer.join('')
            }))
          }

          console.log(`[Terminal] Client joined session ${sessionId} (${session.clients.size} clients)`)
        } catch (e: any) {
          console.error('[Terminal] Error:', e)
          ws.send(JSON.stringify({ type: 'error', message: e.message }))
        }
      },
      message(ws, message) {
        try {
          const msg = JSON.parse(message as string)
          const sessionId = wsToSession.get(ws)
          if (!sessionId) return

          const session = sessions.get(sessionId)
          if (!session) return

          if (msg.type === 'input') {
            session.pty.write(msg.data)
          } else if (msg.type === 'resize' && msg.cols && msg.rows) {
            session.pty.resize(msg.cols, msg.rows)
            console.log(`[Terminal] Session ${sessionId} resized to ${msg.cols}x${msg.rows}`)
          }
        } catch (e: any) {
          console.error('[Terminal] Error:', e)
        }
      },
      close(ws) {
        const sessionId = wsToSession.get(ws)
        if (sessionId) {
          const session = sessions.get(sessionId)
          if (session) {
            session.clients.delete(ws)
            console.log(`[Terminal] Client left session ${sessionId} (${session.clients.size} clients remaining)`)
            // Don't kill PTY - session persists
          }
          wsToSession.delete(ws)
        }
      }
    }
  })

  console.log(`[Terminal] WebSocket running at ws://localhost:${PORT_TERMINAL}`)
  return server
}