import { Terminal } from '@xterm/xterm'
import { FitAddon } from '@xterm/addon-fit'
import { SearchAddon } from '@xterm/addon-search'
import { WebLinksAddon } from '@xterm/addon-web-links'
import { WebglAddon } from '@xterm/addon-webgl'
import { useAuthStore } from '~/stores/auth.store'
import { useSessionStore } from '~/stores/session.store'
import { getTerminalTheme } from '~/composables/useTerminalThemes'

export function useTerminal() {
  const auth = useAuthStore()
  const sessions = useSessionStore()
  let ws: WebSocket | null = null

  function createTerminal(container: HTMLElement, options?: Partial<{ fontSize: number; scrollback: number; themeId: string }>) {
    const themeId = options?.themeId || localStorage.getItem('wraith_terminal_theme') || 'wraith'
    const theme = getTerminalTheme(themeId)

    const term = new Terminal({
      cursorBlink: true,
      fontSize: options?.fontSize || parseInt(localStorage.getItem('wraith_font_size') || '14'),
      fontFamily: "'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace",
      scrollback: options?.scrollback || parseInt(localStorage.getItem('wraith_scrollback') || '10000'),
      theme,
    })

    const fitAddon = new FitAddon()
    const searchAddon = new SearchAddon()
    term.loadAddon(fitAddon)
    term.loadAddon(searchAddon)
    term.loadAddon(new WebLinksAddon())

    term.open(container)

    try {
      const webgl = new WebglAddon()
      webgl.onContextLoss(() => { webgl.dispose() })
      term.loadAddon(webgl)
    } catch {
      // WebGL not available, fall back to canvas
    }

    // Delay fit until container has layout dimensions
    const safeFit = () => {
      try {
        if (container.offsetWidth > 0 && container.offsetHeight > 0) {
          fitAddon.fit()
        }
      } catch { /* ignore fit errors on unmounted containers */ }
    }
    requestAnimationFrame(safeFit)
    const resizeObserver = new ResizeObserver(() => safeFit())
    resizeObserver.observe(container)

    return { term, fitAddon, searchAddon, resizeObserver }
  }

  function connectToHost(hostId: number, hostName: string, protocol: 'ssh', color: string | null, pendingSessionId: string, term: Terminal, fitAddon: FitAddon) {
    const wsUrl = `${location.protocol === 'https:' ? 'wss' : 'ws'}://${location.host}/api/ws/terminal?token=${auth.token}`
    ws = new WebSocket(wsUrl)

    ws.onopen = () => {
      ws!.send(JSON.stringify({ type: 'connect', hostId }))
    }

    ws.onmessage = (event) => {
      const msg = JSON.parse(event.data)
      switch (msg.type) {
        case 'connected':
          // Replace the pending placeholder with the real backend session
          sessions.replaceSession(pendingSessionId, { id: msg.sessionId, hostId, hostName, protocol, color, active: true })
          // Send initial terminal size
          ws!.send(JSON.stringify({ type: 'resize', sessionId: msg.sessionId, cols: term.cols, rows: term.rows }))
          break
        case 'data':
          term.write(msg.data)
          break
        case 'disconnected':
          sessions.removeSession(msg.sessionId)
          break
        case 'host-key-verify':
          // Auto-accept for now — full UX in polish phase
          ws!.send(JSON.stringify({ type: 'host-key-accept' }))
          break
        case 'error':
          term.write(`\r\n\x1b[31mError: ${msg.message}\x1b[0m\r\n`)
          break
      }
    }

    ws.onclose = () => {
      term.write('\r\n\x1b[33mConnection closed.\x1b[0m\r\n')
    }

    // Terminal input → WebSocket
    term.onData((data) => {
      if (ws?.readyState === WebSocket.OPEN) {
        const sessionId = sessions.activeSession?.id
        if (sessionId) {
          ws.send(JSON.stringify({ type: 'data', sessionId, data }))
        }
      }
    })

    // Terminal resize → WebSocket
    term.onResize(({ cols, rows }) => {
      if (ws?.readyState === WebSocket.OPEN) {
        const sessionId = sessions.activeSession?.id
        if (sessionId) {
          ws.send(JSON.stringify({ type: 'resize', sessionId, cols, rows }))
        }
      }
    })

    return ws
  }

  function disconnect(sessionId: string) {
    if (ws?.readyState === WebSocket.OPEN) {
      ws.send(JSON.stringify({ type: 'disconnect', sessionId }))
    }
    sessions.removeSession(sessionId)
  }

  return { createTerminal, connectToHost, disconnect }
}