import { spawn } from 'child_process'
import { createServer } from 'http'
import { resolve } from 'path'

const PORT = 3141
const CLAUDE_BIN = resolve(process.env.HOME ?? '', '.local/bin/claude')

const server = createServer((req, res) => {
  if (req.method === 'OPTIONS') {
    res.writeHead(204, {
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods': 'POST, OPTIONS',
      'Access-Control-Allow-Headers': 'Content-Type',
    })
    res.end()
    return
  }

  if (req.method !== 'POST' || req.url !== '/v1/messages') {
    res.writeHead(404, { 'Content-Type': 'application/json' })
    res.end(JSON.stringify({ error: 'Not found' }))
    return
  }

  let body = ''
  req.on('data', (chunk) => { body += chunk })
  req.on('end', () => {
    try {
      const { model, messages, system } = JSON.parse(body)

      const modelFlag = model?.includes('opus') ? 'opus'
        : model?.includes('haiku') ? 'haiku'
        : 'sonnet'

      const history = (messages ?? []) as { role: string; content: string }[]
      const userMessages = history.filter((m) => m.role === 'user')
      const lastUserMsg = userMessages[userMessages.length - 1]?.content ?? ''

      const contextParts: string[] = []
      if (system) contextParts.push(system)
      const prior = history.slice(0, -1)
      if (prior.length > 0) {
        contextParts.push(
          'Conversation so far:\n' +
          prior.map((m) => `${m.role}: ${m.content}`).join('\n')
        )
      }

      const systemPrompt = contextParts.length > 0 ? contextParts.join('\n\n') : undefined

      const args = ['-p', '--model', modelFlag]
      if (systemPrompt) args.push('--system-prompt', systemPrompt)
      args.push('--', lastUserMsg)

      console.log(`[proxy] → claude -p --model ${modelFlag} "${lastUserMsg.slice(0, 60)}..."`)

      const proc = spawn(CLAUDE_BIN, args, {
        stdio: ['pipe', 'pipe', 'pipe'],
        env: { ...process.env, NO_COLOR: '1', TERM: 'dumb' },
        detached: false,
      })

      proc.stdin.end('')

      res.writeHead(200, {
        'Content-Type': 'text/event-stream',
        'Cache-Control': 'no-cache',
        'Connection': 'keep-alive',
        'Access-Control-Allow-Origin': '*',
        'X-Accel-Buffering': 'no',
      })

      let fullOutput = ''
      let clientDisconnected = false

      proc.stdout.on('data', (chunk: Buffer) => {
        const text = chunk.toString()
        fullOutput += text
        console.log(`[proxy] stdout +${text.length}b total=${fullOutput.length}b`)

        if (!clientDisconnected) {
          const sseData = {
            type: 'content_block_delta',
            delta: { type: 'text_delta', text },
          }
          res.write(`data: ${JSON.stringify(sseData)}\n\n`)
        }
      })

      proc.stderr.on('data', (chunk: Buffer) => {
        const msg = chunk.toString().trim()
        if (msg) console.error('[proxy] stderr:', msg)
      })

      proc.on('error', (err) => {
        console.error('[proxy] spawn error:', err)
        if (!clientDisconnected) {
          const errData = {
            type: 'error',
            error: { message: `Spawn error: ${err.message}` },
          }
          res.write(`data: ${JSON.stringify(errData)}\n\n`)
          res.write('data: [DONE]\n\n')
          res.end()
        }
      })

      proc.on('close', (code, signal) => {
        console.log(`[proxy] ← exit code=${code} signal=${signal} output=${fullOutput.length}b`)
        if (!clientDisconnected) {
          res.write('data: [DONE]\n\n')
          res.end()
        }
      })

      res.on('close', () => {
        clientDisconnected = true
        if (proc.exitCode === null && !proc.killed) {
          console.log('[proxy] Client disconnected, killing process')
          proc.kill('SIGTERM')
        }
      })

    } catch (err) {
      console.error('[proxy] Parse error:', err)
      res.writeHead(400, {
        'Content-Type': 'application/json',
        'Access-Control-Allow-Origin': '*',
      })
      res.end(JSON.stringify({ error: String(err) }))
    }
  })
})

server.listen(PORT, () => {
  console.log(`\n  Claude proxy → http://localhost:${PORT}`)
  console.log(`  Binary: ${CLAUDE_BIN}`)
  console.log(`  Using your Max subscription\n`)
})