'use strict'
const fs = require('node:fs')
const { randomUUID, createHash } = require('node:crypto')
const prefix = '\x1eYCODE_WORKSPACE_READ_V1 '
let selected = false
function error(code, message) { return Object.assign(new Error(message), { code }) }
function frame(operation, args, id) { return '\n' + prefix + JSON.stringify({ version: 1, requestId: id, operation, args }) + '\n' }
function send(operation, args, id) {
  const bytes = Buffer.from(frame(operation, args, id))
  let offset = 0
  while (offset < bytes.length) offset += fs.writeSync(1, bytes, offset, bytes.length - offset)
}
function unpack(line, id) {
  let response
  try { response = JSON.parse(line) } catch { throw error('EPROTO', 'Invalid file bridge reply') }
  if (response.version !== 1 || response.requestId !== id || typeof response.ok !== 'boolean') throw error('EPROTO', 'Unexpected file bridge reply')
  if (!response.ok) throw error(response.error?.code || 'EACCES', response.error?.message || 'Workspace read denied')
  return response.value
}
function claim() {
  if (selected) throw error('EBUSY', 'Choose one bridge client and mode per process; stdin belongs to that client')
  selected = true
}
function decode(part, initial, offset) {
  if (!part || part.snapshotId !== initial.snapshotId || part.sha256 !== initial.sha256 || part.size !== initial.size || part.offset !== offset || typeof part.data !== 'string') throw error('EPROTO', 'Inconsistent read snapshot')
  const bytes = Buffer.from(part.data, 'base64')
  if (bytes.length > 16384 || !bytes.length && offset < initial.size || offset + bytes.length > initial.size || part.eof !== (offset + bytes.length === initial.size)) throw error('EPROTO', 'Invalid read chunk')
  return bytes
}
function complete(chunks, initial, encoding) {
  const bytes = Buffer.concat(chunks)
  if (bytes.length !== initial.size || createHash('sha256').update(bytes).digest('hex') !== initial.sha256) throw error('EPROTO', 'Read snapshot digest mismatch')
  return encoding ? bytes.toString(encoding) : bytes
}
function connectSync() {
  claim()
  let buffered = Buffer.alloc(0), closed = false
  function call(operation, args, id = randomUUID()) {
    if (closed) throw error('EPIPE', 'File bridge client closed')
    send(operation, args, id)
    for (;;) {
      const end = buffered.indexOf(10)
      if (end >= 0) {
        const line = buffered.subarray(0, end).toString('utf8'); buffered = buffered.subarray(end + 1)
        return unpack(line, id)
      }
      if (buffered.length > 32768) throw error('EPROTO', 'File bridge reply exceeds limit')
      const bytes = Buffer.alloc(32768), length = fs.readSync(0, bytes, 0, bytes.length, null)
      if (!length) { closed = true; throw error('EPIPE', 'File bridge disconnected') }
      buffered = Buffer.concat([buffered, bytes.subarray(0, length)])
    }
  }
  return {
    call,
    readFileSync(path, encoding) {
      const initial = call('workspace.readFile', { path }), chunks = []
      try {
        let part = initial, offset = 0
        for (;;) {
          const bytes = decode(part, initial, offset); chunks.push(bytes); offset += bytes.length
          if (part.eof) return complete(chunks, initial, encoding)
          part = call('workspace.readChunk', { snapshotId: initial.snapshotId, offset })
        }
      } finally { call('workspace.closeRead', { snapshotId: initial.snapshotId }) }
    },
    statSync: path => call('workspace.stat', { path }),
    readdirSync: path => call('workspace.readdir', { path }).entries,
    querySync: requestId => call('operation.query', { requestId }),
    close() { closed = true }
  }
}
function connect() {
  claim()
  const waiting = new Map(), queue = []
  let buffered = Buffer.alloc(0), closed = false, failure
  function shutdown(reason) {
    if (closed) return
    closed = true; failure = reason
    process.stdin.off('data', receive); process.stdin.off('end', ended); process.stdin.off('error', failed); process.stdin.pause()
    process.stdin.destroy()
    for (const item of [...waiting.values(), ...queue]) item.reject(reason)
    waiting.clear(); queue.length = 0
  }
  function flush() {
    while (!closed && waiting.size < 8 && queue.length) {
      const item = queue.shift(); waiting.set(item.id, item)
      try { send(item.operation, item.args, item.id) } catch (reason) { shutdown(reason) }
    }
    if (waiting.size) { process.stdin.ref?.(); process.stdin.resume() }
    else { process.stdin.pause(); process.stdin.unref?.() }
  }
  function receive(bytes) {
    buffered = Buffer.concat([buffered, bytes])
    for (;;) {
      const end = buffered.indexOf(10)
      if (end < 0) { if (buffered.length > 32768) shutdown(error('EPROTO', 'File bridge reply exceeds limit')); return }
      const line = buffered.subarray(0, end).toString('utf8'); buffered = buffered.subarray(end + 1)
      let id
      try { id = JSON.parse(line).requestId } catch { shutdown(error('EPROTO', 'Invalid file bridge reply')); return }
      const item = waiting.get(id)
      if (!item) { shutdown(error('EPROTO', 'Unexpected file bridge reply')); return }
      waiting.delete(id)
      try { item.resolve(unpack(line, id)) } catch (reason) { item.reject(reason) }
      flush()
    }
  }
  const ended = () => shutdown(error('EPIPE', 'File bridge disconnected'))
  const failed = reason => shutdown(reason)
  process.stdin.on('data', receive); process.stdin.on('end', ended); process.stdin.on('error', failed); process.stdin.pause()
  function call(operation, args, id = randomUUID()) {
    if (closed) return Promise.reject(failure || error('EPIPE', 'File bridge client closed'))
    if (queue.length + waiting.size >= 32) return Promise.reject(error('EBUSY', 'File bridge client queue full'))
    return new Promise((resolve, reject) => { queue.push({ id, operation, args, resolve, reject }); flush() })
  }
  return {
    call,
    async readFile(path, encoding) {
      const initial = await call('workspace.readFile', { path }), chunks = []
      try {
        let part = initial, offset = 0
        for (;;) {
          const bytes = decode(part, initial, offset); chunks.push(bytes); offset += bytes.length
          if (part.eof) return complete(chunks, initial, encoding)
          part = await call('workspace.readChunk', { snapshotId: initial.snapshotId, offset })
        }
      } finally { await call('workspace.closeRead', { snapshotId: initial.snapshotId }) }
    },
    stat: path => call('workspace.stat', { path }),
    readdir: async path => (await call('workspace.readdir', { path })).entries,
    query: requestId => call('operation.query', { requestId }),
    close() { shutdown(error('EPIPE', 'File bridge client closed')) }
  }
}
module.exports = { connect, connectSync }