import { type ChildProcess, spawn } from 'child_process'
import { createWriteStream, type WriteStream } from 'fs'
import { tmpdir } from 'os'
import { dirname, join } from 'path'
import { createInterface } from 'readline'
import { jsonParse, jsonStringify } from '../utils/slowOperations.js'
import { debugTruncate } from './debugUtils.js'
import type {
  SessionActivity,
  SessionDoneStatus,
  SessionHandle,
  SessionSpawner,
  SessionSpawnOpts,
} from './types.js'

const MAX_ACTIVITIES = 10
const MAX_STDERR_LINES = 10

/**
 * Sanitize a session ID for use in file names.
 * Strips any characters that could cause path traversal (e.g. `../`, `/`)
 * or other filesystem issues, replacing them with underscores.
 */
export function safeFilenameId(id: string): string {
  return id.replace(/[^a-zA-Z0-9_-]/g, '_')
}

/**
 * A control_request emitted by the child CLI when it needs permission to
 * execute a **specific** tool invocation (not a general capability check).
 * The bridge forwards this to the server so the user can approve/deny.
 */
export type PermissionRequest = {
  type: 'control_request'
  request_id: string
  request: {
    /** Per-invocation permission check — "may I run this tool with these inputs?" */
    subtype: 'can_use_tool'
    tool_name: string
    input: Record<string, unknown>
    tool_use_id: string
  }
}

type SessionSpawnerDeps = {
  execPath: string
  /**
   * Arguments that must precede the CLI flags when spawning. Empty for
   * compiled binaries (where execPath is the claude binary itself); contains
   * the script path (process.argv[1]) for npm installs where execPath is the
   * node runtime. Without this, node sees --sdk-url as a node option and
   * exits with "bad option: --sdk-url" (see anthropics/claude-code#28334).
   */
  scriptArgs: string[]
  env: NodeJS.ProcessEnv
  verbose: boolean
  sandbox: boolean
  debugFile?: string
  permissionMode?: string
  onDebug: (msg: string) => void
  onActivity?: (sessionId: string, activity: SessionActivity) => void
  onPermissionRequest?: (
    sessionId: string,
    request: PermissionRequest,
    accessToken: string,
  ) => void
}

/** Map tool names to human-readable verbs for the status display. */
const TOOL_VERBS: Record<string, string> = {
  Read: 'Reading',
  Write: 'Writing',
  Edit: 'Editing',
  MultiEdit: 'Editing',
  Bash: 'Running',
  Glob: 'Searching',
  Grep: 'Searching',
  WebFetch: 'Fetching',
  WebSearch: 'Searching',
  Task: 'Running task',
  FileReadTool: 'Reading',
  FileWriteTool: 'Writing',
  FileEditTool: 'Editing',
  GlobTool: 'Searching',
  GrepTool: 'Searching',
  BashTool: 'Running',
  NotebookEditTool: 'Editing notebook',
  LSP: 'LSP',
}

function toolSummary(name: string, input: Record<string, unknown>): string {
  const verb = TOOL_VERBS[name] ?? name
  const target =
    (input.file_path as string) ??
    (input.filePath as string) ??
    (input.pattern as string) ??
    (input.command as string | undefined)?.slice(0, 60) ??
    (input.url as string) ??
    (input.query as string) ??
    ''
  if (target) {
    return `${verb} ${target}`
  }
  return verb
}

function extractActivities(
  line: string,
  sessionId: string,
  onDebug: (msg: string) => void,
): SessionActivity[] {
  let parsed: unknown
  try {
    parsed = jsonParse(line)
  } catch {
    return []
  }

  if (!parsed || typeof parsed !== 'object') {
    return []
  }

  const msg = parsed as Record<string, unknown>
  const activities: SessionActivity[] = []
  const now = Date.now()

  switch (msg.type) {
    case 'assistant': {
      const message = msg.message as Record<string, unknown> | undefined
      if (!message) break
      const content = message.content
      if (!Array.isArray(content)) break

      for (const block of content) {
        if (!block || typeof block !== 'object') continue
        const b = block as Record<string, unknown>

        if (b.type === 'tool_use') {
          const name = (b.name as string) ?? 'Tool'
          const input = (b.input as Record<string, unknown>) ?? {}
          const summary = toolSummary(name, input)
          activities.push({
            type: 'tool_start',
            summary,
            timestamp: now,
          })
          onDebug(
            `[bridge:activity] sessionId=${sessionId} tool_use name=${name} ${inputPreview(input)}`,
          )
        } else if (b.type === 'text') {
          const text = (b.text as string) ?? ''
          if (text.length > 0) {
            activities.push({
              type: 'text',
              summary: text.slice(0, 80),
              timestamp: now,
            })
            onDebug(
              `[bridge:activity] sessionId=${sessionId} text "${text.slice(0, 100)}"`,
            )
          }
        }
      }
      break
    }
    case 'result': {
      const subtype = msg.subtype as string | undefined
      if (subtype === 'success') {
        activities.push({
          type: 'result',
          summary: 'Session completed',
          timestamp: now,
        })
        onDebug(
          `[bridge:activity] sessionId=${sessionId} result subtype=success`,
        )
      } else if (subtype) {
        const errors = msg.errors as string[] | undefined
        const errorSummary = errors?.[0] ?? `Error: ${subtype}`
        activities.push({
          type: 'error',
          summary: errorSummary,
          timestamp: now,
        })
        onDebug(
          `[bridge:activity] sessionId=${sessionId} result subtype=${subtype} error="${errorSummary}"`,
        )
      } else {
        onDebug(
          `[bridge:activity] sessionId=${sessionId} result subtype=undefined`,
        )
      }
      break
    }
    default:
      break
  }

  return activities
}

/**
 * Extract plain text from a replayed SDKUserMessage NDJSON line. Returns the
 * trimmed text if this looks like a real human-authored message, otherwise
 * undefined so the caller keeps waiting for the first real message.
 */
function extractUserMessageText(
  msg: Record<string, unknown>,
): string | undefined {
  // Skip tool-result user messages (wrapped subagent results) and synthetic
  // caveat messages — neither is human-authored.
  if (msg.parent_tool_use_id != null || msg.isSynthetic || msg.isReplay)
    return undefined

  const message = msg.message as Record<string, unknown> | undefined
  const content = message?.content
  let text: string | undefined
  if (typeof content === 'string') {
    text = content
  } else if (Array.isArray(content)) {
    for (const block of content) {
      if (
        block &&
        typeof block === 'object' &&
        (block as Record<string, unknown>).type === 'text'
      ) {
        text = (block as Record<string, unknown>).text as string | undefined
        break
      }
    }
  }
  text = text?.trim()
  return text ? text : undefined
}

/** Build a short preview of tool input for debug logging. */
function inputPreview(input: Record<string, unknown>): string {
  const parts: string[] = []
  for (const [key, val] of Object.entries(input)) {
    if (typeof val === 'string') {
      parts.push(`${key}="${val.slice(0, 100)}"`)
    }
    if (parts.length >= 3) break
  }
  return parts.join(' ')
}

export function createSessionSpawner(deps: SessionSpawnerDeps): SessionSpawner {
  return {
    spawn(opts: SessionSpawnOpts, dir: string): SessionHandle {
      // Debug file resolution:
      // 1. If deps.debugFile is provided, use it with session ID suffix for uniqueness
      // 2. If verbose or ant build, auto-generate a temp file path
      // 3. Otherwise, no debug file
      const safeId = safeFilenameId(opts.sessionId)
      let debugFile: string | undefined
      if (deps.debugFile) {
        const ext = deps.debugFile.lastIndexOf('.')
        if (ext > 0) {
          debugFile = `${deps.debugFile.slice(0, ext)}-${safeId}${deps.debugFile.slice(ext)}`
        } else {
          debugFile = `${deps.debugFile}-${safeId}`
        }
      } else if (deps.verbose || process.env.USER_TYPE === 'ant') {
        debugFile = join(tmpdir(), 'claude', `bridge-session-${safeId}.log`)
      }

      // Transcript file: write raw NDJSON lines for post-hoc analysis.
      // Placed alongside the debug file when one is configured.
      let transcriptStream: WriteStream | null = null
      let transcriptPath: string | undefined
      if (deps.debugFile) {
        transcriptPath = join(
          dirname(deps.debugFile),
          `bridge-transcript-${safeId}.jsonl`,
        )
        transcriptStream = createWriteStream(transcriptPath, { flags: 'a' })
        transcriptStream.on('error', err => {
          deps.onDebug(
            `[bridge:session] Transcript write error: ${err.message}`,
          )
          transcriptStream = null
        })
        deps.onDebug(`[bridge:session] Transcript log: ${transcriptPath}`)
      }

      const args = [
        ...deps.scriptArgs,
        '--print',
        '--sdk-url',
        opts.sdkUrl,
        '--session-id',
        opts.sessionId,
        '--input-format',
        'stream-json',
        '--output-format',
        'stream-json',
        '--replay-user-messages',
        ...(deps.verbose ? ['--verbose'] : []),
        ...(debugFile ? ['--debug-file', debugFile] : []),
        ...(deps.permissionMode
          ? ['--permission-mode', deps.permissionMode]
          : []),
      ]

      const env: NodeJS.ProcessEnv = {
        ...deps.env,
        // Strip the bridge's OAuth token so the child CC process uses
        // the session access token for inference instead.
        CLAUDE_CODE_OAUTH_TOKEN: undefined,
        CLAUDE_CODE_ENVIRONMENT_KIND: 'bridge',
        ...(deps.sandbox && { CLAUDE_CODE_FORCE_SANDBOX: '1' }),
        CLAUDE_CODE_SESSION_ACCESS_TOKEN: opts.accessToken,
        // v1: HybridTransport (WS reads + POST writes) to Session-Ingress.
        // Harmless in v2 mode — transportUtils checks CLAUDE_CODE_USE_CCR_V2 first.
        CLAUDE_CODE_POST_FOR_SESSION_INGRESS_V2: '1',
        // v2: SSETransport + CCRClient to CCR's /v1/code/sessions/* endpoints.
        // Same env vars environment-manager sets in the container path.
        ...(opts.useCcrV2 && {
          CLAUDE_CODE_USE_CCR_V2: '1',
          CLAUDE_CODE_WORKER_EPOCH: String(opts.workerEpoch),
        }),
      }

      deps.onDebug(
        `[bridge:session] Spawning sessionId=${opts.sessionId} sdkUrl=${opts.sdkUrl} accessToken=${opts.accessToken ? 'present' : 'MISSING'}`,
      )
      deps.onDebug(`[bridge:session] Child args: ${args.join(' ')}`)
      if (debugFile) {
        deps.onDebug(`[bridge:session] Debug log: ${debugFile}`)
      }

      // Pipe all three streams: stdin for control, stdout for NDJSON parsing,
      // stderr for error capture and diagnostics.
      const child: ChildProcess = spawn(deps.execPath, args, {
        cwd: dir,
        stdio: ['pipe', 'pipe', 'pipe'],
        env,
        windowsHide: true,
      })

      deps.onDebug(
        `[bridge:session] sessionId=${opts.sessionId} pid=${child.pid}`,
      )

      const activities: SessionActivity[] = []
      let currentActivity: SessionActivity | null = null
      const lastStderr: string[] = []
      let sigkillSent = false
      let firstUserMessageSeen = false

      // Buffer stderr for error diagnostics
      if (child.stderr) {
        const stderrRl = createInterface({ input: child.stderr })
        stderrRl.on('line', line => {
          // Forward stderr to bridge's stderr in verbose mode
          if (deps.verbose) {
            process.stderr.write(line + '\n')
          }
          // Ring buffer of last N lines
          if (lastStderr.length >= MAX_STDERR_LINES) {
            lastStderr.shift()
          }
          lastStderr.push(line)
        })
      }

      // Parse NDJSON from child stdout
      if (child.stdout) {
        const rl = createInterface({ input: child.stdout })
        rl.on('line', line => {
          // Write raw NDJSON to transcript file
          if (transcriptStream) {
            transcriptStream.write(line + '\n')
          }

          // Log all messages flowing from the child CLI to the bridge
          deps.onDebug(
            `[bridge:ws] sessionId=${opts.sessionId} <<< ${debugTruncate(line)}`,
          )

          // In verbose mode, forward raw output to stderr
          if (deps.verbose) {
            process.stderr.write(line + '\n')
          }

          const extracted = extractActivities(
            line,
            opts.sessionId,
            deps.onDebug,
          )
          for (const activity of extracted) {
            // Maintain ring buffer
            if (activities.length >= MAX_ACTIVITIES) {
              activities.shift()
            }
            activities.push(activity)
            currentActivity = activity

            deps.onActivity?.(opts.sessionId, activity)
          }

          // Detect control_request and replayed user messages.
          // extractActivities parses the same line but swallows parse errors
          // and skips 'user' type — re-parse here is cheap (NDJSON lines are
          // small) and keeps each path self-contained.
          {
            let parsed: unknown
            try {
              parsed = jsonParse(line)
            } catch {
              // Non-JSON line, skip detection
            }
            if (parsed && typeof parsed === 'object') {
              const msg = parsed as Record<string, unknown>

              if (msg.type === 'control_request') {
                const request = msg.request as
                  | Record<string, unknown>
                  | undefined
                if (
                  request?.subtype === 'can_use_tool' &&
                  deps.onPermissionRequest
                ) {
                  deps.onPermissionRequest(
                    opts.sessionId,
                    parsed as PermissionRequest,
                    opts.accessToken,
                  )
                }
                // interrupt is turn-level; the child handles it internally (print.ts)
              } else if (
                msg.type === 'user' &&
                !firstUserMessageSeen &&
                opts.onFirstUserMessage
              ) {
                const text = extractUserMessageText(msg)
                if (text) {
                  firstUserMessageSeen = true
                  opts.onFirstUserMessage(text)
                }
              }
            }
          }
        })
      }

      const done = new Promise<SessionDoneStatus>(resolve => {
        child.on('close', (code, signal) => {
          // Close transcript stream on exit
          if (transcriptStream) {
            transcriptStream.end()
            transcriptStream = null
          }

          if (signal === 'SIGTERM' || signal === 'SIGINT') {
            deps.onDebug(
              `[bridge:session] sessionId=${opts.sessionId} interrupted signal=${signal} pid=${child.pid}`,
            )
            resolve('interrupted')
          } else if (code === 0) {
            deps.onDebug(
              `[bridge:session] sessionId=${opts.sessionId} completed exit_code=0 pid=${child.pid}`,
            )
            resolve('completed')
          } else {
            deps.onDebug(
              `[bridge:session] sessionId=${opts.sessionId} failed exit_code=${code} pid=${child.pid}`,
            )
            resolve('failed')
          }
        })

        child.on('error', err => {
          deps.onDebug(
            `[bridge:session] sessionId=${opts.sessionId} spawn error: ${err.message}`,
          )
          resolve('failed')
        })
      })

      const handle: SessionHandle = {
        sessionId: opts.sessionId,
        done,
        activities,
        accessToken: opts.accessToken,
        lastStderr,
        get currentActivity(): SessionActivity | null {
          return currentActivity
        },
        kill(): void {
          if (!child.killed) {
            deps.onDebug(
              `[bridge:session] Sending SIGTERM to sessionId=${opts.sessionId} pid=${child.pid}`,
            )
            // On Windows, child.kill('SIGTERM') throws; use default signal.
            if (process.platform === 'win32') {
              child.kill()
            } else {
              child.kill('SIGTERM')
            }
          }
        },
        forceKill(): void {
          // Use separate flag because child.killed is set when kill() is called,
          // not when the process exits. We need to send SIGKILL even after SIGTERM.
          if (!sigkillSent && child.pid) {
            sigkillSent = true
            deps.onDebug(
              `[bridge:session] Sending SIGKILL to sessionId=${opts.sessionId} pid=${child.pid}`,
            )
            if (process.platform === 'win32') {
              child.kill()
            } else {
              child.kill('SIGKILL')
            }
          }
        },
        writeStdin(data: string): void {
          if (child.stdin && !child.stdin.destroyed) {
            deps.onDebug(
              `[bridge:ws] sessionId=${opts.sessionId} >>> ${debugTruncate(data)}`,
            )
            child.stdin.write(data)
          }
        },
        updateAccessToken(token: string): void {
          handle.accessToken = token
          // Send the fresh token to the child process via stdin. The child's
          // StructuredIO handles update_environment_variables messages by
          // setting process.env directly, so getSessionIngressAuthToken()
          // picks up the new token on the next refreshHeaders call.
          handle.writeStdin(
            jsonStringify({
              type: 'update_environment_variables',
              variables: { CLAUDE_CODE_SESSION_ACCESS_TOKEN: token },
            }) + '\n',
          )
          deps.onDebug(
            `[bridge:session] Sent token refresh via stdin for sessionId=${opts.sessionId}`,
          )
        },
      }

      return handle
    },
  }
}

export { extractActivities as _extractActivitiesForTesting }