import { feature } from 'bun:bundle'
import { stat } from 'fs/promises'
import {
  OUTPUT_FILE_TAG,
  STATUS_TAG,
  SUMMARY_TAG,
  TASK_ID_TAG,
  TASK_NOTIFICATION_TAG,
  TOOL_USE_ID_TAG,
} from '../../constants/xml.js'
import { abortSpeculation } from '../../services/PromptSuggestion/speculation.js'
import type { AppState } from '../../state/AppState.js'
import type {
  LocalShellSpawnInput,
  SetAppState,
  Task,
  TaskContext,
  TaskHandle,
} from '../../Task.js'
import { createTaskStateBase } from '../../Task.js'
import type { AgentId } from '../../types/ids.js'
import { registerCleanup } from '../../utils/cleanupRegistry.js'
import { tailFile } from '../../utils/fsOperations.js'
import { logError } from '../../utils/log.js'
import { enqueuePendingNotification } from '../../utils/messageQueueManager.js'
import type { ShellCommand } from '../../utils/ShellCommand.js'
import {
  evictTaskOutput,
  getTaskOutputPath,
} from '../../utils/task/diskOutput.js'
import { registerTask, updateTaskState } from '../../utils/task/framework.js'
import { escapeXml } from '../../utils/xml.js'
import {
  backgroundAgentTask,
  isLocalAgentTask,
} from '../LocalAgentTask/LocalAgentTask.js'
import { isMainSessionTask } from '../LocalMainSessionTask.js'
import {
  type BashTaskKind,
  isLocalShellTask,
  type LocalShellTaskState,
} from './guards.js'
import { killTask } from './killShellTasks.js'

/** Prefix that identifies a LocalShellTask summary to the UI collapse transform. */
export const BACKGROUND_BASH_SUMMARY_PREFIX = 'Background command '

const STALL_CHECK_INTERVAL_MS = 5_000
const STALL_THRESHOLD_MS = 45_000
const STALL_TAIL_BYTES = 1024

// Last-line patterns that suggest a command is blocked waiting for keyboard
// input. Used to gate the stall notification — we stay silent on commands that
// are merely slow (git log -S, long builds) and only notify when the tail
// looks like an interactive prompt the model can act on. See CC-1175.
const PROMPT_PATTERNS = [
  /\(y\/n\)/i, // (Y/n), (y/N)
  /\[y\/n\]/i, // [Y/n], [y/N]
  /\(yes\/no\)/i,
  /\b(?:Do you|Would you|Shall I|Are you sure|Ready to)\b.*\? *$/i, // directed questions
  /Press (any key|Enter)/i,
  /Continue\?/i,
  /Overwrite\?/i,
]

export function looksLikePrompt(tail: string): boolean {
  const lastLine = tail.trimEnd().split('\n').pop() ?? ''
  return PROMPT_PATTERNS.some(p => p.test(lastLine))
}

// Output-side analog of peekForStdinData (utils/process.ts): fire a one-shot
// notification if output stops growing and the tail looks like a prompt.
function startStallWatchdog(
  taskId: string,
  description: string,
  kind: BashTaskKind | undefined,
  toolUseId?: string,
  agentId?: AgentId,
): () => void {
  if (kind === 'monitor') return () => {}
  const outputPath = getTaskOutputPath(taskId)
  let lastSize = 0
  let lastGrowth = Date.now()
  let cancelled = false

  const timer = setInterval(() => {
    void stat(outputPath).then(
      s => {
        if (s.size > lastSize) {
          lastSize = s.size
          lastGrowth = Date.now()
          return
        }
        if (Date.now() - lastGrowth < STALL_THRESHOLD_MS) return
        void tailFile(outputPath, STALL_TAIL_BYTES).then(
          ({ content }) => {
            if (cancelled) return
            if (!looksLikePrompt(content)) {
              // Not a prompt — keep watching. Reset so the next check is
              // 45s out instead of re-reading the tail on every tick.
              lastGrowth = Date.now()
              return
            }
            // Latch before the async-boundary-visible side effects so an
            // overlapping tick's callback sees cancelled=true and bails.
            cancelled = true
            clearInterval(timer)
            const toolUseIdLine = toolUseId
              ? `\n<${TOOL_USE_ID_TAG}>${toolUseId}</${TOOL_USE_ID_TAG}>`
              : ''
            const summary = `${BACKGROUND_BASH_SUMMARY_PREFIX}"${description}" appears to be waiting for interactive input`
            // No <status> tag — print.ts treats <status> as a terminal
            // signal and an unknown value falls through to 'completed',
            // falsely closing the task for SDK consumers. Statusless
            // notifications are skipped by the SDK emitter (progress ping).
            const message = `<${TASK_NOTIFICATION_TAG}>
<${TASK_ID_TAG}>${taskId}</${TASK_ID_TAG}>${toolUseIdLine}
<${OUTPUT_FILE_TAG}>${outputPath}</${OUTPUT_FILE_TAG}>
<${SUMMARY_TAG}>${escapeXml(summary)}</${SUMMARY_TAG}>
</${TASK_NOTIFICATION_TAG}>
Last output:
${content.trimEnd()}

The command is likely blocked on an interactive prompt. Kill this task and re-run with piped input (e.g., \`echo y | command\`) or a non-interactive flag if one exists.`
            enqueuePendingNotification({
              value: message,
              mode: 'task-notification',
              priority: 'next',
              agentId,
            })
          },
          () => {},
        )
      },
      () => {}, // File may not exist yet
    )
  }, STALL_CHECK_INTERVAL_MS)
  timer.unref()

  return () => {
    cancelled = true
    clearInterval(timer)
  }
}

function enqueueShellNotification(
  taskId: string,
  description: string,
  status: 'completed' | 'failed' | 'killed',
  exitCode: number | undefined,
  setAppState: SetAppState,
  toolUseId?: string,
  kind: BashTaskKind = 'bash',
  agentId?: AgentId,
): void {
  // Atomically check and set notified flag to prevent duplicate notifications.
  // If the task was already marked as notified (e.g., by TaskStopTool), skip
  // enqueueing to avoid sending redundant messages to the model.
  let shouldEnqueue = false
  updateTaskState(taskId, setAppState, task => {
    if (task.notified) {
      return task
    }
    shouldEnqueue = true
    return { ...task, notified: true }
  })

  if (!shouldEnqueue) {
    return
  }

  // Abort any active speculation — background task state changed, so speculated
  // results may reference stale task output. The prompt suggestion text is
  // preserved; only the pre-computed response is discarded.
  abortSpeculation(setAppState)

  let summary: string
  if (feature('MONITOR_TOOL') && kind === 'monitor') {
    // Monitor is streaming-only (post-#22764) — the script exiting means
    // the stream ended, not "condition met". Distinct from the bash prefix
    // so Monitor completions don't fold into the "N background commands
    // completed" collapse.
    switch (status) {
      case 'completed':
        summary = `Monitor "${description}" stream ended`
        break
      case 'failed':
        summary = `Monitor "${description}" script failed${exitCode !== undefined ? ` (exit ${exitCode})` : ''}`
        break
      case 'killed':
        summary = `Monitor "${description}" stopped`
        break
    }
  } else {
    switch (status) {
      case 'completed':
        summary = `${BACKGROUND_BASH_SUMMARY_PREFIX}"${description}" completed${exitCode !== undefined ? ` (exit code ${exitCode})` : ''}`
        break
      case 'failed':
        summary = `${BACKGROUND_BASH_SUMMARY_PREFIX}"${description}" failed${exitCode !== undefined ? ` with exit code ${exitCode}` : ''}`
        break
      case 'killed':
        summary = `${BACKGROUND_BASH_SUMMARY_PREFIX}"${description}" was stopped`
        break
    }
  }

  const outputPath = getTaskOutputPath(taskId)
  const toolUseIdLine = toolUseId
    ? `\n<${TOOL_USE_ID_TAG}>${toolUseId}</${TOOL_USE_ID_TAG}>`
    : ''
  const message = `<${TASK_NOTIFICATION_TAG}>
<${TASK_ID_TAG}>${taskId}</${TASK_ID_TAG}>${toolUseIdLine}
<${OUTPUT_FILE_TAG}>${outputPath}</${OUTPUT_FILE_TAG}>
<${STATUS_TAG}>${status}</${STATUS_TAG}>
<${SUMMARY_TAG}>${escapeXml(summary)}</${SUMMARY_TAG}>
</${TASK_NOTIFICATION_TAG}>`

  enqueuePendingNotification({
    value: message,
    mode: 'task-notification',
    priority: feature('MONITOR_TOOL') ? 'next' : 'later',
    agentId,
  })
}

export const LocalShellTask: Task = {
  name: 'LocalShellTask',
  type: 'local_bash',
  async kill(taskId, setAppState) {
    killTask(taskId, setAppState)
  },
}

export async function spawnShellTask(
  input: LocalShellSpawnInput & { shellCommand: ShellCommand },
  context: TaskContext,
): Promise<TaskHandle> {
  const { command, description, shellCommand, toolUseId, agentId, kind } = input
  const { setAppState } = context

  // TaskOutput owns the data — use its taskId so disk writes are consistent
  const { taskOutput } = shellCommand
  const taskId = taskOutput.taskId

  const unregisterCleanup = registerCleanup(async () => {
    killTask(taskId, setAppState)
  })

  const taskState: LocalShellTaskState = {
    ...createTaskStateBase(taskId, 'local_bash', description, toolUseId),
    type: 'local_bash',
    status: 'running',
    command,
    completionStatusSentInAttachment: false,
    shellCommand,
    unregisterCleanup,
    lastReportedTotalLines: 0,
    isBackgrounded: true,
    agentId,
    kind,
  }

  registerTask(taskState, setAppState)

  // Data flows through TaskOutput automatically — no stream listeners needed.
  // Just transition to backgrounded state so the process keeps running.
  shellCommand.background(taskId)

  const cancelStallWatchdog = startStallWatchdog(
    taskId,
    description,
    kind,
    toolUseId,
    agentId,
  )

  void shellCommand.result.then(async result => {
    cancelStallWatchdog()
    await flushAndCleanup(shellCommand)
    let wasKilled = false

    updateTaskState<LocalShellTaskState>(taskId, setAppState, task => {
      if (task.status === 'killed') {
        wasKilled = true
        return task
      }

      return {
        ...task,
        status: result.code === 0 ? 'completed' : 'failed',
        result: { code: result.code, interrupted: result.interrupted },
        shellCommand: null,
        unregisterCleanup: undefined,
        endTime: Date.now(),
      }
    })

    enqueueShellNotification(
      taskId,
      description,
      wasKilled ? 'killed' : result.code === 0 ? 'completed' : 'failed',
      result.code,
      setAppState,
      toolUseId,
      kind,
      agentId,
    )

    void evictTaskOutput(taskId)
  })

  return {
    taskId,
    cleanup: () => {
      unregisterCleanup()
    },
  }
}

/**
 * Register a foreground task that could be backgrounded later.
 * Called when a bash command has been running long enough to show the BackgroundHint.
 * @returns taskId for the registered task
 */
export function registerForeground(
  input: LocalShellSpawnInput & { shellCommand: ShellCommand },
  setAppState: SetAppState,
  toolUseId?: string,
): string {
  const { command, description, shellCommand, agentId } = input

  const taskId = shellCommand.taskOutput.taskId

  const unregisterCleanup = registerCleanup(async () => {
    killTask(taskId, setAppState)
  })

  const taskState: LocalShellTaskState = {
    ...createTaskStateBase(taskId, 'local_bash', description, toolUseId),
    type: 'local_bash',
    status: 'running',
    command,
    completionStatusSentInAttachment: false,
    shellCommand,
    unregisterCleanup,
    lastReportedTotalLines: 0,
    isBackgrounded: false, // Not yet backgrounded - running in foreground
    agentId,
  }

  registerTask(taskState, setAppState)
  return taskId
}

/**
 * Background a specific foreground task.
 * @returns true if backgrounded successfully, false otherwise
 */
function backgroundTask(
  taskId: string,
  getAppState: () => AppState,
  setAppState: SetAppState,
): boolean {
  // Step 1: Get the task and shell command from current state
  const state = getAppState()
  const task = state.tasks[taskId]
  if (!isLocalShellTask(task) || task.isBackgrounded || !task.shellCommand) {
    return false
  }

  const shellCommand = task.shellCommand
  const description = task.description
  const { toolUseId, kind, agentId } = task

  // Transition to backgrounded — TaskOutput continues receiving data automatically
  if (!shellCommand.background(taskId)) {
    return false
  }

  setAppState(prev => {
    const prevTask = prev.tasks[taskId]
    if (!isLocalShellTask(prevTask) || prevTask.isBackgrounded) {
      return prev
    }
    return {
      ...prev,
      tasks: {
        ...prev.tasks,
        [taskId]: { ...prevTask, isBackgrounded: true },
      },
    }
  })

  const cancelStallWatchdog = startStallWatchdog(
    taskId,
    description,
    kind,
    toolUseId,
    agentId,
  )

  // Set up result handler
  void shellCommand.result.then(async result => {
    cancelStallWatchdog()
    await flushAndCleanup(shellCommand)
    let wasKilled = false
    let cleanupFn: (() => void) | undefined

    updateTaskState<LocalShellTaskState>(taskId, setAppState, t => {
      if (t.status === 'killed') {
        wasKilled = true
        return t
      }

      // Capture cleanup function to call outside of updater
      cleanupFn = t.unregisterCleanup

      return {
        ...t,
        status: result.code === 0 ? 'completed' : 'failed',
        result: { code: result.code, interrupted: result.interrupted },
        shellCommand: null,
        unregisterCleanup: undefined,
        endTime: Date.now(),
      }
    })

    // Call cleanup outside of the state updater (avoid side effects in updater)
    cleanupFn?.()

    if (wasKilled) {
      enqueueShellNotification(
        taskId,
        description,
        'killed',
        result.code,
        setAppState,
        toolUseId,
        kind,
        agentId,
      )
    } else {
      const finalStatus = result.code === 0 ? 'completed' : 'failed'
      enqueueShellNotification(
        taskId,
        description,
        finalStatus,
        result.code,
        setAppState,
        toolUseId,
        kind,
        agentId,
      )
    }

    void evictTaskOutput(taskId)
  })

  return true
}

/**
 * Background ALL foreground tasks (bash commands and agents).
 * Called when user presses Ctrl+B to background all running tasks.
 */
/**
 * Check if there are any foreground tasks (bash or agent) that can be backgrounded.
 * Used to determine whether Ctrl+B should background existing tasks vs. background the session.
 */
export function hasForegroundTasks(state: AppState): boolean {
  return Object.values(state.tasks).some(task => {
    if (isLocalShellTask(task) && !task.isBackgrounded && task.shellCommand) {
      return true
    }
    // Exclude main session tasks - they display in the main view, not as foreground tasks
    if (
      isLocalAgentTask(task) &&
      !task.isBackgrounded &&
      !isMainSessionTask(task)
    ) {
      return true
    }
    return false
  })
}

export function backgroundAll(
  getAppState: () => AppState,
  setAppState: SetAppState,
): void {
  const state = getAppState()

  // Background all foreground bash tasks
  const foregroundBashTaskIds = Object.keys(state.tasks).filter(id => {
    const task = state.tasks[id]
    return isLocalShellTask(task) && !task.isBackgrounded && task.shellCommand
  })
  for (const taskId of foregroundBashTaskIds) {
    backgroundTask(taskId, getAppState, setAppState)
  }

  // Background all foreground agent tasks
  const foregroundAgentTaskIds = Object.keys(state.tasks).filter(id => {
    const task = state.tasks[id]
    return isLocalAgentTask(task) && !task.isBackgrounded
  })
  for (const taskId of foregroundAgentTaskIds) {
    backgroundAgentTask(taskId, getAppState, setAppState)
  }
}

/**
 * Background an already-registered foreground task in-place.
 * Unlike spawn(), this does NOT re-register the task — it flips isBackgrounded
 * on the existing registration and sets up a completion handler.
 * Used when the auto-background timer fires after registerForeground() has
 * already registered the task (avoiding duplicate task_started SDK events
 * and leaked cleanup callbacks).
 */
export function backgroundExistingForegroundTask(
  taskId: string,
  shellCommand: ShellCommand,
  description: string,
  setAppState: SetAppState,
  toolUseId?: string,
): boolean {
  if (!shellCommand.background(taskId)) {
    return false
  }

  let agentId: AgentId | undefined
  setAppState(prev => {
    const prevTask = prev.tasks[taskId]
    if (!isLocalShellTask(prevTask) || prevTask.isBackgrounded) {
      return prev
    }
    agentId = prevTask.agentId
    return {
      ...prev,
      tasks: {
        ...prev.tasks,
        [taskId]: { ...prevTask, isBackgrounded: true },
      },
    }
  })

  const cancelStallWatchdog = startStallWatchdog(
    taskId,
    description,
    undefined,
    toolUseId,
    agentId,
  )

  // Set up result handler (mirrors backgroundTask's handler)
  void shellCommand.result.then(async result => {
    cancelStallWatchdog()
    await flushAndCleanup(shellCommand)
    let wasKilled = false
    let cleanupFn: (() => void) | undefined

    updateTaskState<LocalShellTaskState>(taskId, setAppState, t => {
      if (t.status === 'killed') {
        wasKilled = true
        return t
      }
      cleanupFn = t.unregisterCleanup
      return {
        ...t,
        status: result.code === 0 ? 'completed' : 'failed',
        result: { code: result.code, interrupted: result.interrupted },
        shellCommand: null,
        unregisterCleanup: undefined,
        endTime: Date.now(),
      }
    })

    cleanupFn?.()

    const finalStatus = wasKilled
      ? 'killed'
      : result.code === 0
        ? 'completed'
        : 'failed'
    enqueueShellNotification(
      taskId,
      description,
      finalStatus,
      result.code,
      setAppState,
      toolUseId,
      undefined,
      agentId,
    )

    void evictTaskOutput(taskId)
  })

  return true
}

/**
 * Mark a task as notified to suppress a pending enqueueShellNotification.
 * Used when backgrounding raced with completion — the tool result already
 * carries the full output, so the <task_notification> would be redundant.
 */
export function markTaskNotified(
  taskId: string,
  setAppState: SetAppState,
): void {
  updateTaskState(taskId, setAppState, t =>
    t.notified ? t : { ...t, notified: true },
  )
}

/**
 * Unregister a foreground task when the command completes without being backgrounded.
 */
export function unregisterForeground(
  taskId: string,
  setAppState: SetAppState,
): void {
  let cleanupFn: (() => void) | undefined

  setAppState(prev => {
    const task = prev.tasks[taskId]
    // Only remove if it's a foreground task (not backgrounded)
    if (!isLocalShellTask(task) || task.isBackgrounded) {
      return prev
    }

    // Capture cleanup function to call outside of updater
    cleanupFn = task.unregisterCleanup

    const { [taskId]: removed, ...rest } = prev.tasks
    return { ...prev, tasks: rest }
  })

  // Call cleanup outside of the state updater (avoid side effects in updater)
  cleanupFn?.()
}

async function flushAndCleanup(shellCommand: ShellCommand): Promise<void> {
  try {
    await shellCommand.taskOutput.flush()
    shellCommand.cleanup()
  } catch (error) {
    logError(error)
  }
}