import type {
  ContentBlockParam,
  TextBlockParam,
} from '@anthropic-ai/sdk/resources/index.mjs'
import { randomUUID, type UUID } from 'crypto'
import figures from 'figures'
import * as React from 'react'
import { useCallback, useEffect, useMemo, useState } from 'react'
import {
  type AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
  logEvent,
} from 'src/services/analytics/index.js'
import { useAppState } from 'src/state/AppState.js'
import {
  type DiffStats,
  fileHistoryCanRestore,
  fileHistoryEnabled,
  fileHistoryGetDiffStats,
} from 'src/utils/fileHistory.js'
import { logError } from 'src/utils/log.js'
import { useExitOnCtrlCDWithKeybindings } from '../hooks/useExitOnCtrlCDWithKeybindings.js'
import { Box, Text, Divider } from '@anthropic/ink'
import { useKeybinding, useKeybindings } from '../keybindings/useKeybinding.js'
import type {
  Message,
  PartialCompactDirection,
  UserMessage,
} from '../types/message.js'
import { stripDisplayTags } from '../utils/displayTags.js'
import {
  createUserMessage,
  extractTag,
  isEmptyMessageText,
  isSyntheticMessage,
  isToolUseResultMessage,
} from '../utils/messages.js'
import { type OptionWithDescription, Select } from './CustomSelect/select.js'
import { Spinner } from './Spinner.js'

function isTextBlock(block: ContentBlockParam): block is TextBlockParam {
  return block.type === 'text'
}

import * as path from 'path'
import { useTerminalSize } from 'src/hooks/useTerminalSize.js'
import type { FileEditOutput } from '@claude-code-best/builtin-tools/tools/FileEditTool/types.js'
import type { Output as FileWriteToolOutput } from '@claude-code-best/builtin-tools/tools/FileWriteTool/FileWriteTool.js'
import {
  BASH_STDERR_TAG,
  BASH_STDOUT_TAG,
  COMMAND_MESSAGE_TAG,
  LOCAL_COMMAND_STDERR_TAG,
  LOCAL_COMMAND_STDOUT_TAG,
  TASK_NOTIFICATION_TAG,
  TEAMMATE_MESSAGE_TAG,
  TICK_TAG,
} from '../constants/xml.js'
import { count } from '../utils/array.js'
import { formatRelativeTimeAgo, truncate } from '../utils/format.js'
import type { Theme } from '../utils/theme.js'
type RestoreOption =
  | 'both'
  | 'conversation'
  | 'code'
  | 'summarize'
  | 'summarize_up_to'
  | 'nevermind'

function isSummarizeOption(
  option: RestoreOption | null,
): option is 'summarize' | 'summarize_up_to' {
  return option === 'summarize' || option === 'summarize_up_to'
}

type Props = {
  messages: Message[]
  onPreRestore: () => void
  onRestoreMessage: (message: UserMessage) => Promise<void>
  onRestoreCode: (message: UserMessage) => Promise<void>
  onSummarize: (
    message: UserMessage,
    feedback?: string,
    direction?: PartialCompactDirection,
  ) => Promise<void>
  onClose: () => void
  /** Skip pick-list, land on confirm. Caller ran skip-check first. Esc closes fully (no back-to-list). */
  preselectedMessage?: UserMessage
}

const MAX_VISIBLE_MESSAGES = 7

export function MessageSelector({
  messages,
  onPreRestore,
  onRestoreMessage,
  onRestoreCode,
  onSummarize,
  onClose,
  preselectedMessage,
}: Props): React.ReactNode {
  const fileHistory = useAppState(s => s.fileHistory)
  const [error, setError] = useState<string | undefined>(undefined)
  const isFileHistoryEnabled = fileHistoryEnabled()

  // Add current prompt as a virtual message
  const currentUUID = useMemo(randomUUID, [])
  const messageOptions = useMemo(
    () => [
      ...messages.filter(selectableUserMessagesFilter),
      {
        ...createUserMessage({
          content: '',
        }),
        uuid: currentUUID,
      } as UserMessage,
    ],
    [messages, currentUUID],
  )
  const [selectedIndex, setSelectedIndex] = useState(messageOptions.length - 1)

  // Orient the selected message as the middle of the visible options
  const firstVisibleIndex = Math.max(
    0,
    Math.min(
      selectedIndex - Math.floor(MAX_VISIBLE_MESSAGES / 2),
      messageOptions.length - MAX_VISIBLE_MESSAGES,
    ),
  )

  const hasMessagesToSelect = messageOptions.length > 1

  const [messageToRestore, setMessageToRestore] = useState<
    UserMessage | undefined
  >(preselectedMessage)
  const [diffStatsForRestore, setDiffStatsForRestore] = useState<
    DiffStats | undefined
  >(undefined)

  useEffect(() => {
    if (!preselectedMessage || !isFileHistoryEnabled) return
    let cancelled = false
    void fileHistoryGetDiffStats(fileHistory, preselectedMessage.uuid).then(
      stats => {
        if (!cancelled) setDiffStatsForRestore(stats)
      },
    )
    return () => {
      cancelled = true
    }
  }, [preselectedMessage, isFileHistoryEnabled, fileHistory])

  const [isRestoring, setIsRestoring] = useState(false)
  const [restoringOption, setRestoringOption] = useState<RestoreOption | null>(
    null,
  )
  const [selectedRestoreOption, setSelectedRestoreOption] =
    useState<RestoreOption>('both')
  // Per-option feedback state; Select's internal inputValues Map persists
  // per-option text independently, so sharing one variable would desync.
  const [summarizeFromFeedback, setSummarizeFromFeedback] = useState('')
  const [summarizeUpToFeedback, setSummarizeUpToFeedback] = useState('')

  // Generate options with summarize as input type for inline context
  function getRestoreOptions(
    canRestoreCode: boolean,
  ): OptionWithDescription<RestoreOption>[] {
    const baseOptions: OptionWithDescription<RestoreOption>[] = canRestoreCode
      ? [
          { value: 'both', label: 'Restore code and conversation' },
          { value: 'conversation', label: 'Restore conversation' },
          { value: 'code', label: 'Restore code' },
        ]
      : [{ value: 'conversation', label: 'Restore conversation' }]

    const summarizeInputProps = {
      type: 'input' as const,
      placeholder: 'add context (optional)',
      initialValue: '',
      allowEmptySubmitToCancel: true,
      showLabelWithValue: true,
      labelValueSeparator: ': ',
    }
    baseOptions.push({
      value: 'summarize',
      label: 'Summarize from here',
      ...summarizeInputProps,
      onChange: setSummarizeFromFeedback,
    })
    if (process.env.USER_TYPE === 'ant') {
      baseOptions.push({
        value: 'summarize_up_to',
        label: 'Summarize up to here',
        ...summarizeInputProps,
        onChange: setSummarizeUpToFeedback,
      })
    }

    baseOptions.push({ value: 'nevermind', label: 'Never mind' })
    return baseOptions
  }

  // Log when selector is opened
  useEffect(() => {
    logEvent('tengu_message_selector_opened', {})
  }, [])

  // Helper to restore conversation without confirmation
  async function restoreConversationDirectly(message: UserMessage) {
    onPreRestore()
    setIsRestoring(true)
    try {
      await onRestoreMessage(message)
      setIsRestoring(false)
      onClose()
    } catch (error) {
      logError(error as Error)
      setIsRestoring(false)
      setError(`Failed to restore the conversation:\n${error}`)
    }
  }

  async function handleSelect(message: UserMessage) {
    const index = messages.indexOf(message)
    const indexFromEnd = messages.length - 1 - index

    logEvent('tengu_message_selector_selected', {
      index_from_end: indexFromEnd,
      message_type:
        message.type as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
      is_current_prompt: false,
    })

    // Do nothing if the message is not found
    if (!messages.includes(message)) {
      onClose()
      return
    }

    if (!isFileHistoryEnabled) {
      await restoreConversationDirectly(message)
      return
    }

    const diffStats = await fileHistoryGetDiffStats(fileHistory, message.uuid)
    setMessageToRestore(message)
    setDiffStatsForRestore(diffStats)
  }

  async function onSelectRestoreOption(option: RestoreOption) {
    logEvent('tengu_message_selector_restore_option_selected', {
      option:
        option as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
    })
    if (!messageToRestore) {
      setError('Message not found.')
      return
    }
    if (option === 'nevermind') {
      if (preselectedMessage) onClose()
      else setMessageToRestore(undefined)
      return
    }

    if (isSummarizeOption(option)) {
      onPreRestore()
      setIsRestoring(true)
      setRestoringOption(option)
      setError(undefined)
      try {
        const direction = option === 'summarize_up_to' ? 'up_to' : 'from'
        const feedback =
          (direction === 'up_to'
            ? summarizeUpToFeedback
            : summarizeFromFeedback
          ).trim() || undefined
        await onSummarize(messageToRestore, feedback, direction)
        setIsRestoring(false)
        setRestoringOption(null)
        setMessageToRestore(undefined)
        onClose()
      } catch (error) {
        logError(error as Error)
        setIsRestoring(false)
        setRestoringOption(null)
        setMessageToRestore(undefined)
        setError(`Failed to summarize:\n${error}`)
      }
      return
    }

    onPreRestore()
    setIsRestoring(true)
    setError(undefined)

    let codeError: Error | null = null
    let conversationError: Error | null = null

    if (option === 'code' || option === 'both') {
      try {
        await onRestoreCode(messageToRestore)
      } catch (error) {
        codeError = error as Error
        logError(codeError)
      }
    }

    if (option === 'conversation' || option === 'both') {
      try {
        await onRestoreMessage(messageToRestore)
      } catch (error) {
        conversationError = error as Error
        logError(conversationError)
      }
    }

    setIsRestoring(false)
    setMessageToRestore(undefined)

    // Handle errors
    if (conversationError && codeError) {
      setError(
        `Failed to restore the conversation and code:\n${conversationError}\n${codeError}`,
      )
    } else if (conversationError) {
      setError(`Failed to restore the conversation:\n${conversationError}`)
    } else if (codeError) {
      setError(`Failed to restore the code:\n${codeError}`)
    } else {
      // Success - close the selector
      onClose()
    }
  }

  const exitState = useExitOnCtrlCDWithKeybindings()

  const handleEscape = useCallback(() => {
    if (messageToRestore && !preselectedMessage) {
      // Go back to message list instead of closing entirely
      setMessageToRestore(undefined)
      return
    }
    logEvent('tengu_message_selector_cancelled', {})
    onClose()
  }, [onClose, messageToRestore, preselectedMessage])

  const moveUp = useCallback(
    () => setSelectedIndex(prev => Math.max(0, prev - 1)),
    [],
  )
  const moveDown = useCallback(
    () =>
      setSelectedIndex(prev => Math.min(messageOptions.length - 1, prev + 1)),
    [messageOptions.length],
  )
  const jumpToTop = useCallback(() => setSelectedIndex(0), [])
  const jumpToBottom = useCallback(
    () => setSelectedIndex(messageOptions.length - 1),
    [messageOptions.length],
  )
  const handleSelectCurrent = useCallback(() => {
    const selected = messageOptions[selectedIndex]
    if (selected) {
      void handleSelect(selected)
    }
  }, [messageOptions, selectedIndex, handleSelect])

  // Escape to close - uses Confirmation context where escape is bound
  useKeybinding('confirm:no', handleEscape, {
    context: 'Confirmation',
    isActive: !messageToRestore,
  })

  // Message selector navigation keybindings
  useKeybindings(
    {
      'messageSelector:up': moveUp,
      'messageSelector:down': moveDown,
      'messageSelector:top': jumpToTop,
      'messageSelector:bottom': jumpToBottom,
      'messageSelector:select': handleSelectCurrent,
    },
    {
      context: 'MessageSelector',
      isActive:
        !isRestoring && !error && !messageToRestore && hasMessagesToSelect,
    },
  )

  const [fileHistoryMetadata, setFileHistoryMetadata] = useState<
    Record<number, DiffStats>
  >({})

  useEffect(() => {
    async function loadFileHistoryMetadata() {
      if (!isFileHistoryEnabled) {
        return
      }
      // Load file snapshot metadata
      void Promise.all(
        messageOptions.map(async (userMessage, itemIndex) => {
          if (userMessage.uuid !== currentUUID) {
            const canRestore = fileHistoryCanRestore(
              fileHistory,
              userMessage.uuid,
            )

            const nextUserMessage = messageOptions.at(itemIndex + 1)
            const diffStats = canRestore
              ? computeDiffStatsBetweenMessages(
                  messages,
                  userMessage.uuid,
                  nextUserMessage?.uuid !== currentUUID
                    ? nextUserMessage?.uuid
                    : undefined,
                )
              : undefined

            if (diffStats !== undefined) {
              setFileHistoryMetadata(prev => ({
                ...prev,
                [itemIndex]: diffStats,
              }))
            } else {
              setFileHistoryMetadata(prev => ({
                ...prev,
                [itemIndex]: undefined,
              }))
            }
          }
        }),
      )
    }
    void loadFileHistoryMetadata()
  }, [messageOptions, messages, currentUUID, fileHistory, isFileHistoryEnabled])

  const canRestoreCode =
    isFileHistoryEnabled &&
    diffStatsForRestore?.filesChanged &&
    diffStatsForRestore.filesChanged.length > 0
  const showPickList =
    !error && !messageToRestore && !preselectedMessage && hasMessagesToSelect

  return (
    <Box flexDirection="column" width="100%">
      <Divider color="suggestion" />
      <Box flexDirection="column" marginX={1} gap={1}>
        <Text bold color="suggestion">
          Rewind
        </Text>

        {error && (
          <>
            <Text color="error">Error: {error}</Text>
          </>
        )}
        {!hasMessagesToSelect && (
          <>
            <Text>Nothing to rewind to yet.</Text>
          </>
        )}
        {!error && messageToRestore && hasMessagesToSelect && (
          <>
            <Text>
              Confirm you want to restore{' '}
              {!diffStatsForRestore && 'the conversation '}to the point before
              you sent this message:
            </Text>
            <Box
              flexDirection="column"
              paddingLeft={1}
              borderStyle="single"
              borderRight={false}
              borderTop={false}
              borderBottom={false}
              borderLeft={true}
              borderLeftDimColor
            >
              <UserMessageOption
                userMessage={messageToRestore}
                color="text"
                isCurrent={false}
              />
              <Text dimColor>
                ({formatRelativeTimeAgo(new Date(messageToRestore.timestamp as string | number | Date))})
              </Text>
            </Box>
            <RestoreOptionDescription
              selectedRestoreOption={selectedRestoreOption}
              canRestoreCode={!!canRestoreCode}
              diffStatsForRestore={diffStatsForRestore}
            />
            {isRestoring && isSummarizeOption(restoringOption) ? (
              <Box flexDirection="row" gap={1}>
                <Spinner />
                <Text>Summarizing…</Text>
              </Box>
            ) : (
              <Select
                isDisabled={isRestoring}
                options={getRestoreOptions(!!canRestoreCode)}
                defaultFocusValue={canRestoreCode ? 'both' : 'conversation'}
                onFocus={value =>
                  setSelectedRestoreOption(value as RestoreOption)
                }
                onChange={value =>
                  onSelectRestoreOption(value as RestoreOption)
                }
                onCancel={() =>
                  preselectedMessage
                    ? onClose()
                    : setMessageToRestore(undefined)
                }
              />
            )}
            {canRestoreCode && (
              <Box marginBottom={1}>
                <Text dimColor>
                  {figures.warning} Rewinding does not affect files edited
                  manually or via bash.
                </Text>
              </Box>
            )}
          </>
        )}
        {showPickList && (
          <>
            {isFileHistoryEnabled ? (
              <Text>
                Restore the code and/or conversation to the point before…
              </Text>
            ) : (
              <Text>
                Restore and fork the conversation to the point before…
              </Text>
            )}
            <Box width="100%" flexDirection="column">
              {messageOptions
                .slice(
                  firstVisibleIndex,
                  firstVisibleIndex + MAX_VISIBLE_MESSAGES,
                )
                .map((msg, visibleOptionIndex) => {
                  const optionIndex = firstVisibleIndex + visibleOptionIndex
                  const isSelected = optionIndex === selectedIndex
                  const isCurrent = msg.uuid === currentUUID

                  const metadataLoaded = optionIndex in fileHistoryMetadata
                  const metadata = fileHistoryMetadata[optionIndex]
                  const numFilesChanged =
                    metadata?.filesChanged && metadata.filesChanged.length

                  return (
                    <Box
                      key={msg.uuid}
                      height={isFileHistoryEnabled ? 3 : 2}
                      overflow="hidden"
                      width="100%"
                      flexDirection="row"
                    >
                      <Box width={2} minWidth={2}>
                        {isSelected ? (
                          <Text color="permission" bold>
                            {figures.pointer}{' '}
                          </Text>
                        ) : (
                          <Text>{'  '}</Text>
                        )}
                      </Box>
                      <Box flexDirection="column">
                        <Box flexShrink={1} height={1} overflow="hidden">
                          <UserMessageOption
                            userMessage={msg}
                            color={isSelected ? 'suggestion' : undefined}
                            isCurrent={isCurrent}
                            paddingRight={10}
                          />
                        </Box>
                        {isFileHistoryEnabled && metadataLoaded && (
                          <Box height={1} flexDirection="row">
                            {metadata ? (
                              <>
                                <Text dimColor={!isSelected} color="inactive">
                                  {numFilesChanged ? (
                                    <>
                                      {numFilesChanged === 1 &&
                                      metadata.filesChanged![0]
                                        ? `${path.basename(metadata.filesChanged![0])} `
                                        : `${numFilesChanged} files changed `}
                                      <DiffStatsText diffStats={metadata} />
                                    </>
                                  ) : (
                                    <>No code changes</>
                                  )}
                                </Text>
                              </>
                            ) : (
                              <Text dimColor color="warning">
                                {figures.warning} No code restore
                              </Text>
                            )}
                          </Box>
                        )}
                      </Box>
                    </Box>
                  )
                })}
            </Box>
          </>
        )}
        {!messageToRestore && (
          <Text dimColor italic>
            {exitState.pending ? (
              <>Press {exitState.keyName} again to exit</>
            ) : (
              <>
                {!error && hasMessagesToSelect && 'Enter to continue · '}Esc to
                exit
              </>
            )}
          </Text>
        )}
      </Box>
    </Box>
  )
}

function getRestoreOptionConversationText(option: RestoreOption): string {
  switch (option) {
    case 'summarize':
      return 'Messages after this point will be summarized.'
    case 'summarize_up_to':
      return 'Preceding messages will be summarized. This and subsequent messages will remain unchanged — you will stay at the end of the conversation.'
    case 'both':
    case 'conversation':
      return 'The conversation will be forked.'
    case 'code':
    case 'nevermind':
      return 'The conversation will be unchanged.'
  }
}

function RestoreOptionDescription({
  selectedRestoreOption,
  canRestoreCode,
  diffStatsForRestore,
}: {
  selectedRestoreOption: RestoreOption
  canRestoreCode: boolean
  diffStatsForRestore: DiffStats | undefined
}): React.ReactNode {
  const showCodeRestore =
    canRestoreCode &&
    (selectedRestoreOption === 'both' || selectedRestoreOption === 'code')

  return (
    <Box flexDirection="column">
      <Text dimColor>
        {getRestoreOptionConversationText(selectedRestoreOption)}
      </Text>
      {!isSummarizeOption(selectedRestoreOption) &&
        (showCodeRestore ? (
          <RestoreCodeConfirmation diffStatsForRestore={diffStatsForRestore} />
        ) : (
          <Text dimColor>The code will be unchanged.</Text>
        ))}
    </Box>
  )
}

function RestoreCodeConfirmation({
  diffStatsForRestore,
}: {
  diffStatsForRestore: DiffStats | undefined
}): React.ReactNode {
  if (diffStatsForRestore === undefined) {
    return undefined
  }
  if (
    !diffStatsForRestore.filesChanged ||
    !diffStatsForRestore.filesChanged[0]
  ) {
    return (
      <Text dimColor>The code has not changed (nothing will be restored).</Text>
    )
  }

  const numFilesChanged = diffStatsForRestore.filesChanged.length

  let fileLabel = ''
  if (numFilesChanged === 1) {
    fileLabel = path.basename(diffStatsForRestore.filesChanged[0] || '')
  } else if (numFilesChanged === 2) {
    const file1 = path.basename(diffStatsForRestore.filesChanged[0] || '')
    const file2 = path.basename(diffStatsForRestore.filesChanged[1] || '')
    fileLabel = `${file1} and ${file2}`
  } else {
    const file1 = path.basename(diffStatsForRestore.filesChanged[0] || '')
    fileLabel = `${file1} and ${diffStatsForRestore.filesChanged.length - 1} other files`
  }

  return (
    <>
      <Text dimColor>
        The code will be restored{' '}
        <DiffStatsText diffStats={diffStatsForRestore} /> in {fileLabel}.
      </Text>
    </>
  )
}

function DiffStatsText({
  diffStats,
}: {
  diffStats: DiffStats | undefined
}): React.ReactNode {
  if (!diffStats || !diffStats.filesChanged) {
    return undefined
  }
  return (
    <>
      <Text color="diffAddedWord">+{diffStats.insertions} </Text>
      <Text color="diffRemovedWord">-{diffStats.deletions}</Text>
    </>
  )
}

function UserMessageOption({
  userMessage,
  color,
  dimColor,
  isCurrent,
  paddingRight,
}: {
  userMessage: UserMessage
  color?: keyof Theme
  dimColor?: boolean
  isCurrent: boolean
  paddingRight?: number
}): React.ReactNode {
  const { columns } = useTerminalSize()
  if (isCurrent) {
    return (
      <Box width="100%">
        <Text italic color={color} dimColor={dimColor}>
          (current)
        </Text>
      </Box>
    )
  }

  const content = userMessage.message!.content
  const lastBlock =
    typeof content === 'string' ? null : content![content!.length - 1]
  const rawMessageText =
    typeof content === 'string'
      ? content.trim()
      : lastBlock && isTextBlock(lastBlock)
        ? lastBlock.text.trim()
        : '(no prompt)'

  // Strip display-unfriendly tags (like <ide_opened_file>) before showing in the list
  const messageText = stripDisplayTags(rawMessageText)

  if (isEmptyMessageText(messageText)) {
    return (
      <Box flexDirection="row" width="100%">
        <Text italic color={color} dimColor={dimColor}>
          ((empty message))
        </Text>
      </Box>
    )
  }

  // Bash inputs
  if (messageText.includes('<bash-input>')) {
    const input = extractTag(messageText, 'bash-input')
    if (input) {
      return (
        <Box flexDirection="row" width="100%">
          <Text color="bashBorder">!</Text>
          <Text color={color} dimColor={dimColor}>
            {' '}
            {input}
          </Text>
        </Box>
      )
    }
  }

  // Skills and slash commands
  if (messageText.includes(`<${COMMAND_MESSAGE_TAG}>`)) {
    const commandMessage = extractTag(messageText, COMMAND_MESSAGE_TAG)
    const args = extractTag(messageText, 'command-args')
    const isSkillFormat = extractTag(messageText, 'skill-format') === 'true'
    if (commandMessage) {
      if (isSkillFormat) {
        // Skills: Display as "Skill(name)"
        return (
          <Box flexDirection="row" width="100%">
            <Text color={color} dimColor={dimColor}>
              Skill({commandMessage})
            </Text>
          </Box>
        )
      } else {
        // Slash commands: Add "/" prefix and include args
        return (
          <Box flexDirection="row" width="100%">
            <Text color={color} dimColor={dimColor}>
              /{commandMessage} {args}
            </Text>
          </Box>
        )
      }
    }
  }

  // User prompts
  return (
    <Box flexDirection="row" width="100%">
      <Text color={color} dimColor={dimColor}>
        {paddingRight
          ? truncate(messageText, columns - paddingRight, true)
          : messageText.slice(0, 500).split('\n').slice(0, 4).join('\n')}
      </Text>
    </Box>
  )
}

/**
 * Computes the diff stats for all the file edits in-between two messages.
 */
function computeDiffStatsBetweenMessages(
  messages: Message[],
  fromMessageId: UUID,
  toMessageId: UUID | undefined,
): DiffStats | undefined {
  const startIndex = messages.findIndex(msg => msg.uuid === fromMessageId)
  if (startIndex === -1) {
    return undefined
  }

  let endIndex = toMessageId
    ? messages.findIndex(msg => msg.uuid === toMessageId)
    : messages.length
  if (endIndex === -1) {
    endIndex = messages.length
  }

  const filesChanged: string[] = []
  let insertions = 0
  let deletions = 0

  for (let i = startIndex + 1; i < endIndex; i++) {
    const msg = messages[i]
    if (!msg || !isToolUseResultMessage(msg)) {
      continue
    }

    const result = msg.toolUseResult as FileEditOutput | FileWriteToolOutput
    if (!result || !result.filePath || !result.structuredPatch) {
      continue
    }

    if (!filesChanged.includes(result.filePath)) {
      filesChanged.push(result.filePath)
    }

    try {
      if ('type' in result && result.type === 'create') {
        insertions += result.content.split(/\r?\n/).length
      } else {
        for (const hunk of result.structuredPatch) {
          const additions = count(hunk.lines, line => line.startsWith('+'))
          const removals = count(hunk.lines, line => line.startsWith('-'))

          insertions += additions
          deletions += removals
        }
      }
    } catch {
    }
  }

  return {
    filesChanged,
    insertions,
    deletions,
  }
}

export function selectableUserMessagesFilter(
  message: Message,
): message is UserMessage {
  if (message.type !== 'user') {
    return false
  }
  if (
    Array.isArray(message.message!.content) &&
    message.message!.content[0]?.type === 'tool_result'
  ) {
    return false
  }
  if (isSyntheticMessage(message)) {
    return false
  }
  if (message.isMeta) {
    return false
  }
  if (message.isCompactSummary || message.isVisibleInTranscriptOnly) {
    return false
  }

  const content = message.message!.content
  const lastBlock =
    typeof content === 'string' ? null : content![content!.length - 1]
  const messageText =
    typeof content === 'string'
      ? content.trim()
      : lastBlock && isTextBlock(lastBlock)
        ? lastBlock.text.trim()
        : ''

  // Filter out non-user-authored messages (command outputs, task notifications, ticks).
  if (
    messageText.indexOf(`<${LOCAL_COMMAND_STDOUT_TAG}>`) !== -1 ||
    messageText.indexOf(`<${LOCAL_COMMAND_STDERR_TAG}>`) !== -1 ||
    messageText.indexOf(`<${BASH_STDOUT_TAG}>`) !== -1 ||
    messageText.indexOf(`<${BASH_STDERR_TAG}>`) !== -1 ||
    messageText.indexOf(`<${TASK_NOTIFICATION_TAG}>`) !== -1 ||
    messageText.indexOf(`<${TICK_TAG}>`) !== -1 ||
    messageText.indexOf(`<${TEAMMATE_MESSAGE_TAG}`) !== -1
  ) {
    return false
  }
  return true
}

/**
 * Checks if all messages after the given index are synthetic (interruptions, cancels, etc.)
 * or non-meaningful content. Returns true if there's nothing meaningful to confirm -
 * for example, if the user hit enter then immediately cancelled.
 */
export function messagesAfterAreOnlySynthetic(
  messages: Message[],
  fromIndex: number,
): boolean {
  for (let i = fromIndex + 1; i < messages.length; i++) {
    const msg = messages[i]
    if (!msg) continue

    // Skip known non-meaningful message types
    if (isSyntheticMessage(msg)) continue
    if (isToolUseResultMessage(msg)) continue
    if (msg.type === 'progress') continue
    if (msg.type === 'system') continue
    if (msg.type === 'attachment') continue
    if (msg.type === 'user' && msg.isMeta) continue

    // Assistant with actual content = meaningful
    if (msg.type === 'assistant') {
      const content = msg.message!.content
      if (Array.isArray(content)) {
        const hasMeaningfulContent = content.some(
          block =>
            (block.type === 'text' && block.text.trim()) ||
            block.type === 'tool_use',
        )
        if (hasMeaningfulContent) return false
      }
      continue
    }

    // User messages that aren't synthetic or meta = meaningful
    if (msg.type === 'user') {
      return false
    }

    // Other types (e.g., tombstone) are non-meaningful, continue
  }
  return true
}