import type {
  ApprovalRequest, ChatMessage, ChatRouteState, ChatUsage, ClarificationRequest, JsonValue, RpcEventFrame, ToolCall,
} from '@shared/types'
import { createId } from './id'
import { toolStatus } from '@shared/chatTools'
import { bool, number, record, string } from './normalize'

type MergePosition = 'append' | 'prepend' | 'snapshot'

function messageTime(message: ChatMessage): number {
  return message.timestamp < 10_000_000_000 ? message.timestamp * 1000 : message.timestamp
}

/**
 * Keep the conversation in its canonical chronological order even when a
 * history snapshot races a realtime event.  Sequence is preferred when both
 * rows carry one; otherwise timestamps retain the order supplied by Hermes.
 */
export function orderChatMessages(messages: ChatMessage[]): ChatMessage[] {
  return messages
    .map((message, index) => ({ message, index }))
    .sort((left, right) => {
      const leftSequence = left.message.sequence
      const rightSequence = right.message.sequence
      if (leftSequence !== undefined && rightSequence !== undefined && leftSequence !== rightSequence) {
        return leftSequence - rightSequence
      }
      const timeDelta = messageTime(left.message) - messageTime(right.message)
      return timeDelta || left.index - right.index
    })
    .map(({ message }) => message)
}

function sameMessage(left: ChatMessage, right: ChatMessage): boolean {
  if (left.id && right.id && left.id === right.id) return true
  return Boolean(left.clientMessageId && right.clientMessageId && left.clientMessageId === right.clientMessageId)
}

function mergeOne(previous: ChatMessage, incoming: ChatMessage): ChatMessage {
  const persistedUser = (message: ChatMessage) => message.role === 'user' && message.stage === 'settled'
    && message.serverMessageId === message.id && message.id !== message.clientMessageId && !message.id.startsWith('user:')
  // A late receipt or a cached optimistic row must not demote persisted history.
  if (persistedUser(previous) && !persistedUser(incoming)) [previous, incoming] = [incoming, previous]
  const replacesContent = Boolean(incoming.content) || Boolean(incoming.attachments?.length)
  return {
    ...previous,
    ...incoming,
    id: incoming.serverMessageId || incoming.stage === 'settled' ? incoming.id : previous.id,
    clientMessageId: incoming.clientMessageId ?? previous.clientMessageId,
    serverMessageId: incoming.serverMessageId ?? previous.serverMessageId,
    content: replacesContent ? incoming.content : previous.content,
    reasoning: incoming.reasoning ?? previous.reasoning,
    attachments: incoming.attachments?.length ? incoming.attachments : previous.attachments,
    toolCalls: incoming.toolCalls?.length ? incoming.toolCalls : previous.toolCalls,
  }
}

/** Merge only by server/client identity. Repeated text is always retained. */
export function mergeChatMessages(existing: ChatMessage[], incoming: ChatMessage[], position: MergePosition = 'append'): ChatMessage[] {
  const base = position === 'prepend' || position === 'snapshot' ? [...incoming, ...existing] : [...existing, ...incoming]
  const result: ChatMessage[] = []
  for (const message of base) {
    let merged = message
    let index: number
    let insertionIndex = result.length
    // An enriched history row can bridge both an old server row and its local
    // echo already in the cache. Consume every identity match, not just the first.
    while ((index = result.findIndex(candidate => sameMessage(candidate, merged))) >= 0) {
      insertionIndex = Math.min(insertionIndex, index)
      merged = mergeOne(result.splice(index, 1)[0]!, merged)
    }
    result.splice(insertionIndex, 0, merged)
  }
  return orderChatMessages(result)
}

function payloadRecord(event: RpcEventFrame['params']): Record<string, unknown> {
  return record(event.payload)
}

function eventSessionId(event: RpcEventFrame['params'], fallback: string): string {
  const payload = payloadRecord(event)
  return string(event.session_id ?? payload.session_id ?? payload.sessionId, fallback)
}

function eventMessageId(payload: Record<string, unknown>, fallback: string): string {
  return string(payload.message_id ?? payload.messageId ?? payload.id ?? payload.run_id ?? payload.runId, fallback)
}

function lastUserMessage(messages: ChatMessage[]): ChatMessage | undefined {
  return [...messages].reverse().find(message => message.role === 'user')
}

function lastStreamingAssistant(messages: ChatMessage[], afterLatestUser = false): ChatMessage | undefined {
  let latestUserIndex = -1
  if (afterLatestUser) {
    for (let index = messages.length - 1; index >= 0; index -= 1) {
      if (messages[index].role === 'user') {
        latestUserIndex = index
        break
      }
    }
  }
  return messages.slice(latestUserIndex + 1).reverse()
    .find(message => message.role === 'assistant' && message.isStreaming)
}

export function chatHasUnfinishedOutput(messages: ChatMessage[]): boolean {
  return messages.some(message => message.role === 'assistant'
    && message.toolCalls?.some(tool => ['pending', 'running'].includes(tool.status)))
}

export function settleChatMessages(messages: ChatMessage[], current?: ChatMessage, interruptUnfinishedTools = true): ChatMessage[] {
  return messages.map(message => message.role === 'assistant' && message !== current
    ? { ...message, stage: message.stage === 'streaming' ? 'settled' : message.stage, isStreaming: false,
      toolCalls: message.toolCalls?.map(tool => interruptUnfinishedTools && ['running', 'pending'].includes(tool.status)
        ? { ...tool, status: 'interrupted' }
        : tool) }
    : message)
}

function streamingSegmentId(state: ChatRouteState): string {
  const latestUser = lastUserMessage(state.messages)
  return `stream:${state.route.profile}:${state.route.sessionId}:${latestUser?.id ?? 'orphan'}:${createId('segment')}`
}

function sealInterimMessage(state: ChatRouteState, payload: Record<string, unknown>): ChatMessage[] {
  const content = string(payload.output ?? payload.text ?? payload.content)
  if (!content.trim()) return state.messages

  const current = lastStreamingAssistant(state.messages)
  const occurredAt = number(payload.timestamp ?? payload.created_at, Date.now() / 1000)
  const sealedId = current?.id ?? streamingSegmentId(state)
  const sealed: ChatMessage = {
    ...(current ?? {}),
    id: sealedId,
    clientMessageId: current?.clientMessageId ?? (sealedId.startsWith('stream:') ? sealedId : undefined),
    sessionId: state.route.sessionId,
    profile: state.route.profile,
    role: 'assistant',
    content,
    timestamp: current?.timestamp ?? occurredAt,
    stage: 'settled',
    isStreaming: false,
    raw: payload as JsonValue,
  }
  const nextId = streamingSegmentId(state)
  const next: ChatMessage = {
    id: nextId,
    clientMessageId: nextId,
    sessionId: state.route.sessionId,
    profile: state.route.profile,
    role: 'assistant',
    content: '',
    timestamp: occurredAt,
    stage: 'streaming',
    isStreaming: true,
    raw: { stream_interim_continuation: true },
  }
  return mergeChatMessages(mergeChatMessages(state.messages, [sealed]), [next])
}

function toolFromEvent(payload: Record<string, unknown>, status: ToolCall['status']): ToolCall {
  return {
    id: string(payload.tool_call_id ?? payload.toolCallId ?? payload.tool_id ?? payload.id, createId('tool')),
    name: string(payload.name ?? payload.tool_name, '工具'),
    status,
    arguments: (payload.arguments ?? payload.args ?? payload.context) as JsonValue | undefined,
    result: (payload.result ?? payload.output) as JsonValue | undefined,
    preview: string(payload.preview ?? payload.summary ?? payload.args_text) || undefined,
    error: string(payload.error) || undefined,
    durationSeconds: number(payload.duration_seconds ?? payload.duration_s) || undefined,
  }
}

function normalizeUsage(payload: Record<string, unknown>): ChatUsage | undefined {
  const raw = record(payload.usage ?? payload)
  if (!Object.keys(raw).length) return undefined
  return {
    inputTokens: number(raw.input_tokens ?? raw.input ?? raw.prompt) || undefined,
    outputTokens: number(raw.output_tokens ?? raw.output ?? raw.completion) || undefined,
    totalTokens: number(raw.total_tokens ?? raw.total) || undefined,
    contextTokens: number(raw.context_tokens ?? raw.context_used ?? raw.current_tokens ?? raw.used) || undefined,
    contextLimit: number(raw.context_limit ?? raw.context_max ?? raw.max_tokens ?? raw.limit) || undefined,
    percentUsed: number(raw.percent_used ?? raw.context_percent ?? raw.percentage) || undefined,
    raw: raw as JsonValue,
  }
}

function updateStreamingMessage(
  state: ChatRouteState,
  payload: Record<string, unknown>,
  mode: 'start' | 'delta' | 'reasoning' | 'complete' | 'failed',
): ChatMessage[] {
  // A start event belongs to the turn after the latest user row. An interrupted
  // turn may never receive a terminal event, so reusing any older streaming row
  // would make the new answer render above the new prompt.
  const current = lastStreamingAssistant(state.messages, mode === 'start')
  const fallbackId = current?.id ?? streamingSegmentId(state)
  const id = eventMessageId(payload, fallbackId)
  const existing = state.messages.find(message => message.id === id) ?? current
  const delta = string(payload.delta ?? payload.text_delta ?? payload.content_delta)
  const full = string(payload.output ?? payload.text ?? payload.content)
  const emptyInterimContinuation = mode === 'complete'
    && existing === current
    && bool(record(current?.raw).stream_interim_continuation)
    && !current?.content.trim()
    && !current?.reasoning?.trim()
    && !current?.toolCalls?.length
  if (emptyInterimContinuation && current) {
    const currentIndex = state.messages.indexOf(current)
    const previous = state.messages.slice(0, currentIndex).reverse()
      .find(message => message.role === 'assistant')
    const previousContent = previous?.content.trim() ?? ''
    const continuesPrevious = Boolean(full && previousContent
      && (full === previousContent || full.startsWith(previousContent) || previousContent.startsWith(full)))
    if (previous && (!full || bool(payload.response_previewed) || continuesPrevious)) {
      return orderChatMessages(state.messages
        .filter(message => message !== current)
        .map(message => message === previous && full
          ? { ...message, content: full, stage: 'settled', isStreaming: false, raw: payload as JsonValue }
          : message))
    }
  }
  let content = existing?.content ?? ''
  let reasoning = existing?.reasoning
  if (mode === 'delta') content += delta || full
  if (mode === 'complete') content = bool(payload.authoritative_output) && full ? full : full || content
  if (mode === 'reasoning') reasoning = `${reasoning ?? ''}${delta || full}`
  const message: ChatMessage = {
    id,
    // Keep a stable local identity while Hermes promotes a synthetic stream ID
    // to its authoritative message/run ID on a later event.
    clientMessageId: existing?.clientMessageId
      ?? (existing?.id.startsWith('stream:') ? existing.id : id.startsWith('stream:') ? id : undefined),
    serverMessageId: id.startsWith('stream:') ? undefined : id,
    sessionId: state.route.sessionId,
    profile: state.route.profile,
    role: 'assistant',
    content,
    reasoning,
    timestamp: number(payload.timestamp ?? payload.created_at, existing?.timestamp ?? Date.now() / 1000),
    stage: mode === 'complete' ? 'settled' : mode === 'failed' ? 'failed' : 'streaming',
    isStreaming: !['complete', 'failed'].includes(mode),
    error: mode === 'failed' ? string(payload.error ?? payload.message, '运行失败') : undefined,
    toolCalls: existing?.toolCalls,
    raw: payload as JsonValue,
  }
  const messages = mode === 'start' ? settleChatMessages(state.messages, current) : state.messages
  return mergeChatMessages(messages, [message])
}

export function applyChatEvent(state: ChatRouteState, event: RpcEventFrame['params']): ChatRouteState {
  if (event.type === 'gateway.ready') return state
  const payload = payloadRecord(event)
  if (eventSessionId(event, state.route.sessionId) !== state.route.sessionId) return state
  const next: ChatRouteState = { ...state, error: undefined }
  switch (event.type) {
    case 'run.peer_user_message':
    case 'peer.user.message': {
      const id=string(payload.message_id),clientMessageId=string(payload.client_message_id ?? payload.queue_id)
      const existing=state.messages.find(m=>m.id===id||m.clientMessageId===clientMessageId)
      const stage=payload.status==='failed'?'failed':payload.status==='accepted'?'accepted':existing?.stage??'pending'
      next.messages=mergeChatMessages(state.messages,[{...existing,id,clientMessageId,sessionId:state.route.sessionId,profile:state.route.profile,
        role:'user',content:string(payload.text ?? payload.content),timestamp:existing?.timestamp??number(payload.timestamp,Date.now()/1000),stage}])
      break
    }
    case 'message.start':
    case 'run.started':
      next.messages = updateStreamingMessage(state, payload, 'start')
      next.isStreaming = true
      next.isQueued = false
      break
    case 'message.delta':
    case 'content.delta':
    case 'assistant.delta':
      next.messages = updateStreamingMessage(state, payload, 'delta')
      next.isStreaming = true
      break
    case 'message.interim':
      // Hermes emits this after commentary that precedes a tool call. Seal the
      // visible text in place and start a fresh segment, otherwise later deltas
      // keep rewriting the older bubble until message.complete replaces it.
      next.messages = sealInterimMessage(state, payload)
      next.isStreaming = true
      break
    case 'reasoning.delta':
      next.messages = updateStreamingMessage(state, payload, 'reasoning')
      next.isStreaming = true
      break
    case 'thinking.delta':
    case 'status.update':
      next.liveStatus = string(payload.text ?? payload.message ?? payload.status) || undefined
      break
    case 'message.complete':
    case 'run.completed': {
      const terminalStatus = string(payload.status).trim().toLowerCase()
      const failed = terminalStatus === 'error' || terminalStatus === 'failed' || Boolean(payload.error)
      next.messages = updateStreamingMessage(state, payload, failed ? 'failed' : 'complete')
      const waitingForOutput = !failed && chatHasUnfinishedOutput(next.messages)
      next.messages = settleChatMessages(next.messages, undefined, !waitingForOutput)
      next.isStreaming = waitingForOutput
      next.isQueued = false
      next.liveStatus = undefined
      next.usage = normalizeUsage(payload) ?? next.usage
      if (failed) next.error = string(payload.error ?? payload.text ?? payload.message, '运行失败')
      break
    }
    case 'error':
    case 'run.failed':
      next.messages = updateStreamingMessage(state, payload, 'failed')
      next.messages = settleChatMessages(next.messages)
      next.isStreaming = false
      next.isQueued = false
      next.error = string(payload.error ?? payload.message, '运行失败')
      break
    case 'run.queued':
      next.isQueued = true
      break
    case 'run.steered':
    case 'submission.acknowledged':
      next.isQueued = false
      break
    case 'session.usage':
    case 'usage.update':
    case 'context.update':
      next.usage = normalizeUsage(payload)
      break
    case 'tool.start':
    case 'tool.progress':
    case 'tool.started':
    case 'tool.generating': {
      const id = string(payload.tool_call_id ?? payload.toolCallId ?? payload.tool_id ?? payload.id)
      if (!id) {
        next.liveStatus = `正在准备 ${string(payload.name ?? payload.tool_name, '工具')}`
        break
      }
      const current = lastStreamingAssistant(next.messages)
        ?? [...next.messages].reverse().find(message => message.role === 'assistant'
          && (message.toolCalls?.some(tool => tool.id === id)
            || message.toolCalls?.some(tool => ['pending', 'running'].includes(tool.status))))
        ?? [...next.messages].reverse().find(message => message.role === 'assistant')
      if (!current) break
      const tool = toolFromEvent(payload, 'running')
      const tools = [...(current.toolCalls ?? [])]
      const index = tools.findIndex(item => item.id === tool.id)
      if (index >= 0) tools[index] = { ...tools[index], ...tool,
        result: tool.result ?? tools[index].result,
        status: ['completed', 'failed'].includes(tools[index].status) ? tools[index].status : tool.status }
      else tools.push(tool)
      next.messages = mergeChatMessages(next.messages, [{ ...current, toolCalls: tools }])
      next.isStreaming = true
      next.liveStatus = undefined
      break
    }
    case 'tool.complete':
    case 'tool.completed':
    case 'tool.failed': {
      const id = string(payload.tool_call_id ?? payload.toolCallId ?? payload.tool_id ?? payload.id)
      if (!id) break
      const current = [...next.messages].reverse().find(message => message.role === 'assistant' && message.toolCalls?.some(tool => tool.id === id))
        ?? lastStreamingAssistant(next.messages)
      if (!current) break
      const tool = toolFromEvent(payload, toolStatus(event.type, payload.result ?? payload.output, payload.error))
      const tools = [...(current.toolCalls ?? [])]
      const index = tools.findIndex(item => item.id === tool.id)
      if (index >= 0) tools[index] = { ...tools[index], ...tool }
      else tools.push(tool)
      next.messages = mergeChatMessages(next.messages, [{ ...current, toolCalls: tools }])
      if (!chatHasUnfinishedOutput(next.messages) && !next.messages.some(message => message.isStreaming)) {
        next.isStreaming = false
        next.isQueued = false
        next.liveStatus = undefined
      }
      break
    }
    case 'approval.request':
    case 'approval.requested': {
      const id = string(payload.request_id ?? payload.requestId ?? payload.id)
      if (id) next.pendingApproval = {
        id, sessionId: state.route.sessionId, message: string(payload.message ?? payload.prompt) || undefined,
        toolName: string(payload.tool_name ?? payload.tool) || undefined,
        choices: Array.isArray(payload.choices) ? payload.choices.map(String) : undefined,
        payload: payload as Record<string, JsonValue>,
      } satisfies ApprovalRequest
      break
    }
    case 'approval.resolved':
      next.pendingApproval = undefined
      break
    case 'clarify.request':
    case 'clarify.requested': {
      const id = string(payload.request_id ?? payload.requestId ?? payload.id)
      if (id) next.pendingClarification = {
        id, sessionId: state.route.sessionId, question: string(payload.question ?? payload.message ?? payload.prompt, '需要补充信息'),
        choices: Array.isArray(payload.choices) ? payload.choices.map(String) : undefined,
        payload: payload as Record<string, JsonValue>,
      } satisfies ClarificationRequest
      break
    }
    case 'clarify.expire':
    case 'clarify.resolved':
      next.pendingClarification = undefined
      break
  }
  return next
}