import { io, type Socket } from 'socket.io-client'
import { request, getBaseUrlValue, getApiKey } from '../client'

export interface ChatMessage {
  role: 'user' | 'assistant' | 'system'
  content: string
}

export interface StartRunRequest {
  input: string | ChatMessage[]
  instructions?: string
  session_id?: string
  model?: string
}

export interface StartRunResponse {
  run_id: string
  status: string
}

// SSE event types from /v1/runs/{id}/events
export interface RunEvent {
  event: string
  run_id?: string
  delta?: string
  /** Payload text for `reasoning.delta` / `thinking.delta` / `reasoning.available` events. */
  text?: string
  tool?: string
  name?: string
  preview?: string
  timestamp?: number
  error?: string
  /** Final response text on `run.completed`. May be empty/null if the agent
   * silently swallowed an upstream error — see chat store for fallback. */
  output?: string | null
  usage?: {
    input_tokens: number
    output_tokens: number
    total_tokens: number
  }
  /** session_id tag added by server for client-side filtering */
  session_id?: string
}

// ============================
// Socket.IO chat run connection
// ============================

let chatRunSocket: Socket | null = null
let globalListenersRegistered = false

/**
 * Session event handlers map
 * Maps session_id to event handling functions for isolating concurrent session streams
 */
const sessionEventHandlers = new Map<string, {
  onMessageDelta: (event: RunEvent) => void
  onReasoningDelta: (event: RunEvent) => void
  onThinkingDelta: (event: RunEvent) => void
  onReasoningAvailable: (event: RunEvent) => void
  onToolStarted: (event: RunEvent) => void
  onToolCompleted: (event: RunEvent) => void
  onRunStarted: (event: RunEvent) => void
  onRunCompleted: (event: RunEvent) => void
  onRunFailed: (event: RunEvent) => void
  onCompressionStarted: (event: RunEvent) => void
  onCompressionCompleted: (event: RunEvent) => void
  onUsageUpdated: (event: RunEvent) => void
}>()

/**
 * Global message.delta event handler
 * Distributes events to appropriate session based on session_id
 */
function globalMessageDeltaHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onMessageDelta) {
    handlers.onMessageDelta(event)
  }
}

/**
 * Global reasoning.delta event handler
 */
function globalReasoningDeltaHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onReasoningDelta) {
    handlers.onReasoningDelta(event)
  }
}

/**
 * Global thinking.delta event handler (alias for reasoning.delta)
 */
function globalThinkingDeltaHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onThinkingDelta) {
    handlers.onThinkingDelta(event)
  }
}

/**
 * Global reasoning.available event handler
 */
function globalReasoningAvailableHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onReasoningAvailable) {
    handlers.onReasoningAvailable(event)
  }
}

/**
 * Global tool.started event handler
 */
function globalToolStartedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onToolStarted) {
    handlers.onToolStarted(event)
  }
}

/**
 * Global tool.completed event handler
 */
function globalToolCompletedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onToolCompleted) {
    handlers.onToolCompleted(event)
  }
}

/**
 * Global run.started event handler
 */
function globalRunStartedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onRunStarted) {
    handlers.onRunStarted(event)
  }
}

/**
 * Global run.completed event handler
 */
function globalRunCompletedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onRunCompleted) {
    handlers.onRunCompleted(event)
  }

  // Auto-cleanup session handlers on completion
  sessionEventHandlers.delete(sid)
}

/**
 * Global run.failed event handler
 */
function globalRunFailedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onRunFailed) {
    handlers.onRunFailed(event)
  }

  // Auto-cleanup session handlers on failure
  sessionEventHandlers.delete(sid)
}

/**
 * Global compression.started event handler
 */
function globalCompressionStartedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onCompressionStarted) {
    handlers.onCompressionStarted(event)
  }
}

/**
 * Global compression.completed event handler
 */
function globalCompressionCompletedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onCompressionCompleted) {
    handlers.onCompressionCompleted(event)
  }
}

/**
 * Global usage.updated event handler
 */
function globalUsageUpdatedHandler(event: RunEvent): void {
  const sid = event.session_id
  if (!sid) return

  const handlers = sessionEventHandlers.get(sid)
  if (handlers?.onUsageUpdated) {
    handlers.onUsageUpdated(event)
  }
}

/**
 * Register event handlers for a session
 * @param sessionId - Session ID
 * @param handlers - Event handling functions
 * @returns Cleanup function to unregister handlers
 */
export function registerSessionHandlers(
  sessionId: string,
  handlers: {
    onMessageDelta: (event: RunEvent) => void
    onReasoningDelta: (event: RunEvent) => void
    onThinkingDelta: (event: RunEvent) => void
    onReasoningAvailable: (event: RunEvent) => void
    onToolStarted: (event: RunEvent) => void
    onToolCompleted: (event: RunEvent) => void
    onRunStarted: (event: RunEvent) => void
    onRunCompleted: (event: RunEvent) => void
    onRunFailed: (event: RunEvent) => void
    onCompressionStarted: (event: RunEvent) => void
    onCompressionCompleted: (event: RunEvent) => void
    onUsageUpdated: (event: RunEvent) => void
  }
): () => void {
  sessionEventHandlers.set(sessionId, handlers)

  // Return cleanup function
  return () => {
    sessionEventHandlers.delete(sessionId)
  }
}

/**
 * Unregister event handlers for a session
 * @param sessionId - Session ID
 */
export function unregisterSessionHandlers(sessionId: string): void {
  sessionEventHandlers.delete(sessionId)
}

export function getChatRunSocket(): Socket | null {
  return chatRunSocket
}

export function connectChatRun(): Socket {
  if (chatRunSocket?.connected) return chatRunSocket

  // Clean up old socket to prevent duplicate event listeners
  if (chatRunSocket) {
    chatRunSocket.removeAllListeners()
    chatRunSocket.disconnect()
    globalListenersRegistered = false
  }

  const baseUrl = getBaseUrlValue()
  const token = getApiKey()
  const profile = localStorage.getItem('hermes_active_profile_name') || 'default'

  chatRunSocket = io(`${baseUrl}/chat-run`, {
    auth: { token },
    query: { profile },
    transports: ['websocket', 'polling'],
    reconnection: true,
    reconnectionAttempts: Infinity,
    reconnectionDelay: 1000,
    reconnectionDelayMax: 10000,
  })

  // Register global listeners only once per socket connection
  if (!globalListenersRegistered) {
    // Message events
    chatRunSocket.on('message.delta', globalMessageDeltaHandler)
    chatRunSocket.on('reasoning.delta', globalReasoningDeltaHandler)
    chatRunSocket.on('thinking.delta', globalThinkingDeltaHandler)
    chatRunSocket.on('reasoning.available', globalReasoningAvailableHandler)

    // Tool events
    chatRunSocket.on('tool.started', globalToolStartedHandler)
    chatRunSocket.on('tool.completed', globalToolCompletedHandler)

    // Run lifecycle events
    chatRunSocket.on('run.started', globalRunStartedHandler)
    chatRunSocket.on('run.failed', globalRunFailedHandler)
    chatRunSocket.on('run.completed', globalRunCompletedHandler)

    // Compression events
    chatRunSocket.on('compression.started', globalCompressionStartedHandler)
    chatRunSocket.on('compression.completed', globalCompressionCompletedHandler)

    // Usage events
    chatRunSocket.on('usage.updated', globalUsageUpdatedHandler)

    globalListenersRegistered = true
  }

  return chatRunSocket
}

export function disconnectChatRun(): void {
  if (chatRunSocket) {
    chatRunSocket.disconnect()
    chatRunSocket = null
    globalListenersRegistered = false
    sessionEventHandlers.clear()
  }
}

/**
 * Start a chat run via Socket.IO and stream events back.
 * Returns an AbortController-compatible handle for cancellation.
 */
/**
 * Resume a session via Socket.IO. Returns messages, working status, and events.
 */
export function resumeSession(
  sessionId: string,
  onResumed: (data: { session_id: string; messages: any[]; isWorking: boolean; events: any[]; inputTokens?: number; outputTokens?: number }) => void,
): Socket {
  const socket = connectChatRun()

  socket.once('resumed', onResumed)
  socket.emit('resume', { session_id: sessionId })

  return socket
}

export function startRunViaSocket(
  body: StartRunRequest,
  onEvent: (event: RunEvent) => void,
  onDone: () => void,
  onError: (err: Error) => void,
  onStarted?: (runId: string) => void,
): { abort: () => void } {
  const sid = body.session_id
  if (!sid) {
    throw new Error('session_id is required for startRunViaSocket')
  }

  let closed = false

  // Define event handlers for this session
  const handlers = {
    onMessageDelta: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onReasoningDelta: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onThinkingDelta: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onReasoningAvailable: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onToolStarted: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onToolCompleted: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onRunStarted: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
      onStarted?.(evt.run_id || '')
    },
    onRunCompleted: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
      closed = true
      onDone()
    },
    onRunFailed: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
      closed = true
      onError(new Error(evt.error || 'Run failed'))
    },
    onCompressionStarted: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onCompressionCompleted: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
    onUsageUpdated: (evt: RunEvent) => {
      if (closed) return
      onEvent(evt)
    },
  }

  // Register handlers in the global session map
  sessionEventHandlers.set(sid, handlers)

  // Emit run request
  const socket = connectChatRun()
  socket.emit('run', body)

  return {
    abort: () => {
      if (!closed) {
        closed = true
        sessionEventHandlers.delete(sid)
        socket.emit('abort', { session_id: sid })
      }
    },
  }
}

export async function fetchModels(): Promise<{ data: Array<{ id: string }> }> {
  return request('/api/hermes/v1/models')
}