'use client';

import { useState, useCallback, useEffect, useRef } from 'react';
import type { Message, MessagesResponse, FileAttachment, SessionStreamSnapshot } from '@/types';
import { MessageList } from './MessageList';
import { MessageInput } from './MessageInput';
import { usePanel } from '@/hooks/usePanel';
import { BatchExecutionDashboard, BatchContextSync } from './batch-image-gen';
import { setLastGeneratedImages, transferPendingToMessage } from '@/lib/image-ref-store';
import {
  startStream,
  stopStream,
  subscribe,
  getSnapshot,
  respondToPermission,
  clearSnapshot,
} from '@/lib/stream-session-manager';

interface ChatViewProps {
  sessionId: string;
  initialMessages?: Message[];
  initialHasMore?: boolean;
  modelName?: string;
  initialMode?: string;
  providerId?: string;
}

export function ChatView({ sessionId, initialMessages = [], initialHasMore = false, modelName, initialMode, providerId }: ChatViewProps) {
  const { setStreamingSessionId, workingDirectory, setWorkingDirectory, setPanelOpen, setPendingApprovalSessionId } = usePanel();
  const [messages, setMessages] = useState<Message[]>(initialMessages);
  const [hasMore, setHasMore] = useState(initialHasMore);
  const [loadingMore, setLoadingMore] = useState(false);
  const loadingMoreRef = useRef(false);
  const [mode, setMode] = useState(initialMode || 'code');
  const [currentModel, setCurrentModel] = useState(modelName || (typeof window !== 'undefined' ? localStorage.getItem('codepilot:last-model') : null) || 'sonnet');
  const [currentProviderId, setCurrentProviderId] = useState(providerId || (typeof window !== 'undefined' ? localStorage.getItem('codepilot:last-provider-id') : null) || '');

  // Stream snapshot from the manager — drives all streaming UI
  const [streamSnapshot, setStreamSnapshot] = useState<SessionStreamSnapshot | null>(
    () => getSnapshot(sessionId)
  );

  // Derive rendering state from snapshot (backward-compatible with MessageList props)
  const isStreaming = streamSnapshot?.phase === 'active';
  const streamingContent = streamSnapshot?.streamingContent ?? '';
  const toolUses = streamSnapshot?.toolUses ?? [];
  const toolResults = streamSnapshot?.toolResults ?? [];
  const streamingToolOutput = streamSnapshot?.streamingToolOutput ?? '';
  const statusText = streamSnapshot?.statusText;
  const pendingPermission = streamSnapshot?.pendingPermission ?? null;
  const permissionResolved = streamSnapshot?.permissionResolved ?? null;

  // Pending image generation notices — flushed into the next user message so the LLM knows about generated images
  const pendingImageNoticesRef = useRef<string[]>([]);
  // Ref for sendMessage to allow self-referencing in timeout auto-retry
  const sendMessageRef = useRef<(content: string, files?: FileAttachment[]) => Promise<void>>(undefined);

  const handleModeChange = useCallback((newMode: string) => {
    setMode(newMode);
    // Persist mode to database and notify chat list
    if (sessionId) {
      fetch(`/api/chat/sessions/${sessionId}`, {
        method: 'PATCH',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ mode: newMode }),
      }).then(() => {
        window.dispatchEvent(new CustomEvent('session-updated'));
      }).catch(() => { /* silent */ });

      // Try to switch SDK permission mode in real-time (works if streaming)
      fetch('/api/chat/mode', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ sessionId, mode: newMode }),
      }).catch(() => { /* silent — will apply on next message */ });
    }
  }, [sessionId]);

  const handleProviderModelChange = useCallback((newProviderId: string, model: string) => {
    setCurrentProviderId(newProviderId);
    setCurrentModel(model);
  }, []);

  // Subscribe to stream-session-manager for this session.
  // On unmount we only unsubscribe — we do NOT abort the stream.
  useEffect(() => {
    // Restore snapshot if stream is already active (e.g., user switched away and back)
    const existing = getSnapshot(sessionId);
    if (existing) {
      setStreamSnapshot(existing);
      if (existing.phase === 'active') {
        setStreamingSessionId(sessionId);
      }
      if (existing.pendingPermission && !existing.permissionResolved) {
        setPendingApprovalSessionId(sessionId);
      }
    } else {
      setStreamSnapshot(null);
    }

    const unsubscribe = subscribe(sessionId, (event) => {
      setStreamSnapshot(event.snapshot);

      // Sync panel state
      if (event.type === 'phase-changed') {
        if (event.snapshot.phase === 'active') {
          setStreamingSessionId(sessionId);
        } else {
          setStreamingSessionId('');
          setPendingApprovalSessionId('');
        }
      }
      if (event.type === 'permission-request') {
        setPendingApprovalSessionId(sessionId);
      }
      if (event.type === 'completed') {
        setStreamingSessionId('');
        setPendingApprovalSessionId('');

        // Append the final assistant message to the messages list
        const finalContent = event.snapshot.finalMessageContent;
        if (finalContent) {
          const assistantMessage: Message = {
            id: 'temp-assistant-' + Date.now(),
            session_id: sessionId,
            role: 'assistant',
            content: finalContent,
            created_at: new Date().toISOString(),
            token_usage: event.snapshot.tokenUsage ? JSON.stringify(event.snapshot.tokenUsage) : null,
          };
          // Transfer pending reference images to this message ID
          transferPendingToMessage(assistantMessage.id);
          setMessages((prev) => [...prev, assistantMessage]);
        }

        // Clear the snapshot from the manager since we've consumed it
        clearSnapshot(sessionId);
      }
    });

    return () => {
      unsubscribe();
      // Do NOT abort — stream continues in the manager
    };
  }, [sessionId, setStreamingSessionId, setPendingApprovalSessionId]);

  const initializedRef = useRef(false);
  useEffect(() => {
    if (initialMessages.length > 0 && !initializedRef.current) {
      initializedRef.current = true;
      setMessages(initialMessages);
    }
  }, [initialMessages]);

  // Sync mode when session data loads
  useEffect(() => {
    if (initialMode) {
      setMode(initialMode);
    }
  }, [initialMode]);

  // Sync hasMore when initial data loads
  useEffect(() => {
    setHasMore(initialHasMore);
  }, [initialHasMore]);

  const loadEarlierMessages = useCallback(async () => {
    // Use ref as atomic lock to prevent double-fetch from rapid clicks
    if (loadingMoreRef.current || !hasMore || messages.length === 0) return;
    loadingMoreRef.current = true;
    setLoadingMore(true);
    try {
      // Use _rowid of the earliest message as cursor
      const earliest = messages[0];
      const earliestRowId = (earliest as Message & { _rowid?: number })._rowid;
      if (!earliestRowId) return;
      const res = await fetch(`/api/chat/sessions/${sessionId}/messages?limit=100&before=${earliestRowId}`);
      if (!res.ok) return;
      const data: MessagesResponse = await res.json();
      setHasMore(data.hasMore ?? false);
      if (data.messages.length > 0) {
        setMessages(prev => [...data.messages, ...prev]);
      }
    } finally {
      loadingMoreRef.current = false;
      setLoadingMore(false);
    }
  }, [sessionId, messages, hasMore]);

  // Stop streaming — delegates to manager
  const stopStreaming = useCallback(() => {
    stopStream(sessionId);
  }, [sessionId]);

  // Permission response — delegates to manager
  const handlePermissionResponse = useCallback(
    async (decision: 'allow' | 'allow_session' | 'deny', updatedInput?: Record<string, unknown>) => {
      setPendingApprovalSessionId('');
      await respondToPermission(sessionId, decision, updatedInput);
    },
    [sessionId, setPendingApprovalSessionId]
  );

  // Send message — delegates stream management to the manager
  const sendMessage = useCallback(
    async (content: string, files?: FileAttachment[], systemPromptAppend?: string, displayOverride?: string) => {
      if (isStreaming) return;

      // Use displayOverride for UI if provided (e.g. image-gen skill injection hides the skill prompt)
      const displayUserContent = displayOverride || content;

      // Build display content: embed file metadata as HTML comment for MessageItem to parse
      let displayContent = displayUserContent;
      if (files && files.length > 0) {
        const fileMeta = files.map(f => ({ id: f.id, name: f.name, type: f.type, size: f.size }));
        displayContent = `<!--files:${JSON.stringify(fileMeta)}-->${displayUserContent}`;
      }

      // Optimistic: add user message to UI immediately
      const userMessage: Message = {
        id: 'temp-' + Date.now(),
        session_id: sessionId,
        role: 'user',
        content: displayContent,
        created_at: new Date().toISOString(),
        token_usage: null,
      };
      setMessages((prev) => [...prev, userMessage]);

      // Flush pending image notices
      const notices = pendingImageNoticesRef.current.length > 0
        ? [...pendingImageNoticesRef.current]
        : undefined;
      if (notices) {
        pendingImageNoticesRef.current = [];
      }

      // Delegate to stream session manager
      startStream({
        sessionId,
        content,
        mode,
        model: currentModel,
        providerId: currentProviderId,
        files,
        systemPromptAppend,
        pendingImageNotices: notices,
        onModeChanged: (sdkMode) => {
          const uiMode = sdkMode === 'plan' ? 'plan' : 'code';
          handleModeChange(uiMode);
        },
        sendMessageFn: (retryContent: string, retryFiles?: FileAttachment[]) => {
          sendMessageRef.current?.(retryContent, retryFiles);
        },
      });
    },
    [sessionId, isStreaming, mode, currentModel, currentProviderId, handleModeChange]
  );

  // Keep sendMessageRef in sync so timeout auto-retry can call it
  sendMessageRef.current = sendMessage;

  const handleCommand = useCallback((command: string) => {
    switch (command) {
      case '/help': {
        const helpMessage: Message = {
          id: 'cmd-' + Date.now(),
          session_id: sessionId,
          role: 'assistant',
          content: `## Available Commands\n\n### Instant Commands\n- **/help** — Show this help message\n- **/clear** — Clear conversation history\n- **/cost** — Show token usage statistics\n\n### Prompt Commands (shown as badge, add context then send)\n- **/compact** — Compress conversation context\n- **/doctor** — Diagnose project health\n- **/init** — Initialize CLAUDE.md for project\n- **/review** — Review code quality\n- **/terminal-setup** — Configure terminal settings\n- **/memory** — Edit project memory file\n\n### Custom Skills\nSkills from \`~/.claude/commands/\` and project \`.claude/commands/\` are also available via \`/\`.\n\n**Tips:**\n- Type \`/\` to browse commands and skills\n- Type \`@\` to mention files\n- Use Shift+Enter for new line\n- Select a project folder to enable file operations`,
          created_at: new Date().toISOString(),
          token_usage: null,
        };
        setMessages(prev => [...prev, helpMessage]);
        break;
      }
      case '/clear':
        setMessages([]);
        // Also clear database messages and reset SDK session
        if (sessionId) {
          fetch(`/api/chat/sessions/${sessionId}`, {
            method: 'PATCH',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ clear_messages: true }),
          }).catch(() => { /* silent */ });
        }
        break;
      case '/cost': {
        // Aggregate token usage from all messages in this session
        let totalInput = 0;
        let totalOutput = 0;
        let totalCacheRead = 0;
        let totalCacheCreation = 0;
        let totalCost = 0;
        let turnCount = 0;

        for (const msg of messages) {
          if (msg.token_usage) {
            try {
              const usage = typeof msg.token_usage === 'string' ? JSON.parse(msg.token_usage) : msg.token_usage;
              totalInput += usage.input_tokens || 0;
              totalOutput += usage.output_tokens || 0;
              totalCacheRead += usage.cache_read_input_tokens || 0;
              totalCacheCreation += usage.cache_creation_input_tokens || 0;
              if (usage.cost_usd) totalCost += usage.cost_usd;
              turnCount++;
            } catch { /* skip */ }
          }
        }

        const totalTokens = totalInput + totalOutput;
        let content: string;

        if (turnCount === 0) {
          content = `## Token Usage\n\nNo token usage data yet. Send a message first.`;
        } else {
          content = `## Token Usage\n\n| Metric | Count |\n|--------|-------|\n| Input tokens | ${totalInput.toLocaleString()} |\n| Output tokens | ${totalOutput.toLocaleString()} |\n| Cache read | ${totalCacheRead.toLocaleString()} |\n| Cache creation | ${totalCacheCreation.toLocaleString()} |\n| **Total tokens** | **${totalTokens.toLocaleString()}** |\n| Turns | ${turnCount} |${totalCost > 0 ? `\n| **Estimated cost** | **$${totalCost.toFixed(4)}** |` : ''}`;
        }

        const costMessage: Message = {
          id: 'cmd-' + Date.now(),
          session_id: sessionId,
          role: 'assistant',
          content,
          created_at: new Date().toISOString(),
          token_usage: null,
        };
        setMessages(prev => [...prev, costMessage]);
        break;
      }
      default:
        // This shouldn't be reached since non-immediate commands are handled via badge
        sendMessage(command);
    }
  }, [sessionId, sendMessage]);

  // Listen for image generation completion — persist notice to DB and queue for next user message.
  // The notice is NOT sent as a separate LLM turn (avoids permission popups).
  // Instead it's flushed into the next user message via pendingImageNoticesRef.
  // MessageItem hides messages matching this prefix so the user doesn't see them.
  useEffect(() => {
    const handler = (e: Event) => {
      const detail = (e as CustomEvent).detail;
      if (!detail) return;
      const paths = (detail.images || [])
        .map((img: { localPath?: string }) => img.localPath)
        .filter(Boolean);
      const pathInfo = paths.length > 0 ? `\nGenerated image file paths:\n${paths.map((p: string) => `- ${p}`).join('\n')}` : '';
      const notice = `[Image generation completed]\n- Prompt: "${detail.prompt}"\n- Aspect ratio: ${detail.aspectRatio}\n- Resolution: ${detail.resolution}${pathInfo}`;

      // Store generated image paths so subsequent edits can use them as reference
      if (paths.length > 0) {
        setLastGeneratedImages(paths);
      }

      // Queue for next user message so the LLM gets the context
      pendingImageNoticesRef.current.push(notice);

      // Also persist to DB for history reload
      const dbNotice = `[__IMAGE_GEN_NOTICE__ prompt: "${detail.prompt}", aspect ratio: ${detail.aspectRatio}, resolution: ${detail.resolution}${paths.length > 0 ? `, file path: ${paths.join(', ')}` : ''}]`;
      fetch('/api/chat/messages', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ session_id: sessionId, role: 'user', content: dbNotice }),
      }).catch(() => {});
    };
    window.addEventListener('image-gen-completed', handler);
    return () => window.removeEventListener('image-gen-completed', handler);
  }, [sessionId]);

  return (
    <div className="flex h-full min-h-0 flex-col">
      <MessageList
        messages={messages}
        streamingContent={streamingContent}
        isStreaming={isStreaming}
        toolUses={toolUses}
        toolResults={toolResults}
        streamingToolOutput={streamingToolOutput}
        statusText={statusText}
        pendingPermission={pendingPermission}
        onPermissionResponse={handlePermissionResponse}
        permissionResolved={permissionResolved}
        onForceStop={stopStreaming}
        hasMore={hasMore}
        loadingMore={loadingMore}
        onLoadMore={loadEarlierMessages}
      />
      {/* Batch image generation panels — shown above the input area */}
      <BatchExecutionDashboard />
      <BatchContextSync />

      <MessageInput
        onSend={sendMessage}
        onCommand={handleCommand}
        onStop={stopStreaming}
        disabled={false}
        isStreaming={isStreaming}
        sessionId={sessionId}
        modelName={currentModel}
        onModelChange={setCurrentModel}
        providerId={currentProviderId}
        onProviderModelChange={handleProviderModelChange}
        workingDirectory={workingDirectory}
        mode={mode}
        onModeChange={handleModeChange}
      />
    </div>
  );
}