'use client';

import { useState, useCallback, useEffect, useRef } from 'react';
import type { Message, SSEEvent, TokenUsage, PermissionRequestEvent } from '@/types';
import { MessageList } from './MessageList';
import { MessageInput } from './MessageInput';
import { usePanel } from '@/hooks/usePanel';

interface ToolUseInfo {
  id: string;
  name: string;
  input: unknown;
}

interface ToolResultInfo {
  tool_use_id: string;
  content: string;
}

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

export function ChatView({ sessionId, initialMessages = [], modelName, initialMode }: ChatViewProps) {
  const { setStreamingSessionId, workingDirectory, setWorkingDirectory, setPanelOpen, setPendingApprovalSessionId } = usePanel();
  const [messages, setMessages] = useState<Message[]>(initialMessages);
  const [streamingContent, setStreamingContent] = useState('');
  const [isStreaming, setIsStreaming] = useState(false);
  const [toolUses, setToolUses] = useState<ToolUseInfo[]>([]);
  const [toolResults, setToolResults] = useState<ToolResultInfo[]>([]);
  const [statusText, setStatusText] = useState<string | undefined>();
  const [mode, setMode] = useState(initialMode || 'code');
  const [currentModel, setCurrentModel] = useState(modelName || 'sonnet');
  const [pendingPermission, setPendingPermission] = useState<PermissionRequestEvent | null>(null);
  const [permissionResolved, setPermissionResolved] = useState<'allow' | 'deny' | null>(null);
  const [streamingToolOutput, setStreamingToolOutput] = useState('');

  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 */ });
    }
  }, [sessionId]);
  const abortControllerRef = useRef<AbortController | null>(null);

  const handleWorkingDirectoryChange = useCallback((dir: string) => {
    setWorkingDirectory(dir);
    setPanelOpen(true);
    // Persist to database
    if (sessionId) {
      fetch(`/api/chat/sessions/${sessionId}`, {
        method: 'PATCH',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ working_directory: dir }),
      }).catch(() => { /* silent */ });
    }
  }, [sessionId, setWorkingDirectory, setPanelOpen]);

  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]);

  const stopStreaming = useCallback(() => {
    abortControllerRef.current?.abort();
    abortControllerRef.current = null;
  }, []);

  const handlePermissionResponse = useCallback(async (decision: 'allow' | 'allow_session' | 'deny') => {
    if (!pendingPermission) return;

    const body: { permissionRequestId: string; decision: { behavior: 'allow'; updatedPermissions?: unknown[] } | { behavior: 'deny'; message?: string } } = {
      permissionRequestId: pendingPermission.permissionRequestId,
      decision: decision === 'deny'
        ? { behavior: 'deny', message: 'User denied permission' }
        : {
            behavior: 'allow',
            ...(decision === 'allow_session' && pendingPermission.suggestions
              ? { updatedPermissions: pendingPermission.suggestions }
              : {}),
          },
    };

    setPermissionResolved(decision === 'deny' ? 'deny' : 'allow');
    setPendingApprovalSessionId('');

    try {
      await fetch('/api/chat/permission', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(body),
      });
    } catch {
      // Best effort - the stream will handle timeout
    }

    // Clear permission state after a short delay so user sees the feedback
    setTimeout(() => {
      setPendingPermission(null);
      setPermissionResolved(null);
    }, 1000);
  }, [pendingPermission, setPendingApprovalSessionId]);

  const sendMessage = useCallback(
    async (content: string) => {
      if (isStreaming) return;

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

      const controller = new AbortController();
      abortControllerRef.current = controller;

      let accumulated = '';

      try {
        const response = await fetch('/api/chat', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({ session_id: sessionId, content, mode, model: currentModel }),
          signal: controller.signal,
        });

        if (!response.ok) {
          const err = await response.json();
          throw new Error(err.error || 'Failed to send message');
        }

        const reader = response.body?.getReader();
        if (!reader) throw new Error('No response stream');

        const decoder = new TextDecoder();
        let tokenUsage: TokenUsage | null = null;
        let buffer = '';

        while (true) {
          const { done, value } = await reader.read();
          if (done) break;

          buffer += decoder.decode(value, { stream: true });
          const lines = buffer.split('\n');
          // Keep the last potentially incomplete line in the buffer
          buffer = lines.pop() || '';

          for (const line of lines) {
            if (!line.startsWith('data: ')) continue;

            try {
              const event: SSEEvent = JSON.parse(line.slice(6));

              switch (event.type) {
                case 'text': {
                  accumulated += event.data;
                  setStreamingContent(accumulated);
                  break;
                }

                case 'tool_use': {
                  try {
                    const toolData = JSON.parse(event.data);
                    // Clear streaming output for new tool
                    setStreamingToolOutput('');
                    setToolUses((prev) => {
                      // Avoid duplicates
                      if (prev.some((t) => t.id === toolData.id)) return prev;
                      return [...prev, {
                        id: toolData.id,
                        name: toolData.name,
                        input: toolData.input,
                      }];
                    });
                  } catch {
                    // skip malformed tool_use data
                  }
                  break;
                }

                case 'tool_result': {
                  try {
                    const resultData = JSON.parse(event.data);
                    setStreamingToolOutput('');
                    setToolResults((prev) => [...prev, {
                      tool_use_id: resultData.tool_use_id,
                      content: resultData.content,
                    }]);
                  } catch {
                    // skip malformed tool_result data
                  }
                  break;
                }

                case 'tool_output': {
                  // Check if this is a progress heartbeat or real stderr output
                  try {
                    const parsed = JSON.parse(event.data);
                    if (parsed._progress) {
                      // SDK tool_progress event — update status with elapsed time
                      setStatusText(`Running ${parsed.tool_name}... (${Math.round(parsed.elapsed_time_seconds)}s)`);
                      break;
                    }
                  } catch {
                    // Not JSON — it's raw stderr output, fall through
                  }
                  // Real-time stderr output from tool execution
                  setStreamingToolOutput((prev) => {
                    const next = prev + (prev ? '\n' : '') + event.data;
                    return next.length > 5000 ? next.slice(-5000) : next;
                  });
                  break;
                }

                case 'status': {
                  try {
                    const statusData = JSON.parse(event.data);
                    if (statusData.session_id) {
                      // Init event — show briefly then clear so tool status can take over
                      setStatusText(`Connected (${statusData.model || 'claude'})`);
                      setTimeout(() => setStatusText(undefined), 2000);
                    } else if (statusData.notification) {
                      // Notification from SDK hooks — show as progress
                      setStatusText(statusData.message || statusData.title || undefined);
                    } else {
                      setStatusText(typeof event.data === 'string' ? event.data : undefined);
                    }
                  } catch {
                    setStatusText(event.data || undefined);
                  }
                  break;
                }

                case 'result': {
                  try {
                    const resultData = JSON.parse(event.data);
                    if (resultData.usage) {
                      tokenUsage = resultData.usage;
                    }
                  } catch {
                    // skip
                  }
                  setStatusText(undefined);
                  break;
                }

                case 'permission_request': {
                  try {
                    const permData: PermissionRequestEvent = JSON.parse(event.data);
                    setPendingPermission(permData);
                    setPermissionResolved(null);
                    setPendingApprovalSessionId(sessionId);
                  } catch {
                    // skip malformed permission_request data
                  }
                  break;
                }

                case 'error': {
                  accumulated += '\n\n**Error:** ' + event.data;
                  setStreamingContent(accumulated);
                  break;
                }

                case 'done': {
                  // Stream complete
                  break;
                }
              }
            } catch {
              // skip malformed SSE lines
            }
          }
        }

        // Add the assistant message to the list
        if (accumulated.trim()) {
          const assistantMessage: Message = {
            id: 'temp-assistant-' + Date.now(),
            session_id: sessionId,
            role: 'assistant',
            content: accumulated.trim(),
            created_at: new Date().toISOString(),
            token_usage: tokenUsage ? JSON.stringify(tokenUsage) : null,
          };
          setMessages((prev) => [...prev, assistantMessage]);
        }
      } catch (error) {
        if (error instanceof DOMException && error.name === 'AbortError') {
          // User stopped generation - still add partial content
          if (accumulated.trim()) {
            const partialMessage: Message = {
              id: 'temp-assistant-' + Date.now(),
              session_id: sessionId,
              role: 'assistant',
              content: accumulated.trim() + '\n\n*(generation stopped)*',
              created_at: new Date().toISOString(),
              token_usage: null,
            };
            setMessages((prev) => [...prev, partialMessage]);
          }
        } else {
          const errMsg = error instanceof Error ? error.message : 'Unknown error';
          const errorMessage: Message = {
            id: 'temp-error-' + Date.now(),
            session_id: sessionId,
            role: 'assistant',
            content: `**Error:** ${errMsg}`,
            created_at: new Date().toISOString(),
            token_usage: null,
          };
          setMessages((prev) => [...prev, errorMessage]);
        }
      } finally {
        setIsStreaming(false);
        setStreamingSessionId('');
        setStreamingContent('');
        setToolUses([]);
        setToolResults([]);
        setStreamingToolOutput('');
        setStatusText(undefined);
        setPendingPermission(null);
        setPermissionResolved(null);
        setPendingApprovalSessionId('');
        abortControllerRef.current = null;
      }
    },
    [sessionId, isStreaming, setStreamingSessionId, setPendingApprovalSessionId, mode, currentModel]
  );

  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- **/help** - Show this help message\n- **/clear** - Clear conversation history\n- **/compact** - Compress conversation context\n- **/cost** - Show token usage statistics\n- **/doctor** - Check system health\n- **/init** - Initialize CLAUDE.md\n- **/review** - Start code review\n- **/terminal-setup** - Configure terminal\n\n**Tips:**\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([]);
        break;
      case '/cost': {
        const costMessage: Message = {
          id: 'cmd-' + Date.now(),
          session_id: sessionId,
          role: 'assistant',
          content: `## Token Usage\n\nToken usage tracking is available after sending messages. Check the token count displayed at the bottom of each assistant response.`,
          created_at: new Date().toISOString(),
          token_usage: null,
        };
        setMessages(prev => [...prev, costMessage]);
        break;
      }
      default:
        sendMessage(command);
    }
  }, [sessionId, sendMessage]);

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