'use client';

import { useCallback, useRef, useState } from 'react';
import { streamMedicineConsult } from '../api';

export interface MedicineWidget {
  id: string;
  type: string;
  params: Record<string, unknown>;
}

export interface MedicineChatMessage {
  id: string;
  role: 'user' | 'assistant';
  content: string;
  isStreaming?: boolean;
  widgets: MedicineWidget[];
  createdAt: Date;
}

function generateId(): string {
  return `${Date.now()}-${Math.random().toString(36).slice(2, 11)}`;
}

export function useMedicineChat() {
  const [messages, setMessages] = useState<MedicineChatMessage[]>([]);
  const [isLoading, setIsLoading] = useState(false);
  const abortControllerRef = useRef<AbortController | null>(null);
  const historyRef = useRef<[string, string][]>([]);

  const sendMessage = useCallback(
    async (content: string, city?: string) => {
      if (!content.trim() || isLoading) return;

      const userMessage: MedicineChatMessage = {
        id: generateId(),
        role: 'user',
        content: content.trim(),
        widgets: [],
        createdAt: new Date(),
      };

      const assistantMessage: MedicineChatMessage = {
        id: generateId(),
        role: 'assistant',
        content: '',
        isStreaming: true,
        widgets: [],
        createdAt: new Date(),
      };

      setMessages((prev) => [...prev, userMessage, assistantMessage]);
      setIsLoading(true);

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

      try {
        let fullContent = '';
        const widgets: MedicineWidget[] = [];

        const stream = streamMedicineConsult(
          content.trim(),
          city?.trim() || undefined,
          historyRef.current,
          controller.signal
        );

        for await (const event of stream) {
          const chunkText = event.chunk || (event.data as Record<string, unknown>)?.chunk;
          if (event.type === 'textChunk' && typeof chunkText === 'string') {
            fullContent += chunkText;
            setMessages((prev) =>
              prev.map((m) => (m.id === assistantMessage.id ? { ...m, content: fullContent } : m))
            );
          }

          if (event.type === 'block' && event.block?.type === 'widget') {
            const data = event.block.data as { widgetType?: string; params?: Record<string, unknown> };
            if (!data.widgetType) continue;
            widgets.push({
              id: event.block.id,
              type: data.widgetType,
              params: data.params || {},
            });
            setMessages((prev) =>
              prev.map((m) => (m.id === assistantMessage.id ? { ...m, widgets: [...widgets] } : m))
            );
          }

          if (event.type === 'messageEnd') {
            setMessages((prev) =>
              prev.map((m) =>
                m.id === assistantMessage.id
                  ? { ...m, isStreaming: false, content: fullContent, widgets: [...widgets] }
                  : m
              )
            );
          }
        }

        if (fullContent.trim()) {
          historyRef.current.push([userMessage.content, fullContent]);
          historyRef.current = historyRef.current.slice(-8);
        }
      } catch (error) {
        const message = error instanceof Error ? error.message : 'Ошибка консультации';
        setMessages((prev) =>
          prev.map((m) =>
            m.id === assistantMessage.id ? { ...m, content: `Ошибка: ${message}`, isStreaming: false } : m
          )
        );
      } finally {
        setIsLoading(false);
        abortControllerRef.current = null;
      }
    },
    [isLoading]
  );

  const stopGeneration = useCallback(() => {
    abortControllerRef.current?.abort();
    setIsLoading(false);
    setMessages((prev) => prev.map((m) => (m.isStreaming ? { ...m, isStreaming: false } : m)));
  }, []);

  const clearChat = useCallback(() => {
    setMessages([]);
    historyRef.current = [];
  }, []);

  return {
    messages,
    isLoading,
    sendMessage,
    stopGeneration,
    clearChat,
  };
}