'use client';

import { create } from 'zustand';
import { persist, createJSONStorage } from 'zustand/middleware';

export interface MessageAttachment {
  name: string;
  type: string;
  dataUrl: string;
  size: number;
}

export interface Message {
  id: string;
  role: 'user' | 'assistant';
  content: string;
  attachments?: MessageAttachment[];
  timestamp: number;
}

export interface ChatSession {
  id: string;
  title: string;
  messages: Message[];
  createdAt: number;
}

interface ChatState {
  sessions: ChatSession[];
  activeSessionId: string | null;
  addMessage: (sessionId: string, message: Omit<Message, 'id' | 'timestamp'>) => void;
  createSession: (title: string) => string;
  setActiveSession: (id: string | null) => void;
  deleteSession: (id: string) => void;
  renameSession: (id: string, title: string) => void;
  clearAll: () => void;
}

function randomId() {
  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) {
    return crypto.randomUUID();
  }
  return Math.random().toString(36).slice(2, 11);
}

export const useChatStore = create<ChatState>()(
  persist(
    (set) => ({
      sessions: [],
      activeSessionId: null,
      createSession: (title) => {
        const id = randomId();
        const trimmed = (title || 'Neue Reparatur').slice(0, 60);
        set((state) => ({
          sessions: [
            { id, title: trimmed, messages: [], createdAt: Date.now() },
            ...state.sessions,
          ],
          activeSessionId: id,
        }));
        return id;
      },
      setActiveSession: (id) => set({ activeSessionId: id }),
      addMessage: (sessionId, msg) => {
        set((state) => ({
          sessions: state.sessions.map((s) =>
            s.id === sessionId
              ? {
                  ...s,
                  messages: [
                    ...s.messages,
                    { ...msg, id: randomId(), timestamp: Date.now() },
                  ],
                }
              : s
          ),
        }));
      },
      deleteSession: (id) =>
        set((state) => ({
          sessions: state.sessions.filter((s) => s.id !== id),
          activeSessionId: state.activeSessionId === id ? null : state.activeSessionId,
        })),
      renameSession: (id, title) =>
        set((state) => ({
          sessions: state.sessions.map((s) =>
            s.id === id ? { ...s, title: title.slice(0, 60) } : s
          ),
        })),
      clearAll: () => set({ sessions: [], activeSessionId: null }),
    }),
    {
      name: 'patchpilot:chat',
      storage: createJSONStorage(() => localStorage),
      version: 2,
    }
  )
);