import AsyncStorage from '@react-native-async-storage/async-storage';
import { useAppStore } from '../store/useAppStore';

const state = () => useAppStore.getState();

beforeEach(() => {
    useAppStore.setState(useAppStore.getInitialState(), true);
});

describe('messages', () => {
    it('addMessage appends with a generated id and timestamp, and returns the id', () => {
        const id = state().addMessage({ role: 'user', content: 'hi' });
        const [msg] = state().messages;

        expect(msg.id).toBe(id);
        expect(msg).toMatchObject({ role: 'user', content: 'hi' });
        expect(typeof msg.timestamp).toBe('number');
    });

    it('generates distinct ids for messages created in the same millisecond', () => {
        const ids = new Set(Array.from({ length: 50 }, () => state().addMessage({ role: 'user', content: 'x' })));
        expect(ids.size).toBe(50);
    });

    it('appendToMessage and updateMessageContent only touch the target message', () => {
        const a = state().addMessage({ role: 'assistant', content: 'He' });
        const b = state().addMessage({ role: 'assistant', content: 'other' });

        state().appendToMessage(a, 'llo');
        expect(state().messages.map((m) => m.content)).toEqual(['Hello', 'other']);

        state().updateMessageContent(b, 'replaced');
        expect(state().messages.map((m) => m.content)).toEqual(['Hello', 'replaced']);
    });

    it('editMessage replaces the content and marks it as edited', () => {
        const id = state().addMessage({ role: 'user', content: 'old' });
        state().editMessage(id, 'new');
        expect(state().messages[0]).toMatchObject({ content: 'new', isEdited: true });
    });

    it('deleteMessage removes only the given message', () => {
        const a = state().addMessage({ role: 'user', content: 'a' });
        state().addMessage({ role: 'assistant', content: 'b' });
        state().deleteMessage(a);
        expect(state().messages.map((m) => m.content)).toEqual(['b']);
    });

    describe('deleteMessagesAfter', () => {
        it('keeps the given message and drops everything after it', () => {
            const a = state().addMessage({ role: 'user', content: 'a' });
            state().addMessage({ role: 'assistant', content: 'b' });
            state().addMessage({ role: 'user', content: 'c' });
            state().deleteMessagesAfter(a);
            expect(state().messages.map((m) => m.content)).toEqual(['a']);
        });

        it('does nothing when the id is unknown', () => {
            state().addMessage({ role: 'user', content: 'a' });
            state().deleteMessagesAfter('missing');
            expect(state().messages).toHaveLength(1);
        });
    });

    it('clearChat empties the conversation and forgets the current session', () => {
        state().addMessage({ role: 'user', content: 'a' });
        state().setCurrentChatId('abc');
        state().clearChat();
        expect(state().messages).toEqual([]);
        expect(state().currentChatId).toBeNull();
    });
});

describe('chat sessions', () => {
    it('saveCurrentChat ignores an empty conversation', () => {
        state().saveCurrentChat();
        expect(state().chatSessions).toEqual([]);
        expect(state().currentChatId).toBeNull();
    });

    it('creates a session titled by the first user message and makes it current', () => {
        state().addMessage({ role: 'assistant', content: 'welcome' });
        state().addMessage({ role: 'user', content: 'first question' });
        state().saveCurrentChat();

        expect(state().chatSessions).toHaveLength(1);
        const [session] = state().chatSessions;
        expect(session.title).toBe('first question');
        expect(session.messages).toHaveLength(2);
        expect(state().currentChatId).toBe(session.id);
    });

    it('truncates long titles to 40 characters plus an ellipsis', () => {
        state().addMessage({ role: 'user', content: 'x'.repeat(60) });
        state().saveCurrentChat();
        expect(state().chatSessions[0].title).toBe(`${'x'.repeat(40)}...`);
    });

    it('falls back to "New Chat" when there is no user message', () => {
        state().addMessage({ role: 'assistant', content: 'hello' });
        state().saveCurrentChat();
        expect(state().chatSessions[0].title).toBe('New Chat');
    });

    it('updates the existing session instead of creating another one', () => {
        state().addMessage({ role: 'user', content: 'q' });
        state().saveCurrentChat();
        const firstId = state().currentChatId;

        state().addMessage({ role: 'assistant', content: 'a' });
        state().saveCurrentChat();

        expect(state().chatSessions).toHaveLength(1);
        expect(state().chatSessions[0].id).toBe(firstId);
        expect(state().chatSessions[0].messages).toHaveLength(2);
    });

    it('only rewrites the session that matches currentChatId', () => {
        useAppStore.setState({
            chatSessions: [
                { id: '1', title: 'one', updatedAt: 1, messages: [] },
                { id: '2', title: 'two', updatedAt: 2, messages: [] },
            ],
            currentChatId: '2',
            messages: [{ id: 'm', role: 'user', content: 'changed', timestamp: 3 }],
        });
        state().saveCurrentChat();
        expect(state().chatSessions[0]).toMatchObject({ id: '1', title: 'one' });
        expect(state().chatSessions[1]).toMatchObject({ id: '2', title: 'changed' });
    });

    it('loadChat restores the messages of a session, and ignores unknown ids', () => {
        const messages = [{ id: 'm', role: 'user' as const, content: 'saved', timestamp: 1 }];
        useAppStore.setState({ chatSessions: [{ id: 's', title: 't', updatedAt: 1, messages }] });

        state().loadChat('missing');
        expect(state().messages).toEqual([]);

        state().loadChat('s');
        expect(state().messages).toEqual(messages);
        expect(state().currentChatId).toBe('s');
    });

    it('deleteChatSession resets the open conversation only when it deletes the current one', () => {
        const session = (id: string) => ({ id, title: id, updatedAt: 1, messages: [] });
        useAppStore.setState({
            chatSessions: [session('a'), session('b')],
            currentChatId: 'a',
            messages: [{ id: 'm', role: 'user', content: 'x', timestamp: 1 }],
        });

        state().deleteChatSession('b');
        expect(state().chatSessions.map((s) => s.id)).toEqual(['a']);
        expect(state().messages).toHaveLength(1);

        state().deleteChatSession('a');
        expect(state().chatSessions).toEqual([]);
        expect(state().messages).toEqual([]);
        expect(state().currentChatId).toBeNull();
    });
});

describe('persistence', () => {
    it('persists settings and chats but not transient connection or streaming state', async () => {
        useAppStore.setState({
            theme: 'dark',
            serverConfig: { host: 'lan.local', port: 4321, apiKey: 'k' },
            isConnected: true,
            isStreaming: true,
            activeModelId: 'model',
            editingMessageId: 'e',
        });
        state().addMessage({ role: 'user', content: 'persist me' });

        await new Promise((resolve) => setTimeout(resolve, 0));
        const raw = await AsyncStorage.getItem('localaiapp-storage');
        const persisted = JSON.parse(raw as string).state;

        expect(Object.keys(persisted).sort()).toEqual(
            ['chatSessions', 'currentChatId', 'messages', 'serverConfig', 'theme'],
        );
        expect(persisted.serverConfig).toEqual({ host: 'lan.local', port: 4321, apiKey: 'k' });
        expect(persisted.messages[0].content).toBe('persist me');
    });
});