const express = require('express');
const argon2 = require('argon2');
const { 
    initDb, 
    getAllArticles, 
    getArticle, 
    createArticle, 
    updateArticle, 
    deleteArticle, 
    searchArticles,
    createUser,
    getUserByUsername,
    getUserByEmail
} = require('./db');
const { generateToken, authenticateToken } = require('./auth');
const app = express();
const cors = require('cors');
const PORT = 9000;

app.use(cors())
app.use(express.json());

initDb().then(() => {

    app.get('/', (req, res) => {
        res.json({message : 'Server is running'});
    });

    app.get('/api/articles', authenticateToken, (req, res) => {
        try {
            const articles = getAllArticles();
            res.json(articles);
        } catch (error) {
            console.error('Error fetching articles:', error);
            res.status(500).json({error: 'Failed to fetch articles', 'details': String(error)});
        }
    });

    app.get('/api/articles/:ka_number', authenticateToken, (req, res) => {
        try {
            const article = getArticle(req.params.ka_number);

            if (!article) {
                return res.status(404).json({ error: 'Article not found' });
            }

            res.json(article);
        } catch (error) {
            console.error('Error fetching article:', error);
            res.status(500).json({error: 'Failed to fetch article', 'details': String(error)});
        }
    });

    app.post('/api/articles', authenticateToken, (req, res) => {
        try {
            const { title, content } = req.body;

            if (!title) {
                return res.status(400).json({error: 'Title is required' });
            }

            const article = createArticle(title, content, req.user.display_name);
            res.status(201).json(article);

        } catch (error) {
            console.error('Error creating article:', error);
            res.status(500).json({error: 'Failed to create article', 'details': String(error)});
        }
    });

    app.put('/api/articles/:ka_number', authenticateToken, (req, res) => {
        try {
            const { title, content } = req.body;

            if (!title) {
                return res.status(400).json({error: 'Title is required' });
            }

            const article = updateArticle(req.params.ka_number, title, content, req.user.display_name);

            if (!article) {
                return res.status(404).json({error: 'Article not found'});
            }

            res.json(article);
        } catch (error) {
            console.error('Error updating article:', error);
            return res.status(500).json({error: 'Error while updating article', 'details': String(error)});
        }
    });

    app.delete('/api/articles/:ka_number', authenticateToken, (req, res) => {
        try {
            deleteArticle(req.params.ka_number);
            return res.status(200).json({'message': 'Successfully deleted article'});

        } catch (error) {
            console.error('Error when deleting article:', error);
            return res.status(500).json({error: 'Failed to delete article', 'details': String(error)});
        }
    });

    app.get('/api/search', authenticateToken, (req, res) => {
        try {
            const query = req.query.q;

            if (!query) {
                return res.status(400).json({error: 'Search query is required'});
            }

            const results = searchArticles(query);
            res.json(results);
        } catch (error) {
            console.error('Error when searching articles:', error);
            return res.status(500).json({error: 'Failed to search articles', 'details': String(error)});
        }
    });
    
    app.post('/api/auth/register', async (req, res) => {
        try {
            const {username, email, password, displayName} = req.body;

            if (!username || !email || !password || !displayName) {
                return res.status(400).json({error: 'Username, email, password, and display name are required'});
            }

            const cur_user_username = getUserByUsername(username);
            if (cur_user_username) {
                return res.status(400).json({error: 'Username already exists'});
            }

            const cur_user_email = getUserByEmail(email);
            if(cur_user_email) {
                return res.status(400).json({error: 'email address already in use'});
            }

            const pass_hash = await argon2.hash(password);
            const newUser = createUser(username, email, pass_hash, displayName);
            const token = generateToken(newUser);

            return res.status(201).json({
                user: {
                    id: newUser.id,
                    username: newUser.username,
                    email: newUser.email,
                    display_name: newUser.display_name,
                    auth_provider: newUser.auth_provider,
                    created_at: newUser.created_at
                },
                token
            });

        } catch (error) {
            console.error('Error when registering new user: ', error);
            return res.status(500).json({error: 'Failed to create user', 'details': String(error)});
        }
    });

    app.post('/api/auth/login', async (req, res) => {
        try {
            const {username, email, password} = req.body;

            if (!password || (!username && !email)) {
                return res.status(400).json({error: 'Username/email & password are required'});
            }

            let user;
            if (!username) {
                user = getUserByEmail(email);
            } else {
                user = getUserByUsername(username);
            }

            if (!user || !await argon2.verify(user.pass_hash, password)) {
                return res.status(401).json({error: 'Invalid credentials'});
            }

            const token = generateToken(user);

            return res.status(200).json({
                user: {
                    id: user.id,
                    username: user.username,
                    email: user.email,
                    display_name: user.display_name,
                    auth_provider: user.auth_provider,
                    created_at: user.created_at
                },
                token
            });
        } catch (error) {
            console.log('Failed to log user in:', error);
            return res.status(500).json({error: 'Failed to login', 'details': String(error)});
        }
    });

    app.listen(PORT, () => {
        console.log(`Server running on http://localhost:${PORT}`);
    });
}).catch(err => {
    console.error('Failed to initialize database:', err);
});