const WarehouseLocation = require('../models/WarehouseLocation');
const AssetMovement    = require('../models/AssetMovement');
const StockThreshold   = require('../models/StockThreshold');
const PurchaseOrder    = require('../models/PurchaseOrder');
const Asset            = require('../models/Asset');
const { getDatabase }  = require('../config/database');

// ─── Locations ────────────────────────────────────────────────────────────────

exports.getLocations = (req, res) => {
    res.json(WarehouseLocation.getAll());
};

exports.createLocation = (req, res) => {
    const { name, description } = req.body;
    if (!name) return res.status(400).json({ error: 'Name ist erforderlich' });
    try {
        const loc = WarehouseLocation.create({ name, description });
        res.status(201).json(loc);
    } catch (e) {
        if (e.message?.includes('UNIQUE')) return res.status(409).json({ error: 'Lagerort existiert bereits' });
        res.status(500).json({ error: e.message });
    }
};

exports.updateLocation = (req, res) => {
    const loc = WarehouseLocation.update(parseInt(req.params.id), req.body);
    if (!loc) return res.status(404).json({ error: 'Nicht gefunden' });
    res.json(loc);
};

exports.deleteLocation = (req, res) => {
    const ok = WarehouseLocation.delete(parseInt(req.params.id));
    if (!ok) return res.status(404).json({ error: 'Nicht gefunden' });
    res.json({ success: true });
};

// ─── Movements ────────────────────────────────────────────────────────────────

exports.getMovements = (req, res) => {
    const asset_id = req.query.asset_id ? parseInt(req.query.asset_id) : undefined;
    res.json(AssetMovement.getAll({ asset_id, limit: 500 }));
};

exports.createMovement = (req, res) => {
    const { asset_id, type, to_location_id, assigned_user_id, ticket_id, reason, notes, new_status } = req.body;
    if (!asset_id || !type) return res.status(400).json({ error: 'asset_id und type sind erforderlich' });

    const asset = Asset.getById(parseInt(asset_id));
    if (!asset) return res.status(404).json({ error: 'Asset nicht gefunden' });

    const db = getDatabase();
    const updateAsset = db.transaction(() => {
        // Create movement record
        const movement = AssetMovement.create({
            asset_id,
            type,
            from_location_id: asset.location_id,
            to_location_id:   to_location_id   || null,
            assigned_user_id: assigned_user_id  || null,
            ticket_id:        ticket_id         || null,
            reason:           reason            || '',
            notes:            notes             || '',
            performed_by:     req.user.id,
        });

        // Update asset location + status if needed
        const updates = {};
        if (to_location_id) updates.location_id = to_location_id;
        if (new_status)     updates.status       = new_status;
        if (assigned_user_id) {
            updates.assigned_to_user_id = assigned_user_id;
            updates.status = 'zugewiesen';
        }
        if (type === 'in') {
            updates.status = 'verfuegbar';
            updates.assigned_to_user_id = null;
        }

        if (Object.keys(updates).length > 0) {
            Asset.update(asset_id, updates, req.user.id);
        }

        return movement;
    });

    try {
        const movement = updateAsset();
        res.status(201).json(movement);
    } catch (e) {
        res.status(500).json({ error: e.message });
    }
};

// ─── Stock Thresholds ─────────────────────────────────────────────────────────

exports.getThresholds = (req, res) => {
    res.json(StockThreshold.getAll());
};

exports.upsertThreshold = (req, res) => {
    const { category, min_stock, notify_email } = req.body;
    if (!category) return res.status(400).json({ error: 'Kategorie ist erforderlich' });
    const threshold = StockThreshold.upsert({ category, min_stock, notify_email });
    res.json(threshold);
};

exports.deleteThreshold = (req, res) => {
    const ok = StockThreshold.delete(req.params.category);
    if (!ok) return res.status(404).json({ error: 'Nicht gefunden' });
    res.json({ success: true });
};

exports.getStockViolations = (req, res) => {
    res.json(StockThreshold.getViolations());
};

// ─── Purchase Orders ──────────────────────────────────────────────────────────

exports.getPurchaseOrders = (req, res) => {
    const { status } = req.query;
    res.json(PurchaseOrder.getAll({ status }));
};

exports.createPurchaseOrder = (req, res) => {
    const { category, item_name, quantity, notes } = req.body;
    if (!category || !item_name) return res.status(400).json({ error: 'Kategorie und Artikelname sind erforderlich' });
    const order = PurchaseOrder.create({ category, item_name, quantity, notes, created_by: req.user.id });
    res.status(201).json(order);
};

exports.updatePurchaseOrder = (req, res) => {
    const order = PurchaseOrder.update(parseInt(req.params.id), req.body);
    if (!order) return res.status(404).json({ error: 'Nicht gefunden' });
    res.json(order);
};

exports.deletePurchaseOrder = (req, res) => {
    const ok = PurchaseOrder.delete(parseInt(req.params.id));
    if (!ok) return res.status(404).json({ error: 'Nicht gefunden' });
    res.json({ success: true });
};

// ─── Dashboard Summary ────────────────────────────────────────────────────────

exports.getSummary = (req, res) => {
    const db = getDatabase();

    const stockByLocation = db.prepare(`
        SELECT wl.name AS location, COUNT(a.id) AS count
        FROM warehouse_locations wl
        LEFT JOIN assets a ON a.location_id = wl.id AND a.status = 'verfuegbar'
        GROUP BY wl.id ORDER BY wl.name
    `).all();

    const stockByCategory = db.prepare(`
        SELECT a.type AS category, a.status, COUNT(*) AS count
        FROM assets a
        GROUP BY a.type, a.status
        ORDER BY a.type, a.status
    `).all();

    const violations     = StockThreshold.getViolations();
    const openOrders     = PurchaseOrder.getOpenCount();
    const recentMovements = AssetMovement.getAll({ limit: 10 });

    res.json({ stockByLocation, stockByCategory, violations, openOrders, recentMovements });
};

// ─── QR Code ──────────────────────────────────────────────────────────────────

exports.getQrCode = async (req, res) => {
    const asset = Asset.getById(parseInt(req.params.id));
    if (!asset) return res.status(404).json({ error: 'Asset nicht gefunden' });

    const QRCode = require('qrcode');
    const url = `${process.env.FRONTEND_URL || 'https://it-nexus.cereda-systems.de'}/assets?scan=${asset.id}`;
    const svg = await QRCode.toString(url, { type: 'svg', width: 200, margin: 1 });

    res.setHeader('Content-Type', 'image/svg+xml');
    res.send(svg);
};