const { outputProgress, formatElapsedTime, estimateRemaining, calculateRate, logError } = require('./utils/progress');
const { getConnection } = require('./utils/db');

async function calculateCategoryMetrics(startTime, totalProducts, processedCount = 0, isCancelled = false) {
    const connection = await getConnection();
    let success = false;
    const BATCH_SIZE = 5000;
    
    try {
        // Get last calculation timestamp
        const [lastCalc] = await connection.query(`
            SELECT last_calculation_timestamp 
            FROM calculate_status 
            WHERE module_name = 'category_metrics'
        `);
        const lastCalculationTime = lastCalc[0]?.last_calculation_timestamp || '1970-01-01';

        // Get total count of categories needing updates
        const [categoryCount] = await connection.query(`
            SELECT COUNT(DISTINCT c.cat_id) as count 
            FROM categories c
            JOIN product_categories pc ON c.cat_id = pc.cat_id
            LEFT JOIN products p ON pc.pid = p.pid AND p.updated > ?
            LEFT JOIN orders o ON p.pid = o.pid AND o.updated > ?
            WHERE c.status = 'active'
              AND (
                  p.pid IS NOT NULL
                  OR o.id IS NOT NULL
              )
        `, [lastCalculationTime, lastCalculationTime]);
        const totalCategories = categoryCount[0].count;

        if (totalCategories === 0) {
            console.log('No categories need metric updates');
            return {
                processedProducts: 0,
                processedOrders: 0,
                processedPurchaseOrders: 0,
                success: true
            };
        }

        if (isCancelled) {
            outputProgress({
                status: 'cancelled',
                operation: 'Category metrics calculation cancelled',
                current: processedCount,
                total: totalCategories,
                elapsed: formatElapsedTime(startTime),
                remaining: null,
                rate: calculateRate(startTime, processedCount),
                percentage: ((processedCount / totalCategories) * 100).toFixed(1),
                timing: {
                    start_time: new Date(startTime).toISOString(),
                    end_time: new Date().toISOString(),
                    elapsed_seconds: Math.round((Date.now() - startTime) / 1000)
                }
            });
            return {
                processedProducts: processedCount,
                processedOrders: 0,
                processedPurchaseOrders: 0,
                success
            };
        }

        outputProgress({
            status: 'running',
            operation: 'Starting category metrics calculation',
            current: processedCount,
            total: totalCategories,
            elapsed: formatElapsedTime(startTime),
            remaining: estimateRemaining(startTime, processedCount, totalCategories),
            rate: calculateRate(startTime, processedCount),
            percentage: ((processedCount / totalCategories) * 100).toFixed(1),
            timing: {
                start_time: new Date(startTime).toISOString(),
                end_time: new Date().toISOString(),
                elapsed_seconds: Math.round((Date.now() - startTime) / 1000)
            }
        });

        // Process in batches
        let lastCatId = 0;
        while (true) {
            if (isCancelled) break;

            const [batch] = await connection.query(`
                SELECT DISTINCT c.cat_id 
                FROM categories c
                JOIN product_categories pc ON c.cat_id = pc.cat_id
                LEFT JOIN products p ON pc.pid = p.pid AND p.updated > ?
                LEFT JOIN orders o ON p.pid = o.pid AND o.updated > ?
                WHERE c.status = 'active'
                  AND c.cat_id > ?
                  AND (
                      p.pid IS NOT NULL
                      OR o.id IS NOT NULL
                  )
                ORDER BY c.cat_id 
                LIMIT ?
            `, [lastCalculationTime, lastCalculationTime, lastCatId, BATCH_SIZE]);

            if (batch.length === 0) break;

            // Update category metrics for this batch
            await connection.query(`
                INSERT INTO category_metrics (
                    category_id,
                    product_count,
                    active_products,
                    total_value,
                    avg_margin,
                    turnover_rate,
                    growth_rate,
                    status,
                    last_calculated_at
                )
                SELECT 
                    c.cat_id,
                    COUNT(DISTINCT p.pid) as product_count,
                    COUNT(DISTINCT CASE WHEN p.visible = true THEN p.pid END) as active_products,
                    SUM(p.stock_quantity * p.cost_price) as total_value,
                    AVG(pm.avg_margin_percent) as avg_margin,
                    AVG(pm.turnover_rate) as turnover_rate,
                    ((SUM(CASE 
                        WHEN o.date >= DATE_SUB(CURRENT_DATE, INTERVAL 30 DAY) 
                        THEN o.quantity * o.price 
                        ELSE 0 
                    END) / NULLIF(SUM(CASE 
                        WHEN o.date BETWEEN DATE_SUB(CURRENT_DATE, INTERVAL 60 DAY) AND DATE_SUB(CURRENT_DATE, INTERVAL 30 DAY)
                        THEN o.quantity * o.price 
                        ELSE 0 
                    END), 0) - 1) * 100) as growth_rate,
                    c.status,
                    NOW() as last_calculated_at
                FROM categories c
                JOIN product_categories pc ON c.cat_id = pc.cat_id
                LEFT JOIN products p ON pc.pid = p.pid
                LEFT JOIN product_metrics pm ON p.pid = pm.pid
                LEFT JOIN orders o ON p.pid = o.pid 
                    AND o.canceled = false
                    AND o.date >= DATE_SUB(CURRENT_DATE, INTERVAL 60 DAY)
                WHERE c.cat_id IN (?)
                GROUP BY c.cat_id, c.status
                ON DUPLICATE KEY UPDATE
                    product_count = VALUES(product_count),
                    active_products = VALUES(active_products),
                    total_value = VALUES(total_value),
                    avg_margin = VALUES(avg_margin),
                    turnover_rate = VALUES(turnover_rate),
                    growth_rate = VALUES(growth_rate),
                    status = VALUES(status),
                    last_calculated_at = NOW()
            `, [batch.map(row => row.cat_id)]);

            lastCatId = batch[batch.length - 1].cat_id;
            processedCount += batch.length;

            outputProgress({
                status: 'running',
                operation: 'Processing category metrics batch',
                current: processedCount,
                total: totalCategories,
                elapsed: formatElapsedTime(startTime),
                remaining: estimateRemaining(startTime, processedCount, totalCategories),
                rate: calculateRate(startTime, processedCount),
                percentage: ((processedCount / totalCategories) * 100).toFixed(1),
                timing: {
                    start_time: new Date(startTime).toISOString(),
                    end_time: new Date().toISOString(),
                    elapsed_seconds: Math.round((Date.now() - startTime) / 1000)
                }
            });
        }

        // If we get here, everything completed successfully
        success = true;
        
        // Update calculate_status
        await connection.query(`
            INSERT INTO calculate_status (module_name, last_calculation_timestamp)
            VALUES ('category_metrics', NOW())
            ON DUPLICATE KEY UPDATE last_calculation_timestamp = NOW()
        `);

        return {
            processedProducts: processedCount,
            processedOrders: 0,
            processedPurchaseOrders: 0,
            success
        };

    } catch (error) {
        success = false;
        logError(error, 'Error calculating category metrics');
        throw error;
    } finally {
        if (connection) {
            connection.release();
        }
    }
}

module.exports = calculateCategoryMetrics;