const { Client } = require('pg');
const path = require('path');
const fs = require('fs');
require('dotenv').config({ path: path.resolve(__dirname, '../.env') });

const dbConfig = {
    host: process.env.DB_HOST,
    user: process.env.DB_USER,
    password: process.env.DB_PASSWORD,
    database: process.env.DB_NAME,
    port: process.env.DB_PORT || 5432
};

function outputProgress(data) {
    if (!data.status) {
        data = {
            status: 'running',
            ...data
        };
    }
    console.log(JSON.stringify(data));
}

// Explicitly define all metrics-related tables in dependency order
const METRICS_TABLES = [
    'brand_metrics',
    'brand_time_metrics',
    'category_forecasts',
    'category_metrics',
    'category_sales_metrics',
    'category_time_metrics',
    'product_metrics',
    'product_time_aggregates',
    'sales_forecasts',
    'temp_purchase_metrics',
    'temp_sales_metrics',
    'vendor_metrics',
    'vendor_time_metrics',
    'vendor_details'
];

// Tables to always protect from being dropped
const PROTECTED_TABLES = [
    'users', 
    'permissions', 
    'user_permissions', 
    'calculate_history', 
    'import_history', 
    'ai_prompts', 
    'ai_validation_performance', 
    'templates', 
    'reusable_images'
];

// Split SQL into individual statements
function splitSQLStatements(sql) {
    sql = sql.replace(/\r\n/g, '\n');
    let statements = [];
    let currentStatement = '';
    let inString = false;
    let stringChar = '';
    
    for (let i = 0; i < sql.length; i++) {
        const char = sql[i];
        const nextChar = sql[i + 1] || '';
        
        if ((char === "'" || char === '"') && sql[i - 1] !== '\\') {
            if (!inString) {
                inString = true;
                stringChar = char;
            } else if (char === stringChar) {
                inString = false;
            }
        }
        
        if (!inString && char === '-' && nextChar === '-') {
            while (i < sql.length && sql[i] !== '\n') i++;
            continue;
        }
        
        if (!inString && char === '/' && nextChar === '*') {
            i += 2;
            while (i < sql.length && (sql[i] !== '*' || sql[i + 1] !== '/')) i++;
            i++;
            continue;
        }
        
        if (!inString && char === ';') {
            if (currentStatement.trim()) {
                statements.push(currentStatement.trim());
            }
            currentStatement = '';
        } else {
            currentStatement += char;
        }
    }
    
    if (currentStatement.trim()) {
        statements.push(currentStatement.trim());
    }
    
    return statements;
}

async function resetMetrics() {
    let client;
    try {
        outputProgress({
            operation: 'Starting metrics reset',
            message: 'Connecting to database...'
        });

        client = new Client(dbConfig);
        await client.connect();

        // Explicitly begin a transaction
        await client.query('BEGIN');

        // First verify current state
        const initialTables = await client.query(`
            SELECT tablename as name
            FROM pg_tables 
            WHERE schemaname = 'public'
            AND tablename = ANY($1)
            AND tablename NOT IN (SELECT unnest($2::text[]))
        `, [METRICS_TABLES, PROTECTED_TABLES]);

        outputProgress({
            operation: 'Initial state',
            message: `Found ${initialTables.rows.length} existing metrics tables: ${initialTables.rows.map(t => t.name).join(', ')}`
        });

        // Disable foreign key checks at the start
        await client.query('SET session_replication_role = \'replica\'');

        // Drop all metrics tables in reverse order to handle dependencies
        outputProgress({
            operation: 'Dropping metrics tables',
            message: 'Removing existing metrics tables...'
        });

        for (const table of [...METRICS_TABLES].reverse()) {
            // Skip protected tables
            if (PROTECTED_TABLES.includes(table)) {
                outputProgress({
                    operation: 'Protected table',
                    message: `Skipping protected table: ${table}`
                });
                continue;
            }
            
            try {
                // Use NOWAIT to avoid hanging if there's a lock
                await client.query(`DROP TABLE IF EXISTS "${table}" CASCADE`);
                
                // Verify the table was actually dropped
                const checkDrop = await client.query(`
                    SELECT COUNT(*) as count 
                    FROM pg_tables 
                    WHERE schemaname = 'public' 
                    AND tablename = $1
                `, [table]);
                
                if (parseInt(checkDrop.rows[0].count) > 0) {
                    throw new Error(`Failed to drop table ${table} - table still exists`);
                }

                outputProgress({
                    operation: 'Table dropped',
                    message: `Successfully dropped table: ${table}`
                });
                
                // Commit after each table drop to ensure locks are released
                await client.query('COMMIT');
                // Start a new transaction for the next table
                await client.query('BEGIN');
                // Re-disable foreign key constraints for the new transaction
                await client.query('SET session_replication_role = \'replica\'');
            } catch (err) {
                outputProgress({
                    status: 'error',
                    operation: 'Drop table error',
                    message: `Error dropping table ${table}: ${err.message}`
                });
                await client.query('ROLLBACK');
                // Re-start transaction for next table
                await client.query('BEGIN');
                await client.query('SET session_replication_role = \'replica\'');
            }
        }

        // Verify all tables were dropped
        const afterDrop = await client.query(`
            SELECT tablename as name
            FROM pg_tables 
            WHERE schemaname = 'public'
            AND tablename = ANY($1)
        `, [METRICS_TABLES]);

        if (afterDrop.rows.length > 0) {
            throw new Error(`Failed to drop all tables. Remaining tables: ${afterDrop.rows.map(t => t.name).join(', ')}`);
        }

        // Make sure we have a fresh transaction here
        await client.query('COMMIT');
        await client.query('BEGIN');
        await client.query('SET session_replication_role = \'replica\'');

        // Read metrics schema
        outputProgress({
            operation: 'Reading schema',
            message: 'Loading metrics schema file...'
        });

        const schemaPath = path.resolve(__dirname, '../db/metrics-schema.sql');
        if (!fs.existsSync(schemaPath)) {
            throw new Error(`Schema file not found at: ${schemaPath}`);
        }

        const schemaSQL = fs.readFileSync(schemaPath, 'utf8');
        const statements = splitSQLStatements(schemaSQL);

        outputProgress({
            operation: 'Schema loaded',
            message: `Found ${statements.length} SQL statements to execute`
        });

        // Execute schema statements
        for (let i = 0; i < statements.length; i++) {
            const stmt = statements[i];
            try {
                const result = await client.query(stmt);

                // If this is a CREATE TABLE statement, verify the table was created
                if (stmt.trim().toLowerCase().startsWith('create table')) {
                    const tableName = stmt.match(/create\s+table\s+(?:if\s+not\s+exists\s+)?["]?(\w+)["]?/i)?.[1];
                    if (tableName) {
                        const checkCreate = await client.query(`
                            SELECT tablename as name
                            FROM pg_tables 
                            WHERE schemaname = 'public' 
                            AND tablename = $1
                        `, [tableName]);
                        
                        if (checkCreate.rows.length === 0) {
                            throw new Error(`Failed to create table ${tableName} - table does not exist after CREATE statement`);
                        }

                        outputProgress({
                            operation: 'Table created',
                            message: `Successfully created table: ${tableName}`
                        });
                    }
                }
                
                outputProgress({
                    operation: 'SQL Progress',
                    message: {
                        statement: i + 1,
                        total: statements.length,
                        preview: stmt.substring(0, 100) + (stmt.length > 100 ? '...' : ''),
                        rowCount: result.rowCount
                    }
                });
                
                // Commit every 10 statements to avoid long-running transactions
                if (i > 0 && i % 10 === 0) {
                    await client.query('COMMIT');
                    await client.query('BEGIN');
                    await client.query('SET session_replication_role = \'replica\'');
                }
            } catch (sqlError) {
                outputProgress({
                    status: 'error',
                    operation: 'SQL Error',
                    message: {
                        error: sqlError.message,
                        statement: stmt,
                        statementNumber: i + 1
                    }
                });
                await client.query('ROLLBACK');
                throw sqlError;
            }
        }

        // Final commit for any pending statements
        await client.query('COMMIT');
        
        // Start new transaction for final checks
        await client.query('BEGIN');

        // Re-enable foreign key checks after all tables are created
        await client.query('SET session_replication_role = \'origin\'');

        // Verify metrics tables were created
        outputProgress({
            operation: 'Verifying metrics tables',
            message: 'Checking all metrics tables were created...'
        });

        const metricsTablesResult = await client.query(`
            SELECT tablename as name
            FROM pg_tables 
            WHERE schemaname = 'public'
            AND tablename = ANY($1)
        `, [METRICS_TABLES]);

        outputProgress({
            operation: 'Tables found',
            message: `Found ${metricsTablesResult.rows.length} tables: ${metricsTablesResult.rows.map(t => t.name).join(', ')}`
        });

        const existingMetricsTables = metricsTablesResult.rows.map(t => t.name);
        const missingMetricsTables = METRICS_TABLES.filter(t => !existingMetricsTables.includes(t));

        if (missingMetricsTables.length > 0) {
            // Do one final check of the actual tables
            const finalCheck = await client.query(`
                SELECT tablename as name
                FROM pg_tables 
                WHERE schemaname = 'public'
            `);
            outputProgress({
                operation: 'Final table check',
                message: `All database tables: ${finalCheck.rows.map(t => t.name).join(', ')}`
            });
            await client.query('ROLLBACK');
            throw new Error(`Failed to create metrics tables: ${missingMetricsTables.join(', ')}`);
        }

        // Commit final transaction
        await client.query('COMMIT');
        
        outputProgress({
            status: 'complete',
            operation: 'Reset complete',
            message: 'All metrics tables have been reset successfully'
        });
    } catch (error) {
        outputProgress({
            status: 'error',
            operation: 'Reset failed',
            message: error.message,
            stack: error.stack
        });
        
        if (client) {
            try {
                await client.query('ROLLBACK');
            } catch (rollbackError) {
                console.error('Error during rollback:', rollbackError);
            }
            // Make sure to re-enable foreign key checks even if there's an error
            await client.query('SET session_replication_role = \'origin\'').catch(() => {});
        }
        throw error;
    } finally {
        if (client) {
            // One final attempt to ensure foreign key checks are enabled
            await client.query('SET session_replication_role = \'origin\'').catch(() => {});
            await client.end();
        }
    }
}

// Export if required as a module
if (typeof module !== 'undefined' && module.exports) {
    module.exports = resetMetrics;
}

// Run if called from command line
if (require.main === module) {
    resetMetrics().catch(error => {
        console.error('Error:', error);
        process.exit(1);
    });
}