const { Client } = require('pg');
const path = require('path');
const dotenv = require('dotenv');
const fs = require('fs');

dotenv.config({ path: path.join(__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
};

// Helper function to output progress in JSON format
function outputProgress(data) {
    if (!data.status) {
        data = {
            status: 'running',
            ...data
        };
    }
    console.log(JSON.stringify(data));
}

// Core tables that must be created
const CORE_TABLES = [
    'products',
    'orders',
    'purchase_orders',
    'categories',
    'product_categories'
];

// Config tables that must be created
const CONFIG_TABLES = [
    'stock_thresholds',
    'lead_time_thresholds',
    'sales_velocity_config',
    'abc_classification_config',
    'safety_stock_config',
    'sales_seasonality',
    'turnover_config'
];

// Split SQL into individual statements
function splitSQLStatements(sql) {
    // First, normalize line endings
    sql = sql.replace(/\r\n/g, '\n');
    
    // Track statement boundaries
    let statements = [];
    let currentStatement = '';
    let inString = false;
    let stringChar = '';
    let inDollarQuote = false;
    let dollarQuoteTag = '';
    
    // Process character by character
    for (let i = 0; i < sql.length; i++) {
        const char = sql[i];
        const nextChar = sql[i + 1] || '';
        
        // Handle dollar quotes
        if (char === '$' && !inString) {
            // Look ahead to find the dollar quote tag
            let tag = '$';
            let j = i + 1;
            while (j < sql.length && sql[j] !== '$') {
                tag += sql[j];
                j++;
            }
            tag += '$';
            
            if (j < sql.length) { // Found closing $
                if (!inDollarQuote) {
                    inDollarQuote = true;
                    dollarQuoteTag = tag;
                    currentStatement += tag;
                    i = j;
                    continue;
                } else if (sql.substring(i, j + 1) === dollarQuoteTag) {
                    inDollarQuote = false;
                    dollarQuoteTag = '';
                    currentStatement += tag;
                    i = j;
                    continue;
                }
            }
        }
        
        // Handle string literals (only if not in dollar quote)
        if (!inDollarQuote && (char === "'" || char === '"') && sql[i - 1] !== '\\') {
            if (!inString) {
                inString = true;
                stringChar = char;
            } else if (char === stringChar) {
                inString = false;
            }
        }
        
        // Handle comments (only if not in string or dollar quote)
        if (!inString && !inDollarQuote) {
            if (char === '-' && nextChar === '-') {
                // Skip to end of line
                while (i < sql.length && sql[i] !== '\n') i++;
                continue;
            }
            
            if (char === '/' && nextChar === '*') {
                // Skip until closing */
                i += 2;
                while (i < sql.length && (sql[i] !== '*' || sql[i + 1] !== '/')) i++;
                i++; // Skip the closing /
                continue;
            }
        }
        
        // Handle statement boundaries (only if not in string or dollar quote)
        if (!inString && !inDollarQuote && char === ';') {
            if (currentStatement.trim()) {
                statements.push(currentStatement.trim());
            }
            currentStatement = '';
        } else {
            currentStatement += char;
        }
    }
    
    // Add the last statement if it exists
    if (currentStatement.trim()) {
        statements.push(currentStatement.trim());
    }
    
    return statements;
}

async function resetDatabase() {
    outputProgress({
        operation: 'Starting database reset',
        message: 'Connecting to database...'
    });

    // Debug: Log current directory and file paths
    outputProgress({
        operation: 'Debug paths',
        message: {
            currentDir: process.cwd(),
            __dirname: __dirname,
            schemaPath: path.join(__dirname, '../db/schema.sql')
        }
    });

    const client = new Client(dbConfig);
    await client.connect();
    
    try {
        // Check PostgreSQL version and user
        outputProgress({
            operation: 'Checking database',
            message: 'Verifying PostgreSQL version and user privileges...'
        });

        const versionResult = await client.query('SELECT version()');
        const userResult = await client.query('SELECT current_user, current_database()');
        
        outputProgress({
            operation: 'Database info',
            message: {
                version: versionResult.rows[0].version,
                user: userResult.rows[0].current_user,
                database: userResult.rows[0].current_database
            }
        });

        // Get list of all tables in the current database
        outputProgress({
            operation: 'Getting table list',
            message: 'Retrieving all table names...'
        });

        const tablesResult = await client.query(`
            SELECT string_agg(tablename, ', ') as tables
            FROM pg_tables
            WHERE schemaname = 'public'
            AND tablename NOT IN ('users', 'permissions', 'user_permissions', 'calculate_history', 'import_history');
        `);

        if (!tablesResult.rows[0].tables) {
            outputProgress({
                operation: 'No tables found',
                message: 'Database is already empty'
            });
        } else {
            outputProgress({
                operation: 'Dropping tables',
                message: 'Dropping all existing tables...'
            });

            // Disable triggers/foreign key checks
            await client.query('SET session_replication_role = \'replica\';');
            
            // Drop all tables except users
            const tables = tablesResult.rows[0].tables.split(', ');
            for (const table of tables) {
                if (!['users'].includes(table)) {
                    await client.query(`DROP TABLE IF EXISTS "${table}" CASCADE`);
                }
            }

            // Only drop types if we're not preserving history tables
            const historyTablesExist = await client.query(`
                SELECT EXISTS (
                    SELECT FROM pg_tables 
                    WHERE schemaname = 'public' 
                    AND tablename IN ('calculate_history', 'import_history')
                );
            `);

            if (!historyTablesExist.rows[0].exists) {
                await client.query('DROP TYPE IF EXISTS calculation_status CASCADE;');
                await client.query('DROP TYPE IF EXISTS module_name CASCADE;');
            }
            
            // Re-enable triggers/foreign key checks
            await client.query('SET session_replication_role = \'origin\';');
        }

        // Create enum types if they don't exist
        outputProgress({
            operation: 'Creating enum types',
            message: 'Setting up required enum types...'
        });

        // Check if types exist before creating
        const typesExist = await client.query(`
            SELECT EXISTS (
                SELECT 1 FROM pg_type 
                WHERE typname = 'calculation_status'
            ) as calc_status_exists,
            EXISTS (
                SELECT 1 FROM pg_type 
                WHERE typname = 'module_name'
            ) as module_name_exists;
        `);

        if (!typesExist.rows[0].calc_status_exists) {
            await client.query(`CREATE TYPE calculation_status AS ENUM ('running', 'completed', 'failed', 'cancelled')`);
        }

        if (!typesExist.rows[0].module_name_exists) {
            await client.query(`
                CREATE TYPE module_name AS ENUM (
                    'product_metrics',
                    'time_aggregates',
                    'financial_metrics',
                    'vendor_metrics',
                    'category_metrics',
                    'brand_metrics',
                    'sales_forecasts',
                    'abc_classification'
                )
            `);
        }

        // Read and execute main schema first (core tables)
        outputProgress({
            operation: 'Running database setup',
            message: 'Creating core tables...'
        });
        const schemaPath = path.join(__dirname, '../db/schema.sql');
        
        // Verify file exists
        if (!fs.existsSync(schemaPath)) {
            throw new Error(`Schema file not found at: ${schemaPath}`);
        }

        const schemaSQL = fs.readFileSync(schemaPath, 'utf8');
        
        outputProgress({
            operation: 'Schema file',
            message: {
                path: schemaPath,
                exists: fs.existsSync(schemaPath),
                size: fs.statSync(schemaPath).size,
                firstFewLines: schemaSQL.split('\n').slice(0, 5).join('\n')
            }
        });

        // Execute schema statements one at a time
        const statements = splitSQLStatements(schemaSQL);
        outputProgress({
            operation: 'SQL Execution',
            message: {
                totalStatements: statements.length,
                statements: statements.map((stmt, i) => ({
                    number: i + 1,
                    preview: stmt.substring(0, 100) + (stmt.length > 100 ? '...' : '')
                }))
            }
        });

        for (let i = 0; i < statements.length; i++) {
            const stmt = statements[i];
            try {
                const result = await client.query(stmt);
                
                // Verify if table was created (if this was a CREATE TABLE statement)
                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 tableExists = await client.query(`
                            SELECT COUNT(*) as count 
                            FROM information_schema.tables 
                            WHERE table_schema = 'public' 
                            AND table_name = $1
                        `, [tableName]);
                        
                        outputProgress({
                            operation: 'Table Creation Verification',
                            message: {
                                table: tableName,
                                exists: tableExists.rows[0].count > 0
                            }
                        });
                    }
                }
                
                outputProgress({
                    operation: 'SQL Progress',
                    message: {
                        statement: i + 1,
                        total: statements.length,
                        preview: stmt.substring(0, 100) + (stmt.length > 100 ? '...' : ''),
                        rowCount: result.rowCount
                    }
                });
            } catch (sqlError) {
                outputProgress({
                    status: 'error',
                    operation: 'SQL Error',
                    error: sqlError.message,
                    statement: stmt,
                    statementNumber: i + 1
                });
                throw sqlError;
            }
        }

        // Verify core tables were created
        const existingTables = (await client.query(`
            SELECT table_name
            FROM information_schema.tables 
            WHERE table_schema = 'public'
        `)).rows.map(t => t.table_name);

        outputProgress({
            operation: 'Core tables verification',
            message: {
                found: existingTables,
                expected: CORE_TABLES
            }
        });

        const missingCoreTables = CORE_TABLES.filter(
            t => !existingTables.includes(t)
        );

        if (missingCoreTables.length > 0) {
            throw new Error(
                `Failed to create core tables: ${missingCoreTables.join(', ')}`
            );
        }

        outputProgress({
            operation: 'Core tables created',
            message: `Successfully created tables: ${CORE_TABLES.join(', ')}`
        });

        // Now read and execute config schema (since core tables exist)
        outputProgress({
            operation: 'Running config setup',
            message: 'Creating configuration tables...'
        });
        const configSchemaSQL = fs.readFileSync(
            path.join(__dirname, '../db/config-schema.sql'),
            'utf8'
        );
        
        // Execute config schema statements one at a time
        const configStatements = splitSQLStatements(configSchemaSQL);
        outputProgress({
            operation: 'Config SQL Execution',
            message: {
                totalStatements: configStatements.length,
                statements: configStatements.map((stmt, i) => ({
                    number: i + 1,
                    preview: stmt.substring(0, 100) + (stmt.length > 100 ? '...' : '')
                }))
            }
        });

        for (let i = 0; i < configStatements.length; i++) {
            const stmt = configStatements[i];
            try {
                const result = await client.query(stmt);
                
                outputProgress({
                    operation: 'Config SQL Progress',
                    message: {
                        statement: i + 1,
                        total: configStatements.length,
                        preview: stmt.substring(0, 100) + (stmt.length > 100 ? '...' : ''),
                        rowCount: result.rowCount
                    }
                });
            } catch (sqlError) {
                outputProgress({
                    status: 'error',
                    operation: 'Config SQL Error',
                    error: sqlError.message,
                    statement: stmt,
                    statementNumber: i + 1
                });
                throw sqlError;
            }
        }

        // Read and execute metrics schema (metrics tables)
        outputProgress({
            operation: 'Running metrics setup',
            message: 'Creating metrics tables...'
        });
        const metricsSchemaSQL = fs.readFileSync(
            path.join(__dirname, '../db/metrics-schema.sql'),
            'utf8'
        );
        
        // Execute metrics schema statements one at a time
        const metricsStatements = splitSQLStatements(metricsSchemaSQL);
        outputProgress({
            operation: 'Metrics SQL Execution',
            message: {
                totalStatements: metricsStatements.length,
                statements: metricsStatements.map((stmt, i) => ({
                    number: i + 1,
                    preview: stmt.substring(0, 100) + (stmt.length > 100 ? '...' : '')
                }))
            }
        });

        for (let i = 0; i < metricsStatements.length; i++) {
            const stmt = metricsStatements[i];
            try {
                const result = await client.query(stmt);
                
                outputProgress({
                    operation: 'Metrics SQL Progress',
                    message: {
                        statement: i + 1,
                        total: metricsStatements.length,
                        preview: stmt.substring(0, 100) + (stmt.length > 100 ? '...' : ''),
                        rowCount: result.rowCount
                    }
                });
            } catch (sqlError) {
                outputProgress({
                    status: 'error',
                    operation: 'Metrics SQL Error',
                    error: sqlError.message,
                    statement: stmt,
                    statementNumber: i + 1
                });
                throw sqlError;
            }
        }

        outputProgress({
            status: 'complete',
            operation: 'Database reset complete',
            message: 'Database has been reset and all tables recreated'
        });
    } catch (error) {
        outputProgress({
            status: 'error',
            operation: 'Failed to reset database',
            error: error.message,
            stack: error.stack
        });
        process.exit(1);
    } finally {
        await client.end();
    }
}

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

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