import { execSync } from 'child_process';
import { existsSync, rmSync } from 'fs';
import { join } from 'path';

/**
 * Comprehensive Build Script for SerpentRace Backend
 * Handles TypeScript compilation, migrations, asset copying, and validation
 */

interface BuildOptions {
    runMigrations?: boolean;
    runTests?: boolean;
    skipLinting?: boolean;
    production?: boolean;
}

class BuildManager {
    private distDir = join(__dirname, '..', 'dist');
    
    constructor(private options: BuildOptions = {}) {}

    private log(message: string, level: 'info' | 'error' | 'warn' = 'info') {
        const timestamp = new Date().toISOString();
        const prefix = {
            info: '🔧',
            error: '❌',
            warn: '⚠️'
        }[level];
        console.log(`${prefix} [${timestamp}] ${message}`);
    }

    private execute(command: string, description: string) {
        this.log(`${description}...`);
        try {
            execSync(command, { 
                stdio: 'inherit', 
                cwd: join(__dirname, '..') 
            });
            this.log(`✅ ${description} completed successfully`);
        } catch (error) {
            this.log(`❌ ${description} failed`, 'error');
            throw error;
        }
    }

    async clean() {
        this.log('Cleaning previous build...');
        if (existsSync(this.distDir)) {
            rmSync(this.distDir, { recursive: true, force: true });
            this.log('✅ Previous build cleaned');
        } else {
            this.log('No previous build found');
        }
    }

    async typecheck() {
        this.execute('npx tsc --noEmit', 'Type checking');
    }

    async lint() {
        if (this.options.skipLinting) {
            this.log('Skipping linting...', 'warn');
            return;
        }
        
        // For now, just check if TypeScript compiles without errors
        this.log('Linting (basic type checking)...');
        await this.typecheck();
    }

    async runTests() {
        if (!this.options.runTests) {
            this.log('Skipping tests...', 'warn');
            return;
        }
        
        this.execute('npm test', 'Running tests');
    }

    async runMigrations() {
        if (!this.options.runMigrations) {
            this.log('Skipping database migrations...', 'warn');
            return;
        }

        try {
            this.log('Checking migration status...');
            execSync('npm run migration:show', { 
                stdio: 'pipe', 
                cwd: join(__dirname, '..') 
            });
            
            this.execute('npm run migration:run', 'Running database migrations');
        } catch (error) {
            this.log('Migration check/run failed - this might be expected in CI/CD environments', 'warn');
            if (this.options.production) {
                throw error; // In production builds, migrations should work
            }
        }
    }

    async compile() {
        this.execute('npx tsc', 'Compiling TypeScript');
    }

    async copyAssets() {
        this.execute('node scripts/copy-assets.js', 'Copying assets');
    }

    async validateBuild() {
        this.log('Validating build output...');
        
        const expectedFiles = [
            'dist/Api/index.js',
            'dist/Api/index.d.ts'
        ];

        const missingFiles = expectedFiles.filter(file => 
            !existsSync(join(__dirname, '..', file))
        );

        if (missingFiles.length > 0) {
            this.log(`Missing expected build files: ${missingFiles.join(', ')}`, 'error');
            throw new Error('Build validation failed');
        }

        this.log('✅ Build validation completed');
    }

    async build() {
        const startTime = Date.now();
        
        try {
            this.log('🚀 Starting SerpentRace Backend build process...');
            
            // Step 1: Clean previous build
            await this.clean();
            
            // Step 2: Lint code (if not skipped)
            await this.lint();
            
            // Step 3: Run tests (if enabled)
            await this.runTests();
            
            // Step 4: Run migrations (if enabled)
            await this.runMigrations();
            
            // Step 5: Compile TypeScript
            await this.compile();
            
            // Step 6: Copy assets
            await this.copyAssets();
            
            // Step 7: Validate build
            await this.validateBuild();
            
            const duration = ((Date.now() - startTime) / 1000).toFixed(2);
            this.log(`🎉 Build completed successfully in ${duration}s`);
            
        } catch (error) {
            const duration = ((Date.now() - startTime) / 1000).toFixed(2);
            this.log(`💥 Build failed after ${duration}s`, 'error');
            
            if (error instanceof Error) {
                this.log(`Error: ${error.message}`, 'error');
            }
            
            process.exit(1);
        }
    }
}

// Parse command line arguments
const args = process.argv.slice(2);
const options: BuildOptions = {
    runMigrations: args.includes('--migrations'),
    runTests: args.includes('--test'),
    skipLinting: args.includes('--skip-lint'),
    production: args.includes('--production')
};

// Create and run build
const buildManager = new BuildManager(options);
buildManager.build().catch(error => {
    console.error('Unhandled build error:', error);
    process.exit(1);
});