/**
 * Build Command - Core Build Process
 * 
 * Compiles grammar.js into C static library and JavaScript package
 */

import { Command } from 'commander';
import { execa } from 'execa';
import chalk from 'chalk';
import { existsSync, mkdirSync, writeFileSync, copyFileSync, readFileSync, cpSync } from 'fs';
import { join, dirname, basename } from 'path';
import { fileURLToPath } from 'url';

/**
 * Create the build command
 */
export function createBuildCommand(): Command {
  const buildCommand = new Command('build');
  
  buildCommand
    .description('Build the DSL parser and packages')
    .option('-v, --verbose', 'Show detailed build output')
    .option('--skip-c', 'Skip C library generation')
    .option('--skip-js', 'Skip JavaScript package generation')
    .action(async (options) => {
      console.log(chalk.blue('🏗️  Building DSL parser and packages...'));
      console.log();
      
      try {
        await runBuildProcess(options);
        
        console.log();
        console.log(chalk.green('✅ Build completed successfully!'));
        console.log();
        console.log(chalk.blue('Generated artifacts:'));
        console.log(`  ${chalk.gray('•')} C library: generated/c/lib/`);
        console.log(`  ${chalk.gray('•')} C headers: generated/c/include/`);
        console.log(`  ${chalk.gray('•')} JS package: generated/js/`);
        
      } catch (error) {
        console.error(chalk.red('❌ Build failed:'), error instanceof Error ? error.message : error);
        process.exit(1);
      }
    });

  return buildCommand;
}

/**
 * Run the complete build process
 */
async function runBuildProcess(options: { verbose?: boolean; skipC?: boolean; skipJs?: boolean }): Promise<void> {
  // Verify we're in a DSL project directory
  if (!existsSync('grammar.js')) {
    throw new Error('No grammar.js found. Are you in a DSL project directory?');
  }

  // Ensure CommonJS semantics locally so tree-sitter can load grammar.js (uses module.exports)
  ensureCommonJsPackageJson();

  // Step 1: Generate parser with Tree-sitter
  console.log(chalk.blue('1️⃣  Generating parser with Tree-sitter...'));
  await generateParser(options.verbose);
  console.log(chalk.green('   ✅ Parser generated'));

  // Step 2: Build C library (unless skipped)
  if (!options.skipC) {
    console.log(chalk.blue('2️⃣  Building C static library...'));
    await buildCLibrary(options.verbose);
    console.log(chalk.green('   ✅ C library built'));
  } else {
    console.log(chalk.yellow('   ⏭️  Skipping C library build'));
  }

  // Step 3: Build JavaScript package (unless skipped)
  if (!options.skipJs) {
    console.log(chalk.blue('3️⃣  Building JavaScript package...'));
    await buildJavaScriptPackage(options.verbose);
    console.log(chalk.green('   ✅ JavaScript package built'));
  } else {
    console.log(chalk.yellow('   ⏭️  Skipping JavaScript package build'));
  }
}

/**
 * Step 1: Generate parser using tree-sitter generate
 */
async function generateParser(verbose?: boolean): Promise<void> {
  try {
    // Check if tree-sitter CLI is available
    await checkTreeSitterAvailable();
    
    // Run tree-sitter generate
    const result = await execa('tree-sitter', ['generate'], {
      stdio: verbose ? 'inherit' : 'pipe'
    });
    
    if (!verbose && result.stdout) {
      console.log(chalk.gray(`   ${result.stdout.split('\n').slice(-2, -1)[0] || 'Generated successfully'}`));
    }
    
  } catch (error: any) {
    if (error.command) {
      throw new Error(`Tree-sitter generation failed: ${error.message}`);
    }
    throw error;
  }
}

/**
 * Step 2: Build C static library
 */
async function buildCLibrary(verbose?: boolean): Promise<void> {
  // Create output directories
  const libDir = 'generated/c/lib';
  const includeDir = 'generated/c/include';
  
  mkdirSync(libDir, { recursive: true });
  mkdirSync(includeDir, { recursive: true });

  // Get project name from grammar.js or directory
  const projectName = getProjectName();
  
  // Compile parser.c to object file
  const objectFile = join(libDir, `${projectName}.o`);
  const libraryFile = join(libDir, `lib${projectName}.a`);
  
  try {
    // Detect C compiler
    const compiler = await detectCCompiler();
    console.log(chalk.gray(`   Using compiler: ${compiler}`));
    
    // Compile to object file
    const compileArgs = [
      '-c',                    // Compile only, don't link
      '-fPIC',                 // Position independent code
      '-O2',                   // Optimize
      'src/parser.c',          // Input file
      '-o', objectFile         // Output file
    ];
    
    await execa(compiler, compileArgs, {
      stdio: verbose ? 'inherit' : 'pipe'
    });
    
    // Create static library with ar
    const arArgs = [
      'rcs',                   // Create archive, insert files, write symbol table
      libraryFile,             // Output library
      objectFile               // Input object file
    ];
    
    await execa('ar', arArgs, {
      stdio: verbose ? 'inherit' : 'pipe'
    });
    
    // Generate header file
    await generateHeaderFile(projectName, includeDir);
    
    console.log(chalk.gray(`   Library: ${libraryFile}`));
    console.log(chalk.gray(`   Header: ${join(includeDir, projectName + '.h')}`));
    
  } catch (error: any) {
    throw new Error(`C library build failed: ${error.message}`);
  }
}

/**
 * Step 3: Build JavaScript package
 */
async function buildJavaScriptPackage(verbose?: boolean): Promise<void> {
  const jsDir = 'generated/js';
  
  // Create JS package directory
  mkdirSync(jsDir, { recursive: true });
  
  // Copy JS addon templates
  await copyJSAddonTemplates(jsDir);
  
  // Copy src directory from tree-sitter generation
  await copySourceFiles(jsDir);
  
  // Update binding.gyp based on available files
  await updateBindingGyp(jsDir);
  
  // Update package.json with project name
  await updateJSPackageJson(jsDir);
  
  // Detect runtime and install dependencies
  const runtime = await detectRuntime();
  console.log(chalk.gray(`   Using runtime: ${runtime}`));
  
  try {
    // Install dependencies and build native addon
    if (runtime === 'bun') {
      await execa('bun', ['install'], {
        cwd: jsDir,
        stdio: verbose ? 'inherit' : 'pipe'
      });
    } else {
      await execa('npm', ['install'], {
        cwd: jsDir,
        stdio: verbose ? 'inherit' : 'pipe'
      });
    }
    
    console.log(chalk.gray(`   Package: ${jsDir}/`));
    
  } catch (error: any) {
    throw new Error(`JavaScript package build failed: ${error.message}`);
  }
}

/**
 * Check if tree-sitter CLI is available
 */
async function checkTreeSitterAvailable(): Promise<void> {
  try {
    await execa('tree-sitter', ['--version'], { stdio: 'pipe' });
  } catch (error) {
    throw new Error(
      'tree-sitter CLI not found. Please install it:\n' +
      '  npm install -g tree-sitter-cli\n' +
      '  # or\n' +
      '  brew install tree-sitter'
    );
  }
}

/**
 * Detect available C compiler
 */
async function detectCCompiler(): Promise<string> {
  const compilers = ['clang', 'gcc', 'cc'];
  
  for (const compiler of compilers) {
    try {
      await execa(compiler, ['--version'], { stdio: 'pipe' });
      return compiler;
    } catch {
      // Try next compiler
    }
  }
  
  throw new Error(
    'No C compiler found. Please install one:\n' +
    '  macOS: xcode-select --install\n' +
    '  Linux: sudo apt install build-essential (Ubuntu) or equivalent'
  );
}

/**
 * Detect runtime (bun vs npm)
 */
async function detectRuntime(): Promise<'bun' | 'npm'> {
  try {
    await execa('bun', ['--version'], { stdio: 'pipe' });
    return 'bun';
  } catch {
    return 'npm';
  }
}

/**
 * Get project name from grammar.js or directory name
 */
function getProjectName(): string {
  try {
    const grammarContent = readFileSync('grammar.js', 'utf-8');
    const nameMatch = grammarContent.match(/name:\s*['"]([^'"]+)['"]/);
    if (nameMatch) {
      return nameMatch[1];
    }
  } catch {
    // Fall back to directory name
  }
  
  return basename(process.cwd());
}

/**
 * Ensure the current directory is treated as CommonJS for Node resolution,
 * so that tree-sitter can load `grammar.js` (which uses module.exports).
 * If no local package.json exists, create a minimal one with "type": "commonjs".
 */
function ensureCommonJsPackageJson(): void {
  const packageJsonPath = 'package.json';
  if (!existsSync(packageJsonPath)) {
    const projectName = basename(process.cwd());
    const minimal = {
      name: `${projectName}-dsl`,
      private: true,
      type: 'commonjs',
      description: `DSL project for ${projectName} generated by DSK`,
      license: 'MIT'
    } as const;
    writeFileSync(packageJsonPath, JSON.stringify(minimal, null, 2));
    console.log(chalk.gray('   Created local package.json with { "type": "commonjs" }'));
  }
}

/**
 * Generate C header file
 */
async function generateHeaderFile(projectName: string, includeDir: string): Promise<void> {
  const headerContent = `#ifndef TREE_SITTER_${projectName.toUpperCase()}_H_
#define TREE_SITTER_${projectName.toUpperCase()}_H_

typedef struct TSLanguage TSLanguage;

#ifdef __cplusplus
extern "C" {
#endif

const TSLanguage *tree_sitter_${projectName}(void);

#ifdef __cplusplus
}
#endif

#endif // TREE_SITTER_${projectName.toUpperCase()}_H_
`;

  writeFileSync(join(includeDir, `${projectName}.h`), headerContent);
}

/**
 * Copy JS addon template files
 */
async function copyJSAddonTemplates(jsDir: string): Promise<void> {
  const __filename = fileURLToPath(import.meta.url);
  const __dirname = dirname(__filename);
  const templateDir = join(__dirname, '..', '..', 'templates', 'js-addon');
  
  if (!existsSync(templateDir)) {
    throw new Error(`JS addon template directory not found: ${templateDir}`);
  }
  
  // Copy all template files
  const { processTemplate } = await import('../utils/template-processor.js');
  const projectName = getProjectName();
  
  const templateContext = {
    architecture: { 
      name: projectName, 
      paradigm: 'mixed' as const, 
      purpose: 'DSL', 
      dataPhilosophy: 'mixed' as const 
    },
    features: { controlFlow: [], dataStructures: [], functionTypes: [] },
    syntax: {
      comments: { type: 'line_comment', pattern: '//' },
      identifiers: { pattern: '[a-zA-Z_][a-zA-Z0-9_]*', examples: ['identifier'] },
      numbers: { pattern: '\\d+', examples: ['42'] },
      strings: { pattern: '"[^"]*"', examples: ['"string"'] },
      variables: { keyword: 'let', operator: '=', terminator: ';', example: 'let x = 42;' },
      paradigmExamples: {}
    }
  };
  
  processTemplate(templateDir, jsDir, templateContext);
}

/**
 * Copy source files from tree-sitter generation to JS package
 */
async function copySourceFiles(jsDir: string): Promise<void> {
  const srcDir = 'src';
  const targetSrcDir = join(jsDir, 'src');
  
  if (!existsSync(srcDir)) {
    throw new Error('src/ directory not found. Run tree-sitter generate first.');
  }
  
  // Copy the entire src directory
  cpSync(srcDir, targetSrcDir, { recursive: true });
  
  console.log(chalk.gray(`   Copied src files to ${targetSrcDir}`));
}

/**
 * Update binding.gyp based on available source files
 */
async function updateBindingGyp(jsDir: string): Promise<void> {
  const bindingGypPath = join(jsDir, 'binding.gyp');
  const scannerPath = join(jsDir, 'src', 'scanner.c');
  
  if (existsSync(bindingGypPath)) {
    let bindingGyp = JSON.parse(readFileSync(bindingGypPath, 'utf-8'));
    
    // Add scanner.c if it exists
    if (existsSync(scannerPath)) {
      const target = bindingGyp.targets[0];
      if (!target.sources.includes('src/scanner.c')) {
        target.sources.push('src/scanner.c');
        console.log(chalk.gray(`   Added scanner.c to build`));
      }
    } else {
      console.log(chalk.gray(`   No scanner.c found, skipping`));
    }
    
    writeFileSync(bindingGypPath, JSON.stringify(bindingGyp, null, 2));
  }
}

/**
 * Update package.json in JS package
 */
async function updateJSPackageJson(jsDir: string): Promise<void> {
  const projectName = getProjectName();
  const packageJsonPath = join(jsDir, 'package.json');
  
  if (existsSync(packageJsonPath)) {
    let packageJson = JSON.parse(readFileSync(packageJsonPath, 'utf-8'));
    
    // Update name and description
    packageJson.name = `tree-sitter-${projectName}`;
    packageJson.description = `Tree-sitter parser for ${projectName}`;
    
    // Update keywords
    if (packageJson.keywords && Array.isArray(packageJson.keywords)) {
      packageJson.keywords = packageJson.keywords.map((keyword: string) => 
        keyword === '__DSL_NAME__' ? projectName : keyword
      );
    }
    
    writeFileSync(packageJsonPath, JSON.stringify(packageJson, null, 2));
  }
}