import fs from 'fs/promises';
import path from 'path';

/**
 * Read and parse .gitignore file
 */
export async function readGitignore(dir: string): Promise<string[]> {
    const gitignorePath = path.join(dir, '.gitignore');
    try {
        const content = await fs.readFile(gitignorePath, 'utf-8');
        return content
            .split('\n')
            .map((line) => line.trim())
            .filter((line) => line && !line.startsWith('#'));
    } catch (error) {
        // No .gitignore file found, return empty array
        return [];
    }
}

/**
 * Check if a path should be ignored based on .gitignore patterns
 */
export function shouldIgnore(filePath: string, patterns: string[]): boolean {
    const relativePath = filePath.replace(/^\.\//, '');

    // Default ignore patterns
    const defaultIgnores = [
        'node_modules',
        '.git',
        'dist',
        'build',
        '.next',
        '.turbo',
        'coverage',
        '.env',
        '.env.local',
    ];

    const allPatterns = [...defaultIgnores, ...patterns];

    for (const pattern of allPatterns) {
        if (pattern.endsWith('/')) {
            // Directory pattern
            const dir = pattern.slice(0, -1);
            if (relativePath.includes(`${dir}/`) || relativePath === dir) {
                return true;
            }
        } else if (pattern.includes('*')) {
            // Glob pattern - simple implementation
            const regex = new RegExp(
                '^' + pattern.replace(/\*/g, '.*').replace(/\?/g, '.') + '$'
            );
            if (regex.test(relativePath)) {
                return true;
            }
        } else {
            // Exact match or contains
            if (relativePath.includes(pattern)) {
                return true;
            }
        }
    }

    return false;
}

/**
 * Check if file is a code file based on extension
 */
export function isCodeFile(filePath: string): boolean {
    const codeExtensions = [
        '.js',
        '.jsx',
        '.ts',
        '.tsx',
        '.py',
        '.java',
        '.go',
        '.rb',
        '.php',
        '.c',
        '.cpp',
        '.h',
        '.cs',
        '.swift',
        '.kt',
        '.rs',
        '.vue',
        '.svelte',
    ];

    const ext = path.extname(filePath).toLowerCase();
    return codeExtensions.includes(ext);
}

/**
 * Read the last N lines of a file
 */
export async function tailFile(filePath: string, lineCount: number = 10): Promise<string[]> {
    try {
        const content = await fs.readFile(filePath, 'utf-8');
        const lines = content.split('\n').filter(l => l.trim() !== '');
        return lines.slice(-lineCount);
    } catch (e) {
        return [];
    }
}