CanIUse MCP

import fs from 'fs'; import path from 'path'; export class ConfigManager { constructor(projectPath = '.') { this.projectPath = projectPath; this.config = null; this.defaultConfig = { defaultBaseline: 'chrome-37', customTargets: {}, polyfills: [], overrides: {}, browserFallbacks: { chrome: ['37'], // fallback versions if specific version not found firefox: ['78'], safari: ['12'], ie: ['11'], edge: ['18'] } }; } async loadConfig() { if (this.config) return this.config; // Try to load from file first const configPath = path.join(this.projectPath, '.caniuse-config.json'); let fileConfig = {}; try { if (fs.existsSync(configPath)) { const configContent = await fs.promises.readFile(configPath, 'utf8'); fileConfig = JSON.parse(configContent); } } catch (error) { console.warn(`Warning: Could not load config from ${configPath}: ${error.message}`); } // Merge with environment variables const envConfig = this._loadFromEnvironment(); // Merge all configurations: default < file < environment this.config = { ...this.defaultConfig, ...fileConfig, ...envConfig, // Merge nested objects properly customTargets: { ...this.defaultConfig.customTargets, ...fileConfig.customTargets, ...envConfig.customTargets }, polyfills: [ ...this.defaultConfig.polyfills, ...(fileConfig.polyfills || []), ...(envConfig.polyfills || []) ], overrides: { ...this.defaultConfig.overrides, ...fileConfig.overrides, ...envConfig.overrides }, browserFallbacks: { ...this.defaultConfig.browserFallbacks, ...fileConfig.browserFallbacks, ...envConfig.browserFallbacks } }; return this.config; } _loadFromEnvironment() { const envConfig = {}; if (process.env.CANIUSE_DEFAULT_BASELINE) { envConfig.defaultBaseline = process.env.CANIUSE_DEFAULT_BASELINE; } if (process.env.CANIUSE_POLYFILLS) { try { envConfig.polyfills = JSON.parse(process.env.CANIUSE_POLYFILLS); } catch (error) { envConfig.polyfills = process.env.CANIUSE_POLYFILLS.split(',').map(p => p.trim()); } } if (process.env.CANIUSE_OVERRIDES) { try { envConfig.overrides = JSON.parse(process.env.CANIUSE_OVERRIDES); } catch (error) { console.warn('Invalid CANIUSE_OVERRIDES environment variable format'); } } return envConfig; } async getBrowserTargets() { const config = await this.loadConfig(); // Built-in targets const builtInTargets = { 'chrome-37': { browser: 'chrome', version: '37' }, 'chrome-latest': { browser: 'chrome', version: 'latest' }, 'firefox-esr': { browser: 'firefox', version: '78' }, 'safari-12': { browser: 'safari', version: '12' }, 'ie-11': { browser: 'ie', version: '11' }, 'edge-legacy': { browser: 'edge', version: '18' } }; // Merge with custom targets return { ...builtInTargets, ...config.customTargets }; } async resolveTargetVersion(targetString) { const config = await this.loadConfig(); const targets = await this.getBrowserTargets(); // Check if it's a known target if (targets[targetString]) { return targets[targetString]; } // Try to parse browser-version format (e.g., "chrome-57") const match = targetString.match(/^([a-z]+)-(.+)$/); if (match) { const [, browser, version] = match; return { browser, version }; } // Fallback to default baseline const defaultTarget = targets[config.defaultBaseline]; if (defaultTarget) { return defaultTarget; } // Final fallback return { browser: 'chrome', version: '37' }; } async isFeaturePolyfilled(featureName) { const config = await this.loadConfig(); return config.polyfills.includes(featureName); } async getFeatureOverride(featureName) { const config = await this.loadConfig(); return config.overrides[featureName]; } async getFallbackVersions(browser) { const config = await this.loadConfig(); return config.browserFallbacks[browser] || []; } async updateConfig(updates) { const config = await this.loadConfig(); const newConfig = { ...config, ...updates }; const configPath = path.join(this.projectPath, '.caniuse-config.json'); await fs.promises.writeFile(configPath, JSON.stringify(newConfig, null, 2)); // Reload config this.config = null; return await this.loadConfig(); } async addPolyfill(featureName) { const config = await this.loadConfig(); if (!config.polyfills.includes(featureName)) { config.polyfills.push(featureName); await this.updateConfig({ polyfills: config.polyfills }); } } async removePolyfill(featureName) { const config = await this.loadConfig(); const index = config.polyfills.indexOf(featureName); if (index > -1) { config.polyfills.splice(index, 1); await this.updateConfig({ polyfills: config.polyfills }); } } async setFeatureOverride(featureName, supportStatus) { const config = await this.loadConfig(); config.overrides[featureName] = supportStatus; await this.updateConfig({ overrides: config.overrides }); } // Helper to create a config file template static async createConfigTemplate(projectPath) { const configPath = path.join(projectPath, '.caniuse-config.json'); const template = { "$schema": "https://json-schema.org/draft-07/schema#", "$comment": "CanIUse MCP Configuration", "defaultBaseline": "chrome-37", "customTargets": { "chrome-57": { "browser": "chrome", "version": "57" }, "chrome-60": { "browser": "chrome", "version": "60" } }, "polyfills": [ "css-grid", "flexbox", "promises" ], "overrides": { "css-variables": "supported" }, "browserFallbacks": { "chrome": ["37", "40", "45"], "firefox": ["78", "68"], "safari": ["12", "11"], "ie": ["11"], "edge": ["18", "16"] } }; await fs.promises.writeFile(configPath, JSON.stringify(template, null, 2)); return configPath; } }