/**
 * @dss/rules - Design System Rules Package
 *
 * Provides versioned rule definitions for enterprise design system enforcement.
 * Pull-based distribution via npm for consistent rule versions across 60+ projects.
 */

const fs = require('fs');
const path = require('path');

// Rule categories
const CATEGORIES = ['colors', 'spacing', 'typography', 'components', 'accessibility'];

/**
 * Load all rules from the rules directory
 * @returns {Object} Rules organized by category
 */
function loadRules() {
  const rules = {};
  const rulesDir = path.join(__dirname, '..', 'rules');

  for (const category of CATEGORIES) {
    const rulePath = path.join(rulesDir, `${category}.json`);
    if (fs.existsSync(rulePath)) {
      try {
        const content = fs.readFileSync(rulePath, 'utf-8');
        rules[category] = JSON.parse(content);
      } catch (error) {
        console.error(`Failed to load rules for ${category}:`, error.message);
        rules[category] = null;
      }
    }
  }

  return rules;
}

/**
 * Get rules for a specific category
 * @param {string} category - Rule category (colors, spacing, etc.)
 * @returns {Object|null} Rule definitions or null if not found
 */
function getRulesByCategory(category) {
  const rules = loadRules();
  return rules[category] || null;
}

/**
 * Get all rule IDs across all categories
 * @returns {string[]} Array of rule IDs in format "category/rule-id"
 */
function getAllRuleIds() {
  const rules = loadRules();
  const ids = [];

  for (const [category, ruleSet] of Object.entries(rules)) {
    if (ruleSet && ruleSet.rules) {
      for (const rule of ruleSet.rules) {
        ids.push(`${category}/${rule.id}`);
      }
    }
  }

  return ids;
}

/**
 * Get a specific rule by its full ID
 * @param {string} ruleId - Full rule ID in format "category/rule-id"
 * @returns {Object|null} Rule definition or null
 */
function getRule(ruleId) {
  const [category, id] = ruleId.split('/');
  const ruleSet = getRulesByCategory(category);

  if (!ruleSet || !ruleSet.rules) return null;

  return ruleSet.rules.find(r => r.id === id) || null;
}

/**
 * Validate a value against rule patterns
 * @param {string} ruleId - Full rule ID
 * @param {string} value - Value to validate
 * @returns {Object} Validation result {valid, violations}
 */
function validateValue(ruleId, value) {
  const rule = getRule(ruleId);
  if (!rule) {
    return { valid: true, violations: [], error: `Rule not found: ${ruleId}` };
  }

  const violations = [];

  // Check forbidden patterns
  if (rule.patterns?.forbidden) {
    for (const pattern of rule.patterns.forbidden) {
      const regex = new RegExp(pattern, 'gi');
      const matches = value.match(regex);
      if (matches) {
        violations.push({
          rule: ruleId,
          pattern,
          matches,
          severity: rule.severity || 'warning',
          message: `Found forbidden pattern: ${matches.join(', ')}`
        });
      }
    }
  }

  return {
    valid: violations.length === 0,
    violations
  };
}

/**
 * Get required tokens from all rule sets
 * @returns {Object} Required tokens organized by category
 */
function getRequiredTokens() {
  const rules = loadRules();
  const required = {};

  for (const [category, ruleSet] of Object.entries(rules)) {
    if (ruleSet?.tokens?.required) {
      required[category] = ruleSet.tokens.required;
    }
  }

  return required;
}

/**
 * Get severity level for a rule
 * @param {string} ruleId - Full rule ID
 * @returns {string} Severity level (error, warning, info)
 */
function getRuleSeverity(ruleId) {
  const rule = getRule(ruleId);
  if (!rule) return 'warning';

  // Rule-specific severity overrides category default
  if (rule.severity) return rule.severity;

  // Fall back to category default
  const [category] = ruleId.split('/');
  const ruleSet = getRulesByCategory(category);
  return ruleSet?.severity || 'warning';
}

/**
 * Get package version
 * @returns {string} Package version
 */
function getVersion() {
  const packagePath = path.join(__dirname, '..', 'package.json');
  const pkg = JSON.parse(fs.readFileSync(packagePath, 'utf-8'));
  return pkg.version;
}

/**
 * Export configuration for CI/CD integration
 * @returns {Object} Configuration object for CI pipelines
 */
function getCIConfig() {
  return {
    version: getVersion(),
    categories: CATEGORIES,
    errorSeverities: ['error'],
    warningSeverities: ['warning'],
    blockingRules: getAllRuleIds().filter(id => getRuleSeverity(id) === 'error'),
    advisoryRules: getAllRuleIds().filter(id => getRuleSeverity(id) !== 'error')
  };
}

module.exports = {
  // Rule loading
  loadRules,
  getRulesByCategory,
  getAllRuleIds,
  getRule,

  // Validation
  validateValue,
  getRuleSeverity,

  // Token helpers
  getRequiredTokens,

  // Metadata
  getVersion,
  getCIConfig,

  // Constants
  CATEGORIES
};