import { describe, it, expect } from 'vitest';
import {
  validateRegexPattern,
  analyzeRegexComplexity,
  isSafeRegexPattern,
  RegexValidationError,
} from '../src/utils/regex-validation';

describe('Regex Validation', () => {
  describe('validateRegexPattern', () => {
    describe('syntax validation', () => {
      it('accepts valid simple patterns', () => {
        expect(() => validateRegexPattern('\\d{3}-\\d{3}-\\d{4}')).not.toThrow();
      });

      it('accepts valid phone number patterns', () => {
        expect(() => validateRegexPattern('^\\+1\\d{10}$')).not.toThrow();
      });

      it('accepts valid character class patterns', () => {
        expect(() => validateRegexPattern('^[a-zA-Z0-9]+$')).not.toThrow();
      });

      it('accepts valid alternation patterns', () => {
        expect(() => validateRegexPattern('^(phone|fax|mobile)$')).not.toThrow();
      });

      it('rejects invalid regex syntax', () => {
        expect(() => validateRegexPattern('(unclosed')).toThrow(RegexValidationError);
      });

      it('rejects empty pattern', () => {
        expect(() => validateRegexPattern('')).toThrow(RegexValidationError);
      });
    });

    describe('ReDoS detection - nested quantifiers', () => {
      it('detects nested quantifier (a+)*', () => {
        expect(() => validateRegexPattern('(a+)*')).toThrow(RegexValidationError);
      });

      it('detects nested quantifier (a*)+', () => {
        expect(() => validateRegexPattern('(a*)+')).toThrow(RegexValidationError);
      });

      it('detects nested quantifier ([0-9]+)+', () => {
        expect(() => validateRegexPattern('([0-9]+)+')).toThrow(RegexValidationError);
      });

      it('detects nested quantifier (a|b+)*', () => {
        expect(() => validateRegexPattern('(a|b+)*')).toThrow(RegexValidationError);
      });
    });

    describe('ReDoS detection - overlapping alternations', () => {
      it('detects overlapping alternation (a|aa)*', () => {
        expect(() => validateRegexPattern('(a|aa)*')).toThrow(RegexValidationError);
      });

      it('detects overlapping alternation (abc|ab|a)*', () => {
        expect(() => validateRegexPattern('(abc|ab|a)*')).toThrow(RegexValidationError);
      });

      it('detects overlapping alternation (foo|foot)*', () => {
        expect(() => validateRegexPattern('(foo|foot)*')).toThrow(RegexValidationError);
      });
    });

    describe('ReDoS detection - complexity limits', () => {
      it('rejects pattern exceeding max length', () => {
        const longPattern = 'a'.repeat(600);
        expect(() => validateRegexPattern(longPattern)).toThrow(RegexValidationError);
      });

      it('rejects pattern exceeding max nesting depth', () => {
        const deepPattern = '((((' + '((((a))))' + '))))';
        expect(() => validateRegexPattern(deepPattern, { maxNestingDepth: 3 })).toThrow(RegexValidationError);
      });

      it('rejects pattern exceeding max alternations', () => {
        const manyAlts = '(a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x)';
        expect(() => validateRegexPattern(manyAlts, { maxAlternations: 5 })).toThrow(RegexValidationError);
      });
    });

    describe('safe patterns', () => {
      it('accepts anchored phone pattern', () => {
        const metrics = validateRegexPattern('^\\+\\d{1,3}\\d{4,14}$');
        expect(metrics.isRedosProne).toBe(false);
      });

      it('accepts simple character class', () => {
        const metrics = validateRegexPattern('^[A-Z]{2}\\d{6}$');
        expect(metrics.isRedosProne).toBe(false);
      });

      it('accepts non-overlapping alternation', () => {
        const metrics = validateRegexPattern('^(spammer|blocker|filter)$');
        expect(metrics.isRedosProne).toBe(false);
      });

      it('accepts escaped special characters', () => {
        const metrics = validateRegexPattern('\\(\\d{3}\\) \\d{3}-\\d{4}');
        expect(metrics.isRedosProne).toBe(false);
      });
    });
  });

  describe('analyzeRegexComplexity', () => {
    it('returns correct metrics for simple pattern', () => {
      const metrics = analyzeRegexComplexity('\\d{3}-\\d{3}-\\d{4}');
      expect(metrics.length).toBe(17);
      expect(metrics.nestingDepth).toBe(0);
      expect(metrics.alternationCount).toBe(0);
      expect(metrics.groupCount).toBe(0);
    });

    it('returns correct metrics for pattern with groups', () => {
      const metrics = analyzeRegexComplexity('(\\d{3})-(\\d{3})-(\\d{4})');
      expect(metrics.groupCount).toBe(3);
      expect(metrics.nestingDepth).toBe(1);
    });

    it('returns correct metrics for pattern with alternations', () => {
      const metrics = analyzeRegexComplexity('(phone|fax|mobile)');
      expect(metrics.alternationCount).toBe(2);
    });

    it('marks nested quantifier as ReDoS prone', () => {
      const metrics = analyzeRegexComplexity('(a+)*');
      expect(metrics.isRedosProne).toBe(true);
      expect(metrics.issues.length).toBeGreaterThan(0);
    });

    it('marks overlapping alternation as ReDoS prone', () => {
      const metrics = analyzeRegexComplexity('(a|aa)*');
      expect(metrics.isRedosProne).toBe(true);
    });

    it('marks long pattern as ReDoS prone', () => {
      const longPattern = 'a'.repeat(600);
      const metrics = analyzeRegexComplexity(longPattern);
      expect(metrics.isRedosProne).toBe(true);
    });

    it('marks deep nesting as ReDoS prone', () => {
      const deepPattern = '((((' + '((((a))))' + '))))';
      const metrics = analyzeRegexComplexity(deepPattern, { maxNestingDepth: 3 });
      expect(metrics.isRedosProne).toBe(true);
    });

    it('marks high alternation count as ReDoS prone', () => {
      const manyAlts = '(a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x)';
      const metrics = analyzeRegexComplexity(manyAlts, { maxAlternations: 5 });
      expect(metrics.isRedosProne).toBe(true);
    });
  });

  describe('isSafeRegexPattern', () => {
    it('returns true for safe patterns', () => {
      expect(isSafeRegexPattern('^\\+\\d{1,3}\\d{4,14}$')).toBe(true);
      expect(isSafeRegexPattern('^[A-Z]{2}\\d{6}$')).toBe(true);
      expect(isSafeRegexPattern('\\d{3}-\\d{3}-\\d{4}')).toBe(true);
    });

    it('returns false for nested quantifiers', () => {
      expect(isSafeRegexPattern('(a+)*')).toBe(false);
      expect(isSafeRegexPattern('([0-9]+)+')).toBe(false);
    });

    it('returns false for overlapping alternations', () => {
      expect(isSafeRegexPattern('(a|aa)*')).toBe(false);
      expect(isSafeRegexPattern('(foo|foot)*')).toBe(false);
    });

    it('returns false for invalid syntax', () => {
      expect(isSafeRegexPattern('(unclosed')).toBe(false);
    });

    it('returns false for empty pattern', () => {
      expect(isSafeRegexPattern('')).toBe(false);
    });

    it('returns false for excessively long patterns', () => {
      expect(isSafeRegexPattern('a'.repeat(600))).toBe(false);
    });
  });

  describe('RegexValidationError', () => {
    it('includes pattern and reason in error', () => {
      const pattern = '(a+)*';
      try {
        validateRegexPattern(pattern);
      } catch (err) {
        const validationErr = err as RegexValidationError;
        expect(validationErr.name).toBe('RegexValidationError');
        expect(validationErr.pattern).toBe(pattern);
        expect(validationErr.reason).toContain('ReDoS risk');
      }
    });

    it('includes syntax error message', () => {
      const pattern = '(unclosed';
      try {
        validateRegexPattern(pattern);
      } catch (err) {
        const validationErr = err as RegexValidationError;
        expect(validationErr.pattern).toBe(pattern);
        expect(validationErr.reason).toContain('Invalid regex syntax');
      }
    });

    it('includes length error message', () => {
      const longPattern = 'a'.repeat(600);
      try {
        validateRegexPattern(longPattern);
      } catch (err) {
        const validationErr = err as RegexValidationError;
        expect(validationErr.reason).toContain('exceeds maximum');
      }
    });
  });

  describe('edge cases', () => {
    it('handles escaped characters correctly', () => {
      expect(() => validateRegexPattern('\\(\\d+\\)')).not.toThrow();
    });

    it('handles character classes without false positives', () => {
      expect(() => validateRegexPattern('[a-z]+')).not.toThrow();
      expect(() => validateRegexPattern('[^0-9]+')).not.toThrow();
      expect(() => validateRegexPattern('[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+')).not.toThrow();
    });

    it('handles non-capturing groups', () => {
      expect(() => validateRegexPattern('(?:abc)+')).not.toThrow();
    });

    it('handles lookaheads', () => {
      expect(() => validateRegexPattern('(?=\\d{3})\\d+')).not.toThrow();
    });

    it('handles quantifiers with ranges', () => {
      expect(() => validateRegexPattern('\\d{1,3}')).not.toThrow();
      expect(() => validateRegexPattern('[a-z]{2,4}')).not.toThrow();
    });

    it('handles Unicode property escapes', () => {
      expect(() => validateRegexPattern('\\p{L}+')).not.toThrow();
    });

    it('handles multiline and dotall flags in pattern', () => {
      expect(() => validateRegexPattern('^.+$')).not.toThrow();
    });

    it('counts quantifiers correctly', () => {
      const metrics = analyzeRegexComplexity('a+b*c?d{2}');
      expect(metrics.quantifierCount).toBe(4);
    });

    it('handles special characters in character classes', () => {
      expect(() => validateRegexPattern('[^\\w\\s]+')).not.toThrow();
    });
  });
});
