import matter from 'gray-matter';
import { ValidationResult, ValidationIssue, ValidatorOptions } from './types.js';
import {
  validateName,
  validateVersion,
  validateDescription,
  validateHomepage,
  validateRepository,
  validateApiBase,
  validateContent,
  extractMetadata,
} from './rules.js';
import { fetchSkillContent, isUrl } from './fetcher.js';
import * as fs from 'fs';
import * as path from 'path';

export function validateSkill(
  content: string,
  filename: string,
  _options: ValidatorOptions = {}
): ValidationResult {
  const errors: ValidationIssue[] = [];
  const warnings: ValidationIssue[] = [];

  // Check for frontmatter markers
  if (!content.startsWith('---')) {
    errors.push({
      code: 'missing-frontmatter',
      message: 'File must start with YAML frontmatter (---)',
    });
    return { valid: false, file: filename, errors, warnings, parsed: null };
  }

  // Parse frontmatter
  let parsed: matter.GrayMatterFile<string>;
  try {
    parsed = matter(content);
  } catch (err) {
    errors.push({
      code: 'invalid-frontmatter',
      message: `Failed to parse frontmatter: ${err instanceof Error ? err.message : 'Unknown error'}`,
    });
    return { valid: false, file: filename, errors, warnings, parsed: null };
  }

  const data = parsed.data as Record<string, unknown>;

  // Validate required fields
  const nameError = validateName(data);
  if (nameError) errors.push(nameError);

  const versionError = validateVersion(data);
  if (versionError) errors.push(versionError);

  const descResult = validateDescription(data);
  if (descResult.error) errors.push(descResult.error);
  if (descResult.warning) warnings.push(descResult.warning);

  // Validate optional URL fields
  const homepageResult = validateHomepage(data);
  if (homepageResult.error) errors.push(homepageResult.error);
  if (homepageResult.warning) warnings.push(homepageResult.warning);

  const repoResult = validateRepository(data);
  if (repoResult.error) errors.push(repoResult.error);
  if (repoResult.warning) warnings.push(repoResult.warning);

  const apiBaseError = validateApiBase(data);
  if (apiBaseError) errors.push(apiBaseError);

  // Validate content body
  const contentResult = validateContent(parsed.content);
  errors.push(...contentResult.errors);
  warnings.push(...contentResult.warnings);

  // Extract metadata for result
  const metadata = extractMetadata(data);

  return {
    valid: errors.length === 0,
    file: filename,
    errors,
    warnings,
    parsed: metadata,
  };
}

export async function validateSkillFile(
  filepath: string,
  options: ValidatorOptions = {}
): Promise<ValidationResult> {
  const absolutePath = path.resolve(filepath);

  if (!fs.existsSync(absolutePath)) {
    return {
      valid: false,
      file: filepath,
      errors: [{ code: 'file-not-found', message: `File not found: ${filepath}` }],
      warnings: [],
      parsed: null,
    };
  }

  const content = fs.readFileSync(absolutePath, 'utf-8');
  return validateSkill(content, filepath, options);
}

export async function validateSkillUrl(
  url: string,
  options: ValidatorOptions = {}
): Promise<ValidationResult> {
  try {
    const content = await fetchSkillContent(url);
    return validateSkill(content, url, options);
  } catch (err) {
    return {
      valid: false,
      file: url,
      errors: [
        {
          code: 'fetch-failed',
          message: err instanceof Error ? err.message : 'Failed to fetch URL',
        },
      ],
      warnings: [],
      parsed: null,
    };
  }
}

export async function validateSkillInput(
  input: string,
  options: ValidatorOptions = {}
): Promise<ValidationResult> {
  if (isUrl(input)) {
    return validateSkillUrl(input, options);
  }
  return validateSkillFile(input, options);
}