export interface GithubTemplate {
  name: string;
  path: string;
  content: string;
  download_url: string;
  variables?: string[];
  variableMetadata?: Record<string, string>;
}

export class TemplateService {
  private static REPO_NAME = 'agent-notes';

  /**
   * Fetches template files from a GitHub repository.
   * @param profile The GitHub username/org (used for token fallback)
   * @param token The GitHub Personal Access Token (optional but recommended)
   * @param owner The owner of the repo to fetch from
   * @param repo The name of the repo to fetch from
   * @param path The subfolder path to fetch from
   */
  async fetchTemplates(
    profile: string,
    token?: string,
    owner?: string,
    repo?: string,
    path?: string,
    branch?: string
  ): Promise<GithubTemplate[]> {
    if (!profile) return [];

    const targetOwner = owner || profile;
    const targetRepo = repo || TemplateService.REPO_NAME;
    const targetPath = path || '';

    const endpoint = `/api/github/contents?owner=${targetOwner}&repo=${targetRepo}&path=${targetPath}${token ? '&token=' + token : ''}&profile=${profile}${branch ? '&ref=' + branch : ''}`;

    try {
      const response = await fetch(endpoint);

      if (!response.ok) {
        if (response.status === 404) {
          console.warn(`Template repository not found for ${profile}`);
          return [];
        }
        throw new Error(`GitHub API error: ${response.status}`);
      }

      const files = await response.json();
      console.log(`[TemplateService] Received ${Array.isArray(files) ? files.length : 'non-array'} entries from GitHub`);

      if (!Array.isArray(files)) {
          console.warn("[TemplateService] GitHub response is not an array:", files);
          return [];
      }

      // Filter for markdown and text files
      const mdFiles = files.filter((file: any) =>
        file.type === 'file' && (file.name.endsWith('.md') || file.name.endsWith('.txt'))
      );
      console.log(`[TemplateService] Found ${mdFiles.length} markdown/text files`);

      // Fetch content for each file
      const templates = await Promise.all(mdFiles.map(async (file: any) => {
        const rawUrl = `/api/github/raw?url=${encodeURIComponent(file.download_url)}${token ? '&token=' + token : ''}&profile=${profile}${branch ? '&ref=' + branch : ''}`;

        const contentResponse = await fetch(rawUrl);
        const content = await contentResponse.text();

        // Parse for new JSON structure
        const { cleanContent, variables, variableMetadata } = this.parseTemplateJson(content);

        return {
          name: file.name.replace('.md', '').replace('.txt', ''),
          path: file.path,
          content: cleanContent,
          download_url: file.download_url,
          variables,
          variableMetadata
        };
      }));

      return templates;
    } catch (error) {
      console.error("Failed to fetch GitHub templates:", error);
      return [];
    }
  }

  /**
   * Detects and parses a JSON block at the start of the template.
   * Format:
   * {
   *   "variables": { "KEY": "Description" }
   * }
   */
  private parseTemplateJson(content: string): {
    cleanContent: string,
    variables?: string[],
    variableMetadata?: Record<string, string>
  } {
    // Look for JSON at the very beginning of the string
    const jsonMatch = content.match(/^\s*(\{[\s\S]*?\})(\s*[\r\n]+|$)/);

    if (jsonMatch) {
        try {
            const json = JSON.parse(jsonMatch[1]);
            if (json.variables) {
                const variables = Object.keys(json.variables);
                const variableMetadata = json.variables;
                // Content starts after the JSON block
                const cleanContent = content.substring(jsonMatch[0].length).trim();
                return { cleanContent, variables, variableMetadata };
            }
        } catch (e) {
            // Not valid JSON or doesn't follow structure, return original
            console.warn("Found potential JSON header but failed to parse it as template metadata.", e);
        }
    }

    return { cleanContent: content, variables: undefined };
  }
}