import { WrappedData } from './types.js';

// Declare global window property for embedded data
declare global {
  interface Window {
    __GIT_WRAPPED_DATA__?: WrappedData;
  }
}

export class DataLoader {
  private data: WrappedData | null = null;

  async load(): Promise<WrappedData> {
    try {
      // Priority 1: Check for embedded data (from --host flag)
      if (window.__GIT_WRAPPED_DATA__) {
        console.log('Loading data from embedded source');
        this.data = window.__GIT_WRAPPED_DATA__;
        return this.data;
      }
      
      // Priority 2: Check for external data URL parameter
      const urlParams = new URLSearchParams(window.location.search);
      const dataUrl = urlParams.get('dataUrl');
      
      let response: Response;
      
      if (dataUrl) {
        // Load from external URL
        console.log('Loading data from external URL:', dataUrl);
        response = await fetch(dataUrl);
      } else {
        // Priority 3: Fetch from local API endpoint (default for CLI usage)
        response = await fetch('/api/data');
      }
      
      if (!response.ok) {
        throw new Error(`Failed to load data: ${response.statusText}`);
      }
      
      const loadedData = await response.json() as WrappedData;
      this.data = loadedData;
      return loadedData;
    } catch (error) {
      console.error('Error loading data:', error);
      throw error;
    }
  }

  getData(): WrappedData {
    if (!this.data) {
      throw new Error('Data not loaded. Call load() first.');
    }
    return this.data;
  }

  getAuthors(): string[] {
    if (!this.data) {
      throw new Error('Data not loaded. Call load() first.');
    }
    return Object.keys(this.data.commitsByAuthor || {});
  }
}