import { NFTMetadata, NFTCollection, NFTDataFetcher } from '../types/nft.js';
import fs from 'fs';
import { promises as fsPromises } from 'fs';
import path from 'path';

// Configuration
const dataDir = path.join(process.cwd(), 'src', 'data');
const outputFile = path.join(dataDir, 'collection-metadata.json');

// Validation function
export const validateMetadata = (metadata: NFTMetadata): boolean => {
  const requiredFields = ['name', 'description', 'image', 'attributes'];
  const missingFields = requiredFields.filter(field => !metadata[field]);
  
  if (missingFields.length > 0) {
    throw new Error(`Missing required fields: ${missingFields.join(', ')}`);
  }

  if (!Array.isArray(metadata.attributes)) {
    throw new Error('Attributes must be an array');
  }

  const invalidAttributes = metadata.attributes.filter(
    attr => !attr.trait_type || !attr.value
  );

  if (invalidAttributes.length > 0) {
    throw new Error('Invalid attributes format. Each attribute must have trait_type and value');
  }

  return true;
};

// Save collection data function
export const saveCollectionData = async (collection: NFTCollection): Promise<void> => {
  // Ensure data directory exists
  if (!fs.existsSync(dataDir)) {
    fs.mkdirSync(dataDir, { recursive: true });
  }

  // Validate each NFT's metadata
  collection.forEach((metadata, index) => {
    try {
      validateMetadata(metadata);
    } catch (error) {
      throw new Error(`Invalid metadata at index ${index}: ${error.message}`);
    }
  });

  // Save to file
  await fsPromises.writeFile(outputFile, JSON.stringify(collection, null, 2));
  console.log(`\n✅ Collection data written to ${outputFile}`);
};

// Retry function
export const fetchWithRetry = async <T>(
  fetchFn: () => Promise<T>,
  retries = 3,
  delay = 1000
): Promise<T> => {
  try {
    return await fetchFn();
  } catch (error) {
    if (retries === 0) throw error;
    await new Promise(resolve => setTimeout(resolve, delay));
    return fetchWithRetry(fetchFn, retries - 1, delay * 2);
  }
};

export abstract class BaseNFTFetcher implements NFTDataFetcher {
  protected readonly dataDir: string;
  protected readonly outputFile: string;

  constructor() {
    this.dataDir = dataDir;
    this.outputFile = outputFile;
  }

  abstract fetchCollectionData(contractAddress: string): Promise<NFTCollection>;
}