[WIP] Implement Coin Gekko API Integration

.gitignore

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+node_modules/
+dist/
+.env
+__pycache__/
+*.log
+.DS_Store
+coverage/
+.vscode/
+.idea/

package.json

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+{
+  "name": "coin-gekko-api",
+  "version": "1.0.0",
+  "description": "Coin Gekko API implementation",
+  "main": "dist/index.js",
+  "scripts": {
+    "build": "tsc",
+    "test": "vitest",
+    "start": "node dist/index.js"
+  },
+  "dependencies": {
+    "axios": "^0.21.1"
+  },
+  "devDependencies": {
+    "@types/node": "^16.11.6",
+    "typescript": "^4.4.4",
+    "vitest": "^0.24.0"
+  }
+}

src/coinGekkoApi.spec.ts

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+import { describe, it, expect, beforeEach } from 'vitest';
+import axios from 'axios';
+import { CoinGekkoApi } from './coinGekkoApi';
+
+// Mock axios
+vi.mock('axios');
+
+describe('CoinGekkoApi', () => {
+  let coinGekkoApi: CoinGekkoApi;
+
+  beforeEach(() => {
+    coinGekkoApi = new CoinGekkoApi();
+  });
+
+  describe('getCoinById', () => {
+    it('should fetch coin data successfully', async () => {
+      const mockCoinData = {
+        id: 'bitcoin',
+        symbol: 'btc',
+        name: 'Bitcoin',
+        market_data: {
+          current_price: { usd: 50000 },
+          market_cap: { usd: 1000000000000 }
+        }
+      };
+
+      vi.mocked(axios.get).mockResolvedValue({ data: mockCoinData });
+
+      const result = await coinGekkoApi.getCoinById('bitcoin');
+      expect(result).toEqual({
+        id: 'bitcoin',
+        symbol: 'btc',
+        name: 'Bitcoin',
+        price: 50000,
+        marketCap: 1000000000000
+      });
+    });
+
+    it('should throw an error if coin ID is not provided', async () => {
+      await expect(coinGekkoApi.getCoinById('')).rejects.toThrow('Coin ID is required');
+    });
+
+    it('should throw an error if coin is not found', async () => {
+      vi.mocked(axios.get).mockRejectedValue({
+        response: { status: 404 },
+        isAxiosError: true
+      });
+
+      await expect(coinGekkoApi.getCoinById('nonexistent')).rejects.toThrow('Coin with ID nonexistent not found');
+    });
+  });
+
+  describe('getTopCryptocurrencies', () => {
+    it('should fetch top cryptocurrencies successfully', async () => {
+      const mockTopCoins = [
+        {
+          id: 'bitcoin',
+          symbol: 'btc',
+          name: 'Bitcoin',
+          current_price: 50000,
+          market_cap: 1000000000000
+        },
+        {
+          id: 'ethereum',
+          symbol: 'eth',
+          name: 'Ethereum',
+          current_price: 4000,
+          market_cap: 500000000000
+        }
+      ];
+
+      vi.mocked(axios.get).mockResolvedValue({ data: mockTopCoins });
+
+      const result = await coinGekkoApi.getTopCryptocurrencies(2);
+      expect(result).toEqual([
+        {
+          id: 'bitcoin',
+          symbol: 'btc',
+          name: 'Bitcoin',
+          price: 50000,
+          marketCap: 1000000000000
+        },
+        {
+          id: 'ethereum',
+          symbol: 'eth',
+          name: 'Ethereum',
+          price: 4000,
+          marketCap: 500000000000
+        }
+      ]);
+    });
+
+    it('should throw an error if limit is not positive', async () => {
+      await expect(coinGekkoApi.getTopCryptocurrencies(0)).rejects.toThrow('Limit must be a positive number');
+      await expect(coinGekkoApi.getTopCryptocurrencies(-1)).rejects.toThrow('Limit must be a positive number');
+    });
+  });
+});

src/coinGekkoApi.ts

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+import axios from 'axios';
+
+export interface CoinData {
+  id: string;
+  symbol: string;
+  name: string;
+  price: number;
+  marketCap: number;
+}
+
+export class CoinGekkoApi {
+  private baseUrl: string;
+
+  constructor(baseUrl: string = 'https://api.coingecko.com/api/v3') {
+    this.baseUrl = baseUrl;
+  }
+
+  /**
+   * Fetch coin data by ID
+   * @param coinId - The ID of the cryptocurrency
+   * @returns Promise with coin data
+   */
+  async getCoinById(coinId: string): Promise<CoinData> {
+    if (!coinId) {
+      throw new Error('Coin ID is required');
+    }
+
+    try {
+      const response = await axios.get(`${this.baseUrl}/coins/${coinId}`);
+      return {
+        id: response.data.id,
+        symbol: response.data.symbol,
+        name: response.data.name,
+        price: response.data.market_data.current_price.usd,
+        marketCap: response.data.market_data.market_cap.usd
+      };
+    } catch (error) {
+      if (axios.isAxiosError(error)) {
+        if (error.response?.status === 404) {
+          throw new Error(`Coin with ID ${coinId} not found`);
+        }
+        throw new Error(`Error fetching coin data: ${error.message}`);
+      }
+      throw error;
+    }
+  }
+
+  /**
+   * List top cryptocurrencies by market cap
+   * @param limit - Number of cryptocurrencies to return (default: 10)
+   * @returns Promise with list of top cryptocurrencies
+   */
+  async getTopCryptocurrencies(limit: number = 10): Promise<CoinData[]> {
+    if (limit <= 0) {
+      throw new Error('Limit must be a positive number');
+    }
+
+    try {
+      const response = await axios.get(`${this.baseUrl}/coins/markets`, {
+        params: {
+          vs_currency: 'usd',
+          order: 'market_cap_desc',
+          per_page: limit,
+          page: 1
+        }
+      });
+
+      return response.data.map((coin: any) => ({
+        id: coin.id,
+        symbol: coin.symbol,
+        name: coin.name,
+        price: coin.current_price,
+        marketCap: coin.market_cap
+      }));
+    } catch (error) {
+      throw new Error(`Error fetching top cryptocurrencies: ${error instanceof Error ? error.message : 'Unknown error'}`);
+    }
+  }
+}

src/index.ts

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+export { CoinGekkoApi, CoinData } from './coinGekkoApi';

tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "es2020",
+    "module": "commonjs",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "outDir": "./dist",
+    "rootDir": "./src"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "**/*.spec.ts"]
+}