feat: Add raw description field and fix npm test compatibility

Major improvements and bug fixes:

🔧 Core Features:
- Add descriptionRaw field to API response (Amazon original text)
- Maintain backward compatibility with existing description field
- Enable comparison between raw and AI-enhanced descriptions

🛠️ Technical Fixes:
- Fix npm test compatibility issues (Chai, Mocha, Cheerio versions)
- Resolve ES module vs CommonJS conflicts
- Fix module variable references and error handling
- Update Gemini AI model to gemini-2.0-flash

🔒 Security:
- Remove hardcoded API keys from source code and tests
- Add input validation for ISBN parameters
- Improve error handling with proper message formatting

✅ Testing:
- Add comprehensive test coverage for raw description feature
- Fix all test failures (15/15 tests passing)
- Add comparison tests between raw and Gemini descriptions

📚 Documentation:
- Add comprehensive analysis and troubleshooting reports
- Document Gemini AI integration and API usage
- Include build and deployment guides

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/index.js

@@ -1,11 +1,11 @@
-const modules = require("./module");
+const { extractBookId, extractBookDetails } = require("./module");
 const config = require("../config");
 const axios = require("axios");
 
 class AmazonBookSearch {
   constructor(location) {
     if (location !== "tr" && location !== "en") {
-      throw new Error("Yanlış konum!");
+      throw new Error("Invalid location! Must be 'tr' or 'en'");
     }
 
     this.url = location === "tr" ? config.tr_base_url : config.en_base_url;
@@ -20,7 +20,7 @@ class AmazonBookSearch {
           throw new Error("Kitap bilgisi bulunamadı!");
         }
 
-        const bookId = modules.extractBookId(response.data);
+        const bookId = extractBookId(response.data);
 
         return bookId;
       } catch (error) {
@@ -29,35 +29,41 @@ class AmazonBookSearch {
     };
 
     this.getBookDetails = async (isbn, geminiApiKey) => {
+      // Input validation
+      if (!isbn || typeof isbn !== 'string') {
+        throw new Error("ISBN is required and must be a string");
+      }
+
+      // Clean ISBN (remove hyphens and spaces) and validate format
+      const cleanIsbn = isbn.replace(/[-\s]/g, '');
+      if (!/^\d{10}(\d{3})?$/.test(cleanIsbn)) {
+        throw new Error("Invalid ISBN format. Must be 10 or 13 digits");
+      }
+
       const headers = config.headers;
       try {
-        const bookId = await fetchBookId(isbn);
+        const bookId = await fetchBookId(cleanIsbn);
         const url = encodeURI(
-          location == "tr"
+          location === "tr"
             ? config.tr_detail_url + bookId
             : config.en_detail_url + bookId
         );
 
-        return new Promise((resolve, reject) => {
-          setTimeout(async () => {
-            try {
-              const response = await axios.get(url, { headers });
+        // Add delay to avoid rate limiting
+        await new Promise(resolve => setTimeout(resolve, config.fetchTimeout));
 
-              if (!response.data) {
-                throw new Error("Detay bilgisi bulunamadı!");
-              }
-              const details = await modules.extractBookDetails(
-                response.data,
-                isbn,
-                geminiApiKey,
-                location
-              );
-              resolve(details);
-            } catch (error) {
-              reject(error);
-            }
-          }, config.fetchTimeout);
-        });
+        const response = await axios.get(url, { headers });
+
+        if (!response.data) {
+          throw new Error("Book details not found!");
+        }
+        const details = await extractBookDetails(
+          response.data,
+          cleanIsbn,
+          geminiApiKey,
+          location
+        );
+        return details;
       } catch (error) {
         throw new Error(error.message);
       }
@@ -67,24 +73,9 @@ class AmazonBookSearch {
 
 module.exports = AmazonBookSearch;
 
-// Gemini API Key girilirse, amazon'da bulunan kitap açıklaması gemini tarafından yeniden oluşturulur.
-// (async () => {
-//   try {
-//     const BookSearch = new AmazonBookSearch("tr");
-//     const bookDetails = await BookSearch.getBookDetails("9786257746168", "AIzaSyAY15XJcK1VIxzMRe48dyDEeNPqeqhQt2I");
-//     console.log(bookDetails);
-//   } catch (error) {
-//     console.log(error.message);
-//   }
-// })();
-
-// //
-// (async () => {
-//   try {
-//     const BookSearch = new AmazonBookSearch("tr");
-//     const bookDetails = await BookSearch.getBookDetails("9944824453");
-//     console.log(bookDetails);
-//   } catch (error) {
-//     console.log(error.message);
-//   }
-// })();
+// Example usage:
+// const AmazonBookSearch = require('./index.js');
+//
+// const bookSearch = new AmazonBookSearch("tr");
+// const bookDetails = await bookSearch.getBookDetails("9944824453", process.env.GEMINI_API_KEY);
+// console.log(bookDetails);