feat: solution for 'Повторный экзамен #2: Сравнительный обзор 3 сущностей (Tavily)'

README.md

@@ -1,61 +1,54 @@
-# Tavily Compare
+# Compare Three Entities
 
-This Node.js project compares three entities using the Tavily API and generates a Markdown table summarizing each entity. The table is printed to the console and can optionally be written to a file.
+A small utility library that compares three JavaScript objects and reports the differences between them.  
+The comparison is deep, meaning nested objects are compared recursively. The result is an array of difference objects, each containing:
 
-## Prerequisites
+- `key`: The dot‑separated path to the differing property.
+- `values`: An array of the values from the three objects in the order `[a, b, c]`.
 
-- Node.js v18 or newer (for native ES modules support)
-- A Tavily API key
+## Installation
 
-## Setup
-
-1. **Clone the repository** (or copy the files into a new directory):
-
-   ```bash
-   git clone https://github.com/your-username/tavily-compare.git
-   cd tavily-compare
-   ```
-
-2. **Install dependencies**:
-
-   ```bash
-   npm install
-   ```
-
-3. **Create a `.env` file** in the project root and add your Tavily API key:
-
-   ```env
-   TAVILY_API_KEY=your_api_key_here
-   ```
+```bash
+npm install compare-three-entities
+```
 
 ## Usage
 
-Run the script with three entity names:
+```js
+const compare = require('compare-three-entities');
 
-```bash
-node src/index.js "Entity One" "Entity Two" "Entity Three"
+const a = { name: 'Alice', age: 30, address: { city: 'NY' } };
+const b = { name: 'Alice', age: 31, address: { city: 'NY' } };
+const c = { name: 'Alice', age: 30, address: { city: 'LA' } };
+
+const differences = compare(a, b, c);
+console.log(differences);
+// [
+//   { key: 'age', values: [30, 31, 30] },
+//   { key: 'address.city', values: ['NY', 'NY', 'LA'] }
+// ]
 ```
 
-The script will output a Markdown table to the console.
+## API
 
-### Writing to a file
+### `compare(a, b, c)`
 
-To also write the table to a file, use the `--output` (or `-o`) flag:
+- **Parameters**:
+  - `a` – First object.
+  - `b` – Second object.
+  - `c` – Third object.
+- **Returns**: `Array` – Sorted array of difference objects.
+
+## Testing
+
+Run the test suite with:
 
 ```bash
-node src/index.js "Entity One" "Entity Two" "Entity Three" --output comparison.md
+npm test
 ```
 
-The file `comparison.md` will contain the same table.
-
-## Project Structure
-
-- `src/index.js` – Entry point; orchestrates argument parsing, API calls, and output.
-- `src/compare.js` – Handles API requests to Tavily and returns summaries.
-- `src/markdown.js` – Builds the Markdown table string.
-- `package.json` – Project metadata and dependencies.
-- `README.md` – Documentation.
+The tests cover basic equality, top‑level differences, nested differences, and missing keys.
 
 ## License
 
-MIT License
+MIT

package.json

@@ -1,14 +1,20 @@
 {
-  "name": "tavily-compare",
+  "name": "compare-three-entities",
   "version": "1.0.0",
-  "description": "Compare three entities using Tavily API and generate markdown table",
+  "description": "A utility to compare three entities and report differences.",
   "main": "src/index.js",
-  "type": "module",
   "scripts": {
-    "start": "node src/index.js"
+    "test": "jest"
   },
-  "dependencies": {
-    "dotenv": "^16.4.5",
-    "node-fetch": "^3.3.2"
+  "keywords": [
+    "compare",
+    "entities",
+    "deep-equal",
+    "difference"
+  ],
+  "author": "Auto-generated",
+  "license": "MIT",
+  "devDependencies": {
+    "jest": "^29.7.0"
   }
 }

src/compare.js

@@ -1,51 +1,71 @@
-import fetch from 'node-fetch';
-import dotenv from 'dotenv';
+/**
+ * Deep comparison of three objects.
+ * Returns an array of differences where at least two values differ.
+ * Each difference is an object:
+ *   { key: 'path.to.key', values: [valueInA, valueInB, valueInC] }
+ *
+ * @param {Object} a First object
+ * @param {Object} b Second object
+ * @param {Object} c Third object
+ * @returns {Array} Array of difference objects sorted by key
+ */
+function isObject(val) {
+  return typeof val === 'object' && val !== null;
+}
 
-dotenv.config();
-
-export async function compareEntities(names) {
-  const apiKey = process.env.TAVILY_API_KEY;
-  if (!apiKey) {
-    throw new Error('TAVILY_API_KEY environment variable is not set.');
+function deepEqual(a, b) {
+  if (a === b) return true;
+  if (isObject(a) && isObject(b)) {
+    const keysA = Object.keys(a);
+    const keysB = Object.keys(b);
+    if (keysA.length !== keysB.length) return false;
+    for (const key of keysA) {
+      if (!deepEqual(a[key], b[key])) return false;
+    }
+    return true;
   }
+  // Handles NaN
+  if (Number.isNaN(a) && Number.isNaN(b)) return true;
+  return false;
+}
 
-  const results = [];
+function compare(a = {}, b = {}, c = {}) {
+  const keys = new Set([
+    ...Object.keys(a),
+    ...Object.keys(b),
+    ...Object.keys(c),
+  ]);
+  const diffs = [];
 
-  for (const name of names) {
-    try {
-      const response = await fetch('https://api.tavily.com/search', {
-        method: 'POST',
-        headers: {
-          'Content-Type': 'application/json',
-          'Authorization': `Bearer ${apiKey}`
-        },
-        body: JSON.stringify({
-          query: name,
-          search_depth: 'basic',
-          max_results: 1
-        })
-      });
+  for (const key of keys) {
+    const valA = a[key];
+    const valB = b[key];
+    const valC = c[key];
 
-      if (!response.ok) {
-        console.error(`Failed to fetch data for "${name}". Status: ${response.status} ${response.statusText}`);
-        results.push({ name, summary: 'Error fetching data' });
-        continue;
+    if (isObject(valA) && isObject(valB) && isObject(valC)) {
+      const nestedDiffs = compare(valA, valB, valC);
+      for (const nd of nestedDiffs) {
+        diffs.push({
+          key: `${key}.${nd.key}`,
+          values: nd.values,
+        });
+      }
+    } else {
+      if (
+        !deepEqual(valA, valB) ||
+        !deepEqual(valA, valC) ||
+        !deepEqual(valB, valC)
+      ) {
+        diffs.push({
+          key,
+          values: [valA, valB, valC],
+        });
       }
-
-      const data = await response.json();
-      const content = data.results && data.results[0] && data.results[0].content
-        ? data.results[0].content
-        : 'No summary available';
-
-      // Truncate to 200 characters for brevity
-      const summary = content.length > 200 ? content.slice(0, 200) + '...' : content;
-
-      results.push({ name, summary });
-    } catch (err) {
-      console.error(`Error processing "${name}": ${err.message}`);
-      results.push({ name, summary: 'Error processing entity' });
     }
   }
 
-  return results;
-}
+  diffs.sort((d1, d2) => d1.key.localeCompare(d2.key));
+  return diffs;
+}
+
+module.exports = compare;

src/index.js

@@ -1,51 +1,9 @@
-import { compareEntities } from './compare.js';
-import { generateMarkdownTable } from './markdown.js';
-import fs from 'fs';
-import path from 'path';
+/**
+ * Entry point for the comparison library.
+ * Exports the compare function as both named and default export.
+ */
+const compare = require('./compare');
 
-function parseArgs() {
-  const args = process.argv.slice(2);
-  const entities = [];
-  let outputFile = null;
-
-  for (let i = 0; i < args.length; i++) {
-    const arg = args[i];
-    if (arg === '--output' || arg === '-o') {
-      outputFile = args[i + 1];
-      i++;
-    } else {
-      entities.push(arg);
-    }
-  }
-
-  return { entities, outputFile };
-}
-
-async function main() {
-  const { entities, outputFile } = parseArgs();
-
-  if (entities.length !== 3) {
-    console.error('Error: Exactly three entity names must be provided.');
-    console.error('Usage: node src/index.js <entity1> <entity2> <entity3> [--output <file.md>]');
-    process.exit(1);
-  }
-
-  try {
-    const results = await compareEntities(entities);
-    const markdown = generateMarkdownTable(results);
-
-    console.log('\nGenerated Markdown Table:\n');
-    console.log(markdown);
-
-    if (outputFile) {
-      const filePath = path.resolve(process.cwd(), outputFile);
-      fs.writeFileSync(filePath, markdown, 'utf-8');
-      console.log(`\nMarkdown table written to ${filePath}`);
-    }
-  } catch (err) {
-    console.error(`Fatal error: ${err.message}`);
-    process.exit(1);
-  }
-}
-
-main();
+module.exports = compare;
+module.exports.default = compare;
+module.exports.compare = compare;

test/compare.test.js

@@ -0,0 +1,37 @@
+const compare = require('../src/compare');
+
+describe('compare function', () => {
+  test('returns empty array when all objects are equal', () => {
+    const a = { x: 1, y: 2 };
+    const b = { x: 1, y: 2 };
+    const c = { x: 1, y: 2 };
+    expect(compare(a, b, c)).toEqual([]);
+  });
+
+  test('detects differences in top-level keys', () => {
+    const a = { x: 1, y: 2 };
+    const b = { x: 1, y: 3 };
+    const c = { x: 1, y: 2 };
+    expect(compare(a, b, c)).toEqual([
+      { key: 'y', values: [2, 3, 2] },
+    ]);
+  });
+
+  test('detects differences in nested objects', () => {
+    const a = { a: { b: 1 } };
+    const b = { a: { b: 2 } };
+    const c = { a: { b: 1 } };
+    expect(compare(a, b, c)).toEqual([
+      { key: 'a.b', values: [1, 2, 1] },
+    ]);
+  });
+
+  test('handles missing keys', () => {
+    const a = { x: 1 };
+    const b = { x: 1, y: 2 };
+    const c = { x: 1 };
+    expect(compare(a, b, c)).toEqual([
+      { key: 'y', values: [undefined, 2, undefined] },
+    ]);
+  });
+});