Create a structure for different diff strategies, starting with unified (#55)

src/core/diff/strategies/__tests__/unified.test.ts

@@ -0,0 +1,214 @@
+import { UnifiedDiffStrategy } from '../unified'
+
+describe('UnifiedDiffStrategy', () => {
+    let strategy: UnifiedDiffStrategy
+
+    beforeEach(() => {
+        strategy = new UnifiedDiffStrategy()
+    })
+
+    describe('getToolDescription', () => {
+        it('should return tool description with correct cwd', () => {
+            const cwd = '/test/path'
+            const description = strategy.getToolDescription(cwd)
+            
+            expect(description).toContain('apply_diff')
+            expect(description).toContain(cwd)
+            expect(description).toContain('Parameters:')
+            expect(description).toContain('Format Requirements:')
+        })
+    })
+
+    describe('applyDiff', () => {
+        it('should successfully apply a function modification diff', () => {
+            const originalContent = `import { Logger } from '../logger';
+
+function calculateTotal(items: number[]): number {
+  return items.reduce((sum, item) => {
+    return sum + item;
+  }, 0);
+}
+
+export { calculateTotal };`
+
+            const diffContent = `--- src/utils/helper.ts
++++ src/utils/helper.ts
+@@ -1,9 +1,10 @@
+ import { Logger } from '../logger';
+ 
+ function calculateTotal(items: number[]): number {
+-  return items.reduce((sum, item) => {
+-    return sum + item;
++  const total = items.reduce((sum, item) => {
++    return sum + item * 1.1;  // Add 10% markup
+   }, 0);
++  return Math.round(total * 100) / 100;  // Round to 2 decimal places
+ }
+ 
+ export { calculateTotal };`
+
+            const expected = `import { Logger } from '../logger';
+
+function calculateTotal(items: number[]): number {
+  const total = items.reduce((sum, item) => {
+    return sum + item * 1.1;  // Add 10% markup
+  }, 0);
+  return Math.round(total * 100) / 100;  // Round to 2 decimal places
+}
+
+export { calculateTotal };`
+
+            const result = strategy.applyDiff(originalContent, diffContent)
+            expect(result).toBe(expected)
+        })
+
+        it('should successfully apply a diff adding a new method', () => {
+            const originalContent = `class Calculator {
+  add(a: number, b: number): number {
+    return a + b;
+  }
+}`
+
+            const diffContent = `--- src/Calculator.ts
++++ src/Calculator.ts
+@@ -1,5 +1,9 @@
+ class Calculator {
+   add(a: number, b: number): number {
+     return a + b;
+   }
++
++  multiply(a: number, b: number): number {
++    return a * b;
++  }
+ }`
+
+            const expected = `class Calculator {
+  add(a: number, b: number): number {
+    return a + b;
+  }
+
+  multiply(a: number, b: number): number {
+    return a * b;
+  }
+}`
+
+            const result = strategy.applyDiff(originalContent, diffContent)
+            expect(result).toBe(expected)
+        })
+
+        it('should successfully apply a diff modifying imports', () => {
+            const originalContent = `import { useState } from 'react';
+import { Button } from './components';
+
+function App() {
+  const [count, setCount] = useState(0);
+  return <Button onClick={() => setCount(count + 1)}>{count}</Button>;
+}`
+
+            const diffContent = `--- src/App.tsx
++++ src/App.tsx
+@@ -1,7 +1,8 @@
+-import { useState } from 'react';
++import { useState, useEffect } from 'react';
+ import { Button } from './components';
+ 
+ function App() {
+   const [count, setCount] = useState(0);
++  useEffect(() => { document.title = \`Count: \${count}\` }, [count]);
+   return <Button onClick={() => setCount(count + 1)}>{count}</Button>;
+ }`
+
+            const expected = `import { useState, useEffect } from 'react';
+import { Button } from './components';
+
+function App() {
+  const [count, setCount] = useState(0);
+  useEffect(() => { document.title = \`Count: \${count}\` }, [count]);
+  return <Button onClick={() => setCount(count + 1)}>{count}</Button>;
+}`
+
+            const result = strategy.applyDiff(originalContent, diffContent)
+            expect(result).toBe(expected)
+        })
+
+        it('should successfully apply a diff with multiple hunks', () => {
+            const originalContent = `import { readFile, writeFile } from 'fs';
+
+function processFile(path: string) {
+  readFile(path, 'utf8', (err, data) => {
+    if (err) throw err;
+    const processed = data.toUpperCase();
+    writeFile(path, processed, (err) => {
+      if (err) throw err;
+    });
+  });
+}
+
+export { processFile };`
+
+            const diffContent = `--- src/file-processor.ts
++++ src/file-processor.ts
+@@ -1,12 +1,14 @@
+-import { readFile, writeFile } from 'fs';
++import { promises as fs } from 'fs';
++import { join } from 'path';
+ 
+-function processFile(path: string) {
+-  readFile(path, 'utf8', (err, data) => {
+-    if (err) throw err;
++async function processFile(path: string) {
++  try {
++    const data = await fs.readFile(join(__dirname, path), 'utf8');
+     const processed = data.toUpperCase();
+-    writeFile(path, processed, (err) => {
+-      if (err) throw err;
+-    });
+-  });
++    await fs.writeFile(join(__dirname, path), processed);
++  } catch (error) {
++    console.error('Failed to process file:', error);
++    throw error;
++  }
+ }
+ 
+ export { processFile };`
+
+            const expected = `import { promises as fs } from 'fs';
+import { join } from 'path';
+
+async function processFile(path: string) {
+  try {
+    const data = await fs.readFile(join(__dirname, path), 'utf8');
+    const processed = data.toUpperCase();
+    await fs.writeFile(join(__dirname, path), processed);
+  } catch (error) {
+    console.error('Failed to process file:', error);
+    throw error;
+  }
+}
+
+export { processFile };`
+
+            const result = strategy.applyDiff(originalContent, diffContent)
+            expect(result).toBe(expected)
+        })
+
+        it('should handle empty original content', () => {
+            const originalContent = ''
+            const diffContent = `--- empty.ts
++++ empty.ts
+@@ -0,0 +1,3 @@
++export function greet(name: string): string {
++  return \`Hello, \${name}!\`;
++}`
+
+            const expected = `export function greet(name: string): string {
+  return \`Hello, \${name}!\`;
+}\n`
+
+            const result = strategy.applyDiff(originalContent, diffContent)
+            expect(result).toBe(expected)
+        })
+    })
+})
+

src/core/diff/strategies/unified.ts

@@ -0,0 +1,114 @@
+import { applyPatch } from "diff"
+import { DiffStrategy } from "../types"
+
+export class UnifiedDiffStrategy implements DiffStrategy {
+    getToolDescription(cwd: string): string {
+        return `## apply_diff
+Description: Apply a unified diff to a file at the specified path. This tool is useful when you need to make specific modifications to a file based on a set of changes provided in unified diff format (diff -U3).
+
+Parameters:
+- path: (required) The path of the file to apply the diff to (relative to the current working directory ${cwd})
+- diff: (required) The diff content in unified format to apply to the file.
+
+Format Requirements:
+
+1. Header (REQUIRED):
+    \`\`\`
+    --- path/to/original/file
+    +++ path/to/modified/file
+    \`\`\`
+    - Must include both lines exactly as shown
+    - Use actual file paths
+    - NO timestamps after paths
+
+2. Hunks:
+    \`\`\`
+    @@ -lineStart,lineCount +lineStart,lineCount @@
+    -removed line
+    +added line
+    \`\`\`
+    - Each hunk starts with @@ showing line numbers for changes
+    - Format: @@ -originalStart,originalCount +newStart,newCount @@
+    - Use - for removed/changed lines
+    - Use + for new/modified lines
+    - Indentation must match exactly
+
+Complete Example:
+
+Original file (with line numbers):
+\`\`\`
+1 | import { Logger } from '../logger';
+2 | 
+3 | function calculateTotal(items: number[]): number {
+4 |   return items.reduce((sum, item) => {
+5 |     return sum + item;
+6 |   }, 0);
+7 | }
+8 | 
+9 | export { calculateTotal };
+\`\`\`
+
+After applying the diff, the file would look like:
+\`\`\`
+1 | import { Logger } from '../logger';
+2 | 
+3 | function calculateTotal(items: number[]): number {
+4 |   const total = items.reduce((sum, item) => {
+5 |     return sum + item * 1.1;  // Add 10% markup
+6 |   }, 0);
+7 |   return Math.round(total * 100) / 100;  // Round to 2 decimal places
+8 | }
+9 | 
+10 | export { calculateTotal };
+\`\`\`
+
+Diff to modify the file:
+\`\`\`
+--- src/utils/helper.ts
++++ src/utils/helper.ts
+@@ -1,9 +1,10 @@
+ import { Logger } from '../logger';
+ 
+ function calculateTotal(items: number[]): number {
+-  return items.reduce((sum, item) => {
+-    return sum + item;
++  const total = items.reduce((sum, item) => {
++    return sum + item * 1.1;  // Add 10% markup
+   }, 0);
++  return Math.round(total * 100) / 100;  // Round to 2 decimal places
+ }
+ 
+ export { calculateTotal };
+\`\`\`
+
+Common Pitfalls:
+1. Missing or incorrect header lines
+2. Incorrect line numbers in @@ lines
+3. Wrong indentation in changed lines
+4. Incomplete context (missing lines that need changing)
+5. Not marking all modified lines with - and +
+
+Best Practices:
+1. Replace entire code blocks:
+    - Remove complete old version with - lines
+    - Add complete new version with + lines
+    - Include correct line numbers
+2. Moving code requires two hunks:
+    - First hunk: Remove from old location
+    - Second hunk: Add to new location
+3. One hunk per logical change
+4. Verify line numbers match the line numbers you have in the file
+
+Usage:
+<apply_diff>
+<path>File path here</path>
+<diff>
+Your diff here
+</diff>
+</apply_diff>`
+    }
+
+    applyDiff(originalContent: string, diffContent: string): string | false {
+        return applyPatch(originalContent, diffContent) as string | false
+    }
+}