feat: integrate git repository diff handling into common route

- Added functions to check if a path is a git repository and to parse git status output into a structured format.
- Refactored diff handling in both git and worktree routes to utilize the new common functions, improving code reuse and maintainability.
- Enhanced error logging for better debugging during git operations.

This update streamlines the process of retrieving diffs for both git and non-git directories, ensuring a consistent approach across the application.

apps/server/src/routes/common.ts

@@ -5,9 +5,14 @@
 import { createLogger } from "../lib/logger.js";
 import fs from "fs/promises";
 import path from "path";
+import { exec } from "child_process";
+import { promisify } from "util";
 
 type Logger = ReturnType<typeof createLogger>;
 
+const execAsync = promisify(exec);
+const logger = createLogger("Common");
+
 // Max file size for generating synthetic diffs (1MB)
 const MAX_SYNTHETIC_DIFF_SIZE = 1024 * 1024;
 
@@ -23,6 +28,26 @@ const BINARY_EXTENSIONS = new Set([
   ".pyc", ".pyo", ".class", ".o", ".obj",
 ]);
 
+// Status map for git status codes
+const GIT_STATUS_MAP: Record<string, string> = {
+  M: "Modified",
+  A: "Added",
+  D: "Deleted",
+  R: "Renamed",
+  C: "Copied",
+  U: "Updated",
+  "?": "Untracked",
+};
+
+/**
+ * File status interface for git status results
+ */
+export interface FileStatus {
+  status: string;
+  path: string;
+  statusText: string;
+}
+
 /**
  * Check if a file is likely binary based on extension
  */
@@ -31,6 +56,36 @@ function isBinaryFile(filePath: string): boolean {
   return BINARY_EXTENSIONS.has(ext);
 }
 
+/**
+ * Check if a path is a git repository
+ */
+export async function isGitRepo(repoPath: string): Promise<boolean> {
+  try {
+    await execAsync("git rev-parse --is-inside-work-tree", { cwd: repoPath });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+/**
+ * Parse the output of `git status --porcelain` into FileStatus array
+ */
+export function parseGitStatus(statusOutput: string): FileStatus[] {
+  return statusOutput
+    .split("\n")
+    .filter(Boolean)
+    .map((line) => {
+      const statusChar = line[0];
+      const filePath = line.slice(3);
+      return {
+        status: statusChar,
+        path: filePath,
+        statusText: GIT_STATUS_MAP[statusChar] || "Unknown",
+      };
+    });
+}
+
 /**
  * Generate a synthetic unified diff for an untracked (new) file
  * This is needed because `git diff HEAD` doesn't include untracked files
@@ -67,10 +122,11 @@ index 0000000..0000000
 
     // Read file content
     const content = await fs.readFile(fullPath, "utf-8");
+    const hasTrailingNewline = content.endsWith("\n");
     const lines = content.split("\n");
 
     // Remove trailing empty line if the file ends with newline
-    if (lines.length > 0 && lines[lines.length - 1] === "") {
+    if (lines.length > 0 && lines.at(-1) === "") {
       lines.pop();
     }
 
@@ -78,16 +134,24 @@ index 0000000..0000000
     const lineCount = lines.length;
     const addedLines = lines.map(line => `+${line}`).join("\n");
 
-    return `diff --git a/${relativePath} b/${relativePath}
+    let diff = `diff --git a/${relativePath} b/${relativePath}
 new file mode 100644
 index 0000000..0000000
 --- /dev/null
 +++ b/${relativePath}
 @@ -0,0 +1,${lineCount} @@
-${addedLines}
-`;
+${addedLines}`;
+
+    // Add "No newline at end of file" indicator if needed
+    if (!hasTrailingNewline && content.length > 0) {
+      diff += "\n\\ No newline at end of file";
+    }
+
+    return diff + "\n";
   } catch (error) {
-    // If we can't read the file, return a placeholder diff
+    // Log the error for debugging
+    logger.error(`Failed to generate synthetic diff for ${fullPath}:`, error);
+    // Return a placeholder diff
     return `diff --git a/${relativePath} b/${relativePath}
 new file mode 100644
 index 0000000..0000000
@@ -162,8 +226,9 @@ export async function listAllFilesInDirectory(
         files.push(entryRelPath);
       }
     }
-  } catch {
-    // Ignore errors (permission denied, etc.)
+  } catch (error) {
+    // Log the error to help diagnose file system issues
+    logger.error(`Error reading directory ${fullPath}:`, error);
   }
 
   return files;
@@ -175,10 +240,10 @@ export async function listAllFilesInDirectory(
  */
 export async function generateDiffsForNonGitDirectory(
   basePath: string
-): Promise<{ diff: string; files: Array<{ status: string; path: string; statusText: string }> }> {
+): Promise<{ diff: string; files: FileStatus[] }> {
   const allFiles = await listAllFilesInDirectory(basePath);
 
-  const files = allFiles.map(filePath => ({
+  const files: FileStatus[] = allFiles.map(filePath => ({
     status: "?",
     path: filePath,
     statusText: "New",
@@ -195,6 +260,47 @@ export async function generateDiffsForNonGitDirectory(
   };
 }
 
+/**
+ * Get git repository diffs for a given path
+ * Handles both git repos and non-git directories
+ */
+export async function getGitRepositoryDiffs(
+  repoPath: string
+): Promise<{ diff: string; files: FileStatus[]; hasChanges: boolean }> {
+  // Check if it's a git repository
+  const isRepo = await isGitRepo(repoPath);
+
+  if (!isRepo) {
+    // Not a git repo - list all files and treat them as new
+    const result = await generateDiffsForNonGitDirectory(repoPath);
+    return {
+      diff: result.diff,
+      files: result.files,
+      hasChanges: result.files.length > 0,
+    };
+  }
+
+  // Get git diff and status
+  const { stdout: diff } = await execAsync("git diff HEAD", {
+    cwd: repoPath,
+    maxBuffer: 10 * 1024 * 1024,
+  });
+  const { stdout: status } = await execAsync("git status --porcelain", {
+    cwd: repoPath,
+  });
+
+  const files = parseGitStatus(status);
+
+  // Generate synthetic diffs for untracked (new) files
+  const combinedDiff = await appendUntrackedFileDiffs(repoPath, diff, files);
+
+  return {
+    diff: combinedDiff,
+    files,
+    hasChanges: files.length > 0,
+  };
+}
+
 /**
  * Get error message from error object
  */

apps/server/src/routes/git/routes/diffs.ts

@@ -3,24 +3,8 @@
  */
 
 import type { Request, Response } from "express";
-import { exec } from "child_process";
-import { promisify } from "util";
 import { getErrorMessage, logError } from "../common.js";
-import { appendUntrackedFileDiffs, generateDiffsForNonGitDirectory } from "../../common.js";
-
-const execAsync = promisify(exec);
-
-/**
- * Check if a path is a git repository
- */
-async function isGitRepo(repoPath: string): Promise<boolean> {
-  try {
-    await execAsync("git rev-parse --is-inside-work-tree", { cwd: repoPath });
-    return true;
-  } catch {
-    return false;
-  }
-}
+import { getGitRepositoryDiffs } from "../../common.js";
 
 export function createDiffsHandler() {
   return async (req: Request, res: Response): Promise<void> => {
@@ -32,70 +16,16 @@ export function createDiffsHandler() {
         return;
       }
 
-      // Check if it's a git repository
-      const isRepo = await isGitRepo(projectPath);
-
-      if (!isRepo) {
-        // Not a git repo - list all files and treat them as new
-        try {
-          const result = await generateDiffsForNonGitDirectory(projectPath);
-          res.json({
-            success: true,
-            diff: result.diff,
-            files: result.files,
-            hasChanges: result.files.length > 0,
-          });
-        } catch (error) {
-          logError(error, "Failed to list files in non-git directory");
-          res.json({ success: true, diff: "", files: [], hasChanges: false });
-        }
-        return;
-      }
-
       try {
-        const { stdout: diff } = await execAsync("git diff HEAD", {
-          cwd: projectPath,
-          maxBuffer: 10 * 1024 * 1024,
-        });
-        const { stdout: status } = await execAsync("git status --porcelain", {
-          cwd: projectPath,
-        });
-
-        const files = status
-          .split("\n")
-          .filter(Boolean)
-          .map((line) => {
-            const statusChar = line[0];
-            const filePath = line.slice(3);
-            const statusMap: Record<string, string> = {
-              M: "Modified",
-              A: "Added",
-              D: "Deleted",
-              R: "Renamed",
-              C: "Copied",
-              U: "Updated",
-              "?": "Untracked",
-            };
-            return {
-              status: statusChar,
-              path: filePath,
-              statusText: statusMap[statusChar] || "Unknown",
-            };
-          });
-
-        // Generate synthetic diffs for untracked (new) files
-        // git diff HEAD doesn't include untracked files, so we need to generate them
-        const combinedDiff = await appendUntrackedFileDiffs(projectPath, diff, files);
-
+        const result = await getGitRepositoryDiffs(projectPath);
         res.json({
           success: true,
-          diff: combinedDiff,
-          files,
-          hasChanges: files.length > 0,
+          diff: result.diff,
+          files: result.files,
+          hasChanges: result.hasChanges,
         });
       } catch (innerError) {
-        // Log the error for debugging instead of silently swallowing it
-        logError(innerError, "Git command failed");
+        logError(innerError, "Git diff failed");
         res.json({ success: true, diff: "", files: [], hasChanges: false });
       }
     } catch (error) {

apps/server/src/routes/worktree/routes/diffs.ts

@@ -3,26 +3,10 @@
  */
 
 import type { Request, Response } from "express";
-import { exec } from "child_process";
-import { promisify } from "util";
 import path from "path";
 import fs from "fs/promises";
 import { getErrorMessage, logError } from "../common.js";
-import { appendUntrackedFileDiffs, generateDiffsForNonGitDirectory } from "../../common.js";
-
-const execAsync = promisify(exec);
-
-/**
- * Check if a path is a git repository
- */
-async function isGitRepo(repoPath: string): Promise<boolean> {
-  try {
-    await execAsync("git rev-parse --is-inside-work-tree", { cwd: repoPath });
-    return true;
-  } catch {
-    return false;
-  }
-}
+import { getGitRepositoryDiffs } from "../../common.js";
 
 export function createDiffsHandler() {
   return async (req: Request, res: Response): Promise<void> => {
@@ -50,121 +34,28 @@ export function createDiffsHandler() {
       );
 
       try {
+        // Check if worktree exists
         await fs.access(worktreePath);
 
-        // Check if worktree is a git repository
-        const isRepo = await isGitRepo(worktreePath);
-
-        if (!isRepo) {
-          // Not a git repo - list all files and treat them as new
-          const result = await generateDiffsForNonGitDirectory(worktreePath);
-          res.json({
-            success: true,
-            diff: result.diff,
-            files: result.files,
-            hasChanges: result.files.length > 0,
-          });
-          return;
-        }
-
-        const { stdout: diff } = await execAsync("git diff HEAD", {
-          cwd: worktreePath,
-          maxBuffer: 10 * 1024 * 1024,
-        });
-        const { stdout: status } = await execAsync("git status --porcelain", {
-          cwd: worktreePath,
-        });
-
-        const files = status
-          .split("\n")
-          .filter(Boolean)
-          .map((line) => {
-            const statusChar = line[0];
-            const filePath = line.slice(3);
-            const statusMap: Record<string, string> = {
-              M: "Modified",
-              A: "Added",
-              D: "Deleted",
-              R: "Renamed",
-              C: "Copied",
-              U: "Updated",
-              "?": "Untracked",
-            };
-            return {
-              status: statusChar,
-              path: filePath,
-              statusText: statusMap[statusChar] || "Unknown",
-            };
-          });
-
-        // Generate synthetic diffs for untracked (new) files
-        // git diff HEAD doesn't include untracked files, so we need to generate them
-        const combinedDiff = await appendUntrackedFileDiffs(worktreePath, diff, files);
-
+        // Get diffs from worktree
+        const result = await getGitRepositoryDiffs(worktreePath);
         res.json({
           success: true,
-          diff: combinedDiff,
-          files,
-          hasChanges: files.length > 0,
+          diff: result.diff,
+          files: result.files,
+          hasChanges: result.hasChanges,
         });
       } catch (innerError) {
         // Worktree doesn't exist - fallback to main project path
         logError(innerError, "Worktree access failed, falling back to main project");
 
         try {
-          // Check if main project is a git repo
-          const isRepo = await isGitRepo(projectPath);
-
-          if (!isRepo) {
-            // Not a git repo - list all files and treat them as new
-            const result = await generateDiffsForNonGitDirectory(projectPath);
-            res.json({
-              success: true,
-              diff: result.diff,
-              files: result.files,
-              hasChanges: result.files.length > 0,
-            });
-            return;
-          }
-
-          // Try main project path for git diffs
-          const { stdout: diff } = await execAsync("git diff HEAD", {
-            cwd: projectPath,
-            maxBuffer: 10 * 1024 * 1024,
-          });
-          const { stdout: status } = await execAsync("git status --porcelain", {
-            cwd: projectPath,
-          });
-
-          const files = status
-            .split("\n")
-            .filter(Boolean)
-            .map((line) => {
-              const statusChar = line[0];
-              const filePath = line.slice(3);
-              const statusMap: Record<string, string> = {
-                M: "Modified",
-                A: "Added",
-                D: "Deleted",
-                R: "Renamed",
-                C: "Copied",
-                U: "Updated",
-                "?": "Untracked",
-              };
-              return {
-                status: statusChar,
-                path: filePath,
-                statusText: statusMap[statusChar] || "Unknown",
-              };
-            });
-
-          const combinedDiff = await appendUntrackedFileDiffs(projectPath, diff, files);
-
+          const result = await getGitRepositoryDiffs(projectPath);
           res.json({
             success: true,
-            diff: combinedDiff,
-            files,
-            hasChanges: files.length > 0,
+            diff: result.diff,
+            files: result.files,
+            hasChanges: result.hasChanges,
           });
         } catch (fallbackError) {
           logError(fallbackError, "Fallback to main project also failed");