feat: add git blame fetch at the opening of a text file

src/extension.ts

@@ -1,6 +1,7 @@
 import * as vscode from "vscode";
 import * as cp from "child_process";
 import { throttle } from "throttle-debounce";
+import { fetchFileBlame, CommitInfo } from "./git"; 
 
 import {
   parseGitBlamePorcelain,
@@ -15,11 +16,14 @@
   },
 });
 
+const FileCommits: Map<string, CommitInfo[]> = new Map();
+
 function showDecoration(e: { readonly textEditor: vscode.TextEditor }) {
   const editor = e.textEditor;
   const document = editor.document;
   const activeLine = document.lineAt(editor.selection.active.line);
   const { uri: file, isDirty } = document;
+
 
   const command = "git";
   const n = activeLine.lineNumber;
@@ -29,6 +33,17 @@
     args.push("--content", "-");
   }
 
+
+  const commitInfos = FileCommits.get(file.fsPath);
+  if (commitInfos !== undefined) {
+    const thiscommitInfo = commitInfos.find(info => info.lineNumber === n);
+    // TODO: get values of fields from thiscommitInfo
+
+  }
+  else {
+    console.log(`No pre-fetched commit information found for ${file.fsPath}`);
+    // TODO: move obsolete logic from down below here if the commitInfos is not found
+  }  
   const workspaceFolder = vscode.workspace.getWorkspaceFolder(file);
   const workspaceFolderPath = workspaceFolder?.uri.fsPath;
   const options = { cwd: workspaceFolderPath };
@@ -73,12 +88,41 @@
   });
 }
 
+function showFileBlame(e: { readonly textEditor: vscode.TextEditor }) {
+
+  const editor = e.textEditor;
+  const document = editor.document;
+  const { uri: file, isDirty } = document;
+
+  fetchFileBlame(file.fsPath)
+    .then(commitInfos => {
+      console.log(`Commit Information for ${file.fsPath}`); 
+      console.log(commitInfos);
+      FileCommits.set(file.fsPath, commitInfos);
+    })
+
+}
 export function activate(context: vscode.ExtensionContext) {
   console.log('Extension "git-line-blame" has activated.');
   let showDecorationThrottled = throttle(100, showDecoration);
   context.subscriptions.push(
     vscode.window.onDidChangeTextEditorSelection(showDecorationThrottled),
     vscode.window.onDidChangeTextEditorVisibleRanges(showDecorationThrottled),
+    vscode.window.onDidChangeActiveTextEditor((e) => {
+      const editor = vscode.window.activeTextEditor;
+      if (editor !== undefined && e === editor) {
+          showFileBlame({ textEditor: editor })
+      }
+    }),
+    vscode.window.onDidChangeVisibleTextEditors(editors => {
+        const closedEditors = vscode.window.visibleTextEditors.filter(editor =>
+            !editors.includes(editor)
+        );
+        closedEditors.forEach(closedEditor => {
+            console.log(`Closed file: ${closedEditor.document.fileName}`);
+            FileCommits.delete(closedEditor.document.fileName);
+        });
+    }),
     vscode.workspace.onDidSaveTextDocument((e) => {
       const editor = vscode.window.activeTextEditor;
       if (editor !== undefined && e === editor.document) {

src/git.ts

@@ -0,0 +1,93 @@
+import { exec } from 'child_process';
+
+export interface CommitInfo {
+  commitHash: string;
+  author: string;
+  lineNumber: number;
+  commitTitle: string;
+}
+
+export function fetchFileBlame(file: string): Promise<CommitInfo[]> {
+  return new Promise<CommitInfo[]>((resolve, reject) => {
+    // Run git blame
+    exec(`git blame -w ${file}`, async (error, stdout, stderr) => {
+      if (error) {
+        console.error(`Error executing git blame: ${error.message}`);
+        reject(error.message);
+        return;
+      }
+
+      const commitInfos: CommitInfo[] = [];
+      const commitHashes = new Set<string>();
+
+      stdout.split('\n').forEach(line => {
+        if (line.trim() === '') {
+          return;
+        }
+
+        const match = line.match(/^([^\s]+) \(([^)]+)\s+(\d+)\) .*/);
+        if (match) {
+          const commitHash = match[1];
+          const authorInfo = match[2];
+          const lineNumber = parseInt(match[3], 10);
+
+          // Extract the author's name from authorInfo
+          const authorName = authorInfo.split(' ').slice(0, -3).join(' ');
+
+          commitHashes.add(commitHash);
+
+          commitInfos.push({
+            commitHash,
+            author: authorName,
+            lineNumber,
+            commitTitle: '', // Placeholder for commit title
+          });
+        } else {
+          console.warn(`Unexpected format for line: ${line}`);
+        }
+      });
+
+      // Fetch commit titles for the found commit hashes
+      try {
+        const commitTitles = await fetchCommitTitles(Array.from(commitHashes));
+
+        // Assign commit titles to commitInfos
+        commitInfos.forEach(info => {
+          if (commitTitles.has(info.commitHash)) {
+            info.commitTitle = commitTitles.get(info.commitHash) || '';
+          }
+        });
+
+        resolve(commitInfos);
+      } catch (fetchError) {
+        reject(`Error fetching commit titles: ${fetchError}`);
+      }
+    });
+  });
+}
+
+// Function to fetch commit titles from commit hashes using git log
+ function fetchCommitTitles(commitHashes: string[]): Promise<Map<string, string>> {
+  return new Promise<Map<string, string>>((resolve, reject) => {
+    const gitLogCommand = `git log --format="%H %s" ${commitHashes.join(' ')}`;
+
+    exec(gitLogCommand, (error, stdout, stderr) => {
+      if (error) {
+        reject(`Error executing git log: ${error.message}`);
+        return;
+      }
+
+      const commitTitles = new Map<string, string>();
+
+      stdout.split('\n').forEach(line => {
+        if (line.trim() !== '') {
+          const [commitHash, ...titleParts] = line.trim().split(' ');
+          const commitTitle = titleParts.join(' ');
+          commitTitles.set(commitHash, commitTitle);
+        }
+      });
+
+      resolve(commitTitles);
+    });
+  });
+}