Fix position mapping for creating comment on file with local changes

Author: Rachel Macfarlane

src/common/diffPositionMapping.ts

@@ -102,19 +102,16 @@ export function getDiffLineByPosition(diffHunks: DiffHunk[], diffLineNumber: num
 }
 
 export function mapHeadLineToDiffHunkPosition(diffHunks: DiffHunk[], localDiff: string, line: number, isBase: boolean = false): number {
-	let delta = 0;
-
 	let localDiffReader = parseDiffHunk(localDiff);
 	let localDiffIter = localDiffReader.next();
 	let lineInPRDiff = line;
 
 	while (!localDiffIter.done) {
 		let diffHunk = localDiffIter.value;
-		if (diffHunk.newLineNumber + diffHunk.newLength - 1 < line) {
-			delta += diffHunk.oldLength - diffHunk.newLength;
-		} else {
-			lineInPRDiff = line + delta;
+		if (diffHunk.oldLineNumber > line) {
 			break;
+		} else {
+			lineInPRDiff += diffHunk.oldLength - diffHunk.newLength;
 		}
 
 		localDiffIter = localDiffReader.next();

src/common/repository.ts

@@ -413,6 +413,24 @@ export class Repository {
 
 		return result.exitCode === 0;
 	}
+
+
+	/**
+	 * Returns the diff between the document's current content and the document's content at lastCommitSha.
+	 */
+	async getFileContentDiff(document: vscode.TextDocument, fileName: string, lastCommitSha: string): Promise<string> {
+		if (document.isDirty) {
+			const documentText = document.getText();
+			const idAtLastCommit = await this.getFileObjectId(lastCommitSha, fileName);
+			const idOfCurrentText = await this.hashObject(documentText);
+
+			// git diff <blobid> <blobid>
+			return await this.diffHashed(idAtLastCommit, idOfCurrentText);
+		} else {
+			// git diff sha -- fileName
+			return await this.diff(fileName, lastCommitSha);
+		}
+	}
 }
 
 function parseRemote(remoteName: string, url: string): Remote | null {

src/view/reviewManager.ts

@@ -269,7 +269,7 @@ export class ReviewManager implements vscode.DecorationProvider {
 			const isBase = query && query.base;
 
 			// git diff sha -- fileName
-			const contentDiff = await this._repository.diff(matchedFile.fileName, this._lastCommitSha);
+			const contentDiff = await this._repository.getFileContentDiff(document, matchedFile.fileName, this._lastCommitSha);
 			const position = mapHeadLineToDiffHunkPosition(matchedFile.diffHunks, contentDiff, range.start.line + 1, isBase);
 
 			if (position < 0) {
@@ -647,18 +647,7 @@ export class ReviewManager implements vscode.DecorationProvider {
 					if (matchedFiles && matchedFiles.length) {
 						matchedFile = matchedFiles[0];
 
-						let contentDiff: string;
-						if (document.isDirty) {
-							const documentText = document.getText();
-							const idAtLastCommit = await this._repository.getFileObjectId(this._lastCommitSha, matchedFile.fileName);
-							const idOfCurrentText = await this._repository.hashObject(documentText);
-
-							// git diff <blobid> <blobid>
-							contentDiff = await this._repository.diffHashed(idAtLastCommit, idOfCurrentText);
-						} else {
-							// git diff sha -- fileName
-							contentDiff = await this._repository.diff(matchedFile.fileName, this._lastCommitSha);
-						}
+						const contentDiff = await this._repository.getFileContentDiff(document, matchedFile.fileName, this._lastCommitSha);
 
 						matchingComments = this._comments.filter(comment => path.resolve(this._repository.path, comment.path) === fileName);
 						matchingComments = mapCommentsToHead(matchedFile.diffHunks, contentDiff, matchingComments);