From 49c2f163515d2130c17a6f6a6a16bc27ea69336a Mon Sep 17 00:00:00 2001
From: Sam Atkins <atkinssj@gmail.com>
Date: Fri, 7 Jun 2024 11:24:44 +0100
Subject: [PATCH] feat(git): Add start-revision and file arguments to `git log`

---
 packages/git/src/git-helpers.js     | 31 ++++++++++++++++++++++++++++-
 packages/git/src/subcommands/log.js | 22 ++++++++++++--------
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/packages/git/src/git-helpers.js b/packages/git/src/git-helpers.js
index 6c90817e..6407144b 100644
--- a/packages/git/src/git-helpers.js
+++ b/packages/git/src/git-helpers.js
@@ -17,7 +17,6 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 import path from 'path-browserify';
-import git from 'isomorphic-git';
 
 export const PROXY_URL = 'https://cors.isomorphic-git.org';
 
@@ -110,3 +109,33 @@ export const determine_fetch_remote = (remote_name_or_url, remotes) => {
         throw new Error(`'${remote_name_or_url}' does not appear to be a git repository`);
     return remote_data;
 }
+
+/**
+ * Divide up the positional arguments into those before the `--` separator, and those after it.
+ * @param arg_tokens Tokens array from parseArgs({ tokens: true })
+ * @returns {{before: string[], after: string[]}}
+ */
+export const group_positional_arguments = (arg_tokens) => {
+    let saw_separator = false;
+    const result = {
+        before: [],
+        after: [],
+    };
+
+    for (const token of arg_tokens) {
+        if (token.kind === 'option-terminator') {
+            saw_separator = true;
+            continue;
+        }
+        if (token.kind === 'positional') {
+            if (saw_separator) {
+                result.after.push(token.value);
+            } else {
+                result.before.push(token.value);
+            }
+            continue;
+        }
+    }
+
+    return result;
+}
diff --git a/packages/git/src/subcommands/log.js b/packages/git/src/subcommands/log.js
index 01bc7b02..6f14fa19 100644
--- a/packages/git/src/subcommands/log.js
+++ b/packages/git/src/subcommands/log.js
@@ -17,15 +17,17 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 import git from 'isomorphic-git';
-import { find_repo_root } from '../git-helpers.js';
+import { find_repo_root, group_positional_arguments } from '../git-helpers.js';
 import { commit_formatting_options, format_commit, process_commit_formatting_options } from '../format.js';
+import { SHOW_USAGE } from '../help.js';
 
 export default {
     name: 'log',
-    usage: 'git log [<formatting-option>...] [--max-count <n>] <revision>',
+    usage: 'git log [<formatting-option>...] [--max-count <n>] [<revision>] [[--] <path>]',
     description: 'Show commit logs, starting at the given revision.',
     args: {
-        allowPositionals: false,
+        allowPositionals: true,
+        tokens: true,
         options: {
             ...commit_formatting_options,
             'max-count': {
@@ -38,23 +40,27 @@ export default {
     execute: async (ctx) => {
         const { io, fs, env, args } = ctx;
         const { stdout, stderr } = io;
-        const { options, positionals } = args;
+        const { options, positionals, tokens } = args;
 
         process_commit_formatting_options(options);
 
-        // TODO: Log of a specific file
-        // TODO: Log of a specific branch
-        // TODO: Log of a specific commit
-
         const depth = Number(options['max-count']) || undefined;
 
         const { dir, gitdir } = await find_repo_root(fs, env.PWD);
 
+        const { before: refs, after: paths } = group_positional_arguments(tokens);
+        if (refs.length > 1 || paths.length > 1) {
+            stderr('error: Too many revisions or paths given. Expected [<revision>] [[--] <path>]');
+            throw SHOW_USAGE;
+        }
+
         const log = await git.log({
             fs,
             dir,
             gitdir,
             depth,
+            ref: refs[0],
+            filepath: paths[0],
         });
 
         for (const commit of log) {