branch-from command

bin/dev

@@ -1,13 +1,16 @@
 #!/usr/bin/env python3
 
+import json
 import os
 import re
+import shlex
 import shutil
 import struct
 import subprocess
 import sys
 
 COMMAND_TO_METHOD = {
+    "branch-from": "branch_from",
     "bash-completions": "bash_completions",
 }
 METHOD_TO_COMMAND = {method: command for command, method in COMMAND_TO_METHOD.items()}
@@ -36,6 +39,28 @@ class DevHelper:
         command = f"rm -rf build && cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug"
         self._exec_in_root(command, replace=True)
 
+    ##
+    # Checks out a branch named after a Gitea issue URL.
+    # If the issue is from this project's repo, the branch name will be:
+    #   issue-<issue_number>/<issue_title>
+    # If the issue is from another repo (presumably upstream), the branch name will be:
+    #   <issue_owner>-issue-<issue_number>/<issue_title>
+    def branch_from(self, *args, **kwargs):
+        issue_url = args[0] if args else None
+        if issue_url is None:
+            raise ValueError("Must provide a Gitea issue URL.")
+
+        base_url, issue_repo, issue_number = self._parse_issue_url(issue_url)
+        issue_title = self._fetch_issue_title(base_url, issue_repo, issue_number)
+        branch_name = self._format_branch_name(issue_repo, issue_number, issue_title)
+
+        exists = subprocess.run(
+            ["git", "-C", self._project_root(), "rev-parse", "--verify", "--quiet", f"refs/heads/{branch_name}"],
+            stdout=subprocess.DEVNULL,
+        ).returncode == 0
+        flag = "" if exists else "-b "
+        self._exec_in_root(f"git checkout {flag}{shlex.quote(branch_name)}", replace=True)
+
     def renderdoc(self, *args, **kwargs):
         qrenderdoc = self._find_qrenderdoc()
         self._exec_in_root(qrenderdoc, replace=True)
@@ -84,6 +109,39 @@ class DevHelper:
         print(" ".join(completions))
 
     # Private helpers
+    def _parse_issue_url(self, url):
+        match = re.match(r"^(https?://[^/]+)/([^/]+)/([^/]+)/issues/(\d+)", url)
+        if match is None:
+            raise ValueError(f"Not a Gitea issue URL: {url}")
+        return match[1], f"{match[2]}/{match[3]}", match[4]
+
+    def _fetch_issue_title(self, base_url, repo, issue_number):
+        if shutil.which("tea") is None:
+            raise RuntimeError("tea not found on PATH (install gitea tea and run `tea login add`)")
+
+        endpoint = f"{base_url}/api/v1/repos/{repo}/issues/{issue_number}"
+        print(f"Running: tea api {endpoint}")
+        result = subprocess.run(["tea", "api", endpoint], stdout=subprocess.PIPE, text=True)
+        if result.returncode != 0:
+            raise RuntimeError(f"failed to fetch issue title from {endpoint}")
+        return json.loads(result.stdout)["title"]
+
+    def _format_branch_name(self, issue_repo, issue_number, issue_title):
+        formatted_title = re.sub(r"-+", "-", re.sub(r"[^a-z0-9\-]", "", re.sub(r"\s+", "-", issue_title.lower().strip())))
+        if issue_repo == self._origin_repo():
+            return f"issue-{issue_number}/{formatted_title}"
+        issue_owner = issue_repo.split("/")[0]
+        return f"{issue_owner}-issue-{issue_number}/{formatted_title}"
+
+    def _origin_repo(self):
+        result = subprocess.run(
+            ["git", "-C", self._project_root(), "remote", "get-url", "origin"],
+            stdout=subprocess.PIPE,
+            text=True,
+        )
+        match = re.search(r"[:/]([^/:]+/[^/]+?)(?:\.git)?$", result.stdout.strip())
+        return match[1] if match else None
+
     def _find_glslc(self):
         glslc = shutil.which("glslc")
         if glslc is None: