Add fetch subcommand

Signed-off-by: Jacob Stopak <jacob@initialcommit.io>

Author: initialcommit-io

README.md

@@ -26,7 +26,7 @@ Example: `$ git-sim merge <branch>`
 
 ## Features
 - Run a one-liner git-sim command in the terminal to generate a custom Git command visualization (.jpg) from your repo
-- Supported commands: `log`, `status`, `add`, `restore`, `commit`, `stash`, `branch`, `tag`, `reset`, `revert`, `merge`, `rebase`, `cherry-pick`, `switch`, `checkout`
+- Supported commands: `log`, `status`, `add`, `restore`, `commit`, `stash`, `branch`, `tag`, `reset`, `revert`, `merge`, `rebase`, `cherry-pick`, `switch`, `checkout`, `fetch`
 - Generate an animated video (.mp4) instead of a static image using the `--animate` flag (note: significant performance slowdown, it is recommended to use `--low-quality` to speed up testing and remove when ready to generate presentation-quality video)
 - Color commits by parameter, such as author the `--color-by=author` option
 - Choose between dark mode (default) and light mode
@@ -126,7 +126,7 @@ $ git-sim <subcommand> -h
 * [Manim (Community version)](https://www.manim.community/)
 
 ## Commands
-Basic usage is similar to Git itself - `git-sim` takes a familiar set of subcommands including "log", "status", "add", "restore", "commit", "stash", "branch", "tag", "reset", "revert", "merge", "rebase", "cherry-pick", "switch", "checkout", along with corresponding options.
+Basic usage is similar to Git itself - `git-sim` takes a familiar set of subcommands including "log", "status", "add", "restore", "commit", "stash", "branch", "tag", "reset", "revert", "merge", "rebase", "cherry-pick", "switch", "checkout", "fetch", along with corresponding options.
 
 ```console
 $ git-sim [global options] <subcommand> [subcommand options]
@@ -292,6 +292,11 @@ Usage: `git-sim checkout [-b] <branch>`
 - Checks out `<branch>` into the working directory, i.e. moves `HEAD` to the specified `<branch>`
 - The `-b` flag creates a new branch with the specified name `<branch>` and checks it out, assuming it doesn't already exist
 
+### git fetch
+Usage: `git-sim fetch <remote> <branch>`
+
+- Fetches the specified `<branch>` from the specified `<remote>` to the local repo
+
 ## Video animation examples
 ```console
 $ git-sim --animate reset HEAD^

git_sim/__main__.py

@@ -21,6 +21,8 @@
 import git_sim.tag
 import git_sim.switch
 import git_sim.checkout
+import git_sim.fetch
+
 from git_sim.settings import ImgFormat, VideoFormat, settings
 from manim import config, WHITE
 
@@ -206,6 +208,7 @@ def main(
 app.command()(git_sim.tag.tag)
 app.command()(git_sim.switch.switch)
 app.command()(git_sim.checkout.checkout)
+app.command()(git_sim.fetch.fetch)
 
 
 if __name__ == "__main__":

git_sim/fetch.py

@@ -0,0 +1,94 @@
+import sys
+import os
+from argparse import Namespace
+
+import git
+import manim as m
+import numpy
+import typer
+import tempfile
+import shutil
+import stat
+
+from git_sim.animations import handle_animations
+from git_sim.git_sim_base_command import GitSimBaseCommand
+from git_sim.settings import settings
+
+
+class Fetch(GitSimBaseCommand):
+    def __init__(self, remote: str, branch: str):
+        super().__init__()
+        self.remote = remote
+        self.branch = branch
+        settings.max_branches_per_commit = 2
+
+        if self.remote not in self.repo.remotes:
+            print("git-sim error: no remote with name '" + self.remote + "'")
+            sys.exit(1)
+
+    def construct(self):
+        if not settings.stdout and not settings.output_only_path and not settings.quiet:
+            print(
+                f"{settings.INFO_STRING } {type(self).__name__.lower()} {self.remote} {self.branch}"
+            )
+
+        self.show_intro()
+
+        git_root = self.repo.git.rev_parse("--show-toplevel")
+        repo_name = os.path.basename(self.repo.working_dir)
+        new_dir = os.path.join(tempfile.gettempdir(), "git_sim", repo_name)
+
+        orig_remotes = self.repo.remotes
+        self.repo = git.Repo.clone_from(git_root, new_dir, no_hardlinks=True)
+        for r1 in orig_remotes:
+            for r2 in self.repo.remotes:
+                if r1.name == r2.name:
+                    r2.set_url(r1.url)
+        self.repo.git.fetch(self.remote, self.branch)
+
+        # local branch doesn't exist
+        if self.branch not in self.repo.heads:
+            start_parse_from_remote = True
+        # fetched branch is ahead of local branch
+        elif (self.remote + "/" + self.branch) in self.repo.git.branch(
+            "-r", "--contains", self.branch
+        ):
+            start_parse_from_remote = True
+        # fetched branch is behind local branch
+        elif self.branch in self.repo.git.branch(
+            "--contains", (self.remote + "/" + self.branch)
+        ):
+            start_parse_from_remote = False
+        else:
+            start_parse_from_remote = True
+
+        if start_parse_from_remote:
+            commit = self.get_commit(self.remote + "/" + self.branch)
+        else:
+            commit = self.get_commit(self.branch)
+        self.parse_commits(commit)
+
+        self.recenter_frame()
+        self.scale_frame()
+        self.color_by()
+        self.fadeout()
+        self.show_outro()
+        self.repo.git.clear_cache()
+        shutil.rmtree(new_dir, onerror=del_rw)
+
+def del_rw(action, name, exc):
+    os.chmod(name, stat.S_IWRITE)
+    os.remove(name)
+
+def fetch(
+    remote: str = typer.Argument(
+        ...,
+        help="The name of the remote to fetch from",
+    ),
+    branch: str = typer.Argument(
+        ...,
+        help="The name of the branch to fetch",
+    ),
+):
+    scene = Fetch(remote=remote, branch=branch)
+    handle_animations(scene=scene)