Add switch subcommand, no detached head supported

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

Author: initialcommit-io

git_sim/__main__.py

@@ -19,6 +19,7 @@
 import git_sim.stash
 import git_sim.status
 import git_sim.tag
+import git_sim.switch
 from git_sim.settings import ImgFormat, VideoFormat, settings
 from manim import config, WHITE
 
@@ -164,6 +165,7 @@ def main(
 app.command()(git_sim.stash.stash)
 app.command()(git_sim.status.status)
 app.command()(git_sim.tag.tag)
+app.command()(git_sim.switch.switch)
 
 
 if __name__ == "__main__":

git_sim/git_sim_base_command.py

@@ -788,6 +788,26 @@ def reset_head_branch(self, hexsha, shift=numpy.array([0.0, 0.0, 0.0])):
                 )
             )
 
+    def reset_head(self, hexsha, shift=numpy.array([0.0, 0.0, 0.0])):
+        if settings.animate:
+            self.play(
+                self.drawnRefs["HEAD"].animate.move_to(
+                    (
+                        self.drawnCommits[hexsha].get_center()[0] + shift[0],
+                        self.drawnCommits[hexsha].get_center()[1] + 2.0 + shift[1],
+                        0,
+                    )
+                ),
+            )
+        else:
+            self.drawnRefs["HEAD"].move_to(
+                (
+                    self.drawnCommits[hexsha].get_center()[0] + shift[0],
+                    self.drawnCommits[hexsha].get_center()[1] + 2.0 + shift[1],
+                    0,
+                )
+            )
+
     def translate_frame(self, shift):
         if settings.animate:
             self.play(self.camera.frame.animate.shift(shift))

git_sim/switch.py

@@ -0,0 +1,119 @@
+import sys
+from argparse import Namespace
+
+import git
+import manim as m
+import numpy
+import typer
+
+from git_sim.animations import handle_animations
+from git_sim.git_sim_base_command import GitSimBaseCommand
+from git_sim.settings import settings
+
+
+class Switch(GitSimBaseCommand):
+    def __init__(self, branch: str):
+        super().__init__()
+        self.branch = branch
+
+        try:
+            git.repo.fun.rev_parse(self.repo, self.branch)
+        except git.exc.BadName:
+            print(
+                "git-sim error: '"
+                + self.branch
+                + "' is not a valid Git ref or identifier."
+            )
+            sys.exit(1)
+
+        self.ff = False
+        if self.branch in [branch.name for branch in self.repo.heads]:
+            self.selected_branches.append(self.branch)
+
+        try:
+            self.selected_branches.append(self.repo.active_branch.name)
+        except TypeError:
+            pass
+
+    def construct(self):
+        if not settings.stdout:
+            print(
+                f"{settings.INFO_STRING } {type(self).__name__.lower()} {self.branch}"
+            )
+
+        if self.repo.active_branch.name in self.repo.git.branch(
+            "--contains", self.branch
+        ):
+            print(
+                "git-sim error: Branch '"
+                + self.branch
+                + "' is already included in the history of active branch '"
+                + self.repo.active_branch.name
+                + "'."
+            )
+            sys.exit(1)
+
+        self.show_intro()
+        self.get_commits()
+        self.orig_commits = self.commits
+        self.get_commits(start=self.branch)
+
+        if not self.is_remote_tracking_branch(self.branch):
+            if self.branch in self.repo.git.branch(
+                "--contains", self.orig_commits[0].hexsha
+            ):
+                self.ff = True
+        else:
+            if self.branch in self.repo.git.branch(
+                "-r", "--contains", self.orig_commits[0].hexsha
+            ):
+                self.ff = True
+
+        if self.ff:
+            self.get_commits(start=self.branch)
+            self.parse_commits(self.commits[0])
+            reset_head_to = self.commits[0].hexsha
+            shift = numpy.array([0.0, 0.6, 0.0])
+
+            if self.no_ff:
+                self.center_frame_on_commit(self.commits[0])
+                commitId = self.setup_and_draw_parent(self.commits[0], "Merge commit")
+                reset_head_to = "abcdef"
+                shift = numpy.array([0.0, 0.0, 0.0])
+
+            self.recenter_frame()
+            self.scale_frame()
+            if "HEAD" in self.drawnRefs:
+                self.reset_head_branch(reset_head_to, shift=shift)
+            else:
+                self.draw_ref(self.commits[0], commitId if self.no_ff else self.topref)
+                self.draw_ref(
+                    self.commits[0],
+                    self.drawnRefs["HEAD"],
+                    text=self.repo.active_branch.name,
+                    color=m.GREEN,
+                )
+
+        else:
+            self.get_commits()
+            self.parse_commits(self.commits[0])
+            self.i = 0
+            self.get_commits(start=self.branch)
+            self.parse_commits(self.commits[0], shift=4 * m.DOWN)
+            self.center_frame_on_commit(self.orig_commits[0])
+            self.recenter_frame()
+            self.scale_frame()
+            self.reset_head(self.commits[0].hexsha)
+
+        self.fadeout()
+        self.show_outro()
+
+
+def switch(
+    branch: str = typer.Argument(
+        ...,
+        help="The name of the branch to switch to",
+    ),
+):
+    scene = Switch(branch=branch)
+    handle_animations(scene=scene)