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773from __future__ import annotations
import argparse
import hashlib
import json
from pathlib import Path
import sys
import time
from typing import Dict, List, Optional, Tuple
import zlib
class GitObject:
def __init__(self, obj_type: str, content: bytes):
self.type = obj_type
self.content = content
def hash(self) -> str:
# f(<type> <size>\0<content>)
header = f"{self.type} {len(self.content)}\0".encode()
return hashlib.sha1(header + self.content).hexdigest()
def serialize(self) -> bytes:
header = f"{self.type} {len(self.content)}\0".encode()
return zlib.compress(header + self.content)
@classmethod
def deserialize(cls, data: bytes) -> GitObject:
decompressed = zlib.decompress(data)
null_idx = decompressed.find(b"\0")
header = decompressed[:null_idx].decode()
content = decompressed[null_idx + 1 :]
obj_type, _ = header.split(" ")
return cls(obj_type, content)
class Blob(GitObject):
def __init__(self, content: bytes):
super().__init__("blob", content)
class Tree(GitObject):
def __init__(self, entries: List[Tuple[str, str, str]] = None):
self.entries = entries or []
content = self._serialize_entries()
super().__init__("tree", content)
def _serialize_entries(self) -> bytes:
# 100644 <name>\0<hash><mode> <name>\0<hash><mode> <name>\0<hash><mode> <name>\0<hash>
content = b""
for mode, name, obj_hash in sorted(self.entries):
content += f"{mode} {name}\0".encode()
content += bytes.fromhex(obj_hash)
return content
def add_entry(self, mode: str, name: str, obj_hash: str):
self.entries.append((mode, name, obj_hash))
self.content = self._serialize_entries()
@classmethod
def from_content(cls, content: bytes) -> Tree:
tree = cls()
i = 0
while i < len(content):
null_idx = content.find(b"\0", i)
if null_idx == -1:
break
mode_name = content[i:null_idx].decode()
mode, name = mode_name.split(" ", 1)
obj_hash = content[null_idx + 1 : null_idx + 21].hex()
tree.entries.append((mode, name, obj_hash))
i = null_idx + 21
return tree
class Commit(GitObject):
def __init__(
self,
tree_hash: str,
parent_hashes: List[str],
author: str,
committer: str,
message: str,
timestamp: int = None,
):
self.tree_hash = tree_hash
self.parent_hashes = parent_hashes
self.author = author
self.committer = committer
self.message = message
self.timestamp = timestamp or int(time.time())
content = self._serialize_commit()
super().__init__("commit", content)
def _serialize_commit(self):
lines = [f"tree {self.tree_hash}"]
for parent in self.parent_hashes:
lines.append(f"parent {parent}")
lines.append(f"author {self.author} {self.timestamp} +0000")
lines.append(f"committer {self.committer} {self.timestamp} +0000")
lines.append("")
lines.append(self.message)
return "\n".join(lines).encode()
@classmethod
def from_content(cls, content: bytes) -> Commit:
lines = content.decode().split("\n")
tree_hash = None
parent_hashes = []
author = None
committer = None
message_start = 0
for i, line in enumerate(lines):
if line.startswith("tree "):
tree_hash = line[5:]
elif line.startswith("parent "):
parent_hashes.append(line[7:])
elif line.startswith("author "):
author_parts = line[7:].rsplit(" ", 2)
author = author_parts[0]
timestamp = int(author_parts[1])
elif line.startswith("committer "):
committer_parts = line[10:].rsplit(" ", 2)
committer = committer_parts[0]
elif line == "":
message_start = i + 1
break
message = "\n".join(lines[message_start:])
commit = cls(tree_hash, parent_hashes, author, committer, message, timestamp)
return commit
class Repository:
def __init__(self, path="."):
self.path = Path(path).resolve()
self.git_dir = self.path / ".git"
# .git/objects
self.objects_dir = self.git_dir / "objects"
# .git/refs
self.ref_dir = self.git_dir / "refs"
self.heads_dir = self.ref_dir / "heads"
# HEAD file
self.head_file = self.git_dir / "HEAD"
# .git/index
self.index_file = self.git_dir / "index"
def init(self) -> bool:
if self.git_dir.exists():
return False
# create directories
self.git_dir.mkdir()
self.objects_dir.mkdir()
self.ref_dir.mkdir()
self.heads_dir.mkdir()
# create initial HEAD pointing to a branch
self.head_file.write_text("ref: refs/heads/master\n")
self.save_index({})
print(f"Initialized empty Git repository in {self.git_dir}")
return True
def store_object(self, obj: GitObject) -> str:
obj_hash = obj.hash()
obj_dir = self.objects_dir / obj_hash[:2]
obj_file = obj_dir / obj_hash[2:]
if not obj_file.exists():
obj_dir.mkdir(exist_ok=True)
obj_file.write_bytes(obj.serialize())
return obj_hash
def load_index(self) -> Dict[str, str]:
if not self.index_file.exists():
return {}
try:
return json.loads(self.index_file.read_text())
except:
return {}
def save_index(self, index: Dict[str, str]):
self.index_file.write_text(json.dumps(index, indent=2))
def add_file(self, path: str):
full_path = self.path / path
if not full_path.exists():
raise FileNotFoundError(f"Path {path} not found")
# Read the file content
content = full_path.read_bytes()
# Create BLOB object from the content
blob = Blob(content)
# store the blob object in database (.git/objects)
blob_hash = self.store_object(blob)
# Update index to include the file
index = self.load_index()
index[path] = blob_hash
self.save_index(index)
print(f"Added {path}")
def add_directory(self, path: str):
full_path = self.path / path
if not full_path.exists():
raise FileNotFoundError(f"Directory {path} not found")
if not full_path.is_dir():
raise ValueError(f"{path} is not a directory")
index = self.load_index()
added_count = 0
# recursively traverse the directory
for file_path in full_path.rglob("*"):
if file_path.is_file():
if ".git" in file_path.parts:
continue
# create & store blob object
content = file_path.read_bytes()
blob = Blob(content)
blob_hash = self.store_object(blob)
# update index
rel_path = str(file_path.relative_to(self.path))
index[rel_path] = blob_hash
added_count += 1
self.save_index(index)
if added_count > 0:
print(f"Added {added_count} files from directory {path}")
else:
print(f"Directory {path} already up to date")
def add_path(self, path: str) -> None:
full_path = self.path / path
if not full_path.exists():
raise FileNotFoundError(f"Path {path} not found")
if full_path.is_file():
self.add_file(path)
elif full_path.is_dir():
self.add_directory(path)
else:
raise ValueError(f"{path} is neither a file nor a directory")
def load_object(self, obj_hash: str) -> GitObject:
obj_dir = self.objects_dir / obj_hash[:2]
obj_file = obj_dir / obj_hash[2:]
if not obj_file.exists():
raise FileNotFoundError(f"Object {obj_hash} not found")
return GitObject.deserialize(obj_file.read_bytes())
def create_tree_from_index(self):
index = self.load_index()
if not index:
tree = Tree()
return self.store_object(tree)
dirs = {}
files = {}
for file_path, blob_hash in index.items():
parts = file_path.split("/")
if len(parts) == 1:
# file in root
files[parts[0]] = blob_hash
else:
dir_name = parts[0]
if dir_name not in dirs:
dirs[dir_name] = {}
current = dirs[dir_name]
for part in parts[1:-1]:
if part not in current:
current[part] = {}
current = current[part]
current[parts[-1]] = blob_hash
def create_tree_recursive(entries_dict: Dict):
tree = Tree()
for name, blob_hash in entries_dict.items():
if isinstance(blob_hash, str):
tree.add_entry("100644", name, blob_hash)
if isinstance(blob_hash, dict):
subtree_hash = create_tree_recursive(blob_hash)
tree.add_entry("40000", name, subtree_hash)
return self.store_object(tree)
root_entries = {**files}
for dir_name, dir_contents in dirs.items():
root_entries[dir_name] = dir_contents
return create_tree_recursive(root_entries)
def get_current_branch(self) -> str:
if not self.head_file.exists():
return "master"
head_content = self.head_file.read_text().strip()
if head_content.startswith("ref: refs/heads/"):
return head_content[16:]
return "HEAD" # detached HEAD
def get_branch_commit(self, current_branch: str):
branch_file = self.heads_dir / current_branch
if branch_file.exists():
return branch_file.read_text().strip()
return None
def set_branch_commit(self, current_branch: str, commit_hash: str):
branch_file = self.heads_dir / current_branch
branch_file.write_text(commit_hash + "\n")
def commit(
self,
message: str,
author: str = "PyGit User <user@pygit.com>",
):
# create a tree object from the index (staging area)
tree_hash = self.create_tree_from_index()
current_branch = self.get_current_branch()
parent_commit = self.get_branch_commit(current_branch)
parent_hashes = [parent_commit] if parent_commit else []
index = self.load_index()
if not index:
print("nothing to commit, working tree clean")
return None
if parent_commit:
parent_git_commit_obj = self.load_object(parent_commit)
parent_commit_data = Commit.from_content(parent_git_commit_obj.content)
if tree_hash == parent_commit_data.tree_hash:
print("nothing to commit, working tree clean")
return None
commit = Commit(
tree_hash=tree_hash,
parent_hashes=parent_hashes,
author=author,
committer=author,
message=message,
)
commit_hash = self.store_object(commit)
self.set_branch_commit(current_branch, commit_hash)
self.save_index({})
print(f"Created commit {commit_hash} on branch {current_branch}")
return commit_hash
def get_files_from_tree_recursive(
self,
tree_hash: str,
prefix: str = "",
):
files = set()
try:
tree_obj = self.load_object(tree_hash)
tree = Tree.from_content(tree_obj.content)
# list<tuple<str, str, str>>
for mode, name, obj_hash in tree.entries:
full_name = f"{prefix}{name}"
if mode.startswith("100"):
files.add(full_name)
elif mode.startswith("400"):
subtree_files = self.get_files_from_tree_recursive(
obj_hash, f"{full_name}/"
)
files.update(subtree_files)
except Exception as e:
print(f"Warning: Could not read tree {tree_hash}: {e}")
return files
def checkout(self, branch: str, create_branch: bool):
# computed the files to clear from the previous branch
previous_branch = self.get_current_branch()
files_to_clear = set()
try:
previous_commit_hash = self.get_branch_commit(previous_branch)
if previous_commit_hash:
prev_commit_object = self.load_object(previous_commit_hash)
prev_commit = Commit.from_content(prev_commit_object.content)
if prev_commit.tree_hash:
files_to_clear = self.get_files_from_tree_recursive(
prev_commit.tree_hash
)
except Exception:
files_to_clear = set()
# created/moved to a new branch
branch_file = self.heads_dir / branch
if not branch_file.exists():
if create_branch:
if previous_commit_hash:
self.set_branch_commit(branch, previous_commit_hash)
print(f"Created new branch {branch}")
else:
print("No commits yet, cannot create a branch")
return
else:
print(f"Branch '{branch}' not found.")
print(
"Use 'python3 main.py checkout -b {branch}' to create and switch to a new branch."
)
return
self.head_file.write_text(f"ref: refs/heads/{branch}\n")
# restore working directory
self.restore_working_directory(branch, files_to_clear)
print(f"Switched to branch {branch}")
def restore_tree(self, tree_hash: str, path: Path):
tree_obj = self.load_object(tree_hash)
tree = Tree.from_content(tree_obj.content)
for mode, name, obj_hash in tree.entries:
file_path = path / name
if mode.startswith("100"):
blob_obj = self.load_object(obj_hash)
blob = Blob(blob_obj.content)
file_path.write_bytes(blob.content)
elif mode.startswith("400"):
file_path.mkdir(exist_ok=True)
self.restore_tree(obj_hash, file_path)
def restore_working_directory(
self,
branch: str,
files_to_clear: set[str],
):
target_commit_hash = self.get_branch_commit(branch)
if not target_commit_hash:
return
# remove files tracked by previous branch
for rel_path in sorted(files_to_clear):
file_path = self.path / rel_path
try:
if file_path.is_file():
file_path.unlink()
# Uncomment if you want this functionality (removing empty directories)
# elif file_path.is_dir():
# if not any(file_path.iterdir()):
# file_path.rmdir()
except Exception:
pass
target_commit_obj = self.load_object(target_commit_hash)
target_commit = Commit.from_content(target_commit_obj.content)
if target_commit.tree_hash:
self.restore_tree(target_commit.tree_hash, self.path)
self.save_index({})
def branch(self, branch_name: str, delete: bool = False):
# delete
if delete and branch_name:
branch_file = self.heads_dir / branch_name
if branch_file.exists():
branch_file.unlink()
print(f"Deleted branch {branch_name}")
else:
print(f"Branch {branch_name} not found")
return
current_branch = self.get_current_branch()
if branch_name:
current_commit = self.get_branch_commit(current_branch)
if current_commit:
self.set_branch_commit(branch_name, current_commit)
print(f"Created branch {branch_name}")
else:
print(f"No commits yet, cannot create a new branch")
else:
branches = []
for branch_file in self.heads_dir.iterdir():
if branch_file.is_file() and not branch_file.name.startswith("."):
branches.append(branch_file.name)
for branch in sorted(branches):
current_marker = "* " if branch == current_branch else " "
print(f"{current_marker}{branch}")
def log(self, max_count: int = 10):
current_branch = self.get_current_branch()
commit_hash = self.get_branch_commit(current_branch)
if not commit_hash:
print("No commits yet!")
return
count = 0
while commit_hash and count < max_count:
commit_obj = self.load_object(commit_hash)
commit = Commit.from_content(commit_obj.content)
print(f"commit {commit_hash}")
print(f"Author: {commit.author}")
print(f"Date: {time.ctime(commit.timestamp)}")
print(f"\n {commit.message}\n")
commit_hash = commit.parent_hashes[0] if commit.parent_hashes else None
count += 1
def build_index_from_tree(self, tree_hash: str, prefix: str = ""):
index = {}
try:
tree_obj = self.load_object(tree_hash)
tree = Tree.from_content(tree_obj.content)
# list<tuple<str, str, str>>
for mode, name, obj_hash in tree.entries:
full_name = f"{prefix}{name}"
if mode.startswith("100"):
index[full_name] = obj_hash
elif mode.startswith("400"):
subindex = self.build_index_from_tree(obj_hash, f"{full_name}/")
index.update(subindex)
except Exception as e:
print(f"Warning: Could not read tree {tree_hash}: {e}")
return index
def get_all_files(self) -> List[Path]:
files = []
for item in self.path.rglob("*"):
if ".git" in item.parts:
continue
if item.is_file():
files.append(item)
return files
def status(self):
# what branch we are on
current_branch = self.get_current_branch()
print(f"On branch {current_branch}")
index = self.load_index()
current_commit_hash = self.get_branch_commit(current_branch)
# build the index of the latest commit
last_index_files = {}
if current_commit_hash:
try:
commit_obj = self.load_object(current_commit_hash)
commit = Commit.from_content(commit_obj.content)
if commit.tree_hash:
last_index_files = self.build_index_from_tree(commit.tree_hash)
except:
last_index_files = {}
# figure out all the files present within the working directory
working_files = {} # file name -> hash
for item in self.get_all_files():
rel_path = str(item.relative_to(self.path))
try:
content = item.read_bytes()
blob = Blob(content)
working_files[rel_path] = blob.hash()
except:
continue
staged_files = []
unstaged_files = []
untracked_files = []
deleted_files = []
# what files are staged for commit
for file_path in set(index.keys()) | set(last_index_files.keys()):
index_hash = index.get(file_path)
last_index_hash = last_index_files.get(file_path)
if index_hash and not last_index_hash:
staged_files.append(("new file", file_path))
elif index_hash and last_index_hash and index_hash != last_index_hash:
staged_files.append(("modified", file_path))
if staged_files:
print("\nChanges to be committed:")
for stage_status, file_path in sorted(staged_files):
print(f" {stage_status}: {file_path}")
# what files have modified but not staged
for file_path in working_files:
if file_path in index:
if working_files[file_path] != index[file_path]:
unstaged_files.append(file_path)
if unstaged_files:
print("\nChanges not staged for commit:")
for file_path in sorted(unstaged_files):
print(f" modified: {file_path}")
# what files are untracked
for file_path in working_files:
if file_path not in index and file_path not in last_index_files:
untracked_files.append(file_path)
if untracked_files:
print("\nUntracked files:")
for file_path in sorted(untracked_files):
print(f" {file_path}")
# what files have been deleted
for file_path in index:
if file_path not in working_files:
deleted_files.append(file_path)
if deleted_files:
print("\nDeleted files:")
for file_path in sorted(deleted_files):
print(f" deleted: {file_path}")
if (
not staged_files
and not unstaged_files
and not deleted_files
and not untracked_files
):
print("\nnothing to commit, working tree clean")
def main():
parser = argparse.ArgumentParser(description="PyGit - A simple git clone!")
subparsers = parser.add_subparsers(dest="command", help="Available commands")
# init command
init_parser = subparsers.add_parser("init", help="Initialize a new repository")
# add command
add_parser = subparsers.add_parser(
"add", help="Add files and directories to the staging area"
)
add_parser.add_argument("paths", nargs="+", help="Files and directories to add")
# commit command
commit_parser = subparsers.add_parser("commit", help="Create a new commit")
commit_parser.add_argument(
"-m",
"--message",
help="Commit message",
required=True,
)
commit_parser.add_argument(
"--author",
help="Author name and email",
)
# checkout command
checkout_parser = subparsers.add_parser("checkout", help="Move/Create a new branch")
checkout_parser.add_argument("branch", help="Branch to switch to")
checkout_parser.add_argument(
"-b",
"--create-branch",
action="store_true",
help="Create and switch to a new branch",
)
# branch command
branch_parser = subparsers.add_parser("branch", help="List or manage branches")
branch_parser.add_argument("name", nargs="?")
branch_parser.add_argument(
"-d",
"--delete",
action="store_true",
help="Delete the branch",
)
# log command
log_parser = subparsers.add_parser("log", help="Show commit history")
log_parser.add_argument(
"-n",
"--max-count",
type=int,
default=10,
help="Limit commits shown",
)
# status command
status_parser = subparsers.add_parser("status", help="Show repository status")
args = parser.parse_args()
if not args.command:
parser.print_help()
return
repo = Repository()
try:
if args.command == "init":
if not repo.init():
print("Repository already exists")
return
elif args.command == "add":
if not repo.git_dir.exists():
print("Not a git repository")
return
for path in args.paths:
repo.add_path(path)
elif args.command == "commit":
if not repo.git_dir.exists():
print("Not a git repository")
return
author = args.author or "PyGit user <user@pygit.com>"
repo.commit(args.message, author)
elif args.command == "checkout":
if not repo.git_dir.exists():
print("Not a git repository")
return
repo.checkout(args.branch, args.create_branch)
elif args.command == "branch":
if not repo.git_dir.exists():
print("Not a git repository")
return
repo.branch(args.name, args.delete)
elif args.command == "log":
if not repo.git_dir.exists():
print("Not a git repository")
return
repo.log(args.max_count)
elif args.command == "status":
if not repo.git_dir.exists():
print("Not a git repository")
return
repo.status()
except Exception as e:
print(f"Error: {e}")
sys.exit(1)
main()