import pathlib
import pygit2
import logging
import subprocess
import fnmatch


class Git:
    """Local git repository"""

    def __init__(self, path, committer=None, committer_email=None):
        self.path = pathlib.Path(path)
        self.committer = committer
        self.committer_email = committer_email

        self.repo = None

    def is_open(self):
        return self.repo is not None

    # TODO: Extend it to packages and files
    def exists(self):
        """Check if the path is a valid git repository"""
        return (self.path / ".git").exists()

    def create(self):
        """Create a local git repository"""
        self.path.mkdir(parents=True, exist_ok=True)
        # Convert the path to string, to avoid some limitations in
        # older pygit2
        self.repo = pygit2.init_repository(str(self.path))
        return self

    def is_dirty(self):
        """Check if there is something to commit"""
        assert self.is_open()

        return self.repo.status()

    def branches(self):
        return list(self.repo.branches)

    def branch(self, branch, commit=None):
        if not commit:
            commit = self.repo.head
        else:
            commit = self.repo.get(commit)
        self.repo.branches.local.create(branch, commit)

    def checkout(self, branch):
        """Checkout into the branch HEAD"""
        new_branch = False
        ref = f"refs/heads/{branch}"
        if branch not in self.branches():
            self.repo.references["HEAD"].set_target(ref)
            new_branch = True
        else:
            self.repo.checkout(ref)
        return new_branch

    def commit(
        self,
        user,
        user_email,
        user_time,
        message,
        parents=None,
        committer=None,
        committer_email=None,
        committer_time=None,
        allow_empty=False,
    ):
        """Add all the files and create a new commit in the current HEAD"""
        assert allow_empty or self.is_dirty()

        if not committer:
            committer = self.committer if self.committer else self.user
            committer_email = (
                self.committer_email if self.committer_email else self.user_email
            )
            committer_time = committer_time if committer_time else user_time

        try:
            self.repo.index.add_all()
        except pygit2.GitError as e:
            if not allow_empty:
                raise e

        self.repo.index.write()
        author = pygit2.Signature(user, user_email, int(user_time.timestamp()))
        committer = pygit2.Signature(
            committer, committer_email, int(committer_time.timestamp())
        )
        if not parents:
            try:
                parents = [self.repo.head.target]
            except pygit2.GitError as e:
                parents = []
                if not allow_empty:
                    raise e

        tree = self.repo.index.write_tree()
        return self.repo.create_commit(
            "HEAD", author, committer, message, tree, parents
        )

    def merge(
        self,
        user,
        user_email,
        user_time,
        message,
        commit,
        committer=None,
        committer_email=None,
        committer_time=None,
        clean_on_conflict=True,
        merged=False,
        allow_empty=False,
    ):
        new_branch = False

        if not merged:
            try:
                self.repo.merge(commit)
            except KeyError:
                # If it is the first commit, we will have a missing
                # "HEAD", but the files will be there.  We can proceed
                # to the commit directly.
                new_branch = True

        if not merged and self.repo.index.conflicts:
            for conflict in self.repo.index.conflicts:
                conflict = [c for c in conflict if c]
                if conflict:
                    logging.info(f"CONFLICT {conflict[0].path}")

            if clean_on_conflict:
                self.clean()
            # Now I miss Rust enums
            return "CONFLICT"

        # Some merges are empty in OBS (no changes, not sure
        # why), for now we signal them
        if not allow_empty and not self.is_dirty():
            # I really really do miss Rust enums
            return "EMPTY"

        if new_branch:
            parents = [commit]
        else:
            parents = [
                self.repo.head.target,
                commit,
            ]
        commit = self.commit(
            user,
            user_email,
            user_time,
            message,
            parents,
            committer,
            committer_email,
            committer_time,
            allow_empty=allow_empty,
        )

        return commit

    def merge_abort(self):
        self.repo.state_cleanup()

    def last_commit(self):
        try:
            return self.repo.head.target
        except:
            return None

    def gc(self):
        logging.info(f"Garbage recollec and repackage {self.path}")
        subprocess.run(
            ["git", "gc", "--auto"],
            cwd=self.path,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
        )

    def clean(self):
        for path, _ in self.repo.status().items():
            logging.debug(f"Cleaning {path}")
            try:
                (self.path / path).unlink()
                self.repo.index.remove(path)
            except Exception as e:
                logging.warning(f"Error removing file {path}: {e}")

    def add(self, filename):
        self.repo.index.add(filename)

    def add_default_lfs_gitattributes(self, force=False):
        if not (self.path / ".gitattributes").exists() or force:
            with (self.path / ".gitattributes").open("w") as f:
                content = ["## Default LFS"]
                content += [f"*{b} {LFS_SUFFIX}" for b in sorted(BINARY)]
                f.write("\n".join(content))
                f.write("\n")
            self.add(".gitattributes")

    def add_specific_lfs_gitattributes(self, binaries):
        self.add_default_lfs_gitattributes(force=True)
        if binaries:
            with (self.path / ".gitattributes").open("a") as f:
                content = ["## Specific LFS patterns"]
                content += [f"{b} {LFS_SUFFIX}" for b in sorted(binaries)]
                f.write("\n".join(content))
                f.write("\n")
        self.add(".gitattributes")

    def get_specific_lfs_gitattributes(self):
        with (self.path / ".gitattributes").open() as f:
            patterns = [
                line.split()[0]
                for line in f
                if line.strip() and not line.startswith("#")
            ]
        binary = {f"*{b}" for b in BINARY}
        return [p for p in patterns if p not in binary]

    def add_lfs(self, filename, sha256, size):
        with (self.path / filename).open("w") as f:
            f.write("version https://git-lfs.github.com/spec/v1\n")
            f.write(f"oid sha256:{sha256}\n")
            f.write(f"size {size}\n")
        self.add(filename)

        if not self.is_lfs_tracked(filename):
            logging.debug(f"Add specific LFS file {filename}")
            specific_patterns = self.get_specific_lfs_gitattributes()
            specific_patterns.append(filename)
            self.add_specific_lfs_gitattributes(specific_patterns)

    def is_lfs_tracked(self, filename):
        with (self.path / ".gitattributes").open() as f:
            patterns = (
                line.split()[0]
                for line in f
                if line.strip() and not line.startswith("#")
            )
            return any(fnmatch.fnmatch(filename, line) for line in patterns)

    def remove(self, filename):
        self.repo.index.remove(filename)
        (self.path / filename).unlink()

        patterns = self.get_specific_lfs_gitattributes()
        if filename in patterns:
            patterns.remove(filename)
            self.add_specific_lfs_gitattributes(patterns)