#!/usr/bin/env python

# git-tidy is free software: you can redistribute it and/or modify it under the terms of the GNU
# General Public License as published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.

# git-tidy is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
# the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.

# You should have received a copy of the GNU General Public License along with git-tidy. If not, see
# <https://www.gnu.org/licenses/>.

import subprocess
import sys

common_default_branches = [
    "main",
    "master",
    "devel",
    "dev",
]

# Check whether we're actually in a git repo before doing anything else.
# TODO: Rename this function to something more obvious.
def get_status():
    git_status = subprocess.run(
        ["git", "status"],
        capture_output=True,  # we don't want to show the user everything
    )
    if git_status.returncode == 0:
        return True

    print(git_status.stderr.decode())
    return False


def get_default_branch() -> str:
    # Try to see if there's a configuration already.
    sp = subprocess.run(["git", "config", "--get", "tidy.defaultbranch"], capture_output=True)
    if sp.returncode != 0:
        print("No default branch for git-tidy configured, will try to figure out which to use...")
        candidates = []
        branch_list = [
            branch.strip()
            for branch in subprocess.run(["git", "branch", "--list"], capture_output=True).stdout.decode().split("\n")
            if len(branch)
        ]
        # Check whether any branches match our list of common defaults.
        for branch in branch_list:
            # Remove the asterisk in front of the active branch name.
            if branch[0] == "*":
                branch = branch[2:]

            if branch in common_default_branches:
                candidates.append(branch)

        if len(candidates) == 1:
            # Only one branch name matches, so we'll go with that one.
            subprocess.run(["git", "config", "--add", "tidy.defaultbranch", candidates[0]])
            return candidates[0]

        # TODO: Handle the zero case.

        # If we don't have one or zero, which do we have?
        selection = -1
        while (selection < 0) or (selection >= len(candidates)):
            print(
                f"{'Several' if len(candidates) > 1 else 'No'}  potential default branch candidates found. Please select one:"
            )
            for n, candidate in enumerate(candidates):
                print(f"{n}: {candidate}")

            # TODO: This breaks if the user is stupid and doesn't input an int.
            selection = int(input("Which to choose?"))

        return candidates[selection]

    # TODO: Might be nice to have a sanity-check that the configured branch is in fact actually on the list. It may just be easiest to do this by trying to switch to it.
    return sp.stdout.decode()


if __name__ == "__main__":
    if not get_status():
        exit()

    default_branch = get_default_branch()
    print(f"Switching to {default_branch}")
    # Checkout the default branch.
    subprocess.run(["git", "switch", default_branch])

    subprocess.run(["git", "pull"])  # Make sure it's the most up-to-date version.

    # Check which branches are `--merged` and delete them.
    merged_branch_output = subprocess.run(["git", "branch", "--merged"], capture_output=True)
    merged_branches = [
        branch for branch in merged_branch_output.stdout.decode().split("\n") if len(branch)
    ]  # Remove zero-length elements.
    for branch in merged_branches:
        if branch[0] != "*":
            subprocess.run(["git", "branch", "-d", branch.strip()])

    # Clear up dangling references to remote branches which are no longer.
    subprocess.run(["git", "fetch", "--all", "-p"])