import os
import shutil
import subprocess
from distutils.dir_util import copy_tree
from shutil import copyfile
from typing import List, Optional

from hydra.utils import instantiate
import click
import git
from omegaconf import DictConfig

#----------------------------------------------------------------------------

def copy_objects(target_dir: os.PathLike, objects_to_copy: List[os.PathLike]):
    for src_path in objects_to_copy:
        trg_path = os.path.join(target_dir, os.path.basename(src_path))

        if os.path.islink(src_path):
            os.symlink(os.readlink(src_path), trg_path)
        elif os.path.isfile(src_path):
            copyfile(src_path, trg_path)
        elif os.path.isdir(src_path):
            copy_tree(src_path, trg_path)
        else:
            raise NotImplementedError(f"Unknown object type: {src_path}")

#----------------------------------------------------------------------------

def create_symlinks(target_dir: os.PathLike, symlinks_to_create: List[os.PathLike]):
    """
    Creates symlinks to the given paths
    """
    for src_path in symlinks_to_create:
        trg_path = os.path.join(target_dir, os.path.basename(src_path))

        if os.path.islink(src_path):
            # Let's not create symlinks to symlinks
            # Since dropping the current symlink will break the experiment
            os.symlink(os.readlink(src_path), trg_path)
        else:
            print(f'Creating a symlink to {src_path}, so try not to delete it occasionally!')
            os.symlink(src_path, trg_path)

#----------------------------------------------------------------------------

def is_git_repo(path: os.PathLike):
    try:
        _ = git.Repo(path).git_dir
        return True
    except git.exc.InvalidGitRepositoryError:
        return False

#----------------------------------------------------------------------------

def create_project_dir(
    project_dir: os.PathLike,
    objects_to_copy: List[os.PathLike],
    symlinks_to_create: List[os.PathLike],
    quiet: bool=False,
    ignore_uncommited_changes: bool=False,
    overwrite: bool=False):

    if is_git_repo(os.getcwd()) and are_there_uncommitted_changes():
        if ignore_uncommited_changes or click.confirm("There are uncommited changes. Continue?", default=False):
            pass
        else:
            raise PermissionError("Cannot created a dir when there are uncommited changes")

    if os.path.exists(project_dir):
        if overwrite or click.confirm(f'Dir {project_dir} already exists. Overwrite it?', default=False):
            shutil.rmtree(project_dir)
        else:
            print('User refused to delete an existing project dir.')
            raise PermissionError("There is an existing dir and I cannot delete it.")

    os.makedirs(project_dir)
    copy_objects(project_dir, objects_to_copy)
    create_symlinks(project_dir, symlinks_to_create)

    if not quiet:
        print(f'Created a project dir: {project_dir}')

#----------------------------------------------------------------------------

def get_git_hash() -> Optional[str]:
    if not is_git_repo(os.getcwd()):
        return None

    try:
        return subprocess \
            .check_output(['git', 'rev-parse', '--short', 'HEAD']) \
            .decode("utf-8") \
            .strip()
    except:
        return None

#----------------------------------------------------------------------------

# def get_experiment_path(master_dir: os.PathLike, experiment_name: str) -> os.PathLike:
#     return os.path.join(master_dir, f"{experiment_name}-{get_git_hash()}")

#----------------------------------------------------------------------------

def get_git_hash_suffix() -> str:
    git_hash: Optional[str] = get_git_hash()
    git_hash_suffix = "-nogit" if git_hash is None else f"-{git_hash}"

    return git_hash_suffix

#----------------------------------------------------------------------------

def are_there_uncommitted_changes() -> bool:
    return len(subprocess.check_output('git status -s'.split()).decode("utf-8")) > 0

#----------------------------------------------------------------------------

def cfg_to_args_str(cfg: DictConfig, use_dashes=True) -> str:
    dashes = '--' if use_dashes else ''

    return ' '.join([f'{dashes}{p}={cfg[p]}' for p in cfg])

#----------------------------------------------------------------------------

def recursive_instantiate(cfg: DictConfig):
    for key in cfg:
        # print(type(cfg[key]))
        if isinstance(cfg[key], DictConfig):
            if '_target_' in cfg[key]:
                cfg[key] = instantiate(cfg[key])
            else:
                recursive_instantiate(cfg[key])

#----------------------------------------------------------------------------

def num_gpus_to_mem(num_gpus: int, mem_per_gpu: 64) -> str:
    # Doing it here since hydra config cannot do formatting for ${...}
    return f"{num_gpus * mem_per_gpu}G"

#----------------------------------------------------------------------------