import os
import re
import logging

log = logging.getLogger(__name__)


def get_paths_from_environ(env_key, return_first=False):
    """Return existing paths from specific envirnment variable.

    Args:
        env_key (str): Environment key where should look for paths.

    Returns:
        (bool): Return first path on `True`, list of all on `False`.


    Difference when none of paths exists:
    - when `return_first` is set to `False` then function returns empty list.
    - when `return_first` is set to `True` then function returns `None`.
    """
    existing_paths = []
    paths = os.environ.get(env_key) or ""
    path_items = paths.split(os.pathsep)
    for path in path_items:
        # Skip empty string
        if not path:
            continue
        # Normalize path
        path = os.path.normpath(path)
        # Check if path exists
        if os.path.exists(path):
            # Return path if `return_first` is set to True
            if return_first:
                return path
            # Store path
            existing_paths.append(path)

    # Return None if none of paths exists
    if return_first:
        return None
    # Return all existing paths from environment variable
    return existing_paths


def get_ffmpeg_tool_path(tool="ffmpeg"):
    """Find path to ffmpeg tool in FFMPEG_PATH paths.

    Function looks for tool in paths set in FFMPEG_PATH environment. If tool
    exists then returns it's full path.

    Args:
        tool (string): tool name

    Returns:
        (str): tool name itself when tool path was not found. (FFmpeg path
        may be set in PATH environment variable)
    """
    dir_paths = get_paths_from_environ("FFMPEG_PATH")
    for dir_path in dir_paths:
        for file_name in os.listdir(dir_path):
            base, _ext = os.path.splitext(file_name)
            if base.lower() == tool.lower():
                return os.path.join(dir_path, tool)
    return tool


def _rreplace(s, a, b, n=1):
    """Replace a with b in string s from right side n times."""
    return b.join(s.rsplit(a, n))


def version_up(filepath):
    """Version up filepath to a new non-existing version.

    Parses for a version identifier like `_v001` or `.v001`
    When no version present _v001 is appended as suffix.

    Args:
        filepath (str): full url

    Returns:
        (str): filepath with increased version number

    """
    dirname = os.path.dirname(filepath)
    basename, ext = os.path.splitext(os.path.basename(filepath))

    regex = r"[._]v\d+"
    matches = re.findall(regex, str(basename), re.IGNORECASE)
    if not matches:
        log.info("Creating version...")
        new_label = "_v{version:03d}".format(version=1)
        new_basename = "{}{}".format(basename, new_label)
    else:
        label = matches[-1]
        version = re.search(r"\d+", label).group()
        padding = len(version)

        new_version = int(version) + 1
        new_version = '{version:0{padding}d}'.format(version=new_version,
                                                     padding=padding)
        new_label = label.replace(version, new_version, 1)
        new_basename = _rreplace(basename, label, new_label)

    if not new_basename.endswith(new_label):
        index = (new_basename.find(new_label))
        index += len(new_label)
        new_basename = new_basename[:index]

    new_filename = "{}{}".format(new_basename, ext)
    new_filename = os.path.join(dirname, new_filename)
    new_filename = os.path.normpath(new_filename)

    if new_filename == filepath:
        raise RuntimeError("Created path is the same as current file,"
                           "this is a bug")

    for file in os.listdir(dirname):
        if file.endswith(ext) and file.startswith(new_basename):
            log.info("Skipping existing version %s" % new_label)
            return version_up(new_filename)

    log.info("New version %s" % new_label)
    return new_filename


def get_version_from_path(file):
    """Find version number in file path string.

    Args:
        file (string): file path

    Returns:
        v: version number in string ('001')

    """
    pattern = re.compile(r"[\._]v([0-9]+)", re.IGNORECASE)
    try:
        return pattern.findall(file)[0]
    except IndexError:
        log.error(
            "templates:get_version_from_workfile:"
            "`{}` missing version string."
            "Example `v004`".format(file)
        )


def get_last_version_from_path(path_dir, filter):
    """Find last version of given directory content.

    Args:
        path_dir (string): directory path
        filter (list): list of strings used as file name filter

    Returns:
        string: file name with last version

    Example:
        last_version_file = get_last_version_from_path(
            "/project/shots/shot01/work", ["shot01", "compositing", "nk"])
    """
    assert os.path.isdir(path_dir), "`path_dir` argument needs to be directory"
    assert isinstance(filter, list) and (
        len(filter) != 0), "`filter` argument needs to be list and not empty"

    filtred_files = list()

    # form regex for filtering
    patern = r".*".join(filter)

    for file in os.listdir(path_dir):
        if not re.findall(patern, file):
            continue
        filtred_files.append(file)

    if filtred_files:
        sorted(filtred_files)
        return filtred_files[-1]

    return None