"""Utilities for loading and reasoning about unparsed tools in directories."""
import fnmatch
import glob
import io
import logging
import os
import re
import sys

import yaml

from galaxy.tool_util import loader
from galaxy.tool_util.parser import get_tool_source
from galaxy.util import checkers

log = logging.getLogger(__name__)

PATH_DOES_NOT_EXIST_ERROR = "Could not load tools from path [%s] - this path does not exist."
PATH_AND_RECURSIVE_ERROR = "Cannot specify a single file and recursive."
LOAD_FAILURE_ERROR = "Failed to load tool with path %s."
TOOL_LOAD_ERROR = object()
TOOL_REGEX = re.compile(r"<tool\s")
DATA_MANAGER_REGEX = re.compile(r"\stool_type=\"manage_data\"")

YAML_EXTENSIONS = [".yaml", ".yml", ".json"]
CWL_EXTENSIONS = YAML_EXTENSIONS + [".cwl"]
EXCLUDE_WALK_DIRS = ['.hg', '.git', '.venv']


def load_exception_handler(path, exc_info):
    """Default exception handler for use by load_tool_elements_from_path."""
    log.warning(LOAD_FAILURE_ERROR % path, exc_info=exc_info)


def find_possible_tools_from_path(
    path,
    recursive=False,
    enable_beta_formats=False,
):
    """Walk a directory and find potential tool files."""
    possible_tool_files = []
    for possible_tool_file in _find_tool_files(
        path, recursive=recursive,
        enable_beta_formats=enable_beta_formats
    ):
        try:
            does_look_like_a_tool = looks_like_a_tool(
                possible_tool_file,
                enable_beta_formats=enable_beta_formats
            )
        except IOError:
            # Some problem reading the tool file, skip.
            continue

        if does_look_like_a_tool:
            possible_tool_files.append(possible_tool_file)

    return possible_tool_files


def load_tool_sources_from_path(
    path,
    load_exception_handler=load_exception_handler,
    recursive=False,
    register_load_errors=False,
):
    """Walk a directory and ToolSource objects."""
    return _load_tools_from_path(
        path,
        load_exception_handler=load_exception_handler,
        recursive=recursive,
        register_load_errors=register_load_errors,
        loader_func=get_tool_source,
        enable_beta_formats=True,
    )


def load_tool_elements_from_path(
    path,
    load_exception_handler=load_exception_handler,
    recursive=False,
    register_load_errors=False,
):
    """Walk a directory and load tool XML elements."""
    return _load_tools_from_path(
        path,
        load_exception_handler=load_exception_handler,
        recursive=recursive,
        register_load_errors=register_load_errors,
        loader_func=loader.load_tool,
        enable_beta_formats=False,
    )


def _load_tools_from_path(
    path,
    load_exception_handler,
    recursive,
    register_load_errors,
    loader_func,
    enable_beta_formats,
):
    loaded_objects = []
    for possible_tool_file in find_possible_tools_from_path(
        path,
        recursive=recursive,
        enable_beta_formats=enable_beta_formats,
    ):
        try:
            tool_element = loader_func(possible_tool_file)
            loaded_objects.append((possible_tool_file, tool_element))
        except Exception:
            exc_info = sys.exc_info()
            load_exception_handler(possible_tool_file, exc_info)
            if register_load_errors:
                loaded_objects.append((possible_tool_file, TOOL_LOAD_ERROR))
    return loaded_objects


def is_tool_load_error(obj):
    """Predicate to determine if object loaded for tool is a tool error."""
    return obj is TOOL_LOAD_ERROR


def looks_like_a_tool(path_or_uri_like, invalid_names=[], enable_beta_formats=False):
    """Quick check to see if a file looks like it may be a tool file.

    Whether true in a strict sense or not, lets say the intention and
    purpose of this procedure is to serve as a filter - all valid tools must
    "looks_like_a_tool" but not everything that looks like a tool is actually
    a valid tool.

    invalid_names may be supplied in the context of the tool shed to quickly
    rule common tool shed XML files.
    """
    path = resolved_path(path_or_uri_like)
    if path is UNRESOLVED_URI:
        # Assume the path maps to a real tool.
        return True

    looks = False

    if os.path.basename(path) in invalid_names:
        return False

    if looks_like_a_tool_xml(path):
        looks = True

    if not looks and enable_beta_formats:
        for tool_checker in BETA_TOOL_CHECKERS.values():
            if tool_checker(path):
                looks = True
                break

    return looks


def looks_like_xml(path, regex=TOOL_REGEX):
    full_path = os.path.abspath(path)

    if not full_path.endswith(".xml"):
        return False

    if not os.path.getsize(full_path):
        return False

    if(checkers.check_binary(full_path) or
       checkers.check_image(full_path) or
       checkers.is_gzip(full_path) or
       checkers.is_bz2(full_path) or
       checkers.is_zip(full_path)):
        return False

    with io.open(path, "r", encoding='utf-8') as f:
        try:
            start_contents = f.read(5 * 1024)
        except UnicodeDecodeError:
            return False
        if regex.search(start_contents):
            return True

    return False


def looks_like_a_tool_xml(path):
    """Quick check to see if a file looks like it may be a Galaxy XML tool file."""
    return looks_like_xml(path=path, regex=TOOL_REGEX)


def looks_like_a_data_manager_xml(path):
    """Quick check to see if a file looks like it may be a Galaxy data manager XML file."""
    return looks_like_xml(path=path, regex=DATA_MANAGER_REGEX)


def is_a_yaml_with_class(path, classes):
    """Determine if a file is a valid YAML with a supplied ``class`` entry."""
    if not _has_extension(path, YAML_EXTENSIONS):
        return False

    with open(path, "r") as f:
        try:
            as_dict = yaml.safe_load(f)
        except Exception:
            return False

    if not isinstance(as_dict, dict):
        return False

    file_class = as_dict.get("class", None)
    return file_class in classes


def looks_like_a_tool_yaml(path):
    """Quick check to see if a file looks like it may be a Galaxy YAML tool file."""
    return is_a_yaml_with_class(path, ["GalaxyTool"])


def looks_like_a_cwl_artifact(path, classes=None):
    """Quick check to see if a file looks like it may be a CWL artifact."""
    if not _has_extension(path, CWL_EXTENSIONS):
        return False

    with open(path, "r") as f:
        try:
            as_dict = yaml.safe_load(f)
        except Exception:
            return False

    if not isinstance(as_dict, dict):
        return False

    file_class = as_dict.get("class", None)
    if classes is not None and file_class not in classes:
        return False

    file_cwl_version = as_dict.get("cwlVersion", None)
    return file_cwl_version is not None


def looks_like_a_tool_cwl(path):
    """Quick check to see if a file looks like it may be a CWL tool."""
    return looks_like_a_cwl_artifact(path, classes=["CommandLineTool", "ExpressionTool"])


def _find_tool_files(path_or_uri_like, recursive, enable_beta_formats):
    path = resolved_path(path_or_uri_like)
    if path is UNRESOLVED_URI:
        # Pass the URI through and assume it maps to a real tool.
        return [path_or_uri_like]

    is_file = not os.path.isdir(path)
    if not os.path.exists(path):
        raise Exception(PATH_DOES_NOT_EXIST_ERROR)
    elif is_file and recursive:
        raise Exception(PATH_AND_RECURSIVE_ERROR)
    elif is_file:
        return [os.path.abspath(path)]
    else:
        if enable_beta_formats:
            if not recursive:
                files = glob.glob(path + "/*")
            else:
                files = _find_files(path, "*")
        else:
            if not recursive:
                files = glob.glob(path + "/*.xml")
            else:
                files = _find_files(path, "*.xml")
        return [os.path.abspath(_) for _ in files]


def _has_extension(path, extensions):
    return any(path.endswith(e) for e in extensions)


def _find_files(directory, pattern='*'):
    if not os.path.exists(directory):
        raise ValueError("Directory not found {}".format(directory))

    matches = []
    for root, dirnames, filenames in os.walk(directory):
        # exclude some directories (like .hg) from traversing
        dirnames[:] = [dir for dir in dirnames if dir not in EXCLUDE_WALK_DIRS]
        for filename in filenames:
            full_path = os.path.join(root, filename)
            if fnmatch.filter([full_path], pattern):
                matches.append(os.path.join(root, filename))
    return matches


UNRESOLVED_URI = object()


def resolved_path(path_or_uri_like):
    """If this is a simple file path, return the path else UNRESOLVED_URI."""
    if "://" not in path_or_uri_like:
        return path_or_uri_like
    elif path_or_uri_like.startswith("file://"):
        return path_or_uri_like[len("file://"):]
    else:
        return UNRESOLVED_URI


BETA_TOOL_CHECKERS = {
    'yaml': looks_like_a_tool_yaml,
    'cwl': looks_like_a_tool_cwl,
}

__all__ = (
    "find_possible_tools_from_path",
    "is_a_yaml_with_class",
    "is_tool_load_error",
    "load_tool_elements_from_path",
    "load_tool_sources_from_path",
    "looks_like_a_cwl_artifact",
    "looks_like_a_tool_cwl",
    "looks_like_a_tool_xml",
    "looks_like_a_tool_yaml",
)
