"""Helper functions for loading InvenTree configuration options."""

import datetime
import json
import logging
import os
import random
import shutil
import string
from pathlib import Path

logger = logging.getLogger('inventree')
CONFIG_DATA = None
CONFIG_LOOKUPS = {}


def to_list(value, delimiter=','):
    """Take a configuration setting and make sure it is a list.

    For example, we might have a configuration setting taken from the .config file,
    which is already a list.

    However, the same setting may be specified via an environment variable,
    using a comma delimited string!
    """

    if type(value) in [list, tuple]:
        return value

    # Otherwise, force string value
    value = str(value)

    return [x.strip() for x in value.split(delimiter)]


def to_dict(value):
    """Take a configuration setting and make sure it is a dict.

    For example, we might have a configuration setting taken from the .config file,
    which is already an object/dict.

    However, the same setting may be specified via an environment variable,
    using a valid JSON string!
    """
    if value is None:
        return {}

    if type(value) == dict:
        return value

    try:
        return json.loads(value)
    except Exception as error:
        logger.error(f"Failed to parse value '{value}' as JSON with error {error}. Ensure value is a valid JSON string.")
    return {}


def is_true(x):
    """Shortcut function to determine if a value "looks" like a boolean"""
    return str(x).strip().lower() in ['1', 'y', 'yes', 't', 'true', 'on']


def get_base_dir() -> Path:
    """Returns the base (top-level) InvenTree directory."""
    return Path(__file__).parent.parent.resolve()


def ensure_dir(path: Path) -> None:
    """Ensure that a directory exists.

    If it does not exist, create it.
    """

    if not path.exists():
        path.mkdir(parents=True, exist_ok=True)


def get_config_file(create=True) -> Path:
    """Returns the path of the InvenTree configuration file.

    Note: It will be created it if does not already exist!
    """
    base_dir = get_base_dir()

    cfg_filename = os.getenv('INVENTREE_CONFIG_FILE')

    if cfg_filename:
        cfg_filename = Path(cfg_filename.strip()).resolve()
    else:
        # Config file is *not* specified - use the default
        cfg_filename = base_dir.joinpath('config.yaml').resolve()

    if not cfg_filename.exists() and create:
        print("InvenTree configuration file 'config.yaml' not found - creating default file")
        ensure_dir(cfg_filename.parent)

        cfg_template = base_dir.joinpath("config_template.yaml")
        shutil.copyfile(cfg_template, cfg_filename)
        print(f"Created config file {cfg_filename}")

    return cfg_filename


def load_config_data(set_cache: bool = False) -> map:
    """Load configuration data from the config file.

    Arguments:
        set_cache(bool): If True, the configuration data will be cached for future use after load.
    """
    global CONFIG_DATA

    # use cache if populated
    # skip cache if cache should be set
    if CONFIG_DATA is not None and not set_cache:
        return CONFIG_DATA

    import yaml

    cfg_file = get_config_file()

    with open(cfg_file, 'r') as cfg:
        data = yaml.safe_load(cfg)

    # Set the cache if requested
    if set_cache:
        CONFIG_DATA = data

    return data


def get_setting(env_var=None, config_key=None, default_value=None, typecast=None):
    """Helper function for retrieving a configuration setting value.

    - First preference is to look for the environment variable
    - Second preference is to look for the value of the settings file
    - Third preference is the default value

    Arguments:
        env_var: Name of the environment variable e.g. 'INVENTREE_STATIC_ROOT'
        config_key: Key to lookup in the configuration file
        default_value: Value to return if first two options are not provided
        typecast: Function to use for typecasting the value
    """
    def try_typecasting(value, source: str):
        """Attempt to typecast the value"""

        # Force 'list' of strings
        if typecast is list:
            value = to_list(value)

        # Valid JSON string is required
        elif typecast is dict:
            value = to_dict(value)

        elif typecast is not None:
            # Try to typecast the value
            try:
                val = typecast(value)
                set_metadata(source)
                return val
            except Exception as error:
                logger.error(f"Failed to typecast '{env_var}' with value '{value}' to type '{typecast}' with error {error}")

        set_metadata(source)
        return value

    def set_metadata(source: str):
        """Set lookup metadata for the setting."""
        key = env_var or config_key
        CONFIG_LOOKUPS[key] = {'env_var': env_var, 'config_key': config_key, 'source': source, 'accessed': datetime.datetime.now()}

    # First, try to load from the environment variables
    if env_var is not None:
        val = os.getenv(env_var, None)

        if val is not None:
            return try_typecasting(val, 'env')

    # Next, try to load from configuration file
    if config_key is not None:
        cfg_data = load_config_data()

        result = None

        # Hack to allow 'path traversal' in configuration file
        for key in config_key.strip().split('.'):

            if type(cfg_data) is not dict or key not in cfg_data:
                result = None
                break

            result = cfg_data[key]
            cfg_data = cfg_data[key]

        if result is not None:
            return try_typecasting(result, 'yaml')

    # Finally, return the default value
    return try_typecasting(default_value, 'default')


def get_boolean_setting(env_var=None, config_key=None, default_value=False):
    """Helper function for retreiving a boolean configuration setting"""

    return is_true(get_setting(env_var, config_key, default_value))


def get_media_dir(create=True):
    """Return the absolute path for the 'media' directory (where uploaded files are stored)"""

    md = get_setting('INVENTREE_MEDIA_ROOT', 'media_root')

    if not md:
        raise FileNotFoundError('INVENTREE_MEDIA_ROOT not specified')

    md = Path(md).resolve()

    if create:
        md.mkdir(parents=True, exist_ok=True)

    return md


def get_static_dir(create=True):
    """Return the absolute path for the 'static' directory (where static files are stored)"""

    sd = get_setting('INVENTREE_STATIC_ROOT', 'static_root')

    if not sd:
        raise FileNotFoundError('INVENTREE_STATIC_ROOT not specified')

    sd = Path(sd).resolve()

    if create:
        sd.mkdir(parents=True, exist_ok=True)

    return sd


def get_backup_dir(create=True):
    """Return the absolute path for the backup directory"""

    bd = get_setting('INVENTREE_BACKUP_DIR', 'backup_dir')

    if not bd:
        raise FileNotFoundError('INVENTREE_BACKUP_DIR not specified')

    bd = Path(bd).resolve()

    if create:
        bd.mkdir(parents=True, exist_ok=True)

    return bd


def get_plugin_file():
    """Returns the path of the InvenTree plugins specification file.

    Note: It will be created if it does not already exist!
    """

    # Check if the plugin.txt file (specifying required plugins) is specified
    plugin_file = get_setting('INVENTREE_PLUGIN_FILE', 'plugin_file')

    if not plugin_file:
        # If not specified, look in the same directory as the configuration file
        config_dir = get_config_file().parent
        plugin_file = config_dir.joinpath('plugins.txt')
    else:
        # Make sure we are using a modern Path object
        plugin_file = Path(plugin_file)

    if not plugin_file.exists():
        logger.warning("Plugin configuration file does not exist - creating default file")
        logger.info(f"Creating plugin file at '{plugin_file}'")
        ensure_dir(plugin_file.parent)

        # If opening the file fails (no write permission, for example), then this will throw an error
        plugin_file.write_text("# InvenTree Plugins (uses PIP framework to install)\n\n")

    return plugin_file


def get_secret_key():
    """Return the secret key value which will be used by django.

    Following options are tested, in descending order of preference:

    A) Check for environment variable INVENTREE_SECRET_KEY => Use raw key data
    B) Check for environment variable INVENTREE_SECRET_KEY_FILE => Load key data from file
    C) Look for default key file "secret_key.txt"
    D) Create "secret_key.txt" if it does not exist
    """

    # Look for environment variable
    if secret_key := get_setting('INVENTREE_SECRET_KEY', 'secret_key'):
        logger.info("SECRET_KEY loaded by INVENTREE_SECRET_KEY")  # pragma: no cover
        return secret_key

    # Look for secret key file
    if secret_key_file := get_setting('INVENTREE_SECRET_KEY_FILE', 'secret_key_file'):
        secret_key_file = Path(secret_key_file).resolve()
    else:
        # Default location for secret key file
        secret_key_file = get_base_dir().joinpath("secret_key.txt").resolve()

    if not secret_key_file.exists():
        logger.info(f"Generating random key file at '{secret_key_file}'")
        ensure_dir(secret_key_file.parent)

        # Create a random key file
        options = string.digits + string.ascii_letters + string.punctuation
        key = ''.join([random.choice(options) for i in range(100)])
        secret_key_file.write_text(key)

    logger.info(f"Loading SECRET_KEY from '{secret_key_file}'")

    key_data = secret_key_file.read_text().strip()

    return key_data


def get_custom_file(env_ref: str, conf_ref: str, log_ref: str, lookup_media: bool = False):
    """Returns the checked path to a custom file.

    Set lookup_media to True to also search in the media folder.
    """
    from django.contrib.staticfiles.storage import StaticFilesStorage
    from django.core.files.storage import default_storage

    value = get_setting(env_ref, conf_ref, None)

    if not value:
        return None

    static_storage = StaticFilesStorage()

    if static_storage.exists(value):
        logger.info(f"Loading {log_ref} from static directory: {value}")
    elif lookup_media and default_storage.exists(value):
        logger.info(f"Loading {log_ref} from media directory: {value}")
    else:
        add_dir_str = ' or media' if lookup_media else ''
        logger.warning(f"The {log_ref} file '{value}' could not be found in the static{add_dir_str} directories")
        value = False

    return value