import yaml
import os
import errno
import logging
import shutil
import copy
import numpy as np
from fractions import Fraction

from .utilities import recursively_apply

"""
Attributes:
    USER_CONFIG_DIR (str): Default path of the user-config directory, containing runtime-config and
        calibration files. Obtained from ``os.path.join(os.path.expanduser("~"), ".openflexure")``.
    USER_CONFIG_FILE (str): Default path of the user microscope_settings.yaml runtime-config file. 
        Obtained from ``os.path.join(USER_CONFIG_DIR, "microscope_settings.yaml")``
"""

# HANDLE THE DEFAULT CONFIGURATION FILE

HERE = os.path.abspath(os.path.dirname(__file__))
DEFAULT_CONFIG_PATH = os.path.join(HERE, "microscope_settings.default.yaml")

USER_CONFIG_DIR = os.path.join(os.path.expanduser("~"), ".openflexure")
USER_CONFIG_FILE = os.path.join(USER_CONFIG_DIR, "microscope_settings.yaml")

USER_CONFIG_FILE_OLD = os.path.join(USER_CONFIG_DIR, "microscoperc.yaml")

# Load the default config
with open(DEFAULT_CONFIG_PATH, "r") as default_rc:
    DEFAULT_CONFIG = default_rc.read()

# HANDLE CUSTOM YAML PARSING
def construct_yaml_bool(self, node):
    """
    Override PyYAML constructors handling of bools.
    YAML otherwise caused grief for picamera properties where 'off' is a valid string value.
    """
    override_bool_values = {
        "yes": True,
        "no": False,
        "true": True,
        "false": False,
        "on": "on",
        "off": "off",
    }
    value = self.construct_scalar(node)
    return override_bool_values[value.lower()]


yaml.Loader.add_constructor(u"tag:yaml.org,2002:bool", construct_yaml_bool)


# HANDLE CONVERTING ARBITRARY CONFIG TO JSON-SAFE JSON


def convert_type_to_json_safe(v):
    """Make an individual attribute JSON-safe"""
    if isinstance(v, Fraction):
        return float(v)
    elif isinstance(v, np.integer):
        return int(v)
    elif isinstance(v, np.ndarray):
        return v.tolist()
    else:
        return v


def settings_to_json(data: dict):
    """
    Make a copy of an input dictionary that's safe for JSON return

    Args:
        data: Input dictionary
    """

    # Do not overwrite original data dictionary
    d = copy.deepcopy(data)

    return recursively_apply(d, convert_type_to_json_safe)


# HANDLE BASIC LOADING AND SAVING OF YAML FILES


def load_yaml_file(config_path) -> dict:
    """
    Open a .yaml config file

    Args:
        config_path (str): Path to the config YAML file. If `None`, defaults to `DEFAULT_CONFIG_PATH`
    """
    config_path = os.path.expanduser(config_path)

    logging.info("Loading {}...".format(config_path))

    with open(config_path) as config_file:
        config_data = yaml.load(config_file)

    # Return loaded config dictionary
    return config_data


def save_yaml_file(config_path: str, config_dict: dict, safe: bool = False):
    """
    Save a .yaml config file

    Args:
        config_dict (dict): Dictionary of config data to save.
        config_path (str): Path to the config YAML file.
        safe (bool): Whether to use PyYAML safe_dump instead of dump
    """
    config_path = os.path.expanduser(config_path)

    logging.info("Saving {}...".format(config_path))
    logging.debug(config_dict)

    with open(config_path, "w") as outfile:
        if not safe:
            yaml.dump(config_dict, outfile)
        else:
            yaml.safe_dump(config_dict, outfile)


def create_file(config_path):
    if not os.path.exists(os.path.dirname(config_path)):
        try:
            os.makedirs(os.path.dirname(config_path))
        except OSError as exc:  # Guard against race condition
            if exc.errno != errno.EEXIST:
                raise


def initialise_file(config_path, populate: str = ""):
    """
    Check if a file exists, and if not, create it
    and optionally populate it with content

    Args:
        config_path (str): Path to the file.
        populate (str): String to dump to the file, if it is being newly created
    """
    config_path = os.path.expanduser(config_path)

    logging.debug("Initialising {}".format(config_path))
    logging.debug("Exists: {}".format(os.path.exists(config_path)))

    if not os.path.exists(config_path):  # If user config file doesn't exist
        logging.warning("No config file found at {}. Creating...".format(config_path))
        create_file(config_path)

        logging.info("Populating {}...".format(config_path))
        with open(config_path, "w") as outfile:
            outfile.write(populate)


# MAIN CONFIG CLASS
class OpenflexureSettingsFile:
    """
    An object to handle expansion, conversion, and saving of the microscope configuration.

    Args:
        config_path (str): Path to the config YAML file (None falls back to default location)
        expand (bool): Expand paths to valid auxillary config files.
    """

    def __init__(self, config_path: str = None, expand: bool = True):
        global DEFAULT_CONFIG, USER_CONFIG_FILE

        self.expandable_keys = {
            "camera_settings": None,
            "stage_settings": None,
        }  #: Dictionary of keys that can be passed as a file path string and expanded automatically

        # Set arguments
        self.config_path = config_path or USER_CONFIG_FILE
        self.expand = expand

        # Initialise basic config file with defaults if it doesn't exist
        initialise_file(self.config_path, populate=DEFAULT_CONFIG)

    def load(self):
        """
        Loads config from a file on-disk, and expands auxillary config files if available.
        """
        # Unexpanded config dictionary (used at load/save time)
        loaded_config = load_yaml_file(self.config_path)

        # If the loaded config is in contracted format
        if self.expand:
            # Expand self.raw_config into self._config
            loaded_config = self.expand_config(loaded_config)

        logging.debug("Reading settings from disk")
        return loaded_config

    def save(self, config: dict, backup: bool = True):
        """
        Save config to a file on-disk, and splits into auxillary config files if available.
        """
        # If the loaded config was in contracted format
        if self.expand:
            # Contract self._config into self.raw_config
            save_config = self.contract_config(config)
        else:
            save_config = config

        if backup:
            if os.path.isfile(self.config_path):
                shutil.copyfile(self.config_path, self.config_path + ".bk")

        logging.debug("Saving settings dictionary to disk")
        save_yaml_file(self.config_path, save_config)

    def merge(self, config: dict, backup: bool = True):
        logging.debug("Merging settings with file on disk")
        settings = self.load()
        settings.update(config)

        return settings

    def expand_config(self, config_dict):
        """
        Search a config dictionary for paths to valid auxillary config files,
        and expand into the config dictionary if available.

        Args:
            config_dict (dict): Dictionary of config data to expand
        """
        return_config = {}
        if not config_dict:
            config_dict = {}
        # For each value in the raw loaded config
        for key, value in config_dict.items():
            # If it's a valid expandable parameter
            if key in self.expandable_keys and type(value) is str:

                logging.debug("Expanding {}".format(value))

                # Store expansion path
                self.expandable_keys[key] = config_dict[key]
                # Create the expansion file if it doesn't yet exist
                initialise_file(value)
                # Load the expansion file into _config
                return_config[key] = load_yaml_file(value) or {}
            else:
                return_config[key] = value

        return return_config

    def contract_config(self, config_dict):
        """
        Split a config dictionary into auxillary config files, if available.

        Args:
            config_dict (dict): Dictionary of config data to contract/split
        """
        return_config = {}
        # For each value in the expanded config
        for key, value in config_dict.items():
            # If it's a valid expandable parameter
            if (
                key in self.expandable_keys
                and self.expandable_keys[key] is not None
                and type(value) is dict
            ):

                logging.debug("Saving to {}".format(self.expandable_keys[key]))
                # Create the file if it doesn't exist
                initialise_file(self.expandable_keys[key])
                # Save the expanded config dictionary to the file
                save_yaml_file(self.expandable_keys[key], value)
                # Replace the expanded dictionary with a file path
                return_config[key] = self.expandable_keys[key]
            else:
                return_config[key] = value

        return return_config