# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Copyright 2016 Continuum Analytics, Inc.
#
# May be copied and distributed freely only as part of an Anaconda or
# Miniconda installation.
# -----------------------------------------------------------------------------
"""
This module provides user configuration file management features.

It's based on the ConfigParser module (present in the standard library).
"""

# yapf: disable

from __future__ import print_function

# Standard library imports
import ast
import os
import os.path as osp
import re
import shutil
import time

# Local imports
from anaconda_navigator.config.base import get_home_dir
from anaconda_navigator.utils.py3compat import configparser as cp
from anaconda_navigator.utils.py3compat import (PY2, is_text_string,
                                                to_text_string)


# yapf: enable

# Standard imports for Python 2
if PY2:
    import codecs


# -----------------------------------------------------------------------------
# --- Auxiliary classes
# -----------------------------------------------------------------------------
class NoDefault:
    """NoDefault object."""

    pass


# -----------------------------------------------------------------------------
# --- Defaults class
# -----------------------------------------------------------------------------
class DefaultsConfig(cp.ConfigParser):
    """Class used to save defaults to a file."""

    def __init__(self, name, subfolder):
        """
        Class used to save defaults to a file.

        Parameters
        -----------
        name: str
            Name of the configuration.
        subfolder: str
            Path to folder location of configuration file.
        """
        cp.ConfigParser.__init__(self)
        self.name = name
        self.subfolder = subfolder

    def _write(self, fp):
        """Private write method for Python 2.

        The one from configparser fails for non-ascii Windows accounts.
        """
        if self._defaults:
            fp.write("[{section}]\n".format(section=cp.DEFAULTSECT))
            for (key, value) in self._defaults.items():
                write_value = str(value).replace('\n', '\n\t')
                fp.write(
                    "{key} = {value}\n".format(
                        key=key, value=write_value
                    )
                )
            fp.write("\n")
        for section in self._sections:
            fp.write("[{section}]\n".format(section=section))
            for (key, value) in self._sections[section].items():
                if key == "__name__":
                    continue
                if (value is not None) or (self._optcre == self.OPTCRE):
                    value = to_text_string(value)
                    key = " = ".join((key, value.replace('\n', '\n\t')))
                fp.write("{0}\n".format(key))
            fp.write("\n")

    def _set(self, section, option, value, verbose):
        """Private set method."""
        if not self.has_section(section):
            self.add_section(section)
        if not is_text_string(value):
            value = repr(value)
        if verbose:
            print(
                '{section}[ {option} ] = {value}'.
                format(section, option, value)
            )
        cp.ConfigParser.set(self, section, option, value)

    def _save(self):
        """Save config into the associated .ini file."""
        fname = self.filename()

        def _write_file(fname):
            if PY2:
                with codecs.open(fname, 'w', encoding='utf-8') as configfile:
                    self._write(configfile)
            else:
                with open(fname, 'w', encoding='utf-8') as configfile:
                    self.write(configfile)

        try:  # the "easy" way
            _write_file(fname)
        except IOError:
            try:  # the "delete and sleep" way
                if osp.isfile(fname):
                    os.remove(fname)
                time.sleep(0.05)
                _write_file(fname)
            except Exception as e:
                print("Failed to write user configuration file.")
                print("Please submit a bug report.")
                raise (e)

    def filename(self):
        """Create a .ini filename located in user home directory."""
        folder = osp.join(get_home_dir(), self.subfolder)
        # Save defaults in a "defaults" dir of .anaconda_navigator to not
        # pollute it
        if 'defaults' in self.name:
            folder = osp.join(folder, 'defaults')
        try:
            os.makedirs(folder)
        except os.error:
            # Folder (or one of its parents) already exists
            pass
        ini_file = osp.join(folder, '{0}.ini'.format(self.name))
        return ini_file

    def set_defaults(self, defaults):
        """Set default configuration."""
        for section, options in defaults:
            for option in options:
                new_value = options[option]
                self._set(section, option, new_value, False)


# -----------------------------------------------------------------------------
# --- User config class
# -----------------------------------------------------------------------------
class UserConfig(DefaultsConfig):
    """
    User configuration class.

    Note that 'get' and 'set' arguments number and type differ from the
    overriden methods.
    """

    DEFAULT_SECTION_NAME = 'main'

    def __init__(
        self,
        name,
        defaults=None,
        load=True,
        version=None,
        subfolder=None,
        backup=False,
        raw_mode=False,
        remove_obsolete=False
    ):
        """
        User configuration class.

        Parameters
        ----------
        name: str
            Name of the configuration.
        defaults: dict
            dictionnary containing options *or* list of tuples (section_name,
            options).
        version: str
            Version of the configuration file (X.Y.Z format).
        subfolder: str
            Configuration file will be saved in HOME/subfolder/name.ini.
        """
        DefaultsConfig.__init__(self, name, subfolder)

        self.raw = 1 if raw_mode else 0
        if (version is not None and
                re.match('^(\d+).(\d+).(\d+)$', version) is None):
            raise ValueError(
                "Version number {0} is incorrect - must be in "
                "X.Y.Z format".format(version)
            )

        if isinstance(defaults, dict):
            defaults = [(self.DEFAULT_SECTION_NAME, defaults)]
        self.defaults = defaults
        if defaults is not None:
            self.reset_to_defaults(save=False)

        fname = self.filename()
        if backup:
            try:
                shutil.copyfile(fname, "{0}.bak".format(fname))
            except IOError:
                pass

        if load:
            # If config file already exists, it overrides Default options:
            self.load_from_ini()
            old_ver = self.get_version(version)

            # Save new defaults
            self.__save_new_defaults(defaults, version, subfolder)

            # Updating defaults only if major/minor version is different
            if self._minor(version) != self._minor(old_ver):
                if backup:
                    try:
                        shutil.copyfile(
                            fname, "{0}-{1}.bak".format(fname, old_ver)
                        )
                    except IOError:
                        pass
                self.__update_defaults(defaults, old_ver)

                # Remove deprecated options if major version has changed
                if (remove_obsolete or
                        self._major(version) != self._major(old_ver)):
                    self.__remove_deprecated_options(old_ver)

                # Set new version number
                self.set_version(version, save=False)
            if defaults is None:
                # If no defaults are defined, set .ini file settings as default
                self.set_as_defaults()

    @staticmethod
    def _major(_t):
        """Return major component in config versions."""
        return _t[:_t.find('.')]

    @staticmethod
    def _minor(_t):
        """Return minor component in config versions."""
        return _t[:_t.rfind('.')]

    def get_version(self, version='0.0.0'):
        """Return configuration (not application!) version."""
        return self.get(self.DEFAULT_SECTION_NAME, 'version', version)

    def set_version(self, version='0.0.0', save=True):
        """Set configuration (not application!) version."""
        self.set(self.DEFAULT_SECTION_NAME, 'version', version, save=save)

    def load_from_ini(self):
        """Load config from the associated .ini file."""
        try:
            if PY2:
                fname = self.filename()
                if osp.isfile(fname):
                    try:
                        with codecs.open(fname, encoding='utf-8') as conf_file:
                            self.readfp(conf_file)
                    except IOError:
                        print("Failed reading file", fname)
            else:
                self.read(self.filename(), encoding='utf-8')
        except cp.MissingSectionHeaderError:
            print("Warning: File contains no section headers.")

    def __load_old_defaults(self, old_version):
        """Read old defaults."""
        old_defaults = cp.ConfigParser()
        path = osp.dirname(self.filename())
        path = osp.join(path, 'defaults')
        old_defaults.read(osp.join(path, 'defaults-' + old_version + '.ini'))
        return old_defaults

    @staticmethod
    def __save_new_defaults(defaults, new_version, subfolder):
        """Save new defaults."""
        new_defaults = DefaultsConfig(
            name='defaults-' + new_version,
            subfolder=subfolder,
        )
        if not osp.isfile(new_defaults.filename()):
            new_defaults.set_defaults(defaults)
            new_defaults._save()

    def __update_defaults(self, defaults, old_version, verbose=False):
        """Update defaults after a change in version."""
        old_defaults = self.__load_old_defaults(old_version)
        for section, options in defaults:
            for option in options:
                new_value = options[option]
                try:
                    old_value = old_defaults.get(section, option)
                except (cp.NoSectionError, cp.NoOptionError):
                    old_value = None
                if (old_value is None or
                        to_text_string(new_value) != old_value):
                    self._set(section, option, new_value, verbose)

    def __remove_deprecated_options(self, old_version):
        """Remove options present in the .ini file but not in defaults."""
        old_defaults = self.__load_old_defaults(old_version)
        for section in old_defaults.sections():
            for option, _ in old_defaults.items(section, raw=self.raw):
                if self.get_default(section, option) is NoDefault:
                    self.remove_option(section, option)
                    if len(self.items(section, raw=self.raw)) == 0:
                        self.remove_section(section)

    def cleanup(self):
        """Remove .ini file associated to config."""
        os.remove(self.filename())

    def set_as_defaults(self):
        """Set defaults from the current config."""
        self.defaults = []
        for section in self.sections():
            secdict = {}
            for option, value in self.items(section, raw=self.raw):
                secdict[option] = value
            self.defaults.append((section, secdict))

    def reset_to_defaults(self, save=True, verbose=False, section=None):
        """Reset config to Default values."""
        for sec, options in self.defaults:
            if section is None or section == sec:
                for option in options:
                    value = options[option]
                    self._set(sec, option, value, verbose)
        if save:
            self._save()

    def __check_section_option(self, section, option):
        """Private method to check section and option types."""
        if section is None:
            section = self.DEFAULT_SECTION_NAME
        elif not is_text_string(section):
            raise RuntimeError("Argument 'section' must be a string")
        if not is_text_string(option):
            raise RuntimeError("Argument 'option' must be a string")
        return section

    def get_default(self, section, option):
        """
        Get Default value for a given (section, option).

        -> useful for type checking in 'get' method
        """
        section = self.__check_section_option(section, option)
        for sec, options in self.defaults:
            if sec == section and option in options:
                return options[option]
        else:
            return NoDefault

    def get(self, section, option, default=NoDefault):
        """
        Get an option.

        section=None: attribute a default section name
        default: default value (if not specified, an exception
        will be raised if option doesn't exist)
        """
        section = self.__check_section_option(section, option)

        if not self.has_section(section):
            if default is NoDefault:
                raise cp.NoSectionError(section)
            else:
                self.add_section(section)

        if not self.has_option(section, option):
            if default is NoDefault:
                raise cp.NoOptionError(option, section)
            else:
                self.set(section, option, default)
                return default

        value = cp.ConfigParser.get(self, section, option, raw=self.raw)
        default_value = self.get_default(section, option)

        if isinstance(default_value, bool):
            value = ast.literal_eval(value)
        elif isinstance(default_value, float):
            value = float(value)
        elif isinstance(default_value, int):
            value = int(value)
        else:
            if PY2 and is_text_string(default_value):
                try:
                    value = value.decode('utf-8')
                except (UnicodeEncodeError, UnicodeDecodeError):
                    pass
            try:
                # lists, tuples, ...
                value = ast.literal_eval(value)
            except Exception:
                pass
        return value

    def set_default(self, section, option, default_value):
        """
        Set Default value for a given (section, option).

        -> called when a new (section, option) is set and no default exists
        """
        section = self.__check_section_option(section, option)
        for sec, options in self.defaults:
            if sec == section:
                options[option] = default_value

    def set(self, section, option, value, verbose=False, save=True):
        """
        Set an option.

        section=None: attribute a default section name
        """
        section = self.__check_section_option(section, option)
        default_value = self.get_default(section, option)
        if default_value is NoDefault:
            # This let us save correctly string value options with
            # no config default that contain non-ascii chars in
            # Python 2
            if PY2 and is_text_string(value):
                value = repr(value)
            default_value = value
            self.set_default(section, option, default_value)

        if isinstance(default_value, bool):
            value = bool(value)
        elif isinstance(default_value, float):
            value = float(value)
        elif isinstance(default_value, int):
            value = int(value)
        elif not is_text_string(default_value):
            value = repr(value)
        self._set(section, option, value, verbose)
        if save:
            self._save()

    def remove_section(self, section):
        """Remove the specified section from the configuration."""
        cp.ConfigParser.remove_section(self, section)
        self._save()

    def remove_option(self, section, option):
        """Remove the specified option from the specified section."""
        cp.ConfigParser.remove_option(self, section, option)
        self._save()
