# _archive_spec.py
#
# Project: AutoArchive
# License: GNU GPLv3
#
# Copyright (C) 2003 - 2014 Róbert Čerňanský



""":class:`_ArchiveSpec` class."""



__all__ = ["_ArchiveSpec", "_ArchiveSpecOptions"]



# {{{ INCLUDES

from abc import *
import os
import re
import glob
import configparser
import itertools

from AutoArchive._infrastructure.configuration import ConfigurationBase, Options, Option, OptionsUtils, \
    SpecialOptionTypes

# }}} INCLUDES



# {{{ CLASSES

class _ArchiveSpec(ConfigurationBase):
    """The :term:`archive` specification.

    Contains all information needed to create the :term:`backup` such as the name, list of files which shall be
    included into the backup, list of files to exclude, etc.  These values can be configured in the
    :term:`archive specification file` (``specFile``) or in the general configuration such as command line or
    configuration files.  Options that can be read from this class are defined as static attributes of
    :class:`_ArchiveSpecOptions` and :class:`.Options`.  If an option is not defined in the
    archive specification file it is read from ``configuration``.

    The instance is fully populated during construction.

    :param specFile: :term:`Archive specification file` name (the “.aa file”).
    :type specFile: ``str``
    :param configuration: The application's configuration.
    :type configuration: :class:`.IConfiguration`
    :param componentUi: The application's :term:`UI` interface.  If ``None`` then messages about non-accessible
       files or other errors during processing of **included** and **excluded** file lists will not be shown.
    :type componentUi: :class:`.CmdlineUi`

    :raise IOError: If ``specFile`` can not be opened.
    :raise LookupError: If a *section* or an *option* is missing in ``specFile``.
    :raise SyntaxError: If ``specFile`` can not be parsed.
    :raise KeyError: If an invalid (unsupported) *section* or *option* is found in the :term:`archive specification
       file`.
    :raise ValueError: If option's *value* is not correct."""

    # section names in the archive specification file
    __CFG_SECTION_ARCHIVE = "Archive"
    __CFG_SECTION_CONTENT = "Content"

    # configuration options that are also supported in the arch. spec. file
    __CONFIG_OPTIONS = frozenset({Options.ARCHIVER,
                                  Options.COMPRESSION_LEVEL,
                                  Options.DEST_DIR,
                                  Options.INCREMENTAL,
                                  Options.RESTARTING,
                                  Options.RESTART_AFTER_LEVEL,
                                  Options.RESTART_AFTER_AGE,
                                  Options.FULL_RESTART_AFTER_COUNT,
                                  Options.FULL_RESTART_AFTER_AGE,
                                  Options.MAX_RESTART_LEVEL_SIZE,
                                  Options.REMOVE_OBSOLETE_BACKUPS,
                                  Options.KEEP_OLD_BACKUPS,
                                  Options.NUMBER_OF_OLD_BACKUPS,
                                  Options.COMMAND_BEFORE_BACKUP,
                                  Options.COMMAND_AFTER_BACKUP})



    def __init__(self, specFile, configuration, componentUi = None):
        super().__init__()

        # {{{ attributes

        self.__configuration = configuration
        self.__componentUi = componentUi

        self.__spec = None

        # }}} attributes

        # read the archive specification file (the .aa file)
        self.__spec = configparser.ConfigParser()
        try:
            self.__spec.read_file(open(specFile))
        except (configparser.InterpolationError,
                configparser.MissingSectionHeaderError,
                configparser.ParsingError) as ex:
            raise SyntaxError(ex)
        except UnicodeDecodeError as ex:
            raise SyntaxError(str.format("Unable to parse file \"{}\" [{}].", specFile, ex))

        # check the specification file for sanity
        supportedSections = {self.__CFG_SECTION_ARCHIVE,
                             self.__CFG_SECTION_CONTENT}

        if len(supportedSections.union(self.__spec.sections())) > len(supportedSections):
            raise KeyError(str.format(
                    "One or more invalid sections found in the archive specification file \"{}\".", specFile))

        invalidOptions = {str(opt)
                          for opt in set(OptionsUtils.getAllOptions()) - self.__CONFIG_OPTIONS}
        for section in self.__spec.sections():
            if not invalidOptions.isdisjoint(self.__spec.options(section)):
                raise KeyError(str.format(
                        "One or more invalid options found in the archive specification file \"{}\".", specFile))

        # populate the instance
        self.__addRequiredSpecFileOptions(specFile)
        self.__addOptionalSpecFileOptions(specFile)
        self.__addOptionalConfigurationOptions()



    # {{{ ConfigurationBase overrides

    def getRawValue(self, option):
        "See: :meth:`.IConfiguration.getValue()`."

        if option in self.options_:
            return super().getRawValue(option)
        else:
            return self.__configuration.getRawValue(option)

    # }}} ConfigurationBase overrides



    # {{{ helpers

    # {{{ options adding

    def __addRequiredSpecFileOptions(self, specFile):
        "Add non-optional options (specific to archive spec. file)."

        try:

            # add path and check its existence
            self.__addOptionFromSpec(self.__CFG_SECTION_CONTENT, _ArchiveSpecOptions.PATH)

            path = self[_ArchiveSpecOptions.PATH]
            if not os.path.exists(path):
                raise ValueError(str.format(
                        "Cannot access directory \"{}\" configured in the \"{}\" option; it does not exists.",
                        path, _ArchiveSpecOptions.PATH))

            if not os.path.isdir(path):
                raise ValueError(str.format(
                        "Cannot access directory \"{}\" configured in the \"{}\" option; it is not a directory.",
                        path, _ArchiveSpecOptions.PATH))

            self.options_[_ArchiveSpecOptions.INCLUDE_FILES] = \
                self.__readFilesLists(str(_ArchiveSpecOptions.INCLUDE_FILES))
            self.options_[_ArchiveSpecOptions.EXCLUDE_FILES] = \
                self.__readFilesLists(str(_ArchiveSpecOptions.EXCLUDE_FILES))

        except configparser.NoSectionError as ex:
            raise LookupError(str.format(
                    "Missing section \"{}\" in specification file \"{}\".", ex.section, specFile))
        except configparser.NoOptionError as ex:
            raise LookupError(str.format(
                    "Missing option \"{}\" in section \"{}\" of specification file \"{}\".",
                    ex.option, ex.section, specFile))



    def __addOptionalSpecFileOptions(self, specFile):
        "Add optional options specific to archive spec. file."

        self.__addOptionFromSpec(
            self.__CFG_SECTION_CONTENT, _ArchiveSpecOptions.NAME, os.path.splitext(os.path.basename(specFile))[0])



    def __addOptionalConfigurationOptions(self):
        "Add optional options that can be present also in configuration."

        if self.__spec.has_section(self.__CFG_SECTION_ARCHIVE):
            for option in self.__CONFIG_OPTIONS:
                self.__tryAddOptionFromSpec(self.__CFG_SECTION_ARCHIVE, option)



    # {{{ options adding sub-helpers

    def __addOrReplaceOption(self, option, value):
        try:
            self.options_[option] = OptionsUtils.strToOptionType(option, value)
        except ValueError:
            raise ValueError(str.format(
                    "Wrong value \"{}\" of the option \"{}\" in the archive specification file.", value, option))



    def __addOptionFromSpec(self, section, option, default = None):
            self.__addOrReplaceOption(option, self.__spec.get(section, str(option), fallback = default))



    def __tryAddOptionFromSpec(self, section, option):
        if self.__spec.has_option(section, str(option)):
            self.__addOrReplaceOption(option, self.__spec.get(section, str(option)))



    # {{{ file lists processing

    def __readFilesLists(self, listKind):
        "Read configured include or exclude files or directories."

        # extract filenames from specFile and store them into list
        files = re.findall(r'(?:".+?")|(?:\S+)', self.__spec.get(self.__CFG_SECTION_CONTENT, listKind))

        # previous regexp leaves quotes in filenames so they must be removed
        files = self.__clearQuotes(files)

        # remove parent directory path elements and absolute path token ("/"); for paths like "../../foo/bar" it
        # returns "foo/bar" and for absolute paths like "/bar/baz" it returns "bar/baz";
        # for each path in files it splits it by "/" and uses dropwhile() function to filter-out
        # first "/" (empty pathElement) and ".." (pathElement == os.pardir); then joins the result back to the path
        # representation
        files = (os.path.join(*(itertools.dropwhile(lambda pathElement: not pathElement or pathElement == os.pardir,
                                                    os.path.normpath(path).split(os.sep)))) for path in files)

        return self.__expandWilds(files)



    def __expandWilds(self, files):
        "Expand wildcards in list of files."

        cwdSave = os.getcwd()
        try:
            os.chdir(os.path.expanduser(self.__spec.get(self.__CFG_SECTION_CONTENT, str(_ArchiveSpecOptions.PATH))))
        except OSError as ex:
            if self.__componentUi:
                self.__componentUi.showError(ex)
            return frozenset()

        expandedFiles = set()
        for fileName in files:
            expanded = glob.glob(fileName)
            if expanded:
                expandedFiles.update(expanded)
            else:
                if self.__componentUi:
                    self.__componentUi.showWarning(
                        str.format("Cannot access \"{}\". No such file or directory.", fileName))

        os.chdir(cwdSave)
        return frozenset(expandedFiles)



    @staticmethod
    def __clearQuotes(files):
        "Remove quotes from file names."

        for fileName in files:
            match = re.search('(?<=").+(?=")', fileName)
            if match is not None:
                yield match.group(0)
            else:
                yield fileName

    # }}} file lists processing

    # }}} options adding sub-helpers

    # }}} options adding

    # }}} helpers



class _ArchiveSpecOptions(metaclass = ABCMeta):
    """Constants for options used specifically in the :term:`archive specification file`.

    These constants should be used to access options in :class:`_ArchiveSpec`.

    .. note:: It is not allowed to change values of these constants."""

    #: Archive name (``str``).  Guaranteed to be defined.
    NAME = Option("name", str)

    #: Path to the base directory for :data:`INCLUDE_FILES`, :data:`EXCLUDE_FILES` (:data:`.SpecialOptionTypes.PATH`).
    #: Guaranteed to be defined.
    PATH = Option("path", SpecialOptionTypes.PATH)

    #: Files and directories that will be included in the :term:`backup` (``frozenset<str>``).
    #: Note that frozenset<str> is not supported by :meth:`.OptionsUtils.strToOptionType()`; it is not used while
    #: populating this option.  Guaranteed to be defined.
    INCLUDE_FILES = Option("include-files", str)

    #: Files and directories that will be excluded from the :term:`backup` (``frozenset<str>``).
    #: Note that frozenset<str> is not supported by :meth:`.OptionsUtils.strToOptionType()`; it is not used while
    #: populating this option.  Guaranteed to be defined.
    EXCLUDE_FILES = Option("exclude-files", str)



    @abstractmethod
    def __init__(self):
        pass

# }}} CLASSES
