# Copyright (C) 2009, Tutorius.org
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
"""
This module contains properties class that can be included in other types.
TutoriusProperties have the same behaviour as python properties (assuming you
also use the TPropContainer), with the added benefit of having builtin dialog
prompts and constraint validation.
"""

from sugar.tutorius.constraints import Constraint, \
        UpperLimitConstraint, LowerLimitConstraint, \
        MaxSizeConstraint, MinSizeConstraint, \
        ColorConstraint, FileConstraint, BooleanConstraint, EnumConstraint
from copy import copy

class TPropContainer(object):
    """
    A class containing properties. This does the attribute wrapping between
    the container instance and the property value. As properties are on the
    containing classes, they allow static introspection of those types
    at the cost of needing a mapping between container instances, and 
    property values. This is what TPropContainer does.
    """
    def __init__(self):
        """
        Prepares the instance for property value storage. This is done at
        object initialization, thus allowing initial mapping of properties
        declared on the class. Properties won't work correctly without
        this call.
        """
        # create property value storage
        object.__setattr__(self, "_props", {})
        for attr_name in dir(type(self)):
            propinstance = object.__getattribute__(self, attr_name)
            if isinstance(propinstance, TutoriusProperty):
                # only care about TutoriusProperty instances
                propinstance.tname = attr_name
                self._props[attr_name] = propinstance.validate(
                        copy(propinstance.default))

    def __getattribute__(self, name):
        """
        Process the 'fake' read of properties in the appropriate instance
        container. Pass 'real' attributes as usual.
        """
        try:
            props = object.__getattribute__(self, "_props")
        except AttributeError:
            # necessary for deepcopy as order of init can't be guaranteed
            object.__setattr__(self, "_props", {})
            props = object.__getattribute__(self, "_props")

        try:
            # try gettin value from property storage
            # if it's not in the map, it's not a property or its default wasn't
            # set at initialization.
            return props[name]
        except KeyError:
            return object.__getattribute__(self, name)

    def __setattr__(self, name, value):
        """
        Process the 'fake' write of properties in the appropriate instance
        container. Pass 'real' attributes as usual.

        @param name the name of the property
        @param value the value to assign to name
        @return the setted value
        """
        props = object.__getattribute__(self, "_props")
        try:
            # We attempt to get the property object with __getattribute__ 
            # to work through inheritance and benefit of the MRO.
            return props.__setitem__(name,
                    object.__getattribute__(self, name).validate(value))
        except AttributeError:
            return object.__setattr__(self, name, value)

    def get_properties(self):
        """
        Return the list of property names.
        """
        return object.__getattribute__(self, "_props").keys()

    def __eq__(self, otherContainer):
        """
        Compare this property container to the other one and returns True only if
        the every property of the first one can be found in the other container, with
        the same name and the same value.
        
        @param otherContainer The other container that we wish to test for equality.
        @returns True if every property in the first container can be found with the same
                    value and the same name in the second container.
        """
        # Make sure both have the same number of properties
        if len(self._props) != len(otherContainer._props):
            return False

        if not(type(self) == type(otherContainer)):
            return False

        # For every property in this container
        for prop in self._props.keys():
            found = False
            # Try to match it with another property present in the other container
            for otherProp in otherContainer._props.keys():
                # If we were able to match the name, then we look up the value
                if prop == otherProp:
                    this_type = getattr(type(self), prop).type
                    other_type = getattr(type(otherContainer), prop).type
                    if this_type != other_type:
                        return False
                    
                    # If this is an addon list, then we need to make sure that
                    # every element of the list is also present in the other list
                    if this_type == "addonlist":
                        if not self._are_lists_identical(self._props[prop], otherContainer._props[prop]):
                            return False
                        found = True
                        break

                    # If this is just an embedded / decorated container, then we want to 
                    # make sure the sub component are identical.
                    elif this_type == "addon":
                        if not (self._props[prop] == otherContainer._props[prop]):
                            return False
                        found = True
                        break
                    else:
                        if self._props[prop] == otherContainer._props[prop]:
                            found = True
                            break
            # If we arrive here, then we couldn't find any property in the second 
            # container that matched the current one. We know that the two containers are
            # not equal.
            if found == False:
                return False
        return True
    
    def _are_lists_identical(self, myList, otherList):
        """
        Compares two lists of property containers to see if they are identical (
        they have the same properties
        
        @param myList The first list of properties containers
        @param otherList The second list of properties containers
        @return True if all of the properties inside the list are identical. False otherwise.
        """
        # For each property in the first list,
        for container in myList:
            found = False
            # Attempt to match it with every property in the other list
            for other_container in otherList:
                # If the containers are identical,
                if container == other_container:
                    # We found a matching container. We don't need to search in the
                    # second list anymore, so we break
                    found = True
                    break
            # In the case the property was not found inside the second list
            if found == False:  
                # We know right away that the two lists are not identical
                return False
        # If we were able to match each property in the first list, then we
        # can say the lists are equal.
        return True
    
class TutoriusProperty(object):
    """
    The base class for all actions' properties. The interface is the following :
    
    value : the value of the property
    
    type : the type of the property
    
    get_contraints() : the constraints inserted on this property. They define
    what is acceptable or not as values.
    """
    def __init__(self):
        super(TutoriusProperty, self).__init__()
        self.type = None
        self._constraints = None
        self.default = None
        
    def get_constraints(self):
        """
        Returns the list of constraints associated to this property.
        """
        if self._constraints is None:
            self._constraints = []
            for i in dir(self):
                typ = getattr(self, i)
                if isinstance(typ, Constraint):
                    self._constraints.append(i)
        return self._constraints

    def validate(self, value):
        """
        Validates the value of the property. If the value does not respect
        the constraints on the property, this method will raise an exception.
        
        The exception should be of the type related to the constraint that
        failed. E.g. When a int is to be set with a value that 
        """
        for constraint_name in self.get_constraints():
            constraint = getattr(self, constraint_name)
            constraint.validate(value)
        return value

class TAddonListProperty(TutoriusProperty):
    """
    Stores an addon component list as a property.
    The purpose of this class is to allow correct mapping of properties
    through encapsulated hierarchies.
    """
    pass

class TIntProperty(TutoriusProperty):
    """
    Represents an integer. Can have an upper value limit and/or a lower value
    limit.
    """
    
    def __init__(self, value, lower_limit=None, upper_limit=None):
        TutoriusProperty.__init__(self)
        self.type = "int"
        self.upper_limit = UpperLimitConstraint(upper_limit)
        self.lower_limit = LowerLimitConstraint(lower_limit)
        
        self.default = self.validate(value)
    
class TFloatProperty(TutoriusProperty):
    """
    Represents a floating point number. Can have an upper value limit and/or
    a lower value limit.
    """
    def __init__(self, value, lower_limit=None, upper_limit=None):
        TutoriusProperty.__init__(self)
        self.type = "float"
        
        self.upper_limit = UpperLimitConstraint(upper_limit)
        self.lower_limit = LowerLimitConstraint(lower_limit)
        
        self.default = self.validate(value)
    
class TStringProperty(TutoriusProperty):
    """
    Represents a string. Can have a maximum size limit.
    """
    def __init__(self, value, size_limit=None):
        TutoriusProperty.__init__(self)
        self.type = "string"
        self.size_limit = MaxSizeConstraint(size_limit)
        
        self.default = self.validate(value)
    
class TArrayProperty(TutoriusProperty):
    """
    Represents an array of properties. Can have a maximum number of element 
    limit, but there are no constraints on the content of the array.
    """
    def __init__(self, value, min_size_limit=None, max_size_limit=None):
        TutoriusProperty.__init__(self)
        self.type = "array"
        self.max_size_limit = MaxSizeConstraint(max_size_limit)
        self.min_size_limit = MinSizeConstraint(min_size_limit)
        self.default = self.validate(value)
    
class TColorProperty(TutoriusProperty):
    """
    Represents a RGB color with 3 8-bit integer values.
    
    The value of the property is the array [R, G, B]
    """
    def __init__(self, red=None, green=None, blue=None):
        TutoriusProperty.__init__(self)
        self.type = "color"
        
        self.color_constraint = ColorConstraint()
        
        self._red = red or 0
        self._green = green or 0
        self._blue = blue or 0
        
        self.default = self.validate([self._red, self._green, self._blue])
    
class TFileProperty(TutoriusProperty):
    """
    Represents a path to a file on the disk.
    """
    def __init__(self, path):
        """
        Defines the path to an existing file on disk file.
        
        For now, the path may be relative or absolute, as long as it exists on
        the local machine.
        TODO : Make sure that we have a file scheme that supports distribution
        on other computers (LP 355197)
        """
        TutoriusProperty.__init__(self)
        
        self.type = "file"
        
        self.file_constraint = FileConstraint()
        
        self.default = self.validate(path)
    
class TEnumProperty(TutoriusProperty):
    """
    Represents a value in a given enumeration. This means that the value will
    always be one in the enumeration and nothing else.
    
    """
    def __init__(self, value, accepted_values):
        """
        Creates the enumeration property.
        
        @param value The initial value of the enum. Must be part of 
        accepted_values
        @param accepted_values A list of values that the property can take
        """
        TutoriusProperty.__init__(self)
        
        self.type = "enum"
        
        self.enum_constraint = EnumConstraint(accepted_values)
        
        self.default = self.validate(value)
    
class TBooleanProperty(TutoriusProperty):
    """
    Represents a True or False value.
    """
    def __init__(self, value=False):
        TutoriusProperty.__init__(self)
        
        self.type = "boolean"
        
        self.boolean_constraint = BooleanConstraint()
        
        self.default = self.validate(value)
    
class TUAMProperty(TutoriusProperty):
    """
    Represents a widget of the interface by storing its UAM.
    """
    # TODO : Pending UAM check-in (LP 355199)
    pass

class TAddonProperty(TutoriusProperty):
    """
    Reprensents an embedded tutorius Addon Component (action, trigger, etc.)
    The purpose of this class is to flag the container for proper
    serialization, as the contained object can't be directly dumped to text
    for its attributes to be saved.
    """
    class NullAction(TPropContainer):
        def do(self): pass
        def undo(self): pass

    def __init__(self):
        super(TAddonProperty, self).__init__()
        self.type = "addon"
        self.default = self.NullAction()

    def validate(self, value):
        if isinstance(value, TPropContainer):
            return super(TAddonProperty, self).validate(value)
        raise ValueError("Expected TPropContainer instance as TaddonProperty value")

class TAddonListProperty(TutoriusProperty):
    """
    Reprensents an embedded tutorius Addon List Component.
    See TAddonProperty
    """
    def __init__(self):
        TutoriusProperty.__init__(self)
        self.type = "addonlist"
        self.default = []

    def validate(self, value):
        if isinstance(value, list):
            for component in value:
                if not (isinstance(component, TPropContainer)):
                    raise ValueError("Expected a list of TPropContainer instances inside TAddonListProperty value, got a %s" % (str(type(component))))
            return value
        raise ValueError("Value proposed to TAddonListProperty is not a list")