#

# Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

# All rights reserved.

# This component and the accompanying materials are made available

# under the terms of "Eclipse Public License v1.0"

# which accompanies this distribution, and is available

# at the URL "http://www.eclipse.org/legal/epl-v10.html".

#

# Initial Contributors:

# Nokia Corporation - initial contribution.

#

# Contributors:

#

# Description: 

#

'''

implementation for ruleml relations.

'''

import os

import StringIO

import logging

import operator as ops

import re

import sys, traceback

log = logging.getLogger('cone.ruleplugin.relations')

from cone.public import api, rules, utils, exceptions, plugin

class RelationFactory(api.FactoryBase):

    @ classmethod

    def get_relation_by_name(cls, relation_name):

        """

        Get the class name by file extension.

        """

        try:

            return rules.RELATIONS.get(relation_name)

        except KeyError:

            raise exceptions.NotSupportedException("No Relation class found for name %s" % relation_name)

    @ classmethod

    def get_relations(cls, configuration, relation):

        try:

            relations = []

            (left_expression,relation_name,right_expression) = parse_rule(relation)

            relation = cls.get_relation_by_name(relation_name)(configuration, left_expression, right_expression)

            relations.append(relation)

            propagated_relations = cls.get_relations(configuration, right_expression)

            if propagated_relations:

                for relation in propagated_relations:

                    relations.append(relation)

            return relations

        except exceptions.ParseError:

            return None

class ConfigurationContext(rules.DefaultContext):

    def __init__(self, data):

        rules.DefaultContext.__init__(self, data)

        # A note on the callback variables that follow:

        # in order to collect rule execution results for the

        # generation report, a callback system is implemented in

        # ConfigurationContext.  It all boils down to ConfigureRelation

        # using configure_expression_result_callback to catch the result

        # in its execute() method. The ConfigurationContext just works as

        # a "callback hub" because a reference to the context is available

        # in all expression evaluations.

        # Callback called with a plugin.RelationExecutionResult object

        # when a ConfigureExpression has been evaluated

        self.configure_expression_result_callback = None

        # Callback called with the setting reference when a setting is dereferenced

        # as a terminal expression

        self.ref_terminal_callback = None

        # Callback called with the setting reference when a setting is dereferenced

        # inside an EvalExpression

        self.ref_eval_callback = None

        # Callback called with the setting reference when the value of a setting

        # is set inside a SetExpression

        self.ref_set_callback = None

    def handle_terminal(self, expression):

        try:

            value = self.data.get_default_view().get_feature(expression).get_value()

            # Got a valid ref, call the callback

            if self.ref_terminal_callback:

                self.ref_terminal_callback(expression)

            return value

        except exceptions.NotFound,e:

            """ return the expression itself if it is not a fearef """

            #print "handle_terminal constant %s" % (expression)

            try:

                return eval(expression)

            except (NameError,SyntaxError), e:

                return expression

    def eval(self, ast, expression, value):

        #print "expression %s = %s" % (expression,value)

        pass

class ConfigurationBaseRelation(rules.BaseRelation):

    def __init__(self, data, left, right):

        self.context = ConfigurationContext(data)

        super(ConfigurationBaseRelation, self).__init__(data, left, right)

class RequireRelation(ConfigurationBaseRelation):

    KEY = 'requires'

    def __init__(self, data, left, right):

        super(RequireRelation, self).__init__(data, left, right)

        self.context = ConfigurationContext(data)

class ConfigureRelation(ConfigurationBaseRelation):

    KEY = 'configures'

    def __init__(self, data, left, right):

        self.context = ConfigurationContext(data)

        super(ConfigureRelation, self).__init__(data, left, right)

        # A plugin.RelationExecutionResult object is stored here

        self._execution_result = None

    def execute(self):

        self._execution_result = None

        exec_results = []

        # Call BaseRelation.execute() and catch any ConfigureExpression result objects

        self.context.configure_expression_result_callback = lambda result: exec_results.append(result)

        result = rules.BaseRelation.execute(self)

        self.context.configure_expression_result_callback = None

        if len(exec_results) > 0:

            # There should be only one ConfigureExpression inside a ConfigureRelation

            if len(exec_results) > 1:

                log.warning("Execution of ConfigureRelation returned more than one result, ignoring all except the first")

            self._execution_result = exec_results[0]

        return result

    def get_execution_result(self):

        """

        Return the execution result from the most recent call to execute().

        """

        return self._execution_result

def handle_configure(self, left, right):

    if left and right:

        return True

    elif not left:

        return True

    return False

def handle_set(self, left, right):

    left.set_value(right)

def handle_filenamejoin(self, left, right):

    def extract_dirname(path):

        """Extract directory name (will always contain a trailing slash or backslash)"""

        pos = max(path.rfind('/'), path.rfind('\\'))

        if pos == -1:   return path + '/'

        else:           return path[:pos + 1]

    def extract_filename(path):

        pos = max(path.rfind('/'), path.rfind('\\'))

        if pos == -1:   return path

        else:           return path[pos + 1:]

    return extract_dirname(left) + extract_filename(right)

def handle_plus(self, left, right):

    return left + right

def handle_minus(self, left, right):

    return left - right

def handle_multiply(self, left, right):

    return left * right

def handle_divide(self, left, right):

    return left / right

class ConfigureExpression(rules.TwoOperatorExpression):

    PRECEDENCE = rules.PRECEDENCES['RELATION_OPERATORS']

    KEY = 'configures'

    OP = handle_configure

    def eval(self, context):

        input_refs = []

        affected_refs = []

        # Evaluate the left-hand side expression, catching refs for the result

        try:

            context.ref_terminal_callback = lambda ref: input_refs.append(ref)

            context.ref_eval_callback = lambda ref: input_refs.append(ref)

            evaluated_left = self.left.eval(context)

        finally:

            context.ref_terminal_callback = None

            context.ref_eval_callback = None

        if evaluated_left:

            # If left evaluated to True, evaluate the right-hand side and

            # catch refs from SetExpression evaluations

            try:

                context.ref_set_callback = lambda ref: affected_refs.append(ref)

                self.value = self.right.eval(context)

            finally:

                context.ref_set_callback = None

        else:

            self.value = True

        if not self.value:

            left_keys = []

            for ref in self.ast.extract_refs(str(self.left)):

                for key in context.get_keys(ref):

                    left_keys.append(key)

            for key in left_keys:

                self.ast.add_error(key, { 'error_string' : 'CONFIGURES right side value is "False"',

                                          'left_key' : key,

                                          'rule' : self.ast.expression

                                          })

        # Return a RelationExecutionResult if necessary

        if input_refs or affected_refs:

            if context.configure_expression_result_callback:

                result = plugin.RelationExecutionResult(utils.distinct_array(input_refs),

                                                        utils.distinct_array(affected_refs))

                context.configure_expression_result_callback(result)

        return self.value

class MultiplyExpression(rules.TwoOperatorExpression):

    expression = "multiply_operation"

    PRECEDENCE = rules.PRECEDENCES['MULDIV_OPERATORS']

    KEY= '*'

    OP = handle_multiply

class DivideExpression(rules.TwoOperatorExpression):

    expression = "divide_operation"

    PRECEDENCE = rules.PRECEDENCES['MULDIV_OPERATORS']

    KEY= '/'

    OP = handle_divide

class PlusExpression(rules.TwoOperatorExpression):

    expression = "plus_operation"

    PRECEDENCE = rules.PRECEDENCES['ADDSUB_OPERATORS']

    KEY= '+'

    OP = handle_plus

class MinusExpression(rules.TwoOperatorExpression):

    expression = "minus_operation"

    PRECEDENCE = rules.PRECEDENCES['ADDSUB_OPERATORS']

    KEY= '-'

    OP = handle_minus

class EvalExpression(rules.OneParamExpression):

    expression = "__eval__"

    PRECEDENCE = rules.PRECEDENCES['PREFIX_OPERATORS']

    KEY = '__eval__'

    def __init__(self, ast, expression):

        super(rules.OneParamExpression, self).__init__(ast)

        self.expression = expression

        self._str_to_eval = eval(expression.expression)

        #self.default_view = default_view

    def extract_refs(self):

        result = []

        result.extend(utils.extract_delimited_tokens(self._str_to_eval, delimiters=('${', '}')))

        result.extend(utils.extract_delimited_tokens(self._str_to_eval, delimiters=('@{', '}')))

        return result

    def eval(self, context):

        # Using the configuration to pass the eval globals dictionary to here,

        # since there isn't any easy way to do this more elegantly

        globals_and_locals = {}

        if hasattr(context.data, '_eval_expression_globals_dict'):

            globals_and_locals = context.data._eval_expression_globals_dict

        str_to_eval = self._str_to_eval

        def expand_feature_ref(ref, index):

            var_name = "__fea_%05d" % index

            globals_and_locals[var_name] = context.data.get_default_view().get_feature(ref)

            if context.ref_eval_callback:

                context.ref_eval_callback(ref)

            return var_name

        def expand_value_ref(ref, index):

            var_name = "__feaval_%05d" % index

            globals_and_locals[var_name] = context.data.get_default_view().get_feature(ref).get_value()

            if context.ref_eval_callback:

                context.ref_eval_callback(ref)

            return var_name

        str_to_eval = utils.expand_delimited_tokens(str_to_eval, expand_feature_ref, delimiters=('@{', '}'))

        str_to_eval = utils.expand_delimited_tokens(str_to_eval, expand_value_ref, delimiters=('${', '}'))

        # Strip leading and trailing whitespace to avoid indentation problems

        str_to_eval = str_to_eval.strip()

        ret = None

        try:

            ret = eval(str_to_eval, globals_and_locals)

            return ret

        except SyntaxError, e:

            logging.getLogger('cone.ruleml').warning("Invalid syntax in eval: %s" % (str_to_eval) )

            self.ast.add_error(self.expression, { 'error_string' : 'Invalid syntax in eval', 'str_to_eval' : str_to_eval, 'rule' : self.ast.expression })

        except Exception, e:

            logging.getLogger('cone.ruleml').warning("Execution failed for eval: %s %s: %s" % (str_to_eval, type(e), e) )

            self.ast.add_error(self.expression, { 'error_string' : 'Execution failed for eval', 'str_to_eval' : str_to_eval, 'rule' : self.ast.expression })

rules.OPERATORS[EvalExpression.KEY] = EvalExpression

class FilenamejoinExpression(rules.TwoOperatorExpression):

    expression = "filenamejoin"

    PRECEDENCE = rules.PRECEDENCES['ADDSUB_OPERATORS']

    KEY = 'filenamejoin'

    OP = handle_filenamejoin

rules.OPERATORS[FilenamejoinExpression.KEY] = FilenamejoinExpression

class SetExpression(rules.TwoOperatorExpression):

    PRECEDENCE = rules.PRECEDENCES['SET_OPERATORS']

    KEY= '='

    OP = handle_set

    def eval(self, context):

        try:

            variable = context.data.get_default_view().get_feature(self.left.expression)

            value = self.right.eval(context)

            variable.set_value(value)

            logging.getLogger('cone.ruleml').info("Set %r = %r from %r" % (self.left.expression, value, self.right.expression) )

            if context.ref_set_callback:

                context.ref_set_callback(self.left.expression)

            return True

        except exceptions.NotFound,e:

            self.ast.add_error(self.left.expression, { 'error_string' : 'Setting value failed, because of %s' % e,

                               'left_key' : self.left.expression,

                               'rule' : self.ast.expression})

            return False

_relations_and_operators_backup = None

def register():

    """

    Register the relations and operators to ConE rules.

    """

    global _relations_and_operators_backup

    if _relations_and_operators_backup is None:

        # Create the backup copies of the dictionaries

        rels_backup = rules.RELATIONS.copy()

        ops_backup = rules.OPERATORS.copy()

        assert rels_backup is not rules.RELATIONS

        assert ops_backup is not rules.OPERATORS

        _relations_and_operators_backup = (rels_backup, ops_backup)

        # Register relations and operators to rules

        rules.RELATIONS[RequireRelation.KEY] = RequireRelation

        rules.RELATIONS[ConfigureRelation.KEY] = ConfigureRelation

        rules.OPERATORS[ConfigureExpression.KEY] = ConfigureExpression

        rules.OPERATORS[PlusExpression.KEY] = PlusExpression

        rules.OPERATORS[SetExpression.KEY] = SetExpression

        rules.OPERATORS[MinusExpression.KEY] = MinusExpression

        rules.OPERATORS[MultiplyExpression.KEY] = MultiplyExpression

        rules.OPERATORS[DivideExpression.KEY] = DivideExpression

def unregister():

    """

    Undo the changes made by a call to register().

    """

    global _relations_and_operators_backup

    if _relations_and_operators_backup is not None:

        rules.RELATIONS = _relations_and_operators_backup[0]

        rules.OPERATORS = _relations_and_operators_backup[1]

        _relations_and_operators_backup = None

def parse_rule(rulestring):

    """

    Divide the given rule string into (left side, relation, right side) components. 

    @return: Triple (left side, relation, right side)

    """

    left_expression = ''

    relation_name = None

    right_expression = ''

    for token in rules.get_tokens(rulestring):

        if relation_name == None:

            if token in rules.RELATIONS.keys():

                relation_name = token

            else:

                left_expression += ' ' + token

        else:

            right_expression += ' ' + token

    if relation_name == None:

        raise exceptions.ParseError('invalid rule definition %s' % rulestring)

    return (left_expression,relation_name,right_expression)