/* <copyright>
Copyright (c) 2012, Motorola Mobility LLC.
All Rights Reserved.

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* Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.

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  this list of conditions and the following disclaimer in the documentation
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  contributors may be used to endorse or promote products derived from this
  software without specific prior written permission.

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</copyright> */

var Montage = require("montage").Montage;
var AbstractLanguage = require("./abstract-language").AbstractLanguage;
var Semantics = require("./semantics").Semantics;
var PropertyLanguage = require("./property-language").PropertyLanguage;

var Language = exports.Language = AbstractLanguage.create(AbstractLanguage, {

    semantics: {
        value: Semantics
    },

    grammar: {
        value: function () {

            // precedence

            this.parsePrimary(function (callback) {
                return parseExpression(callback);
            });

            this.parseProperties();
            this.parseLeftToRight(['startsWith', 'endsWith']);
            this.parseLeftToRight(['pow']);
            this.parseLeftToRight(['mul', 'div', 'mod']);
            this.parseLeftToRight(['add', 'sub']);
            this.parseBinary(['lessThan', 'greaterThan', 'lessThanOrEquals', 'greaterThanOrEquals']);
            this.parseBinary(['equals', 'notEquals']);
            this.parseLeftToRight(['xor']);
            this.parseLeftToRight(['and']);
            this.parseLeftToRight(['or']);
            this.parseConditional();
            var parseScalar = this.precedence();

            this.parseArray();
            this.parseRightToLeft(['has', 'contains', 'every', 'some', 'one', 'only', 'filter', 'map', 'it']);
            this.parseSorted(parseScalar);
            this.parseSlice(parseScalar);
            this.parseRightToLeft(['sum', 'count', 'average', 'unique', 'flatten']);
            var parseExpression = this.precedence();

            // TODO median, mode, flatten, any, all

            // extra

            this.parseOperator(); // to collect the needed tokens

        }
    },

    aliases: {
        value: {
            lt: 'lessThan',
            gt: 'greaterThan',
            le: 'lessThanOrEquals',
            ge: 'greaterThanOrEquals',
            eq: 'equals',
            ne: 'notEquals'
        }
    },

    constants: {
        value: {
            'true': true,
            'false': false
        }
    },

    selectorExtras: {
        value: {

            // Shorthand for chained gets
            property: {
                value: function (path) {
                    try {
                        var self = this;
                        var syntax = PropertyLanguage.parse(path);
                        PropertyLanguage.reemit(syntax, function (token) {
                            self = self.emit(token);
                        })
                        return self;
                    } catch (exception) {
                        throw exception;
                        throw new SyntaxError(
                            "Can't parse property: " + JSON.stringify(path) + ": " +
                            exception.message
                        );
                    }
                }
            },

            // Shorthand using object literals
            matches: {
                value: function (object) {
                    var Selector = this.language.Selector;
                    var selector = this.it["true"];
                    var tokens = selector.language.tokens;
                    for (var property_operator in object) {
                        var value = object[property_operator];
                        property_operator = property_operator.split('_');
                        var property = property_operator.shift();
                        selector.emit(tokens.and);
                        Selector.property(property).tokens.forEach(function (token) {
                            selector.emit(token);
                        });
                        if (property_operator.length) {
                            property_operator.forEach(function (operator) {
                                selector.emit(tokens[operator]);
                            });
                        } else {
                            selector.emit(tokens.equals);
                        }
                        selector.emit({type: 'literal', value: value});
                    }
                    return selector;
                }
            }

        }
    },

    parseIdentifier: {
        value: function (callback) {
            var self = this;
            self.requireTokens(['literal']);
            return function (token) {
                if (token.type === 'literal' && typeof token.value === 'string') {
                    return callback(token.value);
                } else {
                    throw new SyntaxError('Expected identifier, got: ' + JSON.stringify(token.type));
                }
            };
        }
    },

    parseUrPrimary: {
        value: function (callback, parseExpression, negated, rewindNegation) {
            var self = this;
            return function (token) {
                if (token.type === 'begin') {
                    return parseExpression(function (expression) {
                        return self.expect('end', function () {
                            return callback(expression, negated);
                        });
                    });
                } else if (token.type === 'value') {
                    return callback(self.tokens.value, negated);
                } else if (token.type === 'parameter') {
                    return self.parseIdentifier(function (name) {
                        var syntax = name.split(".").reduce(function (previous, name) {
                            return {
                                type: 'get',
                                args: [previous, {
                                    type: 'literal',
                                    value: name
                                }]
                            }
                        }, {type: 'parameters'})
                        return callback(syntax, negated);
                    })
                } else if (token.type === 'literal') {
                    return callback(token, negated);
                } else if (self.constants[token.type]) {
                    return callback(self.constantSyntax[token.type], negated);
                } else {
                    return rewindNegation(
                        callback(
                            self.tokens.value,
                            false
                        )
                    )(token);
                }
            };
        }
    },

    parsePrimary: {
        value: function (parseExpression) {
            var self = this;
            self.requireTokens(['begin', 'end', 'value', 'literal', 'parameter', 'not']);
            return self.precedence(function () { // first level of precedence
                return function (callback) {
                    return self.optional('not', function (negated, rewindNegation) {
                        return self.parseUrPrimary(function (expression, stillNegated) {
                            if (stillNegated) {
                                expression = self.makeSyntax('not', [expression]);
                            }
                            return callback(expression);
                        }, parseExpression, negated, rewindNegation);
                    });
                }
            });
        }
    },

    parseProperties: {
        value: function () {
            var self = this;
            self.requireTokens(['get']);
            var parseSelf = self.precedence(function (parsePrevious) {
                return function (callback, previous) {
                    return function (token) {
                        if (token.type === 'get') {
                            return self.expect('literal', function (literal) {
                                previous = self.makeSyntax('get', [previous || self.tokens.value, literal]);
                                return parseSelf(callback, previous);
                            });
                        } else if (previous) {
                            return callback(previous)(token);
                        } else {
                            return parsePrevious(callback)(token);
                        }
                    }
                };
            });
            return parseSelf;
        }
    },

    parseConditional: {
        value: function () {
            var self = this;
            self.requireTokens(['if', 'then', 'else']);
            return self.precedence(function (parsePrevious) {
                return function (callback) {
                    return function (token) {
                        if (token.type === 'if') {
                            return parsePrevious(function (guard) {
                                return self.expect('then', function () {
                                    return parsePrevious(function (consequent) {
                                        return self.expect('else', function () {
                                            return parsePrevious(function (alternate) {
                                                return callback(self.makeSyntax('if', [
                                                    guard,
                                                    consequent,
                                                    alternate
                                                ]));
                                            });
                                        });
                                    });
                                });
                            });
                        } else {
                            return parsePrevious(callback)(token);
                        }
                    }
                };
            });
        }
    },

    parseArray: {
        value: function () {
            var self = this;
            self.requireTokens(['array', 'comma']);
            var parseSelf = self.precedence(function (parsePrevious) {
                return function (callback) {
                    return self.optional('array', function (array) {
                        if (array) {
                            return self.parseArrayTerms(function (terms) {
                                return callback({
                                    type: 'array',
                                    terms: terms
                                })
                            }, [], parsePrevious);
                        } else {
                            return parsePrevious(callback);
                        }
                    });
                };
            })
            return parseSelf;
        }
    },

    parseArrayTerms: {
        value: function (callback, previousTerms, parsePrevious) {
            var self = this;
            return self.optional('end', function (end, rewindEnd) {
                if (end) {
                    return callback(previousTerms);
                } else {
                    return parsePrevious(function (term) {
                        terms = previousTerms.concat([term]);
                        return self.optional('comma', function (comma) {
                            if (comma) {
                                return self.parseArrayTerms(
                                    callback,
                                    terms,
                                    parsePrevious
                                );
                            } else {
                                return self.expect('end', function () {
                                    return callback(terms);
                                });
                            }
                        });
                    })
                }
            });
        }
    },

    parseSorted: {
        value: function (parseScalar) {
            var self = this;
            self.requireTokens(['sorted', 'by', 'descending']);
            return self.precedence(function (parsePrevious) {
                return function (callback) {
                    return parsePrevious(function (left) {
                        return function (token) {
                            if (token.type === 'sorted') {
                                var parseDescending = function (by) {
                                    return self.optional('descending', function (descending) {
                                        return callback(self.makeSyntax('sorted', [
                                            left,
                                            by || {type: 'value'},
                                            {type: 'literal', value: descending}
                                        ]));
                                    });
                                };
                                return self.optional('by', function (by) {
                                    if (by) {
                                        return parseScalar(parseDescending);
                                    } else {
                                        return parseDescending();
                                    }
                                });
                            } else {
                                return callback(left)(token);
                            }
                        }
                    });
                };
            });
        }
    },

    // TODO rewrite to support slice(length).after(value)
    parseSlice: {
        value: function (parseScalar) {
            var self = this;
            self.requireTokens(['slice', 'from', 'comma']);
            return self.precedence(function (parsePrevious) {
                return function (callback) {
                    return parsePrevious(function (left) {
                        return function (token) {
                            if (token.type === 'slice') {
                                return self.optional('from', function (from) {
                                    return parseScalar(function (start) {
                                        return self.expect('comma', function (comma, rewindComma) {
                                            return parseScalar(function (stop) {
                                                return callback(self.makeSyntax(
                                                    from ? 'sliceFrom' : 'slice',
                                                    [
                                                        left,
                                                        start,
                                                        stop
                                                    ]
                                                ));
                                            });
                                        });
                                    });
                                });
                            } else {
                                return callback(left)(token);
                            }
                        }
                    });
                }
            });
        }
    }

});