var SyntaxReferenceError = require('./error').SyntaxReferenceError;
var SyntaxMatchError = require('./error').SyntaxMatchError;
var names = require('../utils/names');
var generic = require('./generic');
var parse = require('../definition-syntax/parse');
var generate = require('../definition-syntax/generate');
var walk = require('../definition-syntax/walk');
var prepareTokens = require('./prepare-tokens');
var buildMatchGraph = require('./match-graph').buildMatchGraph;
var matchAsTree = require('./match').matchAsTree;
var trace = require('./trace');
var search = require('./search');
var getStructureFromConfig = require('./structure').getStructureFromConfig;
var cssWideKeywords = buildMatchGraph('inherit | initial | unset');
var cssWideKeywordsWithExpression = buildMatchGraph('inherit | initial | unset | <-ms-legacy-expression>');

function dumpMapSyntax(map, compact, syntaxAsAst) {
    var result = {};

    for (var name in map) {
        if (map[name].syntax) {
            result[name] = syntaxAsAst
                ? map[name].syntax
                : generate(map[name].syntax, { compact: compact });
        }
    }

    return result;
}

function dumpAtruleMapSyntax(map, compact, syntaxAsAst) {
    const result = {};

    for (const [name, atrule] of Object.entries(map)) {
        result[name] = {
            prelude: atrule.prelude && (
                syntaxAsAst
                    ? atrule.prelude.syntax
                    : generate(atrule.prelude.syntax, { compact })
            ),
            descriptors: atrule.descriptors && dumpMapSyntax(atrule.descriptors, compact, syntaxAsAst)
        };
    }

    return result;
}

function valueHasVar(tokens) {
    for (var i = 0; i < tokens.length; i++) {
        if (tokens[i].value.toLowerCase() === 'var(') {
            return true;
        }
    }

    return false;
}

function buildMatchResult(match, error, iterations) {
    return {
        matched: match,
        iterations: iterations,
        error: error,
        getTrace: trace.getTrace,
        isType: trace.isType,
        isProperty: trace.isProperty,
        isKeyword: trace.isKeyword
    };
}

function matchSyntax(lexer, syntax, value, useCommon) {
    var tokens = prepareTokens(value, lexer.syntax);
    var result;

    if (valueHasVar(tokens)) {
        return buildMatchResult(null, new Error('Matching for a tree with var() is not supported'));
    }

    if (useCommon) {
        result = matchAsTree(tokens, lexer.valueCommonSyntax, lexer);
    }

    if (!useCommon || !result.match) {
        result = matchAsTree(tokens, syntax.match, lexer);
        if (!result.match) {
            return buildMatchResult(
                null,
                new SyntaxMatchError(result.reason, syntax.syntax, value, result),
                result.iterations
            );
        }
    }

    return buildMatchResult(result.match, null, result.iterations);
}

var Lexer = function(config, syntax, structure) {
    this.valueCommonSyntax = cssWideKeywords;
    this.syntax = syntax;
    this.generic = false;
    this.atrules = {};
    this.properties = {};
    this.types = {};
    this.structure = structure || getStructureFromConfig(config);

    if (config) {
        if (config.types) {
            for (var name in config.types) {
                this.addType_(name, config.types[name]);
            }
        }

        if (config.generic) {
            this.generic = true;
            for (var name in generic) {
                this.addType_(name, generic[name]);
            }
        }

        if (config.atrules) {
            for (var name in config.atrules) {
                this.addAtrule_(name, config.atrules[name]);
            }
        }

        if (config.properties) {
            for (var name in config.properties) {
                this.addProperty_(name, config.properties[name]);
            }
        }
    }
};

Lexer.prototype = {
    structure: {},
    checkStructure: function(ast) {
        function collectWarning(node, message) {
            warns.push({
                node: node,
                message: message
            });
        }

        var structure = this.structure;
        var warns = [];

        this.syntax.walk(ast, function(node) {
            if (structure.hasOwnProperty(node.type)) {
                structure[node.type].check(node, collectWarning);
            } else {
                collectWarning(node, 'Unknown node type `' + node.type + '`');
            }
        });

        return warns.length ? warns : false;
    },

    createDescriptor: function(syntax, type, name, parent = null) {
        var ref = {
            type: type,
            name: name
        };
        var descriptor = {
            type: type,
            name: name,
            parent: parent,
            syntax: null,
            match: null
        };

        if (typeof syntax === 'function') {
            descriptor.match = buildMatchGraph(syntax, ref);
        } else {
            if (typeof syntax === 'string') {
                // lazy parsing on first access
                Object.defineProperty(descriptor, 'syntax', {
                    get: function() {
                        Object.defineProperty(descriptor, 'syntax', {
                            value: parse(syntax)
                        });

                        return descriptor.syntax;
                    }
                });
            } else {
                descriptor.syntax = syntax;
            }

            // lazy graph build on first access
            Object.defineProperty(descriptor, 'match', {
                get: function() {
                    Object.defineProperty(descriptor, 'match', {
                        value: buildMatchGraph(descriptor.syntax, ref)
                    });

                    return descriptor.match;
                }
            });
        }

        return descriptor;
    },
    addAtrule_: function(name, syntax) {
        if (!syntax) {
            return;
        }

        this.atrules[name] = {
            type: 'Atrule',
            name: name,
            prelude: syntax.prelude ? this.createDescriptor(syntax.prelude, 'AtrulePrelude', name) : null,
            descriptors: syntax.descriptors
                ? Object.keys(syntax.descriptors).reduce((res, descName) => {
                    res[descName] = this.createDescriptor(syntax.descriptors[descName], 'AtruleDescriptor', descName, name);
                    return res;
                }, {})
                : null
        };
    },
    addProperty_: function(name, syntax) {
        if (!syntax) {
            return;
        }

        this.properties[name] = this.createDescriptor(syntax, 'Property', name);
    },
    addType_: function(name, syntax) {
        if (!syntax) {
            return;
        }

        this.types[name] = this.createDescriptor(syntax, 'Type', name);

        if (syntax === generic['-ms-legacy-expression']) {
            this.valueCommonSyntax = cssWideKeywordsWithExpression;
        }
    },

    checkAtruleName: function(atruleName) {
        if (!this.getAtrule(atruleName)) {
            return new SyntaxReferenceError('Unknown at-rule', '@' + atruleName);
        }
    },
    checkAtrulePrelude: function(atruleName, prelude) {
        let error = this.checkAtruleName(atruleName);

        if (error) {
            return error;
        }

        var atrule = this.getAtrule(atruleName);

        if (!atrule.prelude && prelude) {
            return new SyntaxError('At-rule `@' + atruleName + '` should not contain a prelude');
        }

        if (atrule.prelude && !prelude) {
            return new SyntaxError('At-rule `@' + atruleName + '` should contain a prelude');
        }
    },
    checkAtruleDescriptorName: function(atruleName, descriptorName) {
        let error = this.checkAtruleName(atruleName);

        if (error) {
            return error;
        }

        var atrule = this.getAtrule(atruleName);
        var descriptor = names.keyword(descriptorName);

        if (!atrule.descriptors) {
            return new SyntaxError('At-rule `@' + atruleName + '` has no known descriptors');
        }

        if (!atrule.descriptors[descriptor.name] &&
            !atrule.descriptors[descriptor.basename]) {
            return new SyntaxReferenceError('Unknown at-rule descriptor', descriptorName);
        }
    },
    checkPropertyName: function(propertyName) {
        var property = names.property(propertyName);

        // don't match syntax for a custom property
        if (property.custom) {
            return new Error('Lexer matching doesn\'t applicable for custom properties');
        }

        if (!this.getProperty(propertyName)) {
            return new SyntaxReferenceError('Unknown property', propertyName);
        }
    },

    matchAtrulePrelude: function(atruleName, prelude) {
        var error = this.checkAtrulePrelude(atruleName, prelude);

        if (error) {
            return buildMatchResult(null, error);
        }

        if (!prelude) {
            return buildMatchResult(null, null);
        }

        return matchSyntax(this, this.getAtrule(atruleName).prelude, prelude, false);
    },
    matchAtruleDescriptor: function(atruleName, descriptorName, value) {
        var error = this.checkAtruleDescriptorName(atruleName, descriptorName);

        if (error) {
            return buildMatchResult(null, error);
        }

        var atrule = this.getAtrule(atruleName);
        var descriptor = names.keyword(descriptorName);

        return matchSyntax(this, atrule.descriptors[descriptor.name] || atrule.descriptors[descriptor.basename], value, false);
    },
    matchDeclaration: function(node) {
        if (node.type !== 'Declaration') {
            return buildMatchResult(null, new Error('Not a Declaration node'));
        }

        return this.matchProperty(node.property, node.value);
    },
    matchProperty: function(propertyName, value) {
        var error = this.checkPropertyName(propertyName);

        if (error) {
            return buildMatchResult(null, error);
        }

        return matchSyntax(this, this.getProperty(propertyName), value, true);
    },
    matchType: function(typeName, value) {
        var typeSyntax = this.getType(typeName);

        if (!typeSyntax) {
            return buildMatchResult(null, new SyntaxReferenceError('Unknown type', typeName));
        }

        return matchSyntax(this, typeSyntax, value, false);
    },
    match: function(syntax, value) {
        if (typeof syntax !== 'string' && (!syntax || !syntax.type)) {
            return buildMatchResult(null, new SyntaxReferenceError('Bad syntax'));
        }

        if (typeof syntax === 'string' || !syntax.match) {
            syntax = this.createDescriptor(syntax, 'Type', 'anonymous');
        }

        return matchSyntax(this, syntax, value, false);
    },

    findValueFragments: function(propertyName, value, type, name) {
        return search.matchFragments(this, value, this.matchProperty(propertyName, value), type, name);
    },
    findDeclarationValueFragments: function(declaration, type, name) {
        return search.matchFragments(this, declaration.value, this.matchDeclaration(declaration), type, name);
    },
    findAllFragments: function(ast, type, name) {
        var result = [];

        this.syntax.walk(ast, {
            visit: 'Declaration',
            enter: function(declaration) {
                result.push.apply(result, this.findDeclarationValueFragments(declaration, type, name));
            }.bind(this)
        });

        return result;
    },

    getAtrule: function(atruleName, fallbackBasename = true) {
        var atrule = names.keyword(atruleName);
        var atruleEntry = atrule.vendor && fallbackBasename
            ? this.atrules[atrule.name] || this.atrules[atrule.basename]
            : this.atrules[atrule.name];

        return atruleEntry || null;
    },
    getAtrulePrelude: function(atruleName, fallbackBasename = true) {
        const atrule = this.getAtrule(atruleName, fallbackBasename);

        return atrule && atrule.prelude || null;
    },
    getAtruleDescriptor: function(atruleName, name) {
        return this.atrules.hasOwnProperty(atruleName) && this.atrules.declarators
            ? this.atrules[atruleName].declarators[name] || null
            : null;
    },
    getProperty: function(propertyName, fallbackBasename = true) {
        var property = names.property(propertyName);
        var propertyEntry = property.vendor && fallbackBasename
            ? this.properties[property.name] || this.properties[property.basename]
            : this.properties[property.name];

        return propertyEntry || null;
    },
    getType: function(name) {
        return this.types.hasOwnProperty(name) ? this.types[name] : null;
    },

    validate: function() {
        function validate(syntax, name, broken, descriptor) {
            if (broken.hasOwnProperty(name)) {
                return broken[name];
            }

            broken[name] = false;
            if (descriptor.syntax !== null) {
                walk(descriptor.syntax, function(node) {
                    if (node.type !== 'Type' && node.type !== 'Property') {
                        return;
                    }

                    var map = node.type === 'Type' ? syntax.types : syntax.properties;
                    var brokenMap = node.type === 'Type' ? brokenTypes : brokenProperties;

                    if (!map.hasOwnProperty(node.name) || validate(syntax, node.name, brokenMap, map[node.name])) {
                        broken[name] = true;
                    }
                }, this);
            }
        }

        var brokenTypes = {};
        var brokenProperties = {};

        for (var key in this.types) {
            validate(this, key, brokenTypes, this.types[key]);
        }

        for (var key in this.properties) {
            validate(this, key, brokenProperties, this.properties[key]);
        }

        brokenTypes = Object.keys(brokenTypes).filter(function(name) {
            return brokenTypes[name];
        });
        brokenProperties = Object.keys(brokenProperties).filter(function(name) {
            return brokenProperties[name];
        });

        if (brokenTypes.length || brokenProperties.length) {
            return {
                types: brokenTypes,
                properties: brokenProperties
            };
        }

        return null;
    },
    dump: function(syntaxAsAst, pretty) {
        return {
            generic: this.generic,
            types: dumpMapSyntax(this.types, !pretty, syntaxAsAst),
            properties: dumpMapSyntax(this.properties, !pretty, syntaxAsAst),
            atrules: dumpAtruleMapSyntax(this.atrules, !pretty, syntaxAsAst)
        };
    },
    toString: function() {
        return JSON.stringify(this.dump());
    }
};

module.exports = Lexer;