var assert = require('assert');
var util = require('util');
var EventEmitter = require('events').EventEmitter;
var traverse = require('traverse');
var ModelBaseClass = require('./model');
var ModelBuilder = require('./model-builder');

/**
 * Model definition
 */
module.exports = ModelDefinition;

/**
 * Constructor for ModelDefinition
 * @param {ModelBuilder} modelBuilder A model builder instance
 * @param {String|Object} name The model name or the schema object
 * @param {Object} properties The model properties, optional
 * @param {Object} settings The model settings, optional
 * @returns {ModelDefinition}
 * @constructor
 *
 */
function ModelDefinition(modelBuilder, name, properties, settings) {
    if (!(this instanceof ModelDefinition)) {
        // Allow to call ModelDefinition without new
        return new ModelDefinition(modelBuilder, name, properties, settings);
    }
    this.modelBuilder = modelBuilder || ModelBuilder.defaultInstance;
    assert(name, 'name is missing');

    if (arguments.length === 2 && typeof name === 'object') {
        var schema = name;
        this.name = schema.name;
        this.rawProperties = schema.properties || {}; // Keep the raw property definitions
        this.settings = schema.settings || {};
    } else {
        assert(typeof name === 'string', 'name must be a string');
        this.name = name;
        this.rawProperties = properties || {}; // Keep the raw property definitions
        this.settings = settings || {};
    }
    this.associations = [];
    this.properties = null;
    this.build();
}

util.inherits(ModelDefinition, EventEmitter);

// Set up types
require('./types')(ModelDefinition);


/**
 * Return table name for specified `modelName`
 * @param {String} connectorType The connector type, such as 'oracle' or 'mongodb'
 */
ModelDefinition.prototype.tableName = function (connectorType) {
    var settings = this.settings;
    if(settings[connectorType]) {
        return settings[connectorType].table || settings[connectorType].tableName || this.name;
    } else {
        return this.name;
    }
};

/**
 * Return column name for specified modelName and propertyName
 * @param {String} connectorType The connector type, such as 'oracle' or 'mongodb'
 * @param propertyName The property name
 * @returns {String} columnName
 */
ModelDefinition.prototype.columnName = function (connectorType, propertyName) {
    if(!propertyName) {
        return propertyName;
    }
    this.build();
    var property = this.properties[propertyName];
    if(property && property[connectorType]) {
        return property[connectorType].column || property[connectorType].columnName || propertyName;
    } else {
        return propertyName;
    }
};

/**
 * Return column metadata for specified modelName and propertyName
 * @param {String} connectorType The connector type, such as 'oracle' or 'mongodb'
 * @param propertyName The property name
 * @returns {Object} column metadata
 */
ModelDefinition.prototype.columnMetadata = function (connectorType, propertyName) {
    if(!propertyName) {
        return propertyName;
    }
    this.build();
    var property = this.properties[propertyName];
    if(property && property[connectorType]) {
        return property[connectorType];
    } else {
        return null;
    }
};

/**
 * Return column names for specified modelName
 * @param {String} connectorType The connector type, such as 'oracle' or 'mongodb'
 * @returns {String[]} column names
 */
ModelDefinition.prototype.columnNames = function (connectorType) {
    this.build();
    var props = this.properties;
    var cols = [];
    for(var p in props) {
        if(props[p][connectorType]) {
            cols.push(property[connectorType].column || props[p][connectorType].columnName || p);
        } else {
            cols.push(p);
        }
    }
    return cols;
};

/**
 * Find the ID properties sorted by the index
 * @returns {Object[]} property name/index for IDs
 */
ModelDefinition.prototype.ids = function () {
    if(this._ids) {
        return this._ids;
    }
    var ids = [];
    this.build();
    var props = this.properties;
    for (var key in props) {
        var id = props[key].id;
        if(!id) {
            continue;
        }
        if(typeof id !== 'number') {
            id = 1;
        }
        ids.push({name: key, id: id});
    }
    ids.sort(function (a, b) {
        return a.key - b.key;
    });
    this._ids = ids;
    return ids;
};

/**
 * Find the ID column name
 * @param {String} modelName The model name
 * @returns {String} columnName for ID
 */
ModelDefinition.prototype.idColumnName = function(connectorType) {
    return this.columnName(connectorType, this.idName());
};

/**
 * Find the ID property name
 * @returns {String} property name for ID
 */
ModelDefinition.prototype.idName = function() {
    var id = this.ids()[0];
    if(this.properties.id && this.properties.id.id) {
        return 'id';
    } else {}
    return id && id.name;
};

/**
 * Find the ID property names sorted by the index
 * @returns {String[]} property names for IDs
 */
ModelDefinition.prototype.idNames = function () {
    var ids = this.ids();
    var names = ids.map(function (id) {
        return id.name;
    });
    return names;
};

/**
 *
 * @returns {{}}
 */
ModelDefinition.prototype.indexes = function () {
    this.build();
    var indexes = {};
    if (this.settings.indexes) {
        for (var i in this.settings.indexes) {
            indexes[i] = this.settings.indexes[i];
        }
    }
    for (var p in this.properties) {
        if (this.properties[p].index) {
            indexes[p + '_index'] = this.properties[p].index;
        }
    }
    return indexes;
};

/**
 * Resolve the type string to be a function, for example, 'String' to String
 * @param {String} type The type string, such as 'number', 'Number', 'boolean', or 'String'. It's case insensitive
 * @returns {Function} if the type is resolved
 */
ModelDefinition.prototype.resolveType = function(type) {
    if (!type) {
        return type;
    }
    if (Array.isArray(type) && type.length > 0) {
        // For array types, the first item should be the type string
        var itemType = this.resolveType(type[0]);
        if (typeof itemType === 'function') {
            return [itemType];
        }
        else {
            return itemType; // Not resolved, return the type string
        }
    }
    if (typeof type === 'string') {
        var schemaType = ModelDefinition.schemaTypes[type.toLowerCase()] || this.modelBuilder.models[type];
        if (schemaType) {
            return schemaType;
        } else {
            return type;
        }
    } else if (type.constructor.name === 'Object') {
        // We also support the syntax {type: 'string', ...}
        if (type.type) {
            return this.resolveType(type.type);
        } else {
            return this.modelBuilder.define(this.modelBuilder.getSchemaName(null),
                type, {anonymous: true, idInjection: false});
        }
    } else if('function' === typeof type ) {
        return type;
    }
    return type;
};

/**
 * Build a model definition
 * @param {Boolean} force Forcing rebuild
 */
ModelDefinition.prototype.build = function (forceRebuild) {
    if(forceRebuild) {
        this.properties = null;
        this.associations = [];
        this._ids = null;
    }
    if (this.properties) {
        return this.properties;
    }
    this.properties = {};
    for (var p in this.rawProperties) {
        var prop = this.rawProperties[p];
        var type = this.resolveType(prop);
        if (typeof type === 'string') {
            this.associations.push({
                source: this.name,
                target: type,
                relation: Array.isArray(prop) ? 'hasMany' : 'belongsTo',
                as: p
            });
        } else {
            var typeDef = {
                type: type
            };
            if (typeof prop === 'object' && prop !== null) {
                for (var a in prop) {
                    // Skip the type property but don't delete it Model.extend() shares same instances of the properties from the base class
                    if (a !== 'type') {
                        typeDef[a] = prop[a];
                    }
                }
            }
            this.properties[p] = typeDef;
        }
    }
    return this.properties;
};

/**
 * Define a property
 * @param {String} propertyName The property name
 * @param {Object} propertyDefinition The property definition
 */
ModelDefinition.prototype.defineProperty = function (propertyName, propertyDefinition) {
    this.rawProperties[propertyName] = propertyDefinition;
    this.build(true);
};


function isModelClass(cls) {
    if(!cls) {
        return false;
    }
    return cls.prototype instanceof ModelBaseClass;
}

ModelDefinition.prototype.toJSON = function(forceRebuild) {
    if(forceRebuild) {
        this.json = null;
    }
    if(this.json) {
        return json;
    }
    var json = {
        name: this.name,
        properties: {},
        settings: this.settings
    };
    this.build(forceRebuild);

    var mapper = function(val) {
        if(val === undefined || val === null) {
            return val;
        }
        if('function' === typeof val.toJSON) {
            // The value has its own toJSON() object
            return val.toJSON();
        }
        if('function' === typeof val) {
            if(isModelClass(val)) {
                if(val.settings && val.settings.anonymous) {
                    return val.definition && val.definition.toJSON().properties;
                } else {
                    return val.modelName;
                }
            }
            return val.name;
        } else {
            return val;
        }
    };
    for(var p in this.properties) {
        json.properties[p] = traverse(this.properties[p]).map(mapper);
    }
    this.json = json;
    return json;
};