/**
Adds object inheritance and manipulation utilities to the YUI instance. This
module is required by most YUI components.

@module oop
**/

var L            = Y.Lang,
    A            = Y.Array,
    OP           = Object.prototype,
    CLONE_MARKER = '_~yuim~_',

    hasOwn   = OP.hasOwnProperty,
    toString = OP.toString;

/**
Calls the specified _action_ method on _o_ if it exists. Otherwise, if _o_ is an
array, calls the _action_ method on `Y.Array`, or if _o_ is an object, calls the
_action_ method on `Y.Object`.

If _o_ is an array-like object, it will be coerced to an array.

This is intended to be used with array/object iteration methods that share
signatures, such as `each()`, `some()`, etc.

@method dispatch
@param {Object} o Array or object to dispatch to.
@param {Function} f Iteration callback.
    @param {Mixed} f.value Value being iterated.
    @param {Mixed} f.key Current object key or array index.
    @param {Mixed} f.object Object or array being iterated.
@param {Object} c `this` object to bind the iteration callback to.
@param {Boolean} proto If `true`, prototype properties of objects will be
    iterated.
@param {String} action Function name to be dispatched on _o_. For example:
    'some', 'each', etc.
@private
@return {Mixed} Returns the value returned by the chosen iteration action, which
    varies.
**/
function dispatch(o, f, c, proto, action) {
    if (o && o[action] && o !== Y) {
        return o[action].call(o, f, c);
    } else {
        switch (A.test(o)) {
            case 1:
                return A[action](o, f, c);
            case 2:
                return A[action](Y.Array(o, 0, true), f, c);
            default:
                return Y.Object[action](o, f, c, proto);
        }
    }
}

/**
Augments the _receiver_ with prototype properties from the _supplier_. The
receiver may be a constructor function or an object. The supplier must be a
constructor function.

If the _receiver_ is an object, then the _supplier_ constructor will be called
immediately after _receiver_ is augmented, with _receiver_ as the `this` object.

If the _receiver_ is a constructor function, then all prototype methods of
_supplier_ that are copied to _receiver_ will be sequestered, and the
_supplier_ constructor will not be called immediately. The first time any
sequestered method is called on the _receiver_'s prototype, all sequestered
methods will be immediately copied to the _receiver_'s prototype, the
_supplier_'s constructor will be executed, and finally the newly unsequestered
method that was called will be executed.

This sequestering logic sounds like a bunch of complicated voodoo, but it makes
it cheap to perform frequent augmentation by ensuring that suppliers'
constructors are only called if a supplied method is actually used. If none of
the supplied methods is ever used, then there's no need to take the performance
hit of calling the _supplier_'s constructor.

@method augment
@param {Function|Object} receiver Object or function to be augmented.
@param {Function} supplier Function that supplies the prototype properties with
  which to augment the _receiver_.
@param {Boolean} [overwrite=false] If `true`, properties already on the receiver
  will be overwritten if found on the supplier's prototype.
@param {String[]} [whitelist] An array of property names. If specified,
  only the whitelisted prototype properties will be applied to the receiver, and
  all others will be ignored.
@param {Array|any} [args] Argument or array of arguments to pass to the
  supplier's constructor when initializing.
@return {Function} Augmented object.
@for YUI
**/
Y.augment = function (receiver, supplier, overwrite, whitelist, args) {
    var rProto    = receiver.prototype,
        sequester = rProto && supplier,
        sProto    = supplier.prototype,
        to        = rProto || receiver,

        copy,
        newPrototype,
        replacements,
        sequestered,
        unsequester;

    args = args ? Y.Array(args) : [];

    if (sequester) {
        newPrototype = {};
        replacements = {};
        sequestered  = {};

        copy = function (value, key) {
            if (overwrite || !(key in rProto)) {
                if (toString.call(value) === '[object Function]') {
                    sequestered[key] = value;

                    newPrototype[key] = replacements[key] = function () {
                        return unsequester(this, value, arguments);
                    };
                } else {
                    newPrototype[key] = value;
                }
            }
        };

        unsequester = function (instance, fn, fnArgs) {
            // Unsequester all sequestered functions.
            for (var key in sequestered) {
                if (hasOwn.call(sequestered, key)
                        && instance[key] === replacements[key]) {

                    instance[key] = sequestered[key];
                }
            }

            // Execute the supplier constructor.
            supplier.apply(instance, args);

            // Finally, execute the original sequestered function.
            return fn.apply(instance, fnArgs);
        };

        if (whitelist) {
            Y.Array.each(whitelist, function (name) {
                if (name in sProto) {
                    copy(sProto[name], name);
                }
            });
        } else {
            Y.Object.each(sProto, copy, null, true);
        }
    }

    Y.mix(to, newPrototype || sProto, overwrite, whitelist);

    if (!sequester) {
        supplier.apply(to, args);
    }

    return receiver;
};

/**
 * Copies object properties from the supplier to the receiver. If the target has
 * the property, and the property is an object, the target object will be
 * augmented with the supplier's value.
 *
 * @method aggregate
 * @param {Object} receiver Object to receive the augmentation.
 * @param {Object} supplier Object that supplies the properties with which to
 *     augment the receiver.
 * @param {Boolean} [overwrite=false] If `true`, properties already on the receiver
 *     will be overwritten if found on the supplier.
 * @param {String[]} [whitelist] Whitelist. If supplied, only properties in this
 *     list will be applied to the receiver.
 * @return {Object} Augmented object.
 */
Y.aggregate = function(r, s, ov, wl) {
    return Y.mix(r, s, ov, wl, 0, true);
};

/**
 * Utility to set up the prototype, constructor and superclass properties to
 * support an inheritance strategy that can chain constructors and methods.
 * Static members will not be inherited.
 *
 * @method extend
 * @param {function} r   the object to modify.
 * @param {function} s the object to inherit.
 * @param {object} px prototype properties to add/override.
 * @param {object} sx static properties to add/override.
 * @return {object} the extended object.
 */
Y.extend = function(r, s, px, sx) {
    if (!s || !r) {
        Y.error('extend failed, verify dependencies');
    }

    var sp = s.prototype, rp = Y.Object(sp);
    r.prototype = rp;

    rp.constructor = r;
    r.superclass = sp;

    // assign constructor property
    if (s != Object && sp.constructor == OP.constructor) {
        sp.constructor = s;
    }

    // add prototype overrides
    if (px) {
        Y.mix(rp, px, true);
    }

    // add object overrides
    if (sx) {
        Y.mix(r, sx, true);
    }

    return r;
};

/**
 * Executes the supplied function for each item in
 * a collection.  Supports arrays, objects, and
 * NodeLists
 * @method each
 * @param {object} o the object to iterate.
 * @param {function} f the function to execute.  This function
 * receives the value, key, and object as parameters.
 * @param {object} c the execution context for the function.
 * @param {boolean} proto if true, prototype properties are
 * iterated on objects.
 * @return {YUI} the YUI instance.
 */
Y.each = function(o, f, c, proto) {
    return dispatch(o, f, c, proto, 'each');
};

/**
 * Executes the supplied function for each item in
 * a collection.  The operation stops if the function
 * returns true. Supports arrays, objects, and
 * NodeLists.
 * @method some
 * @param {object} o the object to iterate.
 * @param {function} f the function to execute.  This function
 * receives the value, key, and object as parameters.
 * @param {object} c the execution context for the function.
 * @param {boolean} proto if true, prototype properties are
 * iterated on objects.
 * @return {boolean} true if the function ever returns true,
 * false otherwise.
 */
Y.some = function(o, f, c, proto) {
    return dispatch(o, f, c, proto, 'some');
};

/**
Deep object/array copy. Function clones are actually wrappers around the
original function. Array-like objects are treated as arrays. Primitives are
returned untouched. Optionally, a function can be provided to handle other data
types, filter keys, validate values, etc.

**Note:** Cloning a non-trivial object is a reasonably heavy operation, due to
the need to recursively iterate down non-primitive properties. Clone should be
used only when a deep clone down to leaf level properties is explicitly
required. This method will also

In many cases (for example, when trying to isolate objects used as hashes for
configuration properties), a shallow copy, using `Y.merge()` is normally
sufficient. If more than one level of isolation is required, `Y.merge()` can be
used selectively at each level which needs to be isolated from the original
without going all the way to leaf properties.

@method clone
@param {object} o what to clone.
@param {boolean} safe if true, objects will not have prototype items from the
    source. If false, they will. In this case, the original is initially
    protected, but the clone is not completely immune from changes to the source
    object prototype. Also, cloned prototype items that are deleted from the
    clone will result in the value of the source prototype being exposed. If
    operating on a non-safe clone, items should be nulled out rather than
    deleted.
@param {function} f optional function to apply to each item in a collection; it
    will be executed prior to applying the value to the new object.
    Return false to prevent the copy.
@param {object} c optional execution context for f.
@param {object} owner Owner object passed when clone is iterating an object.
    Used to set up context for cloned functions.
@param {object} cloned hash of previously cloned objects to avoid multiple
    clones.
@return {Array|Object} the cloned object.
**/
Y.clone = function(o, safe, f, c, owner, cloned) {
    var o2, marked, stamp;

    // Does not attempt to clone:
    //
    // * Non-typeof-object values, "primitive" values don't need cloning.
    //
    // * YUI instances, cloning complex object like YUI instances is not
    //   advised, this is like cloning the world.
    //
    // * DOM nodes (#2528250), common host objects like DOM nodes cannot be
    //   "subclassed" in Firefox and old versions of IE. Trying to use
    //   `Object.create()` or `Y.extend()` on a DOM node will throw an error in
    //   these browsers.
    //
    // Instad, the passed-in `o` will be return as-is when it matches one of the
    // above criteria.
    if (!L.isObject(o) ||
            Y.instanceOf(o, YUI) ||
            (o.addEventListener || o.attachEvent)) {

        return o;
    }

    marked = cloned || {};

    switch (L.type(o)) {
        case 'date':
            return new Date(o);
        case 'regexp':
            // if we do this we need to set the flags too
            // return new RegExp(o.source);
            return o;
        case 'function':
            // o2 = Y.bind(o, owner);
            // break;
            return o;
        case 'array':
            o2 = [];
            break;
        default:

            // #2528250 only one clone of a given object should be created.
            if (o[CLONE_MARKER]) {
                return marked[o[CLONE_MARKER]];
            }

            stamp = Y.guid();

            o2 = (safe) ? {} : Y.Object(o);

            o[CLONE_MARKER] = stamp;
            marked[stamp] = o;
    }

    Y.each(o, function(v, k) {
        if ((k || k === 0) && (!f || (f.call(c || this, v, k, this, o) !== false))) {
            if (k !== CLONE_MARKER) {
                if (k == 'prototype') {
                    // skip the prototype
                // } else if (o[k] === o) {
                //     this[k] = this;
                } else {
                    this[k] =
                        Y.clone(v, safe, f, c, owner || o, marked);
                }
            }
        }
    }, o2);

    if (!cloned) {
        Y.Object.each(marked, function(v, k) {
            if (v[CLONE_MARKER]) {
                try {
                    delete v[CLONE_MARKER];
                } catch (e) {
                    v[CLONE_MARKER] = null;
                }
            }
        }, this);
        marked = null;
    }

    return o2;
};

/**
 * Returns a function that will execute the supplied function in the
 * supplied object's context, optionally adding any additional
 * supplied parameters to the beginning of the arguments collection the
 * supplied to the function.
 *
 * @method bind
 * @param {Function|String} f the function to bind, or a function name
 * to execute on the context object.
 * @param {object} c the execution context.
 * @param {any} args* 0..n arguments to include before the arguments the
 * function is executed with.
 * @return {function} the wrapped function.
 */
Y.bind = function(f, c) {
    var xargs = arguments.length > 2 ?
            Y.Array(arguments, 2, true) : null;
    return function() {
        var fn = L.isString(f) ? c[f] : f,
            args = (xargs) ?
                xargs.concat(Y.Array(arguments, 0, true)) : arguments;
        return fn.apply(c || fn, args);
    };
};

/**
 * Returns a function that will execute the supplied function in the
 * supplied object's context, optionally adding any additional
 * supplied parameters to the end of the arguments the function
 * is executed with.
 *
 * @method rbind
 * @param {Function|String} f the function to bind, or a function name
 * to execute on the context object.
 * @param {object} c the execution context.
 * @param {any} args* 0..n arguments to append to the end of
 * arguments collection supplied to the function.
 * @return {function} the wrapped function.
 */
Y.rbind = function(f, c) {
    var xargs = arguments.length > 2 ? Y.Array(arguments, 2, true) : null;
    return function() {
        var fn = L.isString(f) ? c[f] : f,
            args = (xargs) ?
                Y.Array(arguments, 0, true).concat(xargs) : arguments;
        return fn.apply(c || fn, args);
    };
};
