'use strict';

//Const var NOAH_ARK_CAPACITY = 3;

//List of formatting elements var FormattingElementList = module.exports = function (treeAdapter) {

this.length = 0;
this.entries = [];
this.treeAdapter = treeAdapter;
this.bookmark = null;

};

//Entry types FormattingElementList.MARKER_ENTRY = 'MARKER_ENTRY'; FormattingElementList.ELEMENT_ENTRY = 'ELEMENT_ENTRY';

//Noah Ark's condition //OPTIMIZATION: at first we try to find possible candidates for exclusion using //lightweight heuristics without thorough attributes check. FormattingElementList.prototype._getNoahArkConditionCandidates = function (newElement) {

var candidates = [];
if (this.length >= NOAH_ARK_CAPACITY) {
    var neAttrsLength = this.treeAdapter.getAttrList(newElement).length,
        neTagName = this.treeAdapter.getTagName(newElement),
        neNamespaceURI = this.treeAdapter.getNamespaceURI(newElement);
    for (var i = this.length - 1; i >= 0; i--) {
        var entry = this.entries[i];
        if (entry.type === FormattingElementList.MARKER_ENTRY)
            break;
        var element = entry.element,
            elementAttrs = this.treeAdapter.getAttrList(element);
        if (this.treeAdapter.getTagName(element) === neTagName &&
            this.treeAdapter.getNamespaceURI(element) === neNamespaceURI &&
            elementAttrs.length === neAttrsLength) {
            candidates.push({idx: i, attrs: elementAttrs});
        }
    }
}
return candidates.length < NOAH_ARK_CAPACITY ? [] : candidates;

};

FormattingElementList.prototype._ensureNoahArkCondition = function (newElement) {

var candidates = this._getNoahArkConditionCandidates(newElement),
    cLength = candidates.length;
if (cLength) {
    var neAttrs = this.treeAdapter.getAttrList(newElement),
        neAttrsLength = neAttrs.length,
        neAttrsMap = {};
    //NOTE: build attrs map for the new element so we can perform fast lookups
    for (var i = 0; i < neAttrsLength; i++) {
        var neAttr = neAttrs[i];
        neAttrsMap[neAttr.name] = neAttr.value;
    }
    for (var i = 0; i < neAttrsLength; i++) {
        for (var j = 0; j < cLength; j++) {
            var cAttr = candidates[j].attrs[i];
            if (neAttrsMap[cAttr.name] !== cAttr.value) {
                candidates.splice(j, 1);
                cLength--;
            }
            if (candidates.length < NOAH_ARK_CAPACITY)
                return;
        }
    }
    //NOTE: remove bottommost candidates until Noah's Ark condition will not be met
    for (var i = cLength - 1; i >= NOAH_ARK_CAPACITY - 1; i--) {
        this.entries.splice(candidates[i].idx, 1);
        this.length--;
    }
}

};

//Mutations FormattingElementList.prototype.insertMarker = function () {

this.entries.push({type: FormattingElementList.MARKER_ENTRY});
this.length++;

};

FormattingElementList.prototype.pushElement = function (element, token) {

this._ensureNoahArkCondition(element);
this.entries.push({
    type: FormattingElementList.ELEMENT_ENTRY,
    element: element,
    token: token
});
this.length++;

};

FormattingElementList.prototype.insertElementAfterBookmark = function (element, token) {

var bookmarkIdx = this.length - 1;
for (; bookmarkIdx >= 0; bookmarkIdx--) {
    if (this.entries[bookmarkIdx] === this.bookmark)
        break;
}
this.entries.splice(bookmarkIdx + 1, 0, {
    type: FormattingElementList.ELEMENT_ENTRY,
    element: element,
    token: token
});
this.length++;

};

FormattingElementList.prototype.removeEntry = function (entry) {

for (var i = this.length - 1; i >= 0; i--) {
    if (this.entries[i] === entry) {
        this.entries.splice(i, 1);
        this.length--;
        break;
    }
}

};

FormattingElementList.prototype.clearToLastMarker = function () {

while (this.length) {
    var entry = this.entries.pop();
    this.length--;
    if (entry.type === FormattingElementList.MARKER_ENTRY)
        break;
}

};

//Search FormattingElementList.prototype.getElementEntryInScopeWithTagName = function (tagName) {

for (var i = this.length - 1; i >= 0; i--) {
    var entry = this.entries[i];
    if (entry.type === FormattingElementList.MARKER_ENTRY)
        return null;
    if (this.treeAdapter.getTagName(entry.element) === tagName)
        return entry;
}
return null;

};

FormattingElementList.prototype.getElementEntry = function (element) {

for (var i = this.length - 1; i >= 0; i--) {
    var entry = this.entries[i];
    if (entry.type === FormattingElementList.ELEMENT_ENTRY && entry.element == element)
        return entry;
}
return null;

};