'use strict';

var HTML = require('../common/html');

//Aliases
var $ = HTML.TAG_NAMES,
    NS = HTML.NAMESPACES;

//Element utils

//OPTIMIZATION: Integer comparisons are low-cost, so we can use very fast tag name length filters here.
//It's faster than using dictionary.
function isImpliedEndTagRequired(tn) {
    switch (tn.length) {
        case 1:
            return tn === $.P;

        case 2:
            return tn === $.RP || tn === $.RT || tn === $.DD || tn === $.DT || tn === $.LI;

        case 6:
            return tn === $.OPTION;

        case 8:
            return tn === $.OPTGROUP;
    }

    return false;
}

function isScopingElement(tn, ns) {
    switch (tn.length) {
        case 2:
            if (tn === $.TD || tn === $.TH)
                return ns === NS.HTML;

            else if (tn === $.MI || tn === $.MO || tn == $.MN || tn === $.MS)
                return ns === NS.MATHML;

            break;

        case 4:
            if (tn === $.HTML)
                return ns === NS.HTML;

            else if (tn === $.DESC)
                return ns === NS.SVG;

            break;

        case 5:
            if (tn === $.TABLE)
                return ns === NS.HTML;

            else if (tn === $.MTEXT)
                return ns === NS.MATHML;

            else if (tn === $.TITLE)
                return ns === NS.SVG;

            break;

        case 6:
            return (tn === $.APPLET || tn === $.OBJECT) && ns === NS.HTML;

        case 7:
            return (tn === $.CAPTION || tn === $.MARQUEE) && ns === NS.HTML;

        case 8:
            return tn === $.TEMPLATE && ns === NS.HTML;

        case 13:
            return tn === $.FOREIGN_OBJECT && ns === NS.SVG;

        case 14:
            return tn === $.ANNOTATION_XML && ns === NS.MATHML;
    }

    return false;
}

//Stack of open elements
var OpenElementStack = module.exports = function (document, treeAdapter) {
    this.stackTop = -1;
    this.items = [];
    this.current = document;
    this.currentTagName = null;
    this.currentTmplContent = null;
    this.tmplCount = 0;
    this.treeAdapter = treeAdapter;
};

//Index of element
OpenElementStack.prototype._indexOf = function (element) {
    var idx = -1;

    for (var i = this.stackTop; i >= 0; i--) {
        if (this.items[i] === element) {
            idx = i;
            break;
        }
    }
    return idx;
};

//Update current element
OpenElementStack.prototype._isInTemplate = function () {
    if (this.currentTagName !== $.TEMPLATE)
        return false;

    return this.treeAdapter.getNamespaceURI(this.current) === NS.HTML;
};

OpenElementStack.prototype._updateCurrentElement = function () {
    this.current = this.items[this.stackTop];
    this.currentTagName = this.current && this.treeAdapter.getTagName(this.current);

    this.currentTmplContent = this._isInTemplate() ? this.treeAdapter.getChildNodes(this.current)[0] : null;
};

//Mutations
OpenElementStack.prototype.push = function (element) {
    this.items[++this.stackTop] = element;
    this._updateCurrentElement();

    if (this._isInTemplate())
        this.tmplCount++;

};

OpenElementStack.prototype.pop = function () {
    this.stackTop--;

    if (this.tmplCount > 0 && this._isInTemplate())
        this.tmplCount--;

    this._updateCurrentElement();
};

OpenElementStack.prototype.replace = function (oldElement, newElement) {
    var idx = this._indexOf(oldElement);
    this.items[idx] = newElement;

    if (idx === this.stackTop)
        this._updateCurrentElement();
};

OpenElementStack.prototype.insertAfter = function (referenceElement, newElement) {
    var insertionIdx = this._indexOf(referenceElement) + 1;

    this.items.splice(insertionIdx, 0, newElement);

    if (insertionIdx == ++this.stackTop)
        this._updateCurrentElement();
};

OpenElementStack.prototype.popUntilTagNamePopped = function (tagName) {
    while (this.stackTop > -1) {
        var tn = this.currentTagName;

        this.pop();

        if (tn === tagName)
            break;
    }
};

OpenElementStack.prototype.popUntilTemplatePopped = function () {
    while (this.stackTop > -1) {
        var tn = this.currentTagName,
            ns = this.treeAdapter.getNamespaceURI(this.current);

        this.pop();

        if (tn === $.TEMPLATE && ns === NS.HTML)
            break;
    }
};

OpenElementStack.prototype.popUntilElementPopped = function (element) {
    while (this.stackTop > -1) {
        var poppedElement = this.current;

        this.pop();

        if (poppedElement === element)
            break;
    }
};

OpenElementStack.prototype.popUntilNumberedHeaderPopped = function () {
    while (this.stackTop > -1) {
        var tn = this.currentTagName;

        this.pop();

        if (tn === $.H1 || tn === $.H2 || tn === $.H3 || tn === $.H4 || tn === $.H5 || tn === $.H6)
            break;
    }
};

OpenElementStack.prototype.popAllUpToHtmlElement = function () {
    //NOTE: here we assume that root <html> element is always first in the open element stack, so
    //we perform this fast stack clean up.
    this.stackTop = 0;
    this._updateCurrentElement();
};

OpenElementStack.prototype.clearBackToTableContext = function () {
    while (this.currentTagName !== $.TABLE && this.currentTagName !== $.TEMPLATE && this.currentTagName !== $.HTML)
        this.pop();
};

OpenElementStack.prototype.clearBackToTableBodyContext = function () {
    while (this.currentTagName !== $.TBODY && this.currentTagName !== $.TFOOT &&
           this.currentTagName !== $.THEAD && this.currentTagName !== $.TEMPLATE &&
           this.currentTagName !== $.HTML) {
        this.pop();
    }
};

OpenElementStack.prototype.clearBackToTableRowContext = function () {
    while (this.currentTagName !== $.TR && this.currentTagName !== $.TEMPLATE && this.currentTagName !== $.HTML)
        this.pop();
};

OpenElementStack.prototype.remove = function (element) {
    for (var i = this.stackTop; i >= 0; i--) {
        if (this.items[i] === element) {
            this.items.splice(i, 1);
            this.stackTop--;
            this._updateCurrentElement();
            break;
        }
    }
};

//Search
OpenElementStack.prototype.tryPeekProperlyNestedBodyElement = function () {
    //Properly nested <body> element (should be second element in stack).
    var element = this.items[1];
    return element && this.treeAdapter.getTagName(element) === $.BODY ? element : null;
};

OpenElementStack.prototype.contains = function (element) {
    return this._indexOf(element) > -1;
};

OpenElementStack.prototype.getCommonAncestor = function (element) {
    var elementIdx = this._indexOf(element);

    return --elementIdx >= 0 ? this.items[elementIdx] : null;
};

OpenElementStack.prototype.isRootHtmlElementCurrent = function () {
    return this.stackTop === 0 && this.currentTagName === $.HTML;
};

//Element in scope
OpenElementStack.prototype.hasInScope = function (tagName) {
    for (var i = this.stackTop; i >= 0; i--) {
        var tn = this.treeAdapter.getTagName(this.items[i]);

        if (tn === tagName)
            return true;

        var ns = this.treeAdapter.getNamespaceURI(this.items[i]);

        if (isScopingElement(tn, ns))
            return false;
    }

    return true;
};

OpenElementStack.prototype.hasNumberedHeaderInScope = function () {
    for (var i = this.stackTop; i >= 0; i--) {
        var tn = this.treeAdapter.getTagName(this.items[i]);

        if (tn === $.H1 || tn === $.H2 || tn === $.H3 || tn === $.H4 || tn === $.H5 || tn === $.H6)
            return true;

        if (isScopingElement(tn, this.treeAdapter.getNamespaceURI(this.items[i])))
            return false;
    }

    return true;
};

OpenElementStack.prototype.hasInListItemScope = function (tagName) {
    for (var i = this.stackTop; i >= 0; i--) {
        var tn = this.treeAdapter.getTagName(this.items[i]);

        if (tn === tagName)
            return true;

        var ns = this.treeAdapter.getNamespaceURI(this.items[i]);

        if (((tn === $.UL || tn === $.OL) && ns === NS.HTML) || isScopingElement(tn, ns))
            return false;
    }

    return true;
};

OpenElementStack.prototype.hasInButtonScope = function (tagName) {
    for (var i = this.stackTop; i >= 0; i--) {
        var tn = this.treeAdapter.getTagName(this.items[i]);

        if (tn === tagName)
            return true;

        var ns = this.treeAdapter.getNamespaceURI(this.items[i]);

        if ((tn === $.BUTTON && ns === NS.HTML) || isScopingElement(tn, ns))
            return false;
    }

    return true;
};

OpenElementStack.prototype.hasInTableScope = function (tagName) {
    for (var i = this.stackTop; i >= 0; i--) {
        var tn = this.treeAdapter.getTagName(this.items[i]);

        if (tn === tagName)
            return true;

        var ns = this.treeAdapter.getNamespaceURI(this.items[i]);

        if ((tn === $.TABLE || tn === $.TEMPLATE || tn === $.HTML) && ns === NS.HTML)
            return false;
    }

    return true;
};

OpenElementStack.prototype.hasTableBodyContextInTableScope = function () {
    for (var i = this.stackTop; i >= 0; i--) {
        var tn = this.treeAdapter.getTagName(this.items[i]);

        if (tn === $.TBODY || tn === $.THEAD || tn === $.TFOOT)
            return true;

        var ns = this.treeAdapter.getNamespaceURI(this.items[i]);

        if ((tn === $.TABLE || tn === $.HTML) && ns === NS.HTML)
            return false;
    }

    return true;
};

OpenElementStack.prototype.hasInSelectScope = function (tagName) {
    for (var i = this.stackTop; i >= 0; i--) {
        var tn = this.treeAdapter.getTagName(this.items[i]);

        if (tn === tagName)
            return true;

        var ns = this.treeAdapter.getNamespaceURI(this.items[i]);

        if (tn !== $.OPTION && tn !== $.OPTGROUP && ns === NS.HTML)
            return false;
    }

    return true;
};

//Implied end tags
OpenElementStack.prototype.generateImpliedEndTags = function () {
    while (isImpliedEndTagRequired(this.currentTagName))
        this.pop();
};

OpenElementStack.prototype.generateImpliedEndTagsWithExclusion = function (exclusionTagName) {
    while (isImpliedEndTagRequired(this.currentTagName) && this.currentTagName !== exclusionTagName)
        this.pop();
};
