var content;
var keyState = 0;

var VMermaidDivClass = 'mermaid-diagram';
var VFlowchartDivClass = 'flowchart-diagram';
if (typeof VEnableMermaid == 'undefined') {
    VEnableMermaid = false;
} else if (VEnableMermaid) {
    mermaidAPI.initialize({
        startOnLoad: false
    });
}

if (typeof VEnableFlowchart == 'undefined') {
    VEnableFlowchart = false;
}

if (typeof VEnableMathjax == 'undefined') {
    VEnableMathjax = false;
}

// Add a caption (using alt text) under the image.
var VImageCenterClass = 'img-center';
var VImageCaptionClass = 'img-caption';
var VImagePackageClass = 'img-package';
if (typeof VEnableImageCaption == 'undefined') {
    VEnableImageCaption = false;
}

new QWebChannel(qt.webChannelTransport,
    function(channel) {
        content = channel.objects.content;
        if (typeof updateHtml == "function") {
            updateHtml(content.html);
            content.htmlChanged.connect(updateHtml);
        }
        if (typeof updateText == "function") {
            content.textChanged.connect(updateText);
            content.updateText();
        }
        content.requestScrollToAnchor.connect(scrollToAnchor);

        if (typeof highlightText == "function") {
            content.requestHighlightText.connect(highlightText);
            content.noticeReadyToHighlightText();
        }
    });

var g_muteScroll = false;

var scrollToAnchor = function(anchor) {
    g_muteScroll = true;
    if (!anchor) {
        window.scrollTo(0, 0);
        g_muteScroll = false;
        return;
    }

    var anc = document.getElementById(anchor);
    if (anc != null) {
        anc.scrollIntoView();
    }

    // Disable scroll temporarily.
    setTimeout("g_muteScroll = false", 100);
};

window.onwheel = function(e) {
    e = e || window.event;
    var ctrl = !!e.ctrlKey;
    if (ctrl) {
        e.preventDefault();
    }
}

window.onscroll = function() {
    if (g_muteScroll) {
        return;
    }

    var scrollTop = document.documentElement.scrollTop || document.body.scrollTop || window.pageYOffset;
    var eles = document.querySelectorAll("h1, h2, h3, h4, h5, h6");

    if (eles.length == 0) {
        content.setHeader("");
        return;
    }

    var curIdx = -1;
    var biaScrollTop = scrollTop + 50;
    for (var i = 0; i < eles.length; ++i) {
        if (biaScrollTop >= eles[i].offsetTop) {
            curIdx = i;
        } else {
            break;
        }
    }

    var curHeader = null;
    if (curIdx != -1) {
        curHeader = eles[curIdx].getAttribute("id");
    }

    content.setHeader(curHeader ? curHeader : "");
};

document.onkeydown = function(e) {
    e = e || window.event;
    var key;
    var shift;
    var ctrl;
    if (e.which) {
        key = e.which;
    } else {
        key = e.keyCode;
    }
    shift = !!e.shiftKey;
    ctrl = !!e.ctrlKey;
    switch (key) {
    case 74: // J
        window.scrollBy(0, 100);
        keyState = 0;
    break;

    case 75: // K
        window.scrollBy(0, -100);
        keyState = 0;
    break;

    case 72: // H
        window.scrollBy(-100, 0);
        keyState = 0;
    break;

    case 76: // L
        window.scrollBy(100, 0);
        keyState = 0;
    break;

    case 71: // G
        if (shift) {
            var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft || window.pageXOffset;
            var scrollHeight = document.documentElement.scrollHeight || document.body.scrollHeight;
            window.scrollTo(scrollLeft, scrollHeight);
            keyState = 0;
            break;
        } else {
            if (keyState == 0) {
                keyState = 1;
            } else if (keyState == 1) {
                keyState = 0;
                var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft || window.pageXOffset;
                window.scrollTo(scrollLeft, 0);
            }
            break;
        }
        return;

    case 85: // U
        keyState = 0;
        if (ctrl) {
            var clientHeight = document.documentElement.clientHeight;
            window.scrollBy(0, -clientHeight / 2);
            break;
        }
        return;

    case 68: // D
        keyState = 0;
        if (ctrl) {
            var clientHeight = document.documentElement.clientHeight;
            window.scrollBy(0, clientHeight / 2);
            break;
        }
        return;

    default:
        content.keyPressEvent(key, ctrl, shift);
        keyState = 0;
        return;
    }
    e.preventDefault();
};

var mermaidParserErr = false;
var mermaidIdx = 0;

if (VEnableMermaid) {
    mermaidAPI.parseError = function(err, hash) {
        content.setLog("err: " + err);
        mermaidParserErr = true;

        // Clean the container element, or mermaidAPI won't render the graph with
        // the same id.
        var errGraph = document.getElementById('mermaid-diagram-' + mermaidIdx);
        var parentNode = errGraph.parentElement;
        parentNode.outerHTML = '';
        delete parentNode;
    };
}

// @className, the class name of the mermaid code block, such as 'lang-mermaid'.
var renderMermaid = function(className) {
    if (!VEnableMermaid) {
        return;
    }

    var codes = document.getElementsByTagName('code');
    mermaidIdx = 0;
    for (var i = 0; i < codes.length; ++i) {
        var code = codes[i];
        if (code.classList.contains(className)) {
            if (renderMermaidOne(code)) {
                // replaceChild() will decrease codes.length.
                --i;
            }
        }
    }
};

// Render @code as Mermaid graph.
// Returns true if succeeded.
var renderMermaidOne = function(code) {
    // Mermaid code block.
    mermaidParserErr = false;
    mermaidIdx++;
    try {
        // Do not increment mermaidIdx here.
        var graph = mermaidAPI.render('mermaid-diagram-' + mermaidIdx, code.innerText, function(){});
    } catch (err) {
        content.setLog("err: " + err);
        return false;
    }

    if (mermaidParserErr || typeof graph == "undefined") {
        return false;
    }

    var graphDiv = document.createElement('div');
    graphDiv.classList.add(VMermaidDivClass);
    graphDiv.innerHTML = graph;
    var preNode = code.parentNode;
    preNode.classList.add(VMermaidDivClass);
    preNode.replaceChild(graphDiv, code);
    return true;
};

var flowchartIdx = 0;

// @className, the class name of the flowchart code block, such as 'lang-flowchart'.
var renderFlowchart = function(className) {
    if (!VEnableFlowchart) {
        return;
    }

    var codes = document.getElementsByTagName('code');
    flowchartIdx = 0;
    for (var i = 0; i < codes.length; ++i) {
        var code = codes[i];
        if (code.classList.contains(className)) {
            if (renderFlowchartOne(code, flowchartIdx)) {
                // replaceChild() will decrease codes.length.
                --i;
            }
        }
    }
};

// Render @code as Flowchart.js graph.
// Returns true if succeeded.
var renderFlowchartOne = function(code) {
    // Flowchart code block.
    flowchartIdx++;
    try {
        var graph = flowchart.parse(code.innerText);
    } catch (err) {
        content.setLog("err: " + err);
        return false;
    }

    if (typeof graph == "undefined") {
        return false;
    }

    var graphDiv = document.createElement('div');
    graphDiv.id = 'flowchart-diagram-' + flowchartIdx;
    graphDiv.classList.add(VFlowchartDivClass);
    var preNode = code.parentNode;
    preNode.replaceChild(graphDiv, code);

    // Draw on it after adding it to page.
    try {
        graph.drawSVG(graphDiv.id);
    } catch (err) {
        content.setLog("err: " + err);
        preNode.replaceChild(code, graphDiv);
        delete graphDiv;
        return false;
    }

    preNode.classList.add(VMermaidDivClass);
    return true;
};

var isImageBlock = function(img) {
    var pn = img.parentNode;
    return (pn.children.length == 1) && (pn.innerText == '');
};

var isImageWithBr = function(img) {
    var sibling = img.nextSibling;
    while (sibling) {
        if (sibling.nodeType == 8) {
            // Comment node.
            // Just continue.
            sibling = sibling.nextSibling;
            continue;
        } else if (sibling.nodeType == 1) {
            if (sibling.tagName == 'BR') {
                break;
            }
        }

        return false;
    }

    sibling = img.previousSibling;
    while (sibling) {
        if (sibling.nodeType == 8) {
            // Comment node.
            sibling = sibling.previousSibling;
            continue;
        } else if (sibling.nodeType == 1) {
            // Element node.
            if (sibling.tagName == 'BR') {
                break;
            }
        } else if (sibling.nodeType == 3) {
            // Text node.
            if (sibling.nodeValue == '\n') {
                var tmp = sibling.previousSibling;
                if (tmp && tmp.tagName == 'BR') {
                    break;
                }
            }
        }

        return false;
    }

    return true;
};

var getImageType = function(img) {
    var type = -1;
    if (isImageBlock(img)) {
        type = 0;
    } else if (isImageWithBr(img)) {
        type = 1;
    }

    return type;
};

// Center the image block and insert the alt text as caption.
var insertImageCaption = function() {
    if (!VEnableImageCaption) {
        return;
    }

    var imgs = document.getElementsByTagName('img');
    for (var i = 0; i < imgs.length; ++i) {
        var img = imgs[i];

        var type = getImageType(img);

        if (type == -1) {
            continue;
        } else if (type == 1) {
            // Insert a div as the parent of the img.
            var imgPack = document.createElement('div');
            img.insertAdjacentElement('afterend', imgPack);
            imgPack.appendChild(img);
        }

        // Make the parent img-package.
        img.parentNode.classList.add(VImagePackageClass);

        // Make it center.
        img.classList.add(VImageCenterClass);

        if (img.alt == '') {
            continue;
        }

        // Add caption.
        var captionDiv = document.createElement('div');
        captionDiv.classList.add(VImageCaptionClass);
        captionDiv.innerText = img.alt;
        img.insertAdjacentElement('afterend', captionDiv);
    }
}

// The renderer specific code should call this function once thay have finished
// markdown-specifi handle logics, such as Mermaid, MathJax.
var finishLogics = function() {
    content.finishLogics();
};

// Escape @text to Html.
var escapeHtml = function(text) {
  var map = {
    '&': '&amp;',
    '<': '&lt;',
    '>': '&gt;',
    '"': '&quot;',
    "'": '&#039;'
  };

  return text.replace(/[&<>"']/g, function(m) { return map[m]; });
};

// Return the topest level of @toc, starting from 1.
var baseLevelOfToc = function(p_toc) {
    var level = -1;
    for (i in p_toc) {
        if (level == -1) {
            level = p_toc[i].level;
        } else if (level > p_toc[i].level) {
            level = p_toc[i].level;
        }
    }

    if (level == -1) {
        level = 1;
    }

    return level;
};

// Handle wrong title levels, such as '#' followed by '###'
var toPerfectToc = function(p_toc, p_baseLevel) {
    var i;
    var curLevel = p_baseLevel - 1;
    var perfToc = [];
    for (i in p_toc) {
        var item = p_toc[i];

        // Insert empty header.
        while (item.level > curLevel + 1) {
            curLevel += 1;
            var tmp = { level: curLevel,
                        anchor: '',
                        title: '[EMPTY]'
                      };
            perfToc.push(tmp);
        }

        perfToc.push(item);
        curLevel = item.level;
    }

    return perfToc;
};

var itemToHtml = function(item) {
    return '<a href="#' + item.anchor + '">' + item.title + '</a>';
};

// Turn a perfect toc to a tree using <ul>
var tocToTree = function(p_toc, p_baseLevel) {
    var i;
    var front = '<li>';
    var ending = ['</li>'];
    var curLevel = p_baseLevel;
    for (i in p_toc) {
        var item = p_toc[i];
        if (item.level == curLevel) {
            front += '</li>';
            front += '<li>';
            front += itemToHtml(item);
        } else if (item.level > curLevel) {
            // assert(item.level - curLevel == 1)
            front += '<ul>';
            ending.push('</ul>');
            front += '<li>';
            front += itemToHtml(item);
            ending.push('</li>');
            curLevel = item.level;
        } else {
            while (item.level < curLevel) {
                var ele = ending.pop();
                front += ele;
                if (ele == '</ul>') {
                    curLevel--;
                }
            }
            front += '</li>';
            front += '<li>';
            front += itemToHtml(item);
        }
    }
    while (ending.length > 0) {
        front += ending.pop();
    }
    front = front.replace("<li></li>", "");
    front = '<ul>' + front + '</ul>';
    return front;
};

var handleToc = function(needToc) {
    var baseLevel = baseLevelOfToc(toc);
    var tocTree = tocToTree(toPerfectToc(toc, baseLevel), baseLevel);
    content.setToc(tocTree, baseLevel);

    // Add it to html
    if (needToc) {
        var eles = document.getElementsByClassName('vnote-toc');
        for (var i = 0; i < eles.length; ++i) {
            eles[i].innerHTML = tocTree;
        }
    }
};

// Implement mouse drag with Ctrl and left button pressed to scroll.
var vds_oriMouseClientX = 0;
var vds_oriMouseClientY = 0;
var vds_readyToScroll = false;
var vds_scrolled = false;

window.onmousedown = function(e) {
    e = e || window.event;
    // Left button and Ctrl key.
    if (e.buttons == 1
        && e.ctrlKey
        && window.getSelection().rangeCount == 0) {
        vds_oriMouseClientX = e.clientX;
        vds_oriMouseClientY = e.clientY;
        vds_readyToScroll = true;
        vds_scrolled = false;
        e.preventDefault();
    } else {
        vds_readyToScroll = false;
        vds_scrolled = false;
    }
};

window.onmouseup = function(e) {
    e = e || window.event;
    if (vds_scrolled || vds_readyToScroll) {
        // Have been scrolled, restore the cursor style.
        document.body.style.cursor = "auto";
        e.preventDefault();
    }

    vds_readyToScroll = false;
    vds_scrolled = false;
};

window.onmousemove = function(e) {
    e = e || window.event;
    if (vds_readyToScroll) {
        deltaX = e.clientX - vds_oriMouseClientX;
        deltaY = e.clientY - vds_oriMouseClientY;

        var threshold = 5;
        if (Math.abs(deltaX) >= threshold || Math.abs(deltaY) >= threshold) {
            vds_oriMouseClientX = e.clientX;
            vds_oriMouseClientY = e.clientY;

            if (!vds_scrolled) {
                vds_scrolled = true;
                document.body.style.cursor = "all-scroll";
            }

            var scrollX = -deltaX;
            var scrollY = -deltaY;
            window.scrollBy(scrollX, scrollY);
        }

        e.preventDefault();
    }
};