/**
 * Copyright (c) 2011
 *     OJC Technologies
 *     all rights reserved
 * @author: Jake Smith
 */

var atEndOfLine = false;
var hasCursor = false;
var cursorTag = "span";
var cursorId = "littlecursorelement";

function dropCursorAt(targetNode, offsetIndex) {
    var noFront, noPost;
    noFront = (offsetIndex == 0) ? true : false;
    noPost = (offsetIndex == targetNode.nodeValue.length) ? true : false;
    if (noFront && noPost) {
        addCursorOnly(targetNode);
    } else if (noFront) {
        addCursorWithNoPrefix(targetNode);
    } else if (noPost) {
        addCursorWithNoSuffix(targetNode, offsetIndex);
    } else {
        insertCursor(targetNode, offsetIndex);
    }
    hasCursor = true;
}

function addCursorOnly(node) {
    var cursor, character;
    character = node.nodeValue;
    if (character.length != 1) {
        if (character == "") {
            character = "_";
        } else {
            throw new Error("wanting to add only a cursor when it shouldn't");
        }
    }
    cursor = makeCursor(character);
    node.parentNode.replaceChild(cursor, node);
    atEndOfLine = true;
}

function addCursorWithNoPrefix(node) {
    var parent, cursor, text, suffix, character, postString;
    parent = node.parentNode;
    text = node.nodeValue;
    character = text.substring(0, 1);
    postString = text.substring(1);
    cursor = makeCursor(character);
    suffix = document.createTextNode(postString);
    parent.replaceChild(cursor, node);
    insertAfter(cursor, suffix);
}

function addCursorWithNoSuffix(node, index) {
    var parent, cursor, text, prefix, character, foreString;
    parent = node.parentNode;
    text = node.nodeValue;
    foreString = text.substring(0, index);
    prefix = document.createTextNode(foreString);
    character = text.substring(index);
    if(character == "") {
        character = "_";
    }
    cursor = makeCursor(character);
    parent.replaceChild(prefix, node);
    insertAfter(prefix, cursor);
    atEndOfLine = true;
}

function insertCursor(node, index) {
    var parent, cursor, text, prefix, suffix, character, foreString, postString;
    parent = node.parentNode;
    text = node.nodeValue;
    foreString = text.substring(0, index);
    prefix = document.createTextNode(foreString);
    character = text.substring(index, index + 1);
    cursor = makeCursor(character);
    postString = text.substring(index+1);
    suffix = document.createTextNode(postString);
    parent.replaceChild(prefix, node);
    insertAfter(prefix, cursor);
    insertAfter(cursor, suffix);
}

function makeCursor(character) {
    var cursor = document.createElement(cursorTag);
    cursor.setAttribute("id", cursorId);
    cursor.appendChild(document.createTextNode(character));
    return cursor;
}

function removeStandingCursor() {
    if (!hasCursor) {
        return;
    }
    var cursor, parent;
    cursor = document.getElementById(cursorId);
    parent = cursor.parentNode;
    if(cursor.childNodes[0] != null) {
        if (atEndOfLine) {
            parent.removeChild(cursor);
            atEndOfLine = false;
        } else {
            parent.replaceChild(cursor.childNodes[0], cursor);
        }
    } else {
        parent.removeChild(cursor);
    }
    parent.normalize();
    hasCursor = false;
}

function bumpCursorLeft() {
    var parent, cursor, prevSib, tempNode;
    cursor = document.getElementById(cursorId);
    parent = cursor.parentNode;
    prevSib = cursor.previousSibling;
    if (prevSib == null || prevSib.nodeType != Node.TEXT_NODE) {
        return;
    } else {
        if (atEndOfLine) {
            parent.removeChild(cursor);
            dropCursorAt(prevSib, prevSib.nodeValue.length - 1);
            atEndOfLine = false;
        } else {
            tempNode = document.createTextNode(cursor.childNodes[0].nodeValue);
            parent.replaceChild(tempNode, cursor);
            dropCursorAt(prevSib, prevSib.nodeValue.length - 1);
            parent.normalize();
        }
    }
}

function bumpCursorRight() {
    var parent, cursor, nextSib, tempNode;
    cursor = document.getElementById(cursorId);
    parent = cursor.parentNode;
    nextSib = cursor.nextSibling;
    if (nextSib == null || nextSib.nodeType != Node.TEXT_NODE) {
        if (atEndOfLine) {
            return;
        } else {
            tempNode = document.createTextNode(cursor.childNodes[0].nodeValue);
            parent.replaceChild(tempNode, cursor);
            dropCursorAt(tempNode, tempNode.nodeValue.length);
            parent.normalize();
            atEndOfLine = true;
        }
    } else {
        tempNode = document.createTextNode(cursor.childNodes[0].nodeValue);
        parent.replaceChild(tempNode, cursor);
        dropCursorAt(nextSib, 0);
        parent.normalize();
    }
}

// This function inserts newNode after referenceNode
function insertAfter(referenceNode, newNode) {
    referenceNode.parentNode.insertBefore(newNode, referenceNode.nextSibling);
}