const width = 800;
const height = 600;
const radius = 25;

const settings = {
    physics: true,
    speed: 2,
    snapToPadding: 6,
    hitTargetPadding: 6,
    colors: {
        default: '#000',
        active: '#00f',
        getColor: (object) => selectedObject === object ? settings.colors.active : settings.colors.default
    }
};

const elements = {
    documents: document.getElementById('document-tabs'),
};

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

canvas.width = width;
canvas.height = height;

const documents = [];
let activeDocument = null;

function switchDocument(doc) {
    if (doc instanceof FSMDocument) {
        doc = documents.findIndex(document => document.id === doc.id);
    }

    if(doc < 0) {
        activeDocument = null;
    }

    if (typeof doc === 'number' && doc >= 0 && doc < documents.length) {
        activeDocument = doc;

        const docElements = document.getElementsByClassName('document-tab');
        for (let el of docElements) {
            el.classList.remove('active');
        }
        docElements[doc].classList.add('active');

        resetCaret();
        selectedObject = null;
        currentConnection = null;
        movingObject = false;
        originalClick = null;
        deltaMouseX = 0;
        deltaMouseY = 0;
        shiftPressed = false;
    }
}

function addDocument(doc) {
    documents.push(doc);

    const elem = document.createElement('li');
    elem.classList.add('document-tab');

    const label = elem.addChild('span', 'document-name', doc.name || 'Unbenannt');
    const btn = elem.addChild('button', ['btn', 'btn-close'], 'X');

    elem.addEventListener('click', (e) => {
        if(e.target === elem || e.target === label)
            switchDocument(doc);
    });

    btn.addEventListener('click', () => {
        closeDocument(doc);
    });

    doc.element = elem;

    elements.documents.appendChild(elem);
}

function closeDocument(doc) {
    if (doc instanceof FSMDocument) {
        doc = documents.findIndex(document => document.id === doc.id);
    }

    if (typeof doc === 'number') {
        documents.splice(doc, 1);

        const docElements = document.getElementsByClassName('document-tab');
        docElements[doc].remove();

        if(doc < activeDocument) {
            activeDocument--;
        } else if(doc === activeDocument) {
            if(activeDocument >= documents.length) {
                activeDocument = documents.length - 1;
            }
        }
        switchDocument(activeDocument);
    }
}

const animations = [];

let isPaused = false;

function convertLatexShortcuts(text) {
    for (let i = 0; i < 10; i++) {
        // TODO: Replace with more general way
        text = text.replace(new RegExp('_' + i, 'g'), String.fromCharCode(8320 + i));
    }

    return text;
}

let caretTimer,
    caretVisible = true,
    caretPos = 0;

function resetCaret() {
    clearInterval(caretTimer);
    caretTimer = setInterval(() => caretVisible = !caretVisible, 500);
    caretVisible = true;
}

function tick() {
    if (activeDocument !== null) {
        documents[activeDocument].tick();
    }

    if (!isPaused)
        setTimeout(tick, 1000 / 30);
}

function draw() {
    ctx.clearRect(0, 0, width, height);
    ctx.save();
    ctx.translate(0.5, 0.5);

    if (activeDocument !== null) {
        documents[activeDocument].draw();

        if (!!currentConnection) {
            currentConnection.draw();
        }

        animations.forEach(animation => animation.draw());
    } else {
        ctx.fillStyle = '#eee';
        ctx.fillRect(0, 0, width, height);

        ctx.fillStyle = '#000';
        ctx.drawText('Bitte öffne ein Dokument oder erstelle ein neues...', width / 2, height / 2, null, false);
    }

    ctx.restore();

    if (!isPaused)
        setTimeout(draw, 1000 / 60);
}

function selectObject(x, y) {
    if (activeDocument === null) {
        return null;
    }

    const doc = documents[activeDocument];

    for (let state of doc.states) {
        if (state.containsPoint(x, y)) {
            return state;
        }
    }

    for (let connection of doc.connections) {
        if (connection.containsPoint(x, y)) {
            return connection;
        }
    }

    caretPos = 0;

    return null;
}

let cursorVisible = true,
    selectedObject = null,
    currentConnection = null,
    movingObject = false,
    originalClick = null,
    deltaMouseX = 0,
    deltaMouseY = 0,
    shiftPressed = false;

canvas.addEventListener('mousedown', (event) => {
    const mouse = cbRelMousePos(event);
    selectedObject = selectObject(mouse.x, mouse.y);
    movingObject = false;
    originalClick = mouse;

    if (!!selectedObject) {
        if (shiftPressed && selectedObject instanceof State) {
            currentConnection = new SelfConnection(selectedObject, mouse);
        } else {
            movingObject = true;
            deltaMouseX = deltaMouseY = 0;
            if (selectedObject.setMouseStart) {
                selectedObject.setMouseStart(mouse.x, mouse.y);
            }
        }
        resetCaret();
    } else if (shiftPressed) {
        currentConnection = new TemporaryConnection(mouse, mouse);
    }

    if (canvasHasFocus()) {
        return false;
    } else {
        resetCaret();
        return true;
    }
});

canvas.addEventListener('mousemove', (event) => {
    const mouse = cbRelMousePos(event);

    if (!!currentConnection) {
        let targetNode = selectObject(mouse.x, mouse.y);
        if (!(targetNode instanceof State)) {
            targetNode = null;
        }

        if (!selectedObject) {
            if (!!targetNode) {
                currentConnection = new StartConnection(targetNode, originalClick);
            } else {
                currentConnection = new TemporaryConnection(originalClick, mouse);
            }
        } else {
            if (targetNode === selectedObject) {
                currentConnection = new SelfConnection(selectedObject, mouse);
            } else if (!!targetNode) {
                currentConnection = new Connection(selectedObject, targetNode);
            } else {
                currentConnection = new TemporaryConnection(selectedObject.closestPointOnCircle(mouse.x, mouse.y), mouse)
            }
        }
    }

    if (movingObject) {
        selectedObject.setAnchorPoint(mouse.x, mouse.y);
        if (selectedObject instanceof State) {
            snapNode(selectedObject);
        }
    }

});

canvas.addEventListener('mouseup', () => {
    movingObject = false;

    if (!!currentConnection && activeDocument !== null) {
        if (!(currentConnection instanceof TemporaryConnection)) {
            selectedObject = currentConnection;
            documents[activeDocument].connections.push(currentConnection);
            resetCaret();
        }
        currentConnection = null;
    }
});

canvas.addEventListener('dblclick', (event) => {
    const mouse = cbRelMousePos(event);

    if (activeDocument === null)
        return;

    selectedObject = selectObject(mouse.x, mouse.y);

    documents[activeDocument].onDblClick(mouse.x, mouse.y);
});

canvas.addEventListener('contextmenu', (event) => {
    const mouse = cbRelMousePos(event);

    event.preventDefault();

    if(activeDocument === null)
        return;

    selectedObject = selectObject(mouse.x, mouse.y);

    documents[activeDocument].onRightClick(mouse.x, mouse.y);
});

document.addEventListener('keydown', (event) => {
    const key = crossBrowserKey(event);

    if (!canvasHasFocus()) {
        return true;
    }

    switch (key) {
        case 16: // Shift
            shiftPressed = true;
            break;
        case 8: // Backspace
            if (!!selectedObject) {
                selectedObject.text = selectedObject.text.substr(0, caretPos - 1) + selectedObject.text.substr(caretPos, selectedObject.text.length);
                caretPos--;
                caretPos = Math.max(caretPos, 0);
                resetCaret();
            }

            event.preventDefault();

            return false;
        case 37: // Left Arrow
            if (!(event.ctrlKey || event.metaKey) && !!selectedObject) {
                caretPos--;
                caretPos = Math.max(caretPos, 0);
                resetCaret();

                return false;
            }

            break;
        case 39: // Right Arrow
            if (!(event.ctrlKey || event.metaKey) && !!selectedObject) {
                caretPos++;
                caretPos = Math.min(caretPos, selectedObject.text.length);
                resetCaret();

                return false;
            }
            break;
        case 36: // Home
            if(!(event.ctrlKey || event.metaKey) && !!selectedObject) {
                caretPos = 0;
                resetCaret();

                return false;
            }

            break;
        case 35: // End
            if(!(event.ctrlKey || event.metaKey) && !!selectedObject) {
                caretPos = selectedObject.text.length;

                return false;
            }

            break;
        case 46: // Delete
            if (activeDocument !== null) {
                documents[activeDocument].deleteCurrentObject();
            }
            break;
    }
});

document.addEventListener('keyup', (event) => {
    const key = crossBrowserKey(event);

    if (key === 16) {
        shiftPressed = false;
    }
});

document.addEventListener('keypress', (event) => {
    const key = crossBrowserKey(event);

    if (!canvasHasFocus()) {
        return true;
    }

    if (!!selectedObject && 'text' in selectedObject) {
        const text = selectedObject.text;

        if (!event.metaKey && !event.altKey && !event.ctrlKey) {
            if (key >= 0x20 && key <= 0x7E) {
                selectedObject.text = text.substring(0, caretPos) + String.fromCharCode(key) + text.substring(caretPos, text.length);
                caretPos++;
                resetCaret();

                return false;
            }
        }
    }

    if (key === 8) {
        return false;
    }
});

window.addEventListener('keydown', (event) => {
    const keyCode = crossBrowserKey(event);
    const key = String.fromCharCode(keyCode).toLowerCase();
    if ((event.ctrlKey || event.metaKey) && key === 's') { // Ctrl + S
        if (event.altKey || event.shiftKey) { // Ctrl + Alt + S
            modalExport.open();
        } else {
            saveToLocalStorage();
        }

        event.preventDefault();
        return false;
    }

    if ((event.ctrlKey || event.metaKey) && key === 'e') { // Ctrl + E
        modalExport.open();

        event.preventDefault();
        return false;
    }

    if ((event.ctrlKey || event.metaKey) && keyCode === 37) { // Ctrl + LeftArrow
        let activeDoc = activeDocument;
        activeDoc--;
        activeDoc = activeDoc < 0 ? documents.length - 1 : activeDoc % documents.length;

        switchDocument(activeDoc);

        event.preventDefault();
        return false;
    }

    if ((event.ctrlKey || event.metaKey) && keyCode === 39) { // Ctrl + RightArrow
        let activeDoc = activeDocument;
        activeDoc++;
        activeDoc = activeDoc < 0 ? documents.length - 1 : activeDoc % documents.length;

        switchDocument(activeDoc);

        event.preventDefault();
        return false;
    }
});

CanvasRenderingContext2D.prototype.drawArrow = function (x, y, angle) {
    const dx = Math.cos(angle);
    const dy = Math.sin(angle);

    this.beginPath();

    this.moveTo(x, y);
    this.lineTo(x - 8 * dx + 5 * dy, y - 8 * dy - 5 * dx);
    this.lineTo(x - 8 * dx - 5 * dy, y - 8 * dy + 5 * dx);

    this.fill();
};

CanvasRenderingContext2D.prototype.drawText = function (originalText, x, y, angleOrNull, isSelected) {
    const text = convertLatexShortcuts(originalText);
    this.font = '20px Roboto';
    const width = this.measureText(text).width;

    x -= width / 2; // Centers the text

    if (!!angleOrNull) {
        const dx = Math.cos(angleOrNull),
            dy = Math.sin(angleOrNull),
            cornerPointX = (width / 2 + 5) * (dx > 0 ? 1 : -1),
            cornerPointY = (10 + 5) * (dy > 0 ? 1 : -1),
            slide = dy * (Math.abs(dy) ** 40) * cornerPointX - dx * (Math.abs(dx) ** 10) * cornerPointY;
        x += cornerPointX - dy * slide;
        y += cornerPointY + dx * slide;
    }

    // Draw text and caret
    if ('advancedFillText' in this) {
        // this.advancedFillText()
    } else {
        x = Math.round(x);
        y = Math.round(y);
        this.fillText(text, x, y + 6);
        if (isSelected && caretVisible && canvasHasFocus() && document.hasFocus()) {
            x += this.measureText(text.substring(0, caretPos)).width;

            this.beginPath();

            this.moveTo(x, y - 10);
            this.lineTo(x, y + 10);

            this.stroke();
            this.closePath();
        }
    }
};

Node.prototype.addChild = function (name, classList, text) {
    const elem = document.createElement(name);

    if (classList instanceof Array) {
        elem.classList.add(...classList);
    } else if (!!classList) {
        elem.classList.add(classList);
    }

    if (!!text) {
        elem.innerText = text;
    }

    this.appendChild(elem);

    return elem;
};

function snapNode(targetState) {
    for (let state of documents[activeDocument].states) {
        if (state === targetState)
            continue;

        if (Math.abs(targetState.x - state.x) < settings.snapToPadding) {
            targetState.x = state.x;
        }

        if (Math.abs(targetState.y - state.y) < settings.snapToPadding) {
            targetState.y = state.y;
        }
    }
}

function canvasHasFocus() {
    return (document.activeElement || document.body) === document.body;
}

function crossBrowserKey(event) {
    event = event || window.event;
    return event.which || event.keyCode;
}

function cbElementPos(event) {
    event = event || window.event;
    let obj = event.target || event.srcElement,
        x = 0,
        y = 0;
    while (obj.offsetParent) {
        x += obj.offsetLeft;
        y += obj.offsetTop;
        obj = obj.offsetParent;
    }
    return {x, y};
}

function cbMousePos(event) {
    event = event || window.event;
    return {
        x: event.pageX || event.clientX + document.body.scrollLeft + document.documentElement.scrollLeft,
        y: event.pageY || event.clientY + document.body.scrollTop + document.documentElement.scrollTop,
    }
}

function cbRelMousePos(event) {
    const elem = cbElementPos(event),
        mouse = cbMousePos(event);
    return {
        x: mouse.x - elem.x,
        y: mouse.y - elem.y,
    };
}

function guid() {
    function s4() {
        return Math.floor((1 + Math.random()) * 0x10000)
            .toString(16)
            .substring(1);
    }

    return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
        s4() + '-' + s4() + s4() + s4();
}

window.addEventListener('load', () => {
    const doc = new FSMDocument('Dokument1');
    addDocument(doc);
    switchDocument(doc);

    tick();
    draw();
});

Object.prototype.hashCode = function () {
    let baseString = '';
    Object.values(this).forEach(entry => {
        if (entry === null)
            return;

        if (typeof entry === 'object' && !(entry instanceof Node)) {
            baseString += entry.hashCode();
        } else {
            baseString += entry;
        }
    });
    let hash = 0;
    for (let i = 0; i < baseString.length; i++) {
        const char = baseString.charCodeAt(i);
        hash = ((hash << 5) - hash) + char;
        hash = hash & hash;
    }
    return hash;
};