function Rect(value, name, x, y, w, h){
    this.value = value;
    this.name = name;
    this.x = x;
    this.y = y;
    this.w = w;
    this.h = h;
    this.checkHit = function (mouseX, mouseY) {
        return (mouseX >= x && mouseX <= x + w && mouseY >= y && mouseY <= y + h);
    }
}

function Circle(value, name, x, y, r){
    this.value = value;
    this.name = name;
    this.x = x;
    this.y = y;
    this.r = r;
    this.checkHit = function (mouseX, mouseY) {
        return Math.pow((mouseX - x),2) + Math.pow((mouseY - y),2) <= Math.pow(r, 2);
    }
}

function PieSlice(value, name, x, y, r, sAngle, eAngle){
    this.value = value;
    this.name = name;
    this.x = x;
    this.y = y;
    this.r = r;
    this.sAngle = sAngle;
    this.eAngle = eAngle;
    this.checkHit = function (mouseX, mouseY) {
        if (Math.pow((mouseX - x),2) + Math.pow((mouseY - y),2) <= Math.pow(r, 2)){
            var dy = mouseY - y;
            var dx = mouseX - x;
            var theta = Math.atan2(dy, dx); // range (-PI, PI]
            if (theta < 0) theta += 2*Math.PI;

            return (theta > sAngle && theta < eAngle);
        }
    }
}

let objects = [];

function checkHit(pos) {
    for (let i = 0; i < objects.length; i++){
        if (objects[i].checkHit(pos.x, pos.y)){
            return objects[i];
        }
    }
    return null;
}

function getLargest(data) {
    let largest = data[0].values[0];

    data.forEach(function (categ) {
        for (let i = 0; i < categ.values.length; i++)
            if (categ.values[i] > largest) {
                largest = categ.values[i];
            }
    });

    return largest;
}

function getSmallest(data) {
    let smallest = data[0].values[0];

    data.forEach(function (categ) {
        for (let i = 0; i < categ.values.length; i++)
            if (categ.values[i] < smallest) {
                smallest = categ.values[i];
            }
    });

    return smallest;
}

function drawAxis(bounds, largest, smallest, arrayLen, ctx, graphSettings, drawValues = true) {
    ctx.font = "16px Arial";
    if (graphSettings.y_step <= 0) graphSettings.y_step = 1;

    ctx.beginPath();
    for (let i = (smallest < 0)?smallest:0; i <= ((largest>=0)?largest:0); i += parseFloat(graphSettings.y_step)){

        ctx.strokeStyle = "#BBB";
        ctx.lineWidth = 1;
        let scale = bounds.height - ((largest >= 0)?(bounds.bottom - bounds.xAxis):0);
        let extreme = (largest<=0)?Math.abs(smallest):Math.abs(largest);
        let yPos = Math.round((bounds.xAxis - i * scale / extreme));

        //support line
        if (graphSettings.display_support_lines) {

            ctx.moveTo( bounds.left, yPos );
            ctx.lineTo( bounds.right, yPos );
        }

        //Y axis value
        ctx.fillStyle = "black";
        ctx.textAlign = "center";
        ctx.textAlign = "end";
        ctx.fillText( i, bounds.left - 3, yPos);
        ctx.stroke();
    }

    //X axis value
    if (drawValues) {
        ctx.fillStyle = "black";
        ctx.textAlign = "center";
        for (let i = 0; i < arrayLen; i++){
            let x = bounds.left + bounds.width / (arrayLen - 1) * i;
            let text = (i + 1).toString();
            if (graphSettings.custom_x_values !== "")
                text = graphSettings.custom_x_values.split(';')[i];
            ctx.fillText(text, x, bounds.bottom + 18);
        }
        ctx.closePath();
    }

    //X and Y axis
    ctx.strokeStyle = "black";
    ctx.lineWidth = "2px";
    ctx.beginPath();
    ctx.moveTo( bounds.left, bounds.top );
    ctx.lineTo( bounds.left, bounds.bottom );
    ctx.moveTo( bounds.left, bounds.xAxis);
    ctx.lineTo( bounds.right, bounds.xAxis );
    ctx.stroke();

    //Axis labels
    //X axis text
    ctx.beginPath();
    ctx.font = "20px Arial";
    ctx.fillStyle = "black";
    ctx.textAlign = "center";
    ctx.fillText(graphSettings.x_label, bounds.width/2 + bounds.left, bounds.height + 2*bounds.top - 5);

    //Y axis text
    ctx.save();
    ctx.rotate(-Math.PI / 2);
    ctx.textAlign = "center";
    ctx.fillText(graphSettings.y_label, -(bounds.left + bounds.height/2), 18);
    ctx.restore();
    ctx.stroke();
}

function drawTitle(canvas, graphSettings) {
    let ctx = canvas.getContext("2d");
    let x = canvas.width / 2;
    let y = 25;

    ctx.font = "30px Arial";
    ctx.fillStyle = "black";
    ctx.textAlign = "center";
    ctx.fillText( graphSettings.title, x, y);
}

function drawPoints(ctx, bounds, values, name, arrayLen, largest, color) {
    ctx.fillStyle = color;
    let radius = 3;

    for( let i = 0; i < arrayLen; i++ ){
        ctx.beginPath();
        if(values[i] === null) continue;
        let scale = bounds.height - ((largest >= 0)?(bounds.bottom - bounds.xAxis):0);
        let extreme = (largest<=0)?Math.abs(smallest):Math.abs(largest);
        let x = bounds.left + bounds.width / (arrayLen - 1) * i;
        let y = (bounds.xAxis - values[i] / extreme * scale);
        ctx.arc(x, y, radius, 0, 2 * Math.PI);
        ctx.fill();
        ctx.stroke();
        ctx.closePath();

        let new_object = new Circle(values[i], name, x, y, radius);
        objects.push(new_object);
    }
}

function drawSlice(ctx, centerX, centerY, radius, startAngle, endAngle, color ){
    ctx.fillStyle = color;
    ctx.beginPath();
    ctx.moveTo(centerX,centerY);
    ctx.arc(centerX, centerY, radius, startAngle, endAngle);
    ctx.fill();
    ctx.closePath();
}

function getBounds(canvas, graphMargin) {
    return {
        top: graphMargin,
        bottom: canvas.height - graphMargin,
        left: graphMargin,
        right: canvas.width - graphMargin,
        height: canvas.height - 2*graphMargin,
        width: canvas.width - 2*graphMargin,
        xAxis: canvas.height - graphMargin
    };
}

function drawPieChart(canvas, data, graphSettings) {

    let ctx = canvas.getContext("2d");
    let index = 0;
    let start_angle = 0;
    let total_value = 0;
    let bounds = getBounds(canvas, graphSettings.margin);


    data.forEach(function (categ) {
        let val = categ.values[0];
        if (val !== null)
            total_value += val;
    });

    data.forEach(function (categ) {
        let val = categ.values[0];
        let slice_angle = 2 * Math.PI * val / total_value;

        let x = canvas.width/2;
        let y = canvas.height/2;
        let r = Math.min(bounds.width/2, bounds.height/2);
        let end_angle = start_angle + slice_angle;

        drawSlice(ctx, x, y, r, start_angle, end_angle, categ.color);
        let new_object = new PieSlice(val + " (" + Math.round(val/total_value*100) + "%)", categ.name, x, y, r, start_angle, end_angle);
        objects.push(new_object);

        start_angle = end_angle;
        index++;
    });


}

function drawPointChart(canvas, data, graphSettings){
    let ctx = canvas.getContext( "2d" );

    let bounds = getBounds(canvas, graphSettings.margin);
    let largest = getLargest(data);
    let smallest = getSmallest(data);

    if (smallest < 0)
        bounds.xAxis = bounds.bottom - (bounds.height / (((largest<=0)?0:Math.abs(largest)) + Math.abs(smallest)) * Math.abs(smallest));
    let arrayLen = data[0].values.length;

    drawAxis(bounds, largest, smallest, arrayLen, ctx, graphSettings);

    data.display_points = true;
    data.forEach(function (categ) {
        //Points
        if (graphSettings.display_points)
            drawPoints(ctx, bounds, categ.values, categ.name, arrayLen, largest, categ.color);
    });
}

function drawLineChart(canvas, data, graphSettings){
    let ctx = canvas.getContext( "2d" );

    let bounds = getBounds(canvas, graphSettings.margin);
    let largest = getLargest(data);
    let smallest = getSmallest(data);

    if (smallest < 0)
        bounds.xAxis = bounds.bottom - (bounds.height / (((largest<=0)?0:Math.abs(largest)) + Math.abs(smallest)) * Math.abs(smallest));
    let arrayLen = data[0].values.length;

    drawAxis(bounds, largest, smallest, arrayLen, ctx, graphSettings);

    data.forEach(function (categ) {
        //Lines
        ctx.beginPath();
        ctx.lineJoin = "round";
        ctx.strokeStyle = categ.color;

        for (let i = 0; i < arrayLen; i++) {
            if (categ.values[i] === null) continue;

            let scale = bounds.height - ((largest >= 0)?(bounds.bottom - bounds.xAxis):0);
            let extreme = (largest<=0)?Math.abs(smallest):Math.abs(largest);
            let x = bounds.left + bounds.width / (arrayLen - 1) * i;
            let y = (bounds.xAxis - categ.values[i] / extreme * scale);

            ctx.lineTo(x, y);
        }
        ctx.stroke();
        ctx.closePath();

        //Points
        if (graphSettings.display_points)
            drawPoints(ctx, bounds, categ.values, categ.name, arrayLen, largest, categ.color);
    });
}

function drawAreaChart(canvas, data, graphSettings){
    let ctx = canvas.getContext( "2d" );

    let bounds = getBounds(canvas, graphSettings.margin);
    let largest = getLargest(data);
    let smallest = getSmallest(data);

    if (smallest < 0)
        bounds.xAxis = bounds.bottom - (bounds.height / (((largest<=0)?0:Math.abs(largest)) + Math.abs(smallest)) * Math.abs(smallest));
    let arrayLen = data[0].values.length;

    drawAxis(bounds, largest, smallest, arrayLen, ctx, graphSettings);

    data.forEach(function (categ) {
        //Lines
        ctx.beginPath();
        ctx.lineJoin = "round";
        ctx.strokeStyle = categ.color;

        let xmax = 0;
        for (let i = 0; i < arrayLen; i++) {
            if (categ.values[i] === null) continue;
            let scale = bounds.height - ((largest >= 0)?(bounds.bottom - bounds.xAxis):0);
            let extreme = (largest<=0)?Math.abs(smallest):Math.abs(largest);
            let x = bounds.left + bounds.width / (arrayLen - 1) * i;
            let y = (bounds.xAxis - categ.values[i] / extreme * scale);
            xmax = x;

            ctx.lineTo(x, y);
        }
        ctx.stroke();

        ctx.lineTo(xmax, bounds.xAxis);
        ctx.lineTo(bounds.left, bounds.xAxis);
        ctx.globalAlpha = 0.5;
        ctx.fillStyle = categ.color;
        ctx.closePath();
        ctx.fill();

        ctx.globalAlpha = 1;

        //Points
        if (graphSettings.display_points)
        drawPoints(ctx, bounds, categ.values, categ.name, arrayLen, largest, categ.color);
    });
}

function drawBarChart(canvas, data, graphSettings) {
    let ctx = canvas.getContext( "2d" );

    let bounds = getBounds(canvas, graphSettings.margin);
    ctx.shadowOffsetX = 15;
    ctx.shadowOffsetY = 15;
    ctx.shadowBlur    = 4;

    let largest = getLargest(data);
    let barCount = data.length;
    let dataCount = data[0].values.length;

    let smallest = getSmallest(data);

    if (smallest < 0)
        bounds.xAxis = bounds.bottom - (bounds.height / (((largest<=0)?0:Math.abs(largest)) + Math.abs(smallest)) * Math.abs(smallest));

    drawAxis(bounds, largest, smallest, dataCount, ctx, graphSettings, false);

    let size = bounds.width / dataCount;
    let innerSize = size * 0.8;
    let bar_width = innerSize * 0.7 / barCount;

    for (let i = 0; i < dataCount; i++) {
        let num = 0;
        data.forEach(function (categ) {
            ctx.beginPath();
            let value = categ.values[i];
            let left = bounds.left + (size * (i + 0.15) + (innerSize * num / barCount));
            let scale = bounds.height - ((largest >= 0)?(bounds.bottom - bounds.xAxis):0);
            let extreme = (largest<=0)?Math.abs(smallest):Math.abs(largest);
            let bar_height = value / extreme * scale;
            let top = (bounds.xAxis - categ.values[i] / extreme * scale);

            ctx.fillStyle = categ.color;
            ctx.fillRect(left, top, bar_width, bar_height);

            //x value
            if (num === 0){
                let text = (i + 1).toString();
                if (graphSettings.custom_x_values !== ""){
                    text = graphSettings.custom_x_values.split(';')[i];
                }
                ctx.font = "16px Arial";
                ctx.fillStyle = "black";
                ctx.textAlign = "center";
                ctx.fillText(text, bounds.width / dataCount * i + size / 2 + bounds.left, bounds.bottom + 15);
                ctx.stroke();
            }

            num++;
            let new_object = new Rect(value, categ.name, left, top, bar_width, bar_height);
            objects.push(new_object);
        });
    }
}

function stackedChart(canvas, data, graphSettings) {
    let ctx = canvas.getContext( "2d" );

    let bounds = getBounds(canvas, graphSettings.margin);
    ctx.shadowOffsetX = 15;
    ctx.shadowOffsetY = 15;
    ctx.shadowBlur    = 4;

    let dataCount = data[0].values.length;

    let largest = 0;
    for (let i = 0; i < dataCount; i++){
        let sum = 0;
        data.forEach(function (categ) {
            categ.values[i] = Math.abs(categ.values[i]);
            sum += categ.values[i];
        });
        if (sum > largest) largest = sum;
    }

    let smallest = getSmallest(data);
    if (smallest < 0)
        bounds.xAxis = bounds.bottom - (bounds.height / (((largest<=0)?0:Math.abs(largest)) + Math.abs(smallest)) * Math.abs(smallest));

    drawAxis(bounds, largest, smallest, dataCount, ctx, graphSettings, false);

    let size = bounds.width / dataCount;
    let bar_width = size * 0.7;

    for (let i = 0; i < dataCount; i++) {
        let last_top = bounds.xAxis;
        let num = 0;
        data.forEach(function (categ) {
            ctx.beginPath();

            let value = categ.values[i];
            let bar_height = value / largest * bounds.height;
            let left = bounds.left + (size * (i + 0.15));
            let top = last_top - bar_height;

            ctx.fillStyle = categ.color;
            ctx.fillRect(left, top, bar_width, bar_height);

            last_top = top;

            //x value
            if (num === 0){
                let text = (i + 1).toString();
                if (graphSettings.custom_x_values !== ""){
                    text = graphSettings.custom_x_values.split(';')[i];
                }
                ctx.font = "16px Arial";
                ctx.fillStyle = "black";
                ctx.textAlign = "center";
                ctx.fillText(text, bounds.width / dataCount * i + size / 2 + bounds.left, bounds.bottom + 15);
                ctx.stroke();
            }
            num++;

            let new_object = new Rect(value, categ.name, left, top, bar_width, bar_height);
            objects.push(new_object);
        });
    }
}

function resizeCanvas(canvas, parent, legendHeight = 0, bgColor) {

    if (legendHeight > 0) legendHeight += 3.1;
    //set size
    canvas.style.width = parent.clientWidth.toString();
    canvas.style.height = (parent.clientHeight - legendHeight).toString();
    canvas.width = parent.clientWidth;
    canvas.height = parent.clientHeight - legendHeight;

    //reset canvas color
    let ctx = canvas.getContext( "2d" );
    if (bgColor == null){
        ctx.clearRect(0, 0, canvas.width, canvas.height);
    } else {
        ctx.fillStyle = bgColor;
        ctx.fillRect(0, 0, canvas.width, canvas.height);
    }
}

function updateLegend(displayLegend, data) {
    if (displayLegend){
        let legendHTML = "";
        data.forEach(function (categ) {
            legendHTML += "<div><span style='display:inline-block;width:20px;background-color:" + categ.color + ";'>&nbsp;</span> "+categ.name+"</div>";
        });

        legend.innerHTML = legendHTML;
        legend.style.display = "block";
    } else {
        legend.style.display = "none";
    }
}

function drawChart(graphSettings, data) {
    updateLegend(graphSettings.display_legend, data);
    resizeCanvas(canvas, parent, legend.offsetHeight, graphSettings.b_color);
    objects = [];

    //Choose the correct graph
    switch (graphSettings.type) {
        case "point":
            drawPointChart(canvas, data, graphSettings);
            break;
        case "line":
            drawLineChart(canvas, data, graphSettings);
            break;
        case "pie":
            drawPieChart(canvas, data, graphSettings);
            break;
        case "bar":
            drawBarChart(canvas, data, graphSettings);
            break;
        case "area":
            drawAreaChart(canvas, data, graphSettings);
            break;
        case "stacked":
            stackedChart(canvas, data, graphSettings);
            break;
    }

    if (graphSettings.display_title)
        drawTitle(canvas, graphSettings);
}