fetch('/data.json')
    .then(resp => resp.json())
    .then(plot)
    .catch(err => {
        console.log(err);
    });

function average(window) {
    let y_sum = 0;
    let count = 0;
    for (const sample of window) {
        if (sample['y'] !== undefined) {
            y_sum += sample['y'];
            count += 1;
        }
    }
    if (count === 0) {
        return undefined;
    }
    return y_sum / count;
}

function localLinearRegression(slopeWindowSize, averageWindowSize) {
    return (window) => {
        let x_sum = 0;
        let y_sum = 0;
        let count = 0;
        for (const sample of window.slice(-slopeWindowSize)) {
            if (sample['y'] !== undefined) {
                x_sum += sample['x'];
                y_sum += sample['y'];
                count += 1;
            }
        }
        if (count === 0) {
            return undefined;
        }
        const x_avg = x_sum / count;
        const y_avg = y_sum / count;

        let numerator = 0;
        let denominator = 0;
        for (const sample of window) {
            if (sample['y'] !== undefined) {
                const x_err = sample['x'] - x_avg;
                const y_err = sample['y'] - y_avg;
                numerator += x_err * y_err;
                denominator += x_err * x_err;
            }
        }
        if (denominator === 0) {
            return window.at(-1)['y'];
        }
        const slope = numerator / denominator;

        let short_x_sum = 0;
        let short_y_sum = 0;
        let short_count = 0;
        for (const sample of window.slice(-averageWindowSize)) {
            if (sample['y'] !== undefined) {
                short_x_sum += sample['x'];
                short_y_sum += sample['y'];
                short_count += 1;
            }
        }
        if (short_count === 0) {
            return y_avg + (window.at(-1)['x'] - x_avg) * slope;
        }
        const short_x_avg = short_x_sum / short_count;
        const short_y_avg = short_y_sum / short_count;
        return short_y_avg + (window.at(-1)['x'] - short_x_avg) * slope;
    };
}

function smooth(data, column, windowSize, smoothFunc) {
    const smoothed = [];
    const window = [];
    for (const row of data) {
        window.push({ x: new Date(row['x']).getTime(), y: row[column] });
        if (window.length > windowSize) {
            window.shift();
        }
        smoothed.push({ x: row['x'], y: smoothFunc(window) });
    }
    return smoothed;
}

function extractWithErrorBars(data, region) {
    const extracted = [];
    for (const row of data['rows']) {
        const y = row[region + ' (copies/mL)'];
        if (y !== undefined) {
            extracted.push({
                x: row['Date'],
                y: y,
                yMin: y - (row[region + ' Low Confidence Interval'] || 0),
                yMax: y + (row[region + ' High Confidence Interval'] || 0),
            });
        }
    }
    return extracted;
}

function plot(data) {
    const northData = extractWithErrorBars(data, 'Northern');
    const southData = extractWithErrorBars(data, 'Southern');
    const northCtx = document.getElementById('northCanvas');
    const southCtx = document.getElementById('southCanvas');
    let options = {
        maintainAspectRatio: false,
        interaction: {
            intersect: false,
        },
        scales: {
            x: {
                type: 'timeseries',
                min: document.getElementById('startDate').value,
                max: document.getElementById('endDate').value,
            },
            y: {
                min: 0,
            },
        },
        plugins: {
            title: {
                display: true,
                text: 'Wastewater COVID RNA Signal (copies/mL)',
            },
        },
    };

    const northChart = new Chart(northCtx, {
        data: {
            datasets: [
                {
                    type: 'scatterWithErrorBars',
                    label: 'North System',
                    data: northData,
                    backgroundColor: 'rgba(0,0,255,0.5)',
                    color: 'rgba(0,0,255,0.5)',
                    borderColor: 'rgba(0,0,255,0.5)',
                    spanGaps: true,
                },
/*                {
                    type: 'line',
                    label: 'smoothing 18/14',
                    data: smooth(northData, 'y', 18, localLinearRegression(18, 14)),
                    pointRadius: 0,
                    borderColor: 'rgba(0,0,255,0.6)',
                },
                {
                    type: 'line',
                    label: 'smoothing 14/14',
                    data: smooth(northData, 'y', 14, localLinearRegression(14, 14)),
                    pointRadius: 0,
                    borderColor: 'rgba(255,0,255,0.6)',
                },*/
                {
                    type: 'line',
                    label: 'North System 7-day average (low)',
                    data: smooth(northData, 'yMin', 7, average),
                    pointRadius: 0,
                    borderColor: 'rgba(0,255,0,0.6)',
                    fill: '+1',
                    backgroundColor: 'rgba(0,255,0,0.2)',
                },
                {
                    type: 'line',
                    label: 'North System 7-day average',
                    data: smooth(northData, 'y', 7, average),
                    pointRadius: 0,
                    borderColor: 'rgba(0,128,0,0.9)',
                    backgroundColor: 'rgba(0,128,0,0.9)',
                },
                {
                    type: 'line',
                    label: 'North System 7-day average (high)',
                    data: smooth(northData, 'yMax', 7, average),
                    pointRadius: 0,
                    borderColor: 'rgba(0,255,0,0.6)',
                    fill: '-1',
                    backgroundColor: 'rgba(0,255,0,0.2)',
                },
            ]
        },
        options,
    });
    const southChart = new Chart(southCtx, {
        data: {
            datasets: [
                {
                    type: 'scatterWithErrorBars',
                    label: 'South System',
                    data: southData,
                    backgroundColor: 'rgba(255,0,0,0.5)',
                    color: 'rgba(255,0,0,0.5)',
                    borderColor: 'rgba(255,0,0,0.5)',
                    spanGaps: true,
                },
                {
                    type: 'line',
                    label: 'South System 7-day average (low)',
                    data: smooth(southData, 'yMin', 7, average),
                    pointRadius: 0,
                    borderColor: 'rgba(255,127,0,0.6)',
                    fill: '+1',
                    backgroundColor: 'rgba(255,127,0,0.2)',
                },
                {
                    type: 'line',
                    label: 'South System 7-day average',
                    data: smooth(southData, 'y', 7, average),
                    pointRadius: 0,
                    borderColor: 'rgba(127,63,0,0.9)',
                    backgroundColor: 'rgba(127,63,0,0.9)',
                },
                {
                    type: 'line',
                    label: 'South System 7-day average (high)',
                    data: smooth(southData, 'yMax', 7, average),
                    pointRadius: 0,
                    borderColor: 'rgba(255,127,0,0.6)',
                    fill: '-1',
                    backgroundColor: 'rgba(255,127,0,0.2)',
                },
            ],
        },
        options,
    });
    document.getElementById('startDate').addEventListener('input', (e) => {
        options.scales.x.min = e.target.value;
        northChart.update();
        southChart.update();
    });
    document.getElementById('endDate').addEventListener('input', (e) => {
        options.scales.x.max = e.target.value;
        northChart.update();
        southChart.update();
    });
}