import { Chart, ChartConfiguration, registerables } from 'chart.js';
import type { MetricACWRData, Activity } from '@/types';

// Register all Chart.js components
Chart.register(...registerables);

let distanceChart: Chart | null = null;
let durationChart: Chart | null = null;
let tssChart: Chart | null = null;
let caloriesChart: Chart | null = null;

// ACWR color zones - gradual HSV-based color
function getACWRColor(value: number | null): string {
    if (value === null || value === undefined) return 'rgba(148, 163, 184, 0.3)';

    // ACWR thresholds for color zones
    const BLUE_THRESHOLD = 0.8;    // Below this: detraining risk (blue)
    const GREEN_START = 0.8;       // Green zone start (optimal range)
    const GREEN_END = 1.3;         // Green zone end
    const ORANGE_END = 1.5;        // Orange zone end (warning)
    // Above ORANGE_END: injury risk (red)

    // Hue values for colors
    const HUE_BLUE = 240;
    const HUE_GREEN = 120;
    const HUE_ORANGE = 40;
    const HUE_RED = 0;

    // Calculate transition centers
    const greenCenter = GREEN_START + (GREEN_END - GREEN_START) / 2;
    const orangeCenter = GREEN_END + (ORANGE_END - GREEN_END) / 2;

    // Linear interpolation helper with automatic normalization
    const lerp = (start: number, end: number, value: number, rangeStart: number, rangeEnd: number): number => {
        const t = (value - rangeStart) / (rangeEnd - rangeStart);
        return start * (1 - t) + end * t;
    };

    let hue: number;
    if (value < BLUE_THRESHOLD) {
        hue = HUE_BLUE;
    } else if (value <= greenCenter) {
        hue = lerp(HUE_BLUE, HUE_GREEN, value, GREEN_START, greenCenter);
    } else if (value <= orangeCenter) {
        hue = lerp(HUE_GREEN, HUE_ORANGE, value, greenCenter, orangeCenter);
    } else if (value <= ORANGE_END) {
        hue = lerp(HUE_ORANGE, HUE_RED, value, orangeCenter, ORANGE_END);
    } else {
        hue = HUE_RED;
    }

    return `hsla(${hue}, 85%, 55%, 0.9)`;
}

// Plugin to draw gradient-colored ACWR line
const acwrGradientPlugin = {
    id: 'acwrGradient',
    afterDatasetsDraw(chart: Chart) {
        // Find the ACWR dataset by label
        const acwrDatasetIndex = chart.data.datasets.findIndex(ds => ds.label === 'ACWR');
        if (acwrDatasetIndex === -1) return;

        const meta = chart.getDatasetMeta(acwrDatasetIndex);
        if (!meta || meta.hidden) return;

        const ctx = chart.ctx;
        const data = chart.data.datasets[acwrDatasetIndex].data as (number | null)[];
        const chartArea = chart.chartArea;

        ctx.save();

        // First, fill the area under the curve with gradient colors
        for (let i = 0; i < meta.data.length - 1; i++) {
            const point1 = meta.data[i];
            const point2 = meta.data[i + 1];

            if (!point1 || !point2) continue;

            const value1 = data[i];
            const value2 = data[i + 1];

            // Skip if both values are null
            if (value1 === null && value2 === null) continue;

            // Use the second point value (most recent/rightward)
            const segmentValue = value2 ?? value1;

            const color = getACWRColor(segmentValue);
            // Make the fill more transparent
            const fillColor = color.replace(/[\d.]+\)$/, '0.15)');

            ctx.fillStyle = fillColor;
            ctx.beginPath();
            ctx.moveTo(point1.x, point1.y);
            ctx.lineTo(point2.x, point2.y);
            ctx.lineTo(point2.x, chartArea.bottom);
            ctx.lineTo(point1.x, chartArea.bottom);
            ctx.closePath();
            ctx.fill();
        }

        // Then draw the line on top
        ctx.lineWidth = 4;
        ctx.lineCap = 'round';
        ctx.lineJoin = 'round';

        // Draw line segments with colors based on values
        for (let i = 0; i < meta.data.length - 1; i++) {
            const point1 = meta.data[i];
            const point2 = meta.data[i + 1];

            if (!point1 || !point2) continue;

            const value1 = data[i];
            const value2 = data[i + 1];

            // Skip if both values are null
            if (value1 === null && value2 === null) continue;

            // Use the second point value (most recent/rightward)
            const segmentValue = value2 ?? value1;

            ctx.strokeStyle = getACWRColor(segmentValue);
            ctx.beginPath();
            ctx.moveTo(point1.x, point1.y);
            ctx.lineTo(point2.x, point2.y);
            ctx.stroke();
        }

        ctx.restore();
    },
};

// Register the custom plugin
Chart.register(acwrGradientPlugin);

// Function to get activity emoji based on type
function getActivityEmoji(activityType: string): string {
    const type = activityType.toLowerCase();
    if (type.includes('run')) return '🏃';
    if (type.includes('cycling') || type.includes('bike') || type.includes('ride')) return '🚴';
    if (type.includes('swim')) return '🏊';
    if (type.includes('walk') || type.includes('hiking')) return '🚶';
    if (type.includes('strength') || type.includes('gym')) return '💪';
    if (type.includes('yoga')) return '🧘';
    if (type.includes('row')) return '🚣';
    if (type.includes('ski')) return '⛷️';
    return '⚡'; // Default for other activities
}

// Function to show activity details popover
function showActivityDetails(dateStr: string, activities: Activity[]): void {
    const popover = document.getElementById('activity-popover');
    const dateTitle = document.getElementById('activity-date-title');
    const activityList = document.getElementById('activity-list');

    if (!popover || !dateTitle || !activityList) return;

    // Format date
    const date = new Date(dateStr);
    const formattedDate = date.toLocaleDateString('en-US', {
        weekday: 'long',
        year: 'numeric',
        month: 'long',
        day: 'numeric'
    });

    dateTitle.textContent = formattedDate;

    // Clear previous activities
    activityList.innerHTML = '';

    // Add each activity
    activities.forEach(activity => {
        const activityItem = document.createElement('div');
        activityItem.className = 'activity-item';

        const displayName = activity.title || activity.activityType || 'Activity';
        const emoji = getActivityEmoji(activity.activityType || 'Activity');

        const header = document.createElement('div');
        header.className = 'activity-item-header';
        header.innerHTML = `<span>${emoji}</span><span>${displayName}</span>`;

        const details = document.createElement('div');
        details.className = 'activity-item-details';

        // Distance
        if (activity.distance !== undefined && activity.distance > 0) {
            const distanceDetail = document.createElement('div');
            distanceDetail.className = 'activity-detail';
            distanceDetail.innerHTML = `
                <span class="activity-detail-label">🗺️ Distance</span>
                <span class="activity-detail-value">${activity.distance.toFixed(2)} km</span>
            `;
            details.appendChild(distanceDetail);
        }

        // Duration
        if (activity.duration !== undefined && activity.duration > 0) {
            const durationDetail = document.createElement('div');
            durationDetail.className = 'activity-detail';
            const durationMin = Math.round(activity.duration);
            durationDetail.innerHTML = `
                <span class="activity-detail-label">⏱️ Duration</span>
                <span class="activity-detail-value">${durationMin} min</span>
            `;
            details.appendChild(durationDetail);
        }

        // TSS
        if (activity.trainingStressScore !== undefined && activity.trainingStressScore > 0) {
            const tssDetail = document.createElement('div');
            tssDetail.className = 'activity-detail';
            tssDetail.innerHTML = `
                <span class="activity-detail-label">🥵 TSS</span>
                <span class="activity-detail-value">${activity.trainingStressScore.toFixed(0)}</span>
            `;
            details.appendChild(tssDetail);
        }

        // Calories
        if (activity.calories !== undefined && activity.calories > 0) {
            const caloriesDetail = document.createElement('div');
            caloriesDetail.className = 'activity-detail';
            caloriesDetail.innerHTML = `
                <span class="activity-detail-label">🔋 Calories</span>
                <span class="activity-detail-value">${activity.calories.toFixed(0)} kcal</span>
            `;
            details.appendChild(caloriesDetail);
        }

        // Average HR
        if (activity.averageHR !== undefined && activity.averageHR > 0) {
            const avgHRDetail = document.createElement('div');
            avgHRDetail.className = 'activity-detail';
            avgHRDetail.innerHTML = `
                <span class="activity-detail-label">💚 Avg HR</span>
                <span class="activity-detail-value">${activity.averageHR.toFixed(0)} bpm</span>
            `;
            details.appendChild(avgHRDetail);
        }

        // Max HR
        if (activity.maxHR !== undefined && activity.maxHR > 0) {
            const maxHRDetail = document.createElement('div');
            maxHRDetail.className = 'activity-detail';
            maxHRDetail.innerHTML = `
                <span class="activity-detail-label">❤️ Max HR</span>
                <span class="activity-detail-value">${activity.maxHR.toFixed(0)} bpm</span>
            `;
            details.appendChild(maxHRDetail);
        }

        activityItem.appendChild(header);
        activityItem.appendChild(details);
        activityList.appendChild(activityItem);
    });

    // Show popover
    popover.classList.remove('hidden');
}

// Setup activity popover close handlers
function setupActivityPopoverHandlers(): void {
    const popover = document.getElementById('activity-popover');
    const closeButton = document.getElementById('activity-close');

    if (!popover || !closeButton) return;

    // Close button click
    closeButton.addEventListener('click', () => {
        popover.classList.add('hidden');
    });

    // Click outside to close
    popover.addEventListener('click', (e) => {
        if (e.target === popover) {
            popover.classList.add('hidden');
        }
    });

    // Escape key to close
    document.addEventListener('keydown', (e) => {
        if (e.key === 'Escape' && !popover.classList.contains('hidden')) {
            popover.classList.add('hidden');
        }
    });
}

// Initialize handlers on load
if (typeof window !== 'undefined') {
    setupActivityPopoverHandlers();
}

// Common chart styling inspired by Garmin
const commonOptions = {
    responsive: true,
    maintainAspectRatio: true,
    plugins: {
        legend: {
            display: true,
            position: 'top' as const,
            labels: {
                usePointStyle: true,
                padding: 15,
                font: {
                    size: 12,
                },
            },
        },
        tooltip: {
            mode: 'index' as const,
            intersect: false,
            backgroundColor: 'rgba(255, 255, 255, 0.95)',
            titleColor: '#1e293b',
            bodyColor: '#475569',
            borderColor: '#e2e8f0',
            borderWidth: 1,
            padding: 12,
            displayColors: true,
        },
    },
    scales: {
        x: {
            grid: {
                display: true,
                color: 'rgba(148, 163, 184, 0.15)',
                lineWidth: 1,
                drawBorder: false,
            },
            ticks: {
                maxRotation: 45,
                minRotation: 45,
                padding: 8,
                color: '#64748b',
                font: {
                    size: 10,
                },
                autoSkip: true,
                maxTicksLimit: 20,
            },
        },
    },
};

function createDualAxisChart(
    canvasId: string,
    data: MetricACWRData,
    metricLabel: string,
    metricUnit: string,
    dotColor: string
): Chart {
    const canvas = document.getElementById(canvasId) as HTMLCanvasElement;
    if (!canvas) throw new Error(`Canvas ${canvasId} not found`);

    // Combine historical and future data for charts
    const allDates = [...data.dates];
    const allValues = [...data.values];
    const allAverage7d = [...data.average7d];
    const allAverage28d = [...data.average28d];
    const allAcwr = [...data.acwr];

    // Add future data if available
    if (data.futureDates && data.futureValues) {
        allDates.push(...data.futureDates);
        allValues.push(...data.futureValues);
        allAverage7d.push(...(data.futureAverage7d || []));
        allAverage28d.push(...(data.futureAverage28d || []));
        allAcwr.push(...(data.futureAcwr || []));
    }

    const historicalCount = data.dates.length;

    const config: ChartConfiguration = {
        type: 'line',
        data: {
            labels: allDates,
            datasets: [
                {
                    type: 'scatter',
                    label: `Daily ${metricLabel}`,
                    data: data.values,
                    backgroundColor: dotColor,
                    borderColor: dotColor.replace('0.8)', '1)'),
                    borderWidth: 1,
                    pointRadius: 5,
                    pointHoverRadius: 7,
                    yAxisID: 'y',
                },
                // Future daily values (grey, larger points) - exclude zero values
                ...(data.futureValues ? [{
                    type: 'scatter' as const,
                    label: `Predicted Daily ${metricLabel}`,
                    data: Array(historicalCount).fill(null).concat(
                        data.futureValues.map(v => (v !== null && v > 0) ? v : null)
                    ),
                    backgroundColor: 'rgba(148, 163, 184, 0.6)',
                    borderColor: 'rgba(100, 116, 139, 0.8)',
                    borderWidth: 2,
                    pointRadius: 7,
                    pointHoverRadius: 9,
                    yAxisID: 'y',
                }] : []),
                {
                    type: 'line',
                    label: '7-Day Average',
                    data: data.average7d,
                    borderColor: 'rgba(168, 85, 247, 0.5)',
                    backgroundColor: 'rgba(168, 85, 247, 0.05)',
                    borderWidth: 1.5,
                    pointRadius: 0,
                    pointHoverRadius: 4,
                    tension: 0.4,
                    fill: false,
                    yAxisID: 'y',
                },
                {
                    type: 'line',
                    label: '28-Day Average',
                    data: data.average28d,
                    borderColor: 'rgba(236, 72, 153, 0.5)',
                    backgroundColor: 'rgba(236, 72, 153, 0.05)',
                    borderWidth: 1.5,
                    pointRadius: 0,
                    pointHoverRadius: 4,
                    tension: 0.4,
                    fill: false,
                    yAxisID: 'y',
                },
                {
                    type: 'line',
                    label: 'ACWR',
                    data: data.acwr,
                    borderColor: 'rgba(139, 92, 246, 0)', // Transparent - we draw it in the plugin
                    backgroundColor: 'rgba(139, 92, 246, 0)',
                    borderWidth: 4,
                    pointRadius: 0,
                    pointHoverRadius: 5,
                    pointHoverBackgroundColor: (context: any) => {
                        const value = context.raw;
                        return getACWRColor(value);
                    },
                    tension: 0.4,
                    fill: false,
                    yAxisID: 'y1',
                },
                // Future ACWR (grey, thicker)
                ...(data.futureAcwr ? [{
                    type: 'line' as const,
                    label: 'Predicted ACWR',
                    data: Array(historicalCount).fill(null).concat(data.futureAcwr),
                    borderColor: 'rgba(148, 163, 184, 0.8)',
                    backgroundColor: 'rgba(148, 163, 184, 0.1)',
                    borderWidth: 5,
                    pointRadius: 0,
                    pointHoverRadius: 6,
                    tension: 0.4,
                    fill: false,
                    yAxisID: 'y1',
                    borderDash: [5, 5],
                }] : []),
            ],
        },
        options: {
            ...commonOptions,
            onClick: (_event: any, elements: any[]) => {
                if (elements.length > 0) {
                    const element = elements[0];
                    const datasetIndex = element.datasetIndex;

                    // Only handle clicks on the scatter (daily values) dataset
                    if (datasetIndex === 0) {
                        const index = element.index;
                        const dateStr = data.dates[index];

                        // Get activities for this date
                        if (data.activitiesByDate) {
                            const activities = data.activitiesByDate.get(dateStr);
                            if (activities && activities.length > 0) {
                                showActivityDetails(dateStr, activities);
                            }
                        }
                    }
                }
            },
            scales: {
                ...commonOptions.scales,
                y: {
                    type: 'linear',
                    position: 'left',
                    beginAtZero: true,
                    border: {
                        display: false,
                    },
                    grid: {
                        color: 'rgba(148, 163, 184, 0.1)',
                    },
                    ticks: {
                        padding: 8,
                        color: '#64748b',
                        font: {
                            size: 11,
                        },
                    },
                    title: {
                        display: true,
                        text: `${metricLabel} ${metricUnit}`,
                        color: '#64748b',
                        font: {
                            size: 12,
                            weight: 500,
                        },
                    },
                },
                y1: {
                    type: 'linear',
                    position: 'right',
                    beginAtZero: true,
                    suggestedMin: 0,
                    suggestedMax: 2,
                    grid: {
                        drawOnChartArea: false,
                    },
                    ticks: {
                        padding: 8,
                        color: '#8b5cf6',
                        font: {
                            size: 11,
                        },
                    },
                    title: {
                        display: true,
                        text: 'ACWR',
                        color: '#8b5cf6',
                        font: {
                            size: 12,
                            weight: 500,
                        },
                    },
                },
            },
            interaction: {
                mode: 'index' as const,
                intersect: false,
            },
        },
    };

    return new Chart(canvas, config);
}

export function createDistanceChart(data: MetricACWRData): void {
    if (distanceChart) {
        distanceChart.destroy();
    }
    distanceChart = createDualAxisChart(
        'distance-chart',
        data,
        'Distance',
        '(km)',
        'rgba(234, 179, 8, 0.8)'
    );
    updateTargetInfo('distance-target', data.targetTomorrowValue, 'km', data.targetACWR, data.restTomorrowACWR);
}

export function createDurationChart(data: MetricACWRData): void {
    if (durationChart) {
        durationChart.destroy();
    }
    durationChart = createDualAxisChart(
        'duration-chart',
        data,
        'Duration',
        '(min)',
        'rgba(234, 179, 8, 0.8)'
    );
    updateTargetInfo('duration-target', data.targetTomorrowValue, 'minutes', data.targetACWR, data.restTomorrowACWR);
}

export function createTSSChart(data: MetricACWRData): void {
    if (tssChart) {
        tssChart.destroy();
    }
    tssChart = createDualAxisChart(
        'tss-chart',
        data,
        'TSS',
        '',
        'rgba(234, 179, 8, 0.8)'
    );
    updateTargetInfo('tss-target', data.targetTomorrowValue, 'TSS', data.targetACWR, data.restTomorrowACWR);
}

export function createCaloriesChart(data: MetricACWRData): void {
    if (caloriesChart) {
        caloriesChart.destroy();
    }
    caloriesChart = createDualAxisChart(
        'calories-chart',
        data,
        'Calories',
        '(kcal)',
        'rgba(234, 179, 8, 0.8)'
    );
    updateTargetInfo('calories-target', data.targetTomorrowValue, 'kcal', data.targetACWR, data.restTomorrowACWR);
}

function updateTargetInfo(elementId: string, targetValue: number | null | undefined, unit: string, targetACWR: number | undefined, restTomorrowACWR: number | null | undefined): void {
    const element = document.getElementById(elementId);
    if (!element) return;

    if (targetACWR !== undefined) {
        let html: string;

        if (targetValue === null || targetValue === undefined) {
            html = `<strong>🎯 Next activity :</strong> <span style="color: var(--secondary-color);">ACWR of ${targetACWR} cannot be reached</span>`;
        } else if (targetValue === 0) {
            html = `<strong>🎯 Next activity :</strong> <span style="color: var(--secondary-color);">Rest recommended to reach ACWR of ${targetACWR}</span>`;
        } else {
            const formattedValue = targetValue.toFixed(1);
            html = `<strong>🎯 Next activity :</strong> <span class="target-value">${formattedValue} ${unit}</span> <span style="color: var(--secondary-color);">to reach ACWR of ${targetACWR}</span>`;
        }

        // Add rest tomorrow information
        if (restTomorrowACWR !== null && restTomorrowACWR !== undefined) {
            const color = getACWRColor(restTomorrowACWR);
            html += `<br><strong>😴 If Rest :</strong> <span style="color: ${color};">ACWR ${restTomorrowACWR.toFixed(2)}</span>`;
        }

        element.innerHTML = html;
        element.classList.add('visible');
    } else {
        element.innerHTML = `<strong>ℹ️ Target :</strong> <span style="color: var(--secondary-color);">Need at least 28 days of data to calculate</span>`;
        element.classList.add('visible');
    }
}

export function destroyAllCharts(): void {
    if (distanceChart) {
        distanceChart.destroy();
        distanceChart = null;
    }
    if (durationChart) {
        durationChart.destroy();
        durationChart = null;
    }
    if (tssChart) {
        tssChart.destroy();
        tssChart = null;
    }
    if (caloriesChart) {
        caloriesChart.destroy();
        caloriesChart = null;
    }
}