/**
 * Curve drawing functions
 */

import { hexToRgb } from "../utils/helpers.js";

/**
 * Calculate distance from point to line segment
 * @param {{x: number, y: number}} point - Point coordinates
 * @param {Array<number>} lineStart - Line start point [x, y]
 * @param {Array<number>} lineEnd - Line end point [x, y]
 * @returns {number} Distance from point to line segment
 */
export function pointToLineSegmentDistance(point, lineStart, lineEnd) {
    const A = point.x - lineStart[0];
    const B = point.y - lineStart[1];
    const C = lineEnd[0] - lineStart[0];
    const D = lineEnd[1] - lineStart[1];

    const dot = A * C + B * D;
    const lenSq = C * C + D * D;
    let param = -1;
    if (lenSq !== 0) param = dot / lenSq;

    let xx, yy;

    if (param < 0) {
        xx = lineStart[0];
        yy = lineStart[1];
    } else if (param > 1) {
        xx = lineEnd[0];
        yy = lineEnd[1];
    } else {
        xx = lineStart[0] + param * C;
        yy = lineStart[1] + param * D;
    }

    const dx = point.x - xx;
    const dy = point.y - yy;
    return Math.sqrt(dx * dx + dy * dy);
}

/**
 * Draw control points for a curve
 * @param {CanvasRenderingContext2D} ctx - Canvas context
 * @param {Object} curve - Curve object
 * @param {Object} state - Editor state
 * @param {boolean} isSelected - Whether curve is selected
 */
export function drawPoints(ctx, curve, state, isSelected = false) {
    const pointRadius = 5;
    const selectedRadius = 7;

    curve.points.forEach((point, index) => {
        const pointKey = `${curve.id}:${index}`;
        const isPointSelected = state.selectedPoints.has(pointKey);

        ctx.beginPath();
        ctx.arc(point[0], point[1], isPointSelected ? selectedRadius : pointRadius, 0, Math.PI * 2);

        if (isPointSelected || isSelected) {
            ctx.fillStyle = "#4a9eff";
            ctx.fill();
        } else {
            ctx.fillStyle = "#ffffff";
            ctx.fill();
            ctx.strokeStyle = "#000000";
            ctx.lineWidth = 1;
            ctx.stroke();
        }
        
        // Add stroke outline only for specifically selected points (not just selected curves)
        if (isPointSelected) {
            ctx.beginPath();
            ctx.arc(point[0], point[1], selectedRadius, 0, Math.PI * 2);
            ctx.strokeStyle = "#ffffff";
            ctx.lineWidth = 2;
            ctx.stroke();
        }
    });
}

/**
 * Draw a single curve (polygon)
 * @param {CanvasRenderingContext2D} ctx - Canvas context
 * @param {Object} curve - Curve object
 * @param {Object} state - Editor state
 * @param {boolean} isSelected - Whether curve is selected
 */
export function drawCurve(ctx, curve, state, isSelected = false) {
    if (!curve || !curve.points || curve.points.length < 2) return;

    ctx.save();

    // Get pointTypes with validation (default to all "hard" if missing or invalid)
    let pointTypes;
    if (Array.isArray(curve.pointTypes) && curve.pointTypes.length === curve.points.length) {
        pointTypes = curve.pointTypes;
    } else {
        pointTypes = curve.points.map(() => "hard");
    }

    // Draw polygon path with smooth curves where needed using Catmull-Rom style interpolation
    ctx.beginPath();
    
    const n = curve.points.length;
    const points = curve.points;
    
    // Helper to get point with wrap-around for closed curves
    const getPoint = (index) => {
        if (curve.closed) {
            return points[((index % n) + n) % n];
        } else {
            if (index < 0) return points[0];
            if (index >= n) return points[n - 1];
            return points[index];
        }
    };
    
    // Helper to get point type with wrap-around
    const getType = (index) => {
        if (curve.closed) {
            return pointTypes[((index % n) + n) % n];
        } else {
            if (index < 0) return pointTypes[0];
            if (index >= n) return pointTypes[n - 1];
            return pointTypes[index];
        }
    };
    
    // Start at first point
    ctx.moveTo(points[0][0], points[0][1]);
    
    // For each segment
    const segmentCount = curve.closed ? n : n - 1;
    for (let i = 0; i < segmentCount; i++) {
        const nextI = (i + 1) % n;
        
        const p0 = points[i];
        const p1 = points[nextI];
        const type0 = getType(i);
        const type1 = getType(nextI);
        
        // If both points are hard, use straight line
        if (type0 === "hard" && type1 === "hard") {
            ctx.lineTo(p1[0], p1[1]);
        } else {
            // At least one point is smooth - use cubic curve
            // Calculate control points based on neighboring points (Catmull-Rom style)
            
            const prevP = getPoint(i - 1);
            const nextNextP = getPoint(i + 2);
            
            // Tension factor (0.5 is Catmull-Rom default)
            const tension = 0.5;
            
            // Calculate control point 1 (based on p0's tangent if smooth)
            let cp1x, cp1y;
            if (type0 === "smooth") {
                // Tangent at p0 based on prevP to p1
                cp1x = p0[0] + (p1[0] - prevP[0]) * tension / 2;
                cp1y = p0[1] + (p1[1] - prevP[1]) * tension / 2;
            } else {
                // Hard point - control point is closer to p0
                cp1x = p0[0] + (p1[0] - p0[0]) * 0.25;
                cp1y = p0[1] + (p1[1] - p0[1]) * 0.25;
            }
            
            // Calculate control point 2 (based on p1's tangent if smooth)
            let cp2x, cp2y;
            if (type1 === "smooth") {
                // Tangent at p1 based on p0 to nextNextP
                cp2x = p1[0] - (nextNextP[0] - p0[0]) * tension / 2;
                cp2y = p1[1] - (nextNextP[1] - p0[1]) * tension / 2;
            } else {
                // Hard point - control point is closer to p1
                cp2x = p1[0] - (p1[0] - p0[0]) * 0.25;
                cp2y = p1[1] - (p1[1] - p0[1]) * 0.25;
            }
            
            ctx.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, p1[0], p1[1]);
        }
    }

    if (curve.closed) {
        ctx.closePath();
    }

    // Fill with semi-transparent overlay
    if (curve.closed) {
        // Convert maskOpacity from 0-100 to 0-1 alpha
        const alpha = (state.maskOpacity || 10) / 100;
        
        if (isSelected) {
            // Selected curves use blue color with custom opacity
            ctx.fillStyle = `rgba(74, 158, 255, ${alpha})`;
        } else {
            // Unselected curves use mask color with custom opacity
            const rgb = hexToRgb(state.maskColor || "#ffffff");
            // Convert from 0-1 to 0-255 range
            const r = Math.round(rgb[0] * 255);
            const g = Math.round(rgb[1] * 255);
            const b = Math.round(rgb[2] * 255);
            ctx.fillStyle = `rgba(${r}, ${g}, ${b}, ${alpha})`;
        }
        ctx.fill();
    }

    // Stroke style
    if (isSelected) {
        ctx.strokeStyle = "#4a9eff";
        ctx.lineWidth = 3;
    } else {
        ctx.strokeStyle = "#ffffff";
        ctx.lineWidth = 2;
    }

    ctx.stroke();

    // Draw control points
    drawPoints(ctx, curve, state, isSelected);

    ctx.restore();
}