import type { BodyInfo } from '$lib/wasm/types';
import { rgbToCss } from '$lib/utils/colors';

const AU_TO_PIXELS_BASE = 80; // pixels per AU at zoom level 1

interface Camera2D {
	x: number; // center offset in AU
	y: number;
	zoom: number;
}

export class SolarSystem2DRenderer {
	private canvas: HTMLCanvasElement;
	private ctx: CanvasRenderingContext2D;
	private camera: Camera2D = { x: 0, y: 0, zoom: 1 };
	private bodyInfos: BodyInfo[] = [];
	private positions: Float64Array = new Float64Array(0);
	private orbitPoints: Map<number, Float64Array> = new Map();
	private isDragging = false;
	private lastMouse = { x: 0, y: 0 };
	private animFrameId: number = 0;

	constructor(canvas: HTMLCanvasElement) {
		this.canvas = canvas;
		this.ctx = canvas.getContext('2d')!;
		this.setupEventListeners();
	}

	private setupEventListeners() {
		this.canvas.addEventListener('wheel', (e) => {
			e.preventDefault();
			const zoomFactor = e.deltaY > 0 ? 0.9 : 1.1;
			this.camera.zoom *= zoomFactor;
			this.camera.zoom = Math.max(0.05, Math.min(50, this.camera.zoom));
		});

		this.canvas.addEventListener('mousedown', (e) => {
			this.isDragging = true;
			this.lastMouse = { x: e.clientX, y: e.clientY };
		});

		this.canvas.addEventListener('mousemove', (e) => {
			if (!this.isDragging) return;
			const scale = this.getScale();
			this.camera.x -= (e.clientX - this.lastMouse.x) / scale;
			this.camera.y -= (e.clientY - this.lastMouse.y) / scale;
			this.lastMouse = { x: e.clientX, y: e.clientY };
		});

		this.canvas.addEventListener('mouseup', () => { this.isDragging = false; });
		this.canvas.addEventListener('mouseleave', () => { this.isDragging = false; });
	}

	private getScale(): number {
		return AU_TO_PIXELS_BASE * this.camera.zoom;
	}

	private auToScreen(xAU: number, yAU: number): [number, number] {
		const scale = this.getScale();
		const rect = this.canvas.getBoundingClientRect();
		const cx = rect.width / 2;
		const cy = rect.height / 2;
		return [
			cx + (xAU - this.camera.x) * scale,
			cy - (yAU - this.camera.y) * scale, // flip Y for screen coords
		];
	}

	updateBodies(infos: BodyInfo[], positions: Float64Array) {
		this.bodyInfos = infos;
		this.positions = positions;
	}

	updateOrbit(bodyId: number, points: Float64Array) {
		this.orbitPoints.set(bodyId, points);
	}

	render() {
		const { canvas, ctx } = this;
		const dpr = window.devicePixelRatio || 1;
		const rect = canvas.getBoundingClientRect();

		canvas.width = rect.width * dpr;
		canvas.height = rect.height * dpr;
		ctx.scale(dpr, dpr);

		// Clear
		ctx.fillStyle = '#0a0a0f';
		ctx.fillRect(0, 0, rect.width, rect.height);

		// Draw grid
		this.drawGrid(rect.width, rect.height);

		// Draw orbit ellipses
		for (const [bodyId, points] of this.orbitPoints) {
			if (bodyId < this.bodyInfos.length) {
				this.drawOrbit(points, this.bodyInfos[bodyId]);
			}
		}

		// Draw bodies on top
		if (this.positions.length > 0) {
			for (let i = 0; i < this.bodyInfos.length; i++) {
				const info = this.bodyInfos[i];
				const x = this.positions[i * 3];
				const y = this.positions[i * 3 + 1];

				if (i === 0) {
					this.drawSun(x, y, info);
				} else {
					this.drawBody(x, y, info);
				}
			}
		}

		// Scale indicator
		this.drawScaleBar(rect.width, rect.height);
	}

	private drawGrid(w: number, h: number) {
		const ctx = this.ctx;
		const scale = this.getScale();

		// Determine grid spacing in AU
		let gridAU = 1;
		const pixelsPerGrid = gridAU * scale;
		if (pixelsPerGrid < 30) gridAU = 5;
		if (pixelsPerGrid > 200) gridAU = 0.5;
		if (pixelsPerGrid > 400) gridAU = 0.1;

		ctx.strokeStyle = 'rgba(255, 255, 255, 0.04)';
		ctx.lineWidth = 0.5;

		// Vertical lines
		const startXAU = Math.floor((this.camera.x - w / 2 / scale) / gridAU) * gridAU;
		const endXAU = Math.ceil((this.camera.x + w / 2 / scale) / gridAU) * gridAU;
		for (let xAU = startXAU; xAU <= endXAU; xAU += gridAU) {
			const [sx] = this.auToScreen(xAU, 0);
			ctx.beginPath();
			ctx.moveTo(sx, 0);
			ctx.lineTo(sx, h);
			ctx.stroke();
		}

		// Horizontal lines
		const startYAU = Math.floor((this.camera.y - h / 2 / scale) / gridAU) * gridAU;
		const endYAU = Math.ceil((this.camera.y + h / 2 / scale) / gridAU) * gridAU;
		for (let yAU = startYAU; yAU <= endYAU; yAU += gridAU) {
			const [, sy] = this.auToScreen(0, yAU);
			ctx.beginPath();
			ctx.moveTo(0, sy);
			ctx.lineTo(w, sy);
			ctx.stroke();
		}

		// Concentric orbit reference circles (centered on Sun)
		ctx.strokeStyle = 'rgba(255, 255, 255, 0.03)';
		const [sunX, sunY] = this.auToScreen(0, 0);
		for (let r = 1; r <= 40; r++) {
			const radiusPx = r * scale;
			if (radiusPx < 10 || radiusPx > 5000) continue;
			ctx.beginPath();
			ctx.arc(sunX, sunY, radiusPx, 0, Math.PI * 2);
			ctx.stroke();
		}
	}

	private drawOrbit(points: Float64Array, info: BodyInfo) {
		if (points.length < 6) return;
		const ctx = this.ctx;
		const [r, g, b] = info.color;

		ctx.strokeStyle = `rgba(${r}, ${g}, ${b}, 0.2)`;
		ctx.lineWidth = 0.8;
		ctx.beginPath();

		const [sx0, sy0] = this.auToScreen(points[0], points[1]);
		ctx.moveTo(sx0, sy0);

		for (let i = 3; i < points.length; i += 3) {
			const [sx, sy] = this.auToScreen(points[i], points[i + 1]);
			ctx.lineTo(sx, sy);
		}

		ctx.closePath();
		ctx.stroke();
	}

	private drawSun(xAU: number, yAU: number, info: BodyInfo) {
		const ctx = this.ctx;
		const [sx, sy] = this.auToScreen(xAU, yAU);
		const [r, g, b] = info.color;

		// Glow
		const gradient = ctx.createRadialGradient(sx, sy, 0, sx, sy, 30);
		gradient.addColorStop(0, `rgba(${r}, ${g}, ${b}, 0.8)`);
		gradient.addColorStop(0.3, `rgba(${r}, ${g}, ${b}, 0.3)`);
		gradient.addColorStop(1, `rgba(${r}, ${g}, ${b}, 0)`);
		ctx.fillStyle = gradient;
		ctx.beginPath();
		ctx.arc(sx, sy, 30, 0, Math.PI * 2);
		ctx.fill();

		// Core
		ctx.fillStyle = rgbToCss(r, g, b);
		ctx.beginPath();
		ctx.arc(sx, sy, 6, 0, Math.PI * 2);
		ctx.fill();

		// Label
		ctx.fillStyle = 'rgba(255, 255, 255, 0.6)';
		ctx.font = '10px monospace';
		ctx.fillText(info.name, sx + 10, sy + 4);
	}

	private drawBody(xAU: number, yAU: number, info: BodyInfo) {
		const ctx = this.ctx;
		const [sx, sy] = this.auToScreen(xAU, yAU);
		const [r, g, b] = info.color;

		// Size based on radius (with minimum for visibility)
		let size = Math.max(2, Math.log10(info.radius_km / 1000) * 2);
		// Moons are smaller
		if (info.radius_km < 3000) size = 1.5;

		// Body dot
		ctx.fillStyle = rgbToCss(r, g, b);
		ctx.beginPath();
		ctx.arc(sx, sy, size, 0, Math.PI * 2);
		ctx.fill();

		// Subtle glow
		ctx.fillStyle = `rgba(${r}, ${g}, ${b}, 0.15)`;
		ctx.beginPath();
		ctx.arc(sx, sy, size * 3, 0, Math.PI * 2);
		ctx.fill();

		// Label
		ctx.fillStyle = 'rgba(255, 255, 255, 0.5)';
		ctx.font = '9px monospace';
		ctx.fillText(info.name, sx + size + 4, sy + 3);
	}

	private drawScaleBar(w: number, h: number) {
		const ctx = this.ctx;
		const scale = this.getScale();

		// Find a nice round AU value for the bar
		let barAU = 1;
		let barPx = barAU * scale;
		if (barPx > 200) { barAU = 0.5; barPx = barAU * scale; }
		if (barPx > 200) { barAU = 0.1; barPx = barAU * scale; }
		if (barPx < 30) { barAU = 5; barPx = barAU * scale; }
		if (barPx < 30) { barAU = 10; barPx = barAU * scale; }

		const x = 20;
		const y = h - 20;

		ctx.strokeStyle = 'rgba(255, 255, 255, 0.4)';
		ctx.lineWidth = 1;
		ctx.beginPath();
		ctx.moveTo(x, y);
		ctx.lineTo(x + barPx, y);
		ctx.stroke();

		// End caps
		ctx.beginPath();
		ctx.moveTo(x, y - 4);
		ctx.lineTo(x, y + 4);
		ctx.stroke();
		ctx.beginPath();
		ctx.moveTo(x + barPx, y - 4);
		ctx.lineTo(x + barPx, y + 4);
		ctx.stroke();

		ctx.fillStyle = 'rgba(255, 255, 255, 0.4)';
		ctx.font = '10px monospace';
		ctx.fillText(`${barAU} AU`, x + barPx / 2 - 15, y - 8);
	}

	destroy() {
		if (this.animFrameId) cancelAnimationFrame(this.animFrameId);
	}
}