import {
  Component, ChangeDetectionStrategy, input, output, inject,
  viewChild, ElementRef, afterNextRender, DestroyRef,
} from '@angular/core';
import { ReducedMotionService } from '../../services/reduced-motion.service';
import { AnimationLoopService } from '../../services/animation-loop.service';
import { FL_CONFIG } from '../../providers/flair-config.provider';
import { getPixelRatio } from '../../utils/canvas.utils';
import { randomInRange } from '../../utils/math.utils';

@Component({
  selector: 'fl-fractal-landscape',
  standalone: true,
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `<canvas #canvas></canvas>`,
  styleUrl: './fl-fractal-landscape.component.scss',
  host: { 'class': 'fl-fractal-landscape' },
})
export class FlFractalLandscapeComponent {
  private config = inject(FL_CONFIG);
  private reducedMotion = inject(ReducedMotionService);
  private animationLoop = inject(AnimationLoopService);
  private destroyRef = inject(DestroyRef);

  protected canvasRef = viewChild.required<ElementRef<HTMLCanvasElement>>('canvas');

  // Inputs
  readonly gridSize = input(64);
  readonly roughness = input(0.6);
  readonly speed = input(0.3);
  readonly wireColor = input('#6366f1');
  readonly wireOpacity = input(0.6);
  readonly perspective = input(400);
  readonly elevation = input(0.4);
  readonly rotationSpeed = input(0.1);
  readonly responsive = input(true);

  // Outputs
  readonly ready = output<void>();

  private heightmap: number[][] = [];
  private ctx: CanvasRenderingContext2D | null = null;
  private width = 0;
  private height = 0;
  private pixelRatio = 1;
  private loopCleanup: (() => void) | null = null;
  private resizeObserver: ResizeObserver | null = null;

  constructor() {
    afterNextRender(() => {
      this.initialize();
    });

    this.destroyRef.onDestroy(() => {
      this.loopCleanup?.();
      this.resizeObserver?.disconnect();
    });
  }

  private initialize(): void {
    const canvas = this.canvasRef().nativeElement;
    this.ctx = canvas.getContext('2d');
    if (!this.ctx) return;

    this.pixelRatio = getPixelRatio(this.config.maxPixelRatio);
    this.resize();

    if (this.responsive()) {
      this.resizeObserver = new ResizeObserver(() => this.resize());
      this.resizeObserver.observe(canvas.parentElement!);
    }

    this.generateHeightmap();

    if (this.reducedMotion.reduced()) {
      this.renderFrame(0);
    } else {
      const id = `fractal-${Math.random().toString(36).slice(2)}`;
      this.loopCleanup = this.animationLoop.register(id, (_, elapsed) => this.renderFrame(elapsed));
    }

    this.ready.emit();
  }

  private resize(): void {
    const canvas = this.canvasRef().nativeElement;
    const parent = canvas.parentElement;
    if (!parent) return;

    this.width = parent.clientWidth;
    this.height = parent.clientHeight;
    canvas.width = this.width * this.pixelRatio;
    canvas.height = this.height * this.pixelRatio;
    canvas.style.width = `${this.width}px`;
    canvas.style.height = `${this.height}px`;
    this.ctx?.scale(this.pixelRatio, this.pixelRatio);
  }

  /** Diamond-square heightmap generation */
  private generateHeightmap(): void {
    const size = this.gridSize() + 1;
    const roughness = this.roughness();

    this.heightmap = Array.from({ length: size }, () => new Array(size).fill(0));

    // Seed corners
    this.heightmap[0][0] = randomInRange(-1, 1);
    this.heightmap[0][size - 1] = randomInRange(-1, 1);
    this.heightmap[size - 1][0] = randomInRange(-1, 1);
    this.heightmap[size - 1][size - 1] = randomInRange(-1, 1);

    let step = size - 1;
    let scale = roughness;

    while (step > 1) {
      const half = step >> 1;

      // Diamond step
      for (let y = 0; y < size - 1; y += step) {
        for (let x = 0; x < size - 1; x += step) {
          const avg = (
            this.heightmap[y][x] +
            this.heightmap[y][x + step] +
            this.heightmap[y + step][x] +
            this.heightmap[y + step][x + step]
          ) / 4;
          this.heightmap[y + half][x + half] = avg + randomInRange(-scale, scale);
        }
      }

      // Square step
      for (let y = 0; y < size; y += half) {
        for (let x = (y + half) % step; x < size; x += step) {
          let sum = 0;
          let count = 0;

          if (y - half >= 0) { sum += this.heightmap[y - half][x]; count++; }
          if (y + half < size) { sum += this.heightmap[y + half][x]; count++; }
          if (x - half >= 0) { sum += this.heightmap[y][x - half]; count++; }
          if (x + half < size) { sum += this.heightmap[y][x + half]; count++; }

          this.heightmap[y][x] = sum / count + randomInRange(-scale, scale);
        }
      }

      step = half;
      scale *= 0.5;
    }
  }

  private renderFrame(elapsed: number): void {
    if (!this.ctx) return;

    const ctx = this.ctx;
    const w = this.width;
    const h = this.height;
    const size = this.gridSize() + 1;
    const perspective = this.perspective();
    const elevation = this.elevation();
    const rotation = elapsed * this.rotationSpeed();
    const color = this.wireColor();
    const opacity = this.wireOpacity();

    ctx.clearRect(0, 0, w, h);
    ctx.strokeStyle = color;
    ctx.globalAlpha = opacity;
    ctx.lineWidth = 0.5;

    const cx = w / 2;
    const cy = h * 0.65;
    const cosR = Math.cos(rotation);
    const sinR = Math.sin(rotation);

    const project = (gx: number, gy: number, gz: number): { x: number; y: number; z: number } => {
      // Rotate around Y axis
      const rx = gx * cosR - gz * sinR;
      const rz = gx * sinR + gz * cosR;
      const ry = gy;

      // Perspective projection
      const scale = perspective / (perspective + rz + size * 0.5);
      return {
        x: cx + rx * scale,
        y: cy + ry * scale,
        z: rz,
      };
    };

    // Draw wireframe grid
    for (let y = 0; y < size - 1; y++) {
      for (let x = 0; x < size - 1; x++) {
        const gx = (x - size / 2) * 4;
        const gz = (y - size / 2) * 4;
        const gy = -this.heightmap[y][x] * size * elevation;

        const gx1 = ((x + 1) - size / 2) * 4;
        const gz1 = ((y + 1) - size / 2) * 4;
        const gy1x = -this.heightmap[y][x + 1] * size * elevation;
        const gy1y = -this.heightmap[y + 1][x] * size * elevation;

        const p0 = project(gx, gy, gz);
        const p1 = project(gx1, gy1x, gz);
        const p2 = project(gx, gy1y, gz1);

        // Depth-based opacity
        const depthAlpha = Math.max(0.1, 1 - (p0.z + size) / (size * 2));
        ctx.globalAlpha = opacity * depthAlpha;

        // Horizontal line
        ctx.beginPath();
        ctx.moveTo(p0.x, p0.y);
        ctx.lineTo(p1.x, p1.y);
        ctx.stroke();

        // Vertical line
        ctx.beginPath();
        ctx.moveTo(p0.x, p0.y);
        ctx.lineTo(p2.x, p2.y);
        ctx.stroke();
      }
    }
    ctx.globalAlpha = 1;
  }
}