import { beforeAll, describe, expect, it } from 'vitest';
import { detect } from '../src/lib/detect';
import { bounds } from '../src/lib/geometry';
import { loadOpenCV, type CV } from '../src/lib/opencv-loader';
import type { DetectParams } from '../src/lib/types';
import { grayImage, inCircle, inRect } from './helpers/images';

let cv: CV;
beforeAll(async () => {
  ({ cv } = await loadOpenCV());
});

const params = (overrides: Partial<DetectParams> = {}): DetectParams => ({
  threshold: 128, invert: false, seed: null, marginPx: 0, minHolePx: 0, ...overrides,
});

/** Light plate x 40..159, y 30..129 with hole r=15 at (100,80), plus a small light blob, on dark ground. */
const plateScene = grayImage(200, 160, (x, y) => {
  const plate = inRect(x, y, 40, 30, 160, 130) && !inCircle(x, y, 100, 80, 15);
  const blob = inRect(x, y, 170, 140, 185, 152);
  return plate || blob ? 220 : 30;
});

const near = (actual: number, expected: number) => expect(Math.abs(actual - expected)).toBeLessThanOrEqual(2);

describe('detect', () => {
  it('finds the plate and its hole, ignoring the smaller blob', () => {
    const shape = detect(cv, plateScene, params())!;
    const b = bounds(shape.outer);
    near(b.minX, 40); near(b.maxX, 159); near(b.minY, 30); near(b.maxY, 129);
    expect(shape.holes).toHaveLength(1);
  });

  it('handles a dark piece on a light background with invert', () => {
    const inverted = grayImage(200, 160, (x, y) => 250 - (inRect(x, y, 40, 30, 160, 130) ? 220 : 30));
    expect(detect(cv, inverted, params())).toBeNull();
    const b = bounds(detect(cv, inverted, params({ invert: true }))!.outer);
    near(b.minX, 40); near(b.maxX, 159);
  });

  it('selects the clicked piece even when another piece is larger', () => {
    const shape = detect(cv, plateScene, params({ seed: { x: 177, y: 146 } }))!;
    const b = bounds(shape.outer);
    near(b.minX, 170); near(b.maxX, 184);
  });

  it('falls back to the automatic choice when the seed is on background or in a hole', () => {
    for (const seed of [{ x: 5, y: 5 }, { x: 100, y: 80 }]) {
      const b = bounds(detect(cv, plateScene, params({ seed }))!.outer);
      near(b.minX, 40);
    }
  });

  it('ignores a seed outside the image', () => {
    const b = bounds(detect(cv, plateScene, params({ seed: { x: -10, y: 500 } }))!.outer);
    near(b.minX, 40);
  });

  it('needs a seed for a piece touching the photo border', () => {
    const framed = grayImage(200, 160, (x, y) => (inRect(x, y, 0, 30, 120, 130) ? 220 : 30));
    expect(detect(cv, framed, params())).toBeNull();
    const b = bounds(detect(cv, framed, params({ seed: { x: 50, y: 80 } }))!.outer);
    near(b.minX, 0); near(b.maxX, 119);
  });

  it('returns null when the clicked region is the whole image', () => {
    const allLight = grayImage(100, 100, () => 220);
    expect(detect(cv, allLight, params({ seed: { x: 50, y: 50 } }))).toBeNull();
  });

  it('returns null when nothing passes the threshold', () => {
    expect(detect(cv, grayImage(100, 100, () => 30), params())).toBeNull();
  });

  it('applies the margin', () => {
    const b = bounds(detect(cv, plateScene, params({ marginPx: -5 }))!.outer);
    near(b.minX, 45); near(b.maxX, 154);
  });

  it('removes single-pixel speckle from the piece', () => {
    const speckled = grayImage(200, 160, (x, y) => {
      if (x === 70 && y === 50) return 30; // one dark pixel inside the plate
      return inRect(x, y, 40, 30, 160, 130) ? 220 : 30;
    });
    expect(detect(cv, speckled, params())!.holes).toHaveLength(0);
  });

  it('fills specks smaller than minHolePx before the margin can grow them', () => {
    const glare = grayImage(200, 160, (x, y) => {
      const plate = inRect(x, y, 40, 30, 160, 130) && !inCircle(x, y, 100, 80, 15) && !inCircle(x, y, 60, 50, 3);
      return plate ? 220 : 30;
    });
    expect(detect(cv, glare, params({ marginPx: -6 }))!.holes).toHaveLength(2);
    expect(detect(cv, glare, params({ marginPx: -6, minHolePx: 10 }))!.holes).toHaveLength(1);
  });

  it('keeps a long thin hole that is under minHolePx in only one direction', () => {
    const slotted = grayImage(200, 160, (x, y) => (inRect(x, y, 40, 30, 160, 130) && !inRect(x, y, 60, 60, 120, 66) ? 220 : 30));
    expect(detect(cv, slotted, params({ minHolePx: 10 }))!.holes).toHaveLength(1);
  });

  it('does not auto-pick a speck when the real piece touches the border', () => {
    const framed = grayImage(400, 300, (x, y) => (inRect(x, y, 0, 60, 240, 260) || inRect(x, y, 330, 100, 340, 110) ? 220 : 30));
    expect(detect(cv, framed, params())).toBeNull();
  });
});