import { detectPrepared, disposePrepared, prepareImage, preparedThreshold, type PreparedImage } from './detect';
import { prepareForExport } from './geometry';
import { loadPhoto } from './load-image';
import { shapeFromPolygons } from './margin';
import type { CV } from './opencv-loader';
import { scaleFromLine } from './scale';
import type { Point, RasterImage, Shape } from './types';

export type Tool = 'none' | 'scale' | 'seed' | 'draw';

const DEFAULT_THRESHOLD = 128;
const MIN_HOLE_MM = 3;

export class AppState {
  // Raw: the cv module and pixel buffers must never be wrapped in reactive proxies.
  cv = $state.raw<CV | null>(null);
  cvError = $state<string | null>(null);
  image = $state.raw<RasterImage | null>(null);
  /** Lighting-corrected grayscale of `image`, computed once per photo; owns WASM memory. */
  prepared = $state.raw<PreparedImage | null>(null);
  loadError = $state<string | null>(null);

  tool = $state<Tool>('none');
  scalePoints = $state<Point[]>([]);
  lengthMm = $state<number | null>(null);
  threshold = $state(DEFAULT_THRESHOLD);
  seed = $state<Point | null>(null);
  marginMm = $state(-2);
  mode = $state<'auto' | 'manual'>('auto');
  manualOuter = $state<Point[]>([]);
  manualHoles = $state<Point[][]>([]);
  drawing = $state<Point[]>([]);

  pxPerMm = $derived(
    this.scalePoints.length === 2 && this.lengthMm !== null
      ? scaleFromLine(this.scalePoints[0], this.scalePoints[1], this.lengthMm)
      : null,
  );
  scaleInvalid = $derived(this.scalePoints.length === 2 && this.lengthMm !== null && this.pxPerMm === null);
  marginPx = $derived(this.pxPerMm ? this.marginMm * this.pxPerMm : 0);

  shapePx = $derived.by((): Shape | null => {
    const { cv, image, prepared } = this;
    if (!cv || !image) return null;
    if (this.mode === 'manual') {
      return shapeFromPolygons(cv, image.width, image.height, { outer: this.manualOuter, holes: this.manualHoles }, this.marginPx);
    }
    if (!prepared) return null;
    return detectPrepared(cv, prepared, {
      threshold: this.threshold, seed: this.seed, marginPx: this.marginPx,
      minHolePx: this.pxPerMm ? MIN_HOLE_MM * this.pxPerMm : 0,
    });
  });

  exportShape = $derived(this.shapePx && this.pxPerMm ? prepareForExport(this.shapePx, this.pxPerMm) : null);

  setCv(cv: CV) {
    this.cv = cv;
    this.prepare();
  }

  setImage(image: RasterImage) {
    this.image = image;
    this.tool = 'none';
    this.scalePoints = [];
    this.seed = null;
    this.clearManual();
    this.prepare();
  }

  private prepare() {
    if (this.prepared) disposePrepared(this.prepared);
    const { cv, image } = this;
    this.prepared = cv && image ? prepareImage(cv, image) : null;
    this.threshold = cv && this.prepared ? preparedThreshold(cv, this.prepared) : DEFAULT_THRESHOLD;
  }

  async loadFile(file: Blob) {
    try {
      this.loadError = null;
      this.setImage(await loadPhoto(file));
    } catch {
      this.loadError = 'Could not read this image file.';
    }
  }

  autoThreshold() {
    if (this.cv && this.prepared) this.threshold = preparedThreshold(this.cv, this.prepared);
  }

  handleImageClick(p: Point) {
    const image = this.image;
    if (!image || p.x < 0 || p.y < 0 || p.x >= image.width || p.y >= image.height) return;
    switch (this.tool) {
      case 'scale':
        if (this.scalePoints.length === 1) {
          this.scalePoints.push(p);
          this.tool = 'none';
        } else {
          this.scalePoints = [p];
        }
        break;
      case 'seed':
        this.seed = p;
        this.tool = 'none';
        break;
      case 'draw':
        this.drawing.push(p);
        break;
    }
  }

  finishPolygon() {
    if (this.drawing.length >= 3) {
      if (this.manualOuter.length === 0) this.manualOuter = this.drawing;
      else this.manualHoles.push(this.drawing);
      this.mode = 'manual';
    }
    this.drawing = [];
  }

  clearManual() {
    this.manualOuter = [];
    this.manualHoles = [];
    this.drawing = [];
    this.mode = 'auto';
    if (this.tool === 'draw') this.tool = 'none';
  }
}