import L, { Bounds, LatLng, Point } from 'leaflet'

export const TileSize = 100
export const HnHMaxZoom = 6
export const HnHMinZoom = 1
export const HnHDefaultZoom = 6

export interface GridCoordLayerOptions extends L.GridLayerOptions {
  visible?: boolean
}

/**
 * Grid layer that draws one coordinate label per Leaflet tile in the top-left corner.
 * Uses only coords.z (do not use map.getZoom()) so labels stay in sync with tiles.
 * SmartTileLayer has zoomReverse: true, so URL z = 6 - coords.z; backend maps z=6 → storageZ=0.
 * Game tile for this Leaflet tile: scaleFactor = 2^(HnHMaxZoom - coords.z),
 * topLeft = (coords.x * scaleFactor, coords.y * scaleFactor) — same (x,y) as backend tile.
 */
export const GridCoordLayer = L.GridLayer.extend({
  options: {
    visible: true,
  },
  createTile(coords: { x: number; y: number; z: number }) {
    if (!this.options.visible) {
      const element = document.createElement('div')
      element.style.width = TileSize + 'px'
      element.style.height = TileSize + 'px'
      element.classList.add('map-tile')
      return element
    }
    const element = document.createElement('div')
    element.style.width = TileSize + 'px'
    element.style.height = TileSize + 'px'
    element.style.position = 'relative'
    element.classList.add('map-tile')

    const scaleFactor = Math.pow(2, HnHMaxZoom - coords.z)
    const topLeft = { x: coords.x * scaleFactor, y: coords.y * scaleFactor }

    // One label per Leaflet tile at top-left (2px, 2px); same (x,y) as backend tile for this coords.
    const textElement = document.createElement('div')
    textElement.classList.add('map-tile-text')
    textElement.textContent = `(${topLeft.x}, ${topLeft.y})`
    textElement.style.position = 'absolute'
    textElement.style.left = '2px'
    textElement.style.top = '2px'
    textElement.style.fontSize = Math.max(8, 12 - Math.log2(scaleFactor) * 2) + 'px'
    element.appendChild(textElement)
    return element
  },
}) as unknown as new (options?: GridCoordLayerOptions) => L.GridLayer

export interface ImageIconOptions extends L.IconOptions {
  /** When the main icon image fails to load, use this URL (e.g. data URL or default marker). */
  fallbackIconUrl?: string
}

export const ImageIcon = L.Icon.extend({
  options: {
    iconSize: [32, 32],
    iconAnchor: [16, 16],
  } as ImageIconOptions,

  createIcon(oldIcon?: HTMLElement): HTMLElement {
    const img = L.Icon.prototype.createIcon.call(this, oldIcon) as HTMLImageElement
    const fallback = (this.options as ImageIconOptions).fallbackIconUrl
    if (fallback && img && img.tagName === 'IMG') {
      img.onerror = () => {
        img.onerror = null
        img.src = fallback
      }
    }
    return img
  },
}) as unknown as new (options?: ImageIconOptions) => L.Icon

const latNormalization = (90.0 * TileSize) / 2500000.0
const lngNormalization = (180.0 * TileSize) / 2500000.0

const HnHProjection = {
  project(latlng: LatLng) {
    return new Point(latlng.lat / latNormalization, latlng.lng / lngNormalization)
  },
  unproject(point: Point) {
    return new LatLng(point.x * latNormalization, point.y * lngNormalization)
  },
  bounds: (() => new Bounds([-latNormalization, -lngNormalization], [latNormalization, lngNormalization]))(),
}

export const HnHCRS = L.extend({}, L.CRS.Simple, {
  projection: HnHProjection,
}) as L.CRS