import type { ExpressionSpecification, Map as MapLibreMap, StyleSpecification } from "maplibre-gl";

export const SCADA_SOURCE_ID = "scada";
export const SCADA_SOURCE_LAYER = "scada_points";
export const SCADA_HIT_LAYER_ID = "scada-hit";

export const SCADA_ICON_PATHS = {
  waterQuality: "/icons/scada-water-quality.svg",
  radarLevel: "/icons/scada-radar-level.svg",
  ultrasonicFlow: "/icons/scada-ultrasonic-flow.svg",
  unknown: "/icons/scada-unknown.svg"
} as const;

export const SCADA_MAP_ICON_PATHS = {
  waterQuality: "/icons/scada-water-quality.png",
  radarLevel: "/icons/scada-radar-level.png",
  ultrasonicFlow: "/icons/scada-ultrasonic-flow.png",
  unknown: "/icons/scada-unknown.png"
} as const;

export const SCADA_IMAGE_IDS = {
  waterQuality: "scada-water-quality",
  radarLevel: "scada-radar-level",
  ultrasonicFlow: "scada-ultrasonic-flow",
  unknown: "scada-unknown"
} as const;

export const SCADA_ICON_EXPRESSION: ExpressionSpecification = [
  "match", ["to-number", ["get", "device_type_id"]],
  72, SCADA_IMAGE_IDS.waterQuality,
  58, SCADA_IMAGE_IDS.radarLevel,
  45, SCADA_IMAGE_IDS.ultrasonicFlow,
  SCADA_IMAGE_IDS.unknown
];

const stateOpacity = (state: "hovered" | "selected"): ExpressionSpecification => [
  "case", ["boolean", ["feature-state", state], false], 1, 0
];

type Layer = NonNullable<StyleSpecification["layers"]>[number];

export type ScadaImageRegistrationResult = {
  status: "ready" | "degraded" | "unavailable";
  failedImageIds: string[];
};

const scadaSymbolLayer: Layer = {
  id: "scada-symbol", type: "symbol", source: SCADA_SOURCE_ID, "source-layer": SCADA_SOURCE_LAYER, minzoom: 12,
  layout: { "icon-image": SCADA_ICON_EXPRESSION, "icon-size": ["interpolate", ["linear"], ["zoom"], 12, 0.625, 20, 0.875], "icon-allow-overlap": true, "icon-ignore-placement": true }
};

const scadaFallbackLayer: Layer = {
  id: "scada-fallback", type: "circle", source: SCADA_SOURCE_ID, "source-layer": SCADA_SOURCE_LAYER, minzoom: 12,
  paint: { "circle-radius": ["interpolate", ["linear"], ["zoom"], 12, 5, 20, 8], "circle-color": "#0E7490", "circle-stroke-color": "white", "circle-stroke-width": 2 }
};

const scadaInteractionLayers: Layer[] = [
  { id: "scada-hover", type: "circle", source: SCADA_SOURCE_ID, "source-layer": SCADA_SOURCE_LAYER, minzoom: 12, paint: { "circle-radius": 14, "circle-color": "rgba(255,255,255,0)", "circle-stroke-color": "#0E7490", "circle-stroke-width": 2, "circle-opacity": stateOpacity("hovered"), "circle-stroke-opacity": stateOpacity("hovered") } },
  { id: "scada-selected-outer", type: "circle", source: SCADA_SOURCE_ID, "source-layer": SCADA_SOURCE_LAYER, minzoom: 12, paint: { "circle-radius": 16, "circle-color": "rgba(255,255,255,0)", "circle-stroke-color": "white", "circle-stroke-width": 6, "circle-opacity": stateOpacity("selected"), "circle-stroke-opacity": stateOpacity("selected") } },
  { id: "scada-selected", type: "circle", source: SCADA_SOURCE_ID, "source-layer": SCADA_SOURCE_LAYER, minzoom: 12, paint: { "circle-radius": 16, "circle-color": "rgba(255,255,255,0)", "circle-stroke-color": "#2563EB", "circle-stroke-width": 3, "circle-opacity": stateOpacity("selected"), "circle-stroke-opacity": stateOpacity("selected") } },
  { id: SCADA_HIT_LAYER_ID, type: "circle", source: SCADA_SOURCE_ID, "source-layer": SCADA_SOURCE_LAYER, minzoom: 12, paint: { "circle-radius": 16, "circle-color": "rgba(0,0,0,0)", "circle-opacity": 0 } }
];

export const scadaLayers: Layer[] = [
  scadaSymbolLayer,
  ...scadaInteractionLayers
];

export const scadaFallbackLayers: Layer[] = [
  scadaFallbackLayer,
  ...scadaInteractionLayers
];

export async function registerScadaImages(
  map: Pick<MapLibreMap, "loadImage" | "addImage" | "hasImage">
): Promise<ScadaImageRegistrationResult> {
  let unknown: Awaited<ReturnType<typeof loadImage>>;

  try {
    unknown = await loadImage(map, SCADA_MAP_ICON_PATHS.unknown);
    addImageIfMissing(map, SCADA_IMAGE_IDS.unknown, unknown);
  } catch {
    return { status: "unavailable", failedImageIds: Object.values(SCADA_IMAGE_IDS) };
  }

  const failedImageIds: string[] = [];
  for (const [key, path] of Object.entries(SCADA_MAP_ICON_PATHS)) {
    if (key === "unknown") continue;
    const imageId = SCADA_IMAGE_IDS[key as Exclude<keyof typeof SCADA_IMAGE_IDS, "unknown">];
    if (map.hasImage(imageId)) continue;

    try {
      const image = await loadImage(map, path);
      addImageIfMissing(map, imageId, image);
    } catch {
      failedImageIds.push(imageId);
      try {
        addImageIfMissing(map, imageId, unknown);
      } catch {
        return { status: "unavailable", failedImageIds };
      }
    }
  }

  return {
    status: failedImageIds.length > 0 ? "degraded" : "ready",
    failedImageIds
  };
}

async function loadImage(map: Pick<MapLibreMap, "loadImage">, path: string) {
  const response = await map.loadImage(path);
  return response.data;
}

function addImageIfMissing(
  map: Pick<MapLibreMap, "addImage" | "hasImage">,
  imageId: string,
  image: Awaited<ReturnType<typeof loadImage>>
) {
  if (!map.hasImage(imageId)) map.addImage(imageId, image, { pixelRatio: 2 });
}