import type { DungeonDefinition, DungeonTransform, Vector3Tuple } from "./dungeonTypes";
import { RUNEWAKER_NATIVE_LIGHTING_SOURCE } from "./generated/runewakerNativeLighting.generated";

type Vector = readonly [number, number, number];
type Quaternion = readonly [number, number, number, number];

interface NativeColor {
  readonly argb: string;
  /** Rune Engine's direct ARGB byte-to-float conversion; values are linear. */
  readonly rgba: readonly [number, number, number, number];
}

interface NativeZoneSettings {
  readonly timeGroup: number;
  readonly weatherGroup: number;
  readonly primary: NativeColor;
  readonly secondary: NativeColor;
  readonly ambient: NativeColor;
  readonly specular: NativeColor;
  readonly fogColor: NativeColor;
  readonly fog: { readonly constant: number; readonly start: number; readonly end: number };
  readonly standardAnglesRadians: Vector;
  readonly specularAnglesRadians: Vector;
  readonly nativeDirectionsLeftHandedYUp: {
    readonly primary: Vector;
    readonly secondary0: Vector;
    readonly secondary1: Vector;
    readonly specular: Vector;
  };
  readonly weatherSystem: string;
  readonly skyGradientTexture: string;
  readonly customSkyBox: string;
  readonly cloudCover: number;
  readonly cloudSharpness: number;
  readonly cloudColors: readonly [NativeColor, NativeColor];
}

interface NativeZone {
  readonly id: number;
  readonly parentId: number;
  readonly name: string;
  readonly zoneType: number;
  readonly settings: readonly NativeZoneSettings[];
}

interface NativeZoneTrigger {
  readonly triggerType: number;
  readonly zoneId: number;
  readonly zoneType: number;
  readonly priority: number;
  readonly obb: {
    readonly center: Vector;
    readonly axes: readonly [Vector, Vector, Vector];
    readonly halfExtents: Vector;
  };
}

interface NativeDungeonLightingData {
  readonly source: {
    readonly wdb: string;
    readonly wdbSha256: string;
    readonly coordinateSystem: string;
    readonly metersPerSourceUnit: number;
    readonly primaryPlacement: { readonly scale: Vector; readonly rotation: Quaternion; readonly translation: Vector };
  };
  readonly zones: readonly NativeZone[];
  readonly zoneTriggers: readonly NativeZoneTrigger[];
}

const SOURCE = RUNEWAKER_NATIVE_LIGHTING_SOURCE as unknown as {
  readonly runtimeDefaults: { readonly timeGroup: number; readonly weatherGroup: number };
  readonly dungeons: Readonly<Record<string, NativeDungeonLightingData>>;
};

export interface RunewakerLightingOptions {
  readonly timeGroup?: number;
  readonly weatherGroup?: number;
  /** Three.js world-space camera far distance, in runtime units/meters. */
  readonly cameraFarDistance?: number;
}

export interface ResolvedRunewakerDirectionalLight {
  readonly role: "primary" | "secondary-0" | "secondary-1";
  readonly colorArgb: string;
  readonly colorLinear: Vector;
  readonly intensity: number;
  /** Adapted source `m_direction`, which points in the light-ray direction. */
  readonly rayDirection: Vector;
  /** Opposite of Rune's stored direction; Rune's SH code uses this convention. */
  readonly toLightDirection: Vector;
}

export interface ResolvedRunewakerLighting {
  readonly dungeonId: string;
  readonly sourceWdb: string;
  readonly sourceWdbSha256: string;
  readonly sourceCoordinateSystem: string;
  readonly metersPerSourceUnit: number;
  readonly sourcePosition: Vector;
  readonly triggerZone: {
    readonly id: number;
    readonly name: string;
    readonly priority: number;
    readonly verticalHitDistanceSourceUnits: number;
  };
  readonly settingsZone: { readonly id: number; readonly name: string };
  readonly timeGroup: number;
  readonly weatherGroup: number;
  readonly ambient: { readonly colorArgb: string; readonly colorLinear: Vector; readonly intensity: 1 };
  readonly directionalLights: readonly [
    ResolvedRunewakerDirectionalLight,
    ResolvedRunewakerDirectionalLight,
    ResolvedRunewakerDirectionalLight,
  ];
  readonly specular: { readonly colorArgb: string; readonly colorLinear: Vector; readonly direction: Vector };
  readonly fog: {
    readonly colorArgb: string;
    readonly colorLinear: Vector;
    readonly constant: number;
    readonly startFactor: number;
    readonly endFactor: number;
    readonly startDistance?: number;
    readonly endDistance?: number;
  };
  readonly sky: {
    readonly weatherSystem: string;
    readonly skyGradientTexture: string;
    readonly customSkyBox: string;
    readonly cloudCover: number;
    readonly cloudSharpness: number;
    readonly cloudColorsLinear: readonly [Vector, Vector];
  };
}

interface ZoneSelection {
  readonly trigger: NativeZoneTrigger;
  readonly boundaryDistance: number;
  readonly triggerZone: NativeZone;
  readonly settingsZone: NativeZone;
  readonly settings: NativeZoneSettings;
  readonly timeGroup: number;
  readonly weatherGroup: number;
}

function add(a: Vector, b: Vector): Vector {
  return [a[0] + b[0], a[1] + b[1], a[2] + b[2]];
}

function subtract(a: Vector, b: Vector): Vector {
  return [a[0] - b[0], a[1] - b[1], a[2] - b[2]];
}

function multiply(a: Vector, b: Vector): Vector {
  return [a[0] * b[0], a[1] * b[1], a[2] * b[2]];
}

function divide(a: Vector, b: Vector): Vector | null {
  if (b.some((component) => Math.abs(component) < 1e-12)) return null;
  return [a[0] / b[0], a[1] / b[1], a[2] / b[2]];
}

function dot(a: Vector, b: Vector): number {
  return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}

function normalize(value: Vector): Vector {
  const length = Math.hypot(value[0], value[1], value[2]);
  if (length < 1e-12) return [0, 0, 0];
  return [value[0] / length, value[1] / length, value[2] / length];
}

function conjugate(q: Quaternion): Quaternion {
  return [-q[0], -q[1], -q[2], q[3]];
}

function multiplyQuaternions(a: Quaternion, b: Quaternion): Quaternion {
  const [ax, ay, az, aw] = a;
  const [bx, by, bz, bw] = b;
  return [
    ax * bw + aw * bx + ay * bz - az * by,
    ay * bw + aw * by + az * bx - ax * bz,
    az * bw + aw * bz + ax * by - ay * bx,
    aw * bw - ax * bx - ay * by - az * bz,
  ];
}

function rotateByQuaternion(value: Vector, quaternion: Quaternion): Vector {
  const length = Math.hypot(quaternion[0], quaternion[1], quaternion[2], quaternion[3]);
  if (length < 1e-12) return value;
  const normalized: Quaternion = quaternion.map((component) => component / length) as unknown as Quaternion;
  const qv: Quaternion = [value[0], value[1], value[2], 0];
  const result = multiplyQuaternions(multiplyQuaternions(normalized, qv), conjugate(normalized));
  return [result[0], result[1], result[2]];
}

function quaternionFromEulerXYZ(rotation: Vector3Tuple): Quaternion {
  const [x, y, z] = rotation;
  const c1 = Math.cos(x / 2);
  const c2 = Math.cos(y / 2);
  const c3 = Math.cos(z / 2);
  const s1 = Math.sin(x / 2);
  const s2 = Math.sin(y / 2);
  const s3 = Math.sin(z / 2);
  return [
    s1 * c2 * c3 + c1 * s2 * s3,
    c1 * s2 * c3 - s1 * c2 * s3,
    c1 * c2 * s3 + s1 * s2 * c3,
    c1 * c2 * c3 - s1 * s2 * s3,
  ];
}

function pointFromRuntimeWorldToDungeonLocal(transform: DungeonTransform, point: Vector): Vector | null {
  if (Math.abs(transform.scale) < 1e-12) return null;
  const inverseRotation = conjugate(quaternionFromEulerXYZ(transform.rotation));
  return divide(rotateByQuaternion(subtract(point, transform.position), inverseRotation), [transform.scale, transform.scale, transform.scale]);
}

function pointFromDungeonLocalToSource(data: NativeDungeonLightingData, point: Vector): Vector | null {
  const sourceLocal = divide([point[0], point[1], -point[2]], [
    data.source.metersPerSourceUnit,
    data.source.metersPerSourceUnit,
    data.source.metersPerSourceUnit,
  ]);
  if (!sourceLocal) return null;
  const scaled = multiply(sourceLocal, data.source.primaryPlacement.scale);
  return add(rotateByQuaternion(scaled, data.source.primaryPlacement.rotation), data.source.primaryPlacement.translation);
}

function sourceDirectionToRuntime(data: NativeDungeonLightingData, transform: DungeonTransform, direction: Vector): Vector | null {
  const placementLocal = rotateByQuaternion(direction, conjugate(data.source.primaryPlacement.rotation));
  const unscaled = divide(placementLocal, data.source.primaryPlacement.scale);
  if (!unscaled) return null;
  const localThree: Vector = [unscaled[0], unscaled[1], -unscaled[2]];
  const runtimeDirection = rotateByQuaternion(
    [localThree[0] * transform.scale, localThree[1] * transform.scale, localThree[2] * transform.scale],
    quaternionFromEulerXYZ(transform.rotation),
  );
  return normalize(runtimeDirection);
}

function segmentObbEntry(point: Vector, delta: Vector, trigger: NativeZoneTrigger): number | null {
  let entry = 0;
  let exit = 1;
  const relative = subtract(point, trigger.obb.center);
  for (let axisIndex = 0; axisIndex < 3; axisIndex += 1) {
    const axis = trigger.obb.axes[axisIndex];
    const originProjection = dot(relative, axis);
    const deltaProjection = dot(delta, axis);
    const extent = trigger.obb.halfExtents[axisIndex];
    if (Math.abs(deltaProjection) < 1e-12) {
      if (originProjection < -extent || originProjection > extent) return null;
      continue;
    }
    let t0 = (-extent - originProjection) / deltaProjection;
    let t1 = (extent - originProjection) / deltaProjection;
    if (t0 > t1) [t0, t1] = [t1, t0];
    entry = Math.max(entry, t0);
    exit = Math.min(exit, t1);
    if (entry > exit) return null;
  }
  return entry;
}

function verticalTriggerDistance(point: Vector, trigger: NativeZoneTrigger): number | null {
  const down = segmentObbEntry(point, [0, -10000, 0], trigger);
  const up = segmentObbEntry(point, [0, 10000, 0], trigger);
  if (down == null) return up;
  if (up == null) return down;
  return Math.min(down, up);
}

function isDescendant(zones: readonly NativeZone[], candidateId: number, ancestorId: number): boolean {
  const byId = new Map(zones.map((zone) => [zone.id, zone]));
  let zone = byId.get(candidateId);
  while (zone && zone.parentId !== -1) {
    if (zone.parentId === ancestorId) return true;
    zone = byId.get(zone.parentId);
  }
  return false;
}

function selectSettings(zone: NativeZone, timeGroup: number, weatherGroup: number): { settings: NativeZoneSettings; timeGroup: number; weatherGroup: number } | null {
  const exact = zone.settings.find((entry) => entry.timeGroup === timeGroup && entry.weatherGroup === weatherGroup);
  if (exact) return { settings: exact, timeGroup: exact.timeGroup, weatherGroup: exact.weatherGroup };
  const sameTime = zone.settings.find((entry) => entry.timeGroup === timeGroup);
  if (sameTime) return { settings: sameTime, timeGroup: sameTime.timeGroup, weatherGroup: sameTime.weatherGroup };
  const any = zone.settings[0];
  return any ? { settings: any, timeGroup: any.timeGroup, weatherGroup: any.weatherGroup } : null;
}

function selectZoneSettings(
  data: NativeDungeonLightingData,
  sourcePosition: Vector,
  requestedTimeGroup: number,
  requestedWeatherGroup: number,
): ZoneSelection | null {
  let selectedTrigger: NativeZoneTrigger | null = null;
  let selectedDistance = Number.POSITIVE_INFINITY;
  // The native selector initializes its signed priority to 0xFFFFFFFF (-1).
  let selectedPriority = -1;
  for (const trigger of data.zoneTriggers) {
    const distance = verticalTriggerDistance(sourcePosition, trigger);
    if (distance == null) continue;
    const prefer = trigger.priority > selectedPriority
      || (trigger.priority === selectedPriority && distance < selectedDistance)
      || (trigger.priority === selectedPriority
        && distance === selectedDistance
        && selectedTrigger != null
        && isDescendant(data.zones, trigger.zoneId, selectedTrigger.zoneId));
    if (prefer) {
      selectedTrigger = trigger;
      selectedDistance = distance;
      selectedPriority = trigger.priority;
    }
  }
  if (!selectedTrigger) return null;
  const triggerZone = data.zones.find((zone) => zone.id === selectedTrigger!.zoneId);
  if (!triggerZone) return null;
  let settingsZone: NativeZone | undefined = triggerZone;
  let chosen: ReturnType<typeof selectSettings> = null;
  while (settingsZone) {
    chosen = selectSettings(settingsZone, requestedTimeGroup, requestedWeatherGroup);
    if (chosen) break;
    settingsZone = data.zones.find((zone) => zone.id === settingsZone!.parentId);
  }
  if (!settingsZone || !chosen) return null;
  return {
    trigger: selectedTrigger,
    boundaryDistance: selectedDistance,
    triggerZone,
    settingsZone,
    settings: chosen.settings,
    timeGroup: chosen.timeGroup,
    weatherGroup: chosen.weatherGroup,
  };
}

/** Convert a Three.js world point back to the source WDB world coordinates. */
export function runewakerRuntimePositionToSource(
  definition: Pick<DungeonDefinition, "id" | "transform">,
  runtimeWorldPosition: Vector3Tuple,
): Vector | null {
  const data = SOURCE.dungeons[definition.id];
  if (!data) return null;
  const local = pointFromRuntimeWorldToDungeonLocal(definition.transform, runtimeWorldPosition);
  return local ? pointFromDungeonLocalToSource(data, local) : null;
}

/** Convert a source WDB point to the current dungeon's Three.js world space. */
export function runewakerSourcePositionToRuntime(
  definition: Pick<DungeonDefinition, "id" | "transform">,
  sourcePosition: Vector3Tuple,
): Vector | null {
  const data = SOURCE.dungeons[definition.id];
  if (!data) return null;
  const sourceDelta = subtract(sourcePosition, data.source.primaryPlacement.translation);
  const inversePrimaryRotation = conjugate(data.source.primaryPlacement.rotation);
  const localSource = rotateByQuaternion(sourceDelta, inversePrimaryRotation);
  const scaledLocal = divide(localSource, data.source.primaryPlacement.scale);
  if (!scaledLocal) return null;
  const localThree: Vector = [scaledLocal[0] * data.source.metersPerSourceUnit, scaledLocal[1] * data.source.metersPerSourceUnit, -scaledLocal[2] * data.source.metersPerSourceUnit];
  return add(
    rotateByQuaternion(
      [localThree[0] * definition.transform.scale, localThree[1] * definition.transform.scale, localThree[2] * definition.transform.scale],
      quaternionFromEulerXYZ(definition.transform.rotation),
    ),
    definition.transform.position,
  );
}

/** Resolve source zone lighting at a runtime world position; null keeps the authored profile. */
export function resolveRunewakerNativeLighting(
  definition: Pick<DungeonDefinition, "id" | "transform">,
  runtimeWorldPosition: Vector3Tuple,
  options: RunewakerLightingOptions = {},
): ResolvedRunewakerLighting | null {
  const data = SOURCE.dungeons[definition.id];
  if (!data) return null;
  const sourcePosition = runewakerRuntimePositionToSource(definition, runtimeWorldPosition);
  if (!sourcePosition) return null;
  const selection = selectZoneSettings(
    data,
    sourcePosition,
    options.timeGroup ?? SOURCE.runtimeDefaults.timeGroup,
    options.weatherGroup ?? SOURCE.runtimeDefaults.weatherGroup,
  );
  if (!selection) return null;
  const settings = selection.settings;
  const rayDirection = (sourceDirection: Vector): Vector => sourceDirectionToRuntime(data, definition.transform, sourceDirection) ?? [0, 0, 0];
  const far = options.cameraFarDistance;
  const fogScale = settings.fog.end > 1 ? 1 / 1600 : 1;
  const startFactor = settings.fog.start * fogScale;
  const endFactor = settings.fog.end * fogScale;
  const triggerDistance = selection.boundaryDistance * 10000;

  return {
    dungeonId: definition.id,
    sourceWdb: data.source.wdb,
    sourceWdbSha256: data.source.wdbSha256,
    sourceCoordinateSystem: data.source.coordinateSystem,
    metersPerSourceUnit: data.source.metersPerSourceUnit,
    sourcePosition,
    triggerZone: {
      id: selection.triggerZone.id,
      name: selection.triggerZone.name,
      priority: selection.trigger.priority,
      verticalHitDistanceSourceUnits: triggerDistance,
    },
    settingsZone: { id: selection.settingsZone.id, name: selection.settingsZone.name },
    timeGroup: selection.timeGroup,
    weatherGroup: selection.weatherGroup,
    ambient: { colorArgb: settings.ambient.argb, colorLinear: settings.ambient.rgba.slice(0, 3) as unknown as Vector, intensity: 1 },
    directionalLights: [
      {
        role: "primary",
        colorArgb: settings.primary.argb,
        colorLinear: settings.primary.rgba.slice(0, 3) as unknown as Vector,
        intensity: 1,
        rayDirection: rayDirection(settings.nativeDirectionsLeftHandedYUp.primary),
        toLightDirection: scaleVector(rayDirection(settings.nativeDirectionsLeftHandedYUp.primary), -1),
      },
      {
        role: "secondary-0",
        colorArgb: settings.secondary.argb,
        colorLinear: settings.secondary.rgba.slice(0, 3) as unknown as Vector,
        intensity: 0.8,
        rayDirection: rayDirection(settings.nativeDirectionsLeftHandedYUp.secondary0),
        toLightDirection: scaleVector(rayDirection(settings.nativeDirectionsLeftHandedYUp.secondary0), -1),
      },
      {
        role: "secondary-1",
        colorArgb: settings.secondary.argb,
        colorLinear: settings.secondary.rgba.slice(0, 3) as unknown as Vector,
        intensity: 0.8,
        rayDirection: rayDirection(settings.nativeDirectionsLeftHandedYUp.secondary1),
        toLightDirection: scaleVector(rayDirection(settings.nativeDirectionsLeftHandedYUp.secondary1), -1),
      },
    ],
    specular: {
      colorArgb: settings.specular.argb,
      colorLinear: settings.specular.rgba.slice(0, 3) as unknown as Vector,
      direction: rayDirection(settings.nativeDirectionsLeftHandedYUp.specular),
    },
    fog: {
      colorArgb: settings.fogColor.argb,
      colorLinear: settings.fogColor.rgba.slice(0, 3) as unknown as Vector,
      constant: settings.fog.constant,
      startFactor,
      endFactor,
      ...(far != null ? { startDistance: startFactor * far, endDistance: endFactor * far } : {}),
    },
    sky: {
      weatherSystem: settings.weatherSystem,
      skyGradientTexture: settings.skyGradientTexture,
      customSkyBox: settings.customSkyBox,
      cloudCover: settings.cloudCover,
      cloudSharpness: settings.cloudSharpness,
      cloudColorsLinear: [
        settings.cloudColors[0].rgba.slice(0, 3) as unknown as Vector,
        settings.cloudColors[1].rgba.slice(0, 3) as unknown as Vector,
      ],
    },
  };
}

function scaleVector(vector: Vector, scalar: number): Vector {
  return [vector[0] * scalar, vector[1] * scalar, vector[2] * scalar];
}

/** Source map for generated-data integrity checks; consumers should use the resolver. */
export const RUNEWAKER_NATIVE_LIGHTING_DUNGEON_IDS = Object.freeze(Object.keys(SOURCE.dungeons));