import { JSONMeta, Object3D } from "../core/Object3D.js";
import { ColorRepresentation } from "../math/Color.js";
import { Vector3 } from "../math/Vector3.js";
import { Texture } from "../textures/Texture.js";
import { Light, LightJSON } from "./Light.js";
import { LightShadowJSON } from "./LightShadow.js";
import { SpotLightShadow } from "./SpotLightShadow.js";

export interface SpotLightJSON extends LightJSON {
    distance: number;
    angle: number;
    decay: number;
    penumbra: number;

    target: string;
    map?: string | undefined;

    shadow: LightShadowJSON;
}

/**
 * This light gets emitted from a single point in one direction, along a cone that increases in size the further from the light it gets.
 * @example
 * ```typescript
 * // white {@link SpotLight} shining from the side, modulated by a texture, casting a shadow
 * const {@link SpotLight} = new THREE.SpotLight(0xffffff);
 * spotLight.position.set(100, 1000, 100);
 * spotLight.map = new THREE.TextureLoader().load(url);
 * spotLight.castShadow = true;
 * spotLight.shadow.mapSize.width = 1024;
 * spotLight.shadow.mapSize.height = 1024;
 * spotLight.shadow.camera.near = 500;
 * spotLight.shadow.camera.far = 4000;
 * spotLight.shadow.camera.fov = 30;
 * scene.add(spotLight);
 * ```
 * @see Example: {@link https://threejs.org/examples/#webgl_lights_spotlight | lights / {@link SpotLight} }
 * @see Example: {@link https://threejs.org/examples/#webgl_lights_spotlights | lights / spotlights }
 * @see {@link https://threejs.org/docs/index.html#api/en/lights/SpotLight | Official Documentation}
 * @see {@link https://github.com/mrdoob/three.js/blob/master/src/lights/SpotLight.js | Source}
 */
export class SpotLight extends Light<SpotLightShadow> {
    /**
     * Creates a new SpotLight.
     * @param color Hexadecimal color of the light. Default `0xffffff` _(white)_.
     * @param intensity Numeric value of the light's strength/intensity. Expects a `Float`. Default `1`.
     * @param distance Maximum range of the light. Default is 0 (no limit). Expects a `Float`.
     * @param angle Maximum angle of light dispersion from its direction whose upper bound is Math.PI/2.
     * @param penumbra Percent of the {@link SpotLight} cone that is attenuated due to penumbra. Takes values between zero and 1. Expects a `Float`. Default `0`.
     * @param decay The amount the light dims along the distance of the light. Expects a `Float`. Default `2`.
     */
    constructor(
        color?: ColorRepresentation,
        intensity?: number,
        distance?: number,
        angle?: number,
        penumbra?: number,
        decay?: number,
    );

    /**
     * Read-only flag to check if a given object is of type {@link SpotLight}.
     * @remarks This is a _constant_ value
     * @defaultValue `true`
     */
    readonly isSpotLight: true;

    /**
     * A Read-only _string_ to check if `this` object type.
     * @remarks Sub-classes will update this value.
     * @defaultValue `SpotLight`
     */
    override readonly type: string | "SpotLight";

    /**
     * This is set equal to {@link THREE.Object3D.DEFAULT_UP | Object3D.DEFAULT_UP} (0, 1, 0), so that the light shines from the top down.
     * @defaultValue `{@link Object3D.DEFAULT_UP}`
     */
    readonly position: Vector3;

    /**
     * The {@link SpotLight} points from its {@link SpotLight.position | position} to target.position.
     * @remarks
     * **Note**: For the target's position to be changed to anything other than the default,
     * it must be added to the {@link Scene | scene} using
     *
     * ```typescript
     * scene.add( light.target );
     * ```
     *
     * This is so that the target's {@link Object3D.matrixWorld | matrixWorld} gets automatically updated each frame.
     * It is also possible to set the target to be another object in the scene (anything with a {@link THREE.Object3D.position | position} property), like so:
     * ```typescript
     * const targetObject = new THREE.Object3D();
     * scene.add(targetObject);
     * light.target = targetObject;
     * ```
     * The {@link SpotLight} will now track the target object.
     * @defaultValue `new THREE.Object3D()` _The default position of the target is *(0, 0, 0)*._
     */
    target: Object3D;

    /**
     * If set to `true` light will cast dynamic shadows.
     * @remarks  **Warning**: This is expensive and requires tweaking to get shadows looking right. the {@link THREE.SpotLightShadow | SpotLightShadow} for details.
     * @defaultValue `false`
     */
    override castShadow: boolean;

    /**
     * The light's intensity.
     * @remarks Changing the intensity will also change the light's power.
     * When **{@link WebGLRenderer.useLegacyLights | legacy lighting mode} is disabled** — intensity is the luminous intensity of the light measured in candela (cd).
     * @remarks Expects a `Float`
     * @defaultValue `1`
     */
    intensity: number;

    /**
     * When **Default mode** — When distance is zero, light does not attenuate. When distance is non-zero,
     * light will attenuate linearly from maximum intensity at the light's position down to zero at this distance from the light.
     *
     * When **{@link WebGLRenderer.useLegacyLights | legacy lighting mode} is disabled** — When distance is zero,
     * light will attenuate according to inverse-square law to infinite distance.
     * When distance is non-zero, light will attenuate according to inverse-square law until near the distance cutoff,
     * where it will then attenuate quickly and smoothly to `0`. Inherently, cutoffs are not physically correct.
     * @remarks Expects a `Float`
     * @defaultValue `0.0`
     */
    distance: number;

    /**
     * Maximum extent of the spotlight, in radians, from its direction.
     * @remarks Should be no more than `Math.PI/2`.
     * @remarks Expects a `Float`
     * @defaultValue `Math.PI / 3`
     */
    angle: number;

    /**
     * The amount the light dims along the distance of the light.
     * In context of physically-correct rendering the default value should not be changed.
     * @remarks Expects a `Float`
     * @defaultValue `2`
     */
    decay: number;

    /**
     * A {@link THREE.SpotLightShadow | SpotLightShadow} used to calculate shadows for this light.
     * @defaultValue `new THREE.SpotLightShadow()`
     */
    shadow: SpotLightShadow;

    /**
     * The light's power.
     * @remarks Changing the power will also change the light's intensity.
     * When **{@link WebGLRenderer.useLegacyLights | legacy lighting mode} is disabled** —  power is the luminous power of the light measured in lumens (lm).
     * @remarks Expects a `Float`
     */
    power: number;

    /**
     * Percent of the {@link SpotLight} cone that is attenuated due to penumbra.
     * @remarks Takes values between zero and 1.
     * @remarks Expects a `Float`
     * @defaultValue `0.0`
     */
    penumbra: number;

    /**
     * A {@link THREE.Texture | Texture} used to modulate the color of the light.
     * The spot light color is mixed with the _RGB_ value of this texture, with a ratio corresponding to its alpha value.
     * The cookie-like masking effect is reproduced using pixel values (0, 0, 0, 1-cookie_value).
     * @remarks **Warning**: {@link SpotLight.map} is disabled if {@link SpotLight.castShadow} is `false`.
     */
    map: Texture | null;

    toJSON(meta?: JSONMeta): SpotLightJSON;
}