/*
 * Copyright (c) 2015-2018, IGN France.
 * Copyright (c) 2018-2026, Giro3D team.
 * SPDX-License-Identifier: MIT
 */

import type { BufferAttribute } from 'three';

import {
    Float16BufferAttribute,
    Float32BufferAttribute,
    Int16BufferAttribute,
    Int32BufferAttribute,
    Int8BufferAttribute,
    Uint16BufferAttribute,
    Uint32BufferAttribute,
    Uint8BufferAttribute,
    Uint8ClampedBufferAttribute,
} from 'three';

export interface HasDefines {
    defines: Record<string, unknown>;
    needsUpdate: boolean;
}

/**
 * Sets or unsets a define directive according to the condition.
 * The material is updated only if the directive has changed, avoiding unnecessary recompilations.
 *
 * @param material - The material to update.
 * @param name - The name of the directive
 * @param condition - The condition to enable the directive.
 * @example
 *
 * setDefine(mat, 'ENABLE_FOO', true); // material.needsUpdate === true;
 * setDefine(mat, 'ENABLE_FOO', true); // material.needsUpdate === false;
 * setDefine(mat, 'ENABLE_FOO', false); // material.needsUpdate === true;
 */
function setDefine<M extends HasDefines, K extends keyof M['defines']>(
    material: M,
    name: K,
    condition: boolean | undefined | null,
): void {
    condition = condition ?? false;
    if (material.defines == null) {
        throw new Error('material.defines is null');
    }

    const key = name as string;
    if (material.defines[key] === undefined) {
        if (condition) {
            material.defines[key] = 1;
            material.needsUpdate = true;
        }
    } else if (!condition) {
        delete material.defines[key];
        material.needsUpdate = true;
    }
}

/**
 * Sets or unsets a valued define directive.
 * The material is updated only if the value has changed, avoiding unnecessary recompilations.
 *
 * @param material - The material to update.
 * @param name - The name of the directive
 * @param value - The value of the define.
 * @returns `true` if the define value has actually changed, `false` otherwise.
 * @example
 *
 * setValueDefine(mat, 'FOO_COUNT', 5); // material.needsUpdate === true;
 * setValueDefine(mat, 'FOO_COUNT', 5); // material.needsUpdate === false;
 * setValueDefine(mat, 'FOO_COUNT', 4); // material.needsUpdate === true;
 */
function setDefineValue<M extends HasDefines, K extends keyof M['defines']>(
    material: M,
    name: K,
    value?: number | string,
): boolean {
    if (material.defines == null) {
        throw new Error('material.defines is null');
    }

    const key = name as string;
    const changed = material.defines[key] !== value;

    if (value != null) {
        material.defines[key] = value;
    } else {
        delete material.defines[key];
    }

    if (changed) {
        material.needsUpdate = true;
    }

    return changed;
}

export type VertexAttributeType = 'int' | 'uint' | 'float';

/**
 * Returns the GLSL attribute type that most closely matches the type of the {@link BufferAttribute}.
 */
function getVertexAttributeType(attribute: BufferAttribute): VertexAttributeType {
    if (
        attribute instanceof Float32BufferAttribute ||
        attribute instanceof Float16BufferAttribute
    ) {
        return 'float';
    }
    if (
        attribute instanceof Int32BufferAttribute ||
        attribute instanceof Int16BufferAttribute ||
        attribute instanceof Int8BufferAttribute
    ) {
        return 'int';
    }
    if (
        attribute instanceof Uint32BufferAttribute ||
        attribute instanceof Uint16BufferAttribute ||
        attribute instanceof Uint8BufferAttribute ||
        attribute instanceof Uint8ClampedBufferAttribute
    ) {
        return 'uint';
    }

    throw new Error('unsupported vertex attribute type');
}

export default {
    setDefine,
    setDefineValue,
    getVertexAttributeType,
};