import { Nullable, DataArray } from "../types";
import { ThinEngine } from "../Engines/thinEngine";
import { DataBuffer } from './dataBuffer';

/**
 * Class used to store data that will be store in GPU memory
 */
export class Buffer {
    private _engine: ThinEngine;
    private _buffer: Nullable<DataBuffer>;
    /** @hidden */
    public _data: Nullable<DataArray>;
    private _updatable: boolean;
    private _instanced: boolean;
    private _divisor: number;

    /**
     * Gets the byte stride.
     */
    public readonly byteStride: number;

    /**
     * Constructor
     * @param engine the engine
     * @param data the data to use for this buffer
     * @param updatable whether the data is updatable
     * @param stride the stride (optional)
     * @param postponeInternalCreation whether to postpone creating the internal WebGL buffer (optional)
     * @param instanced whether the buffer is instanced (optional)
     * @param useBytes set to true if the stride in in bytes (optional)
     * @param divisor sets an optional divisor for instances (1 by default)
     */
    constructor(engine: any, data: DataArray, updatable: boolean, stride = 0, postponeInternalCreation = false, instanced = false, useBytes = false, divisor?: number) {
        if (engine.getScene) { // old versions of VertexBuffer accepted 'mesh' instead of 'engine'
            this._engine = engine.getScene().getEngine();
        }
        else {
            this._engine = engine;
        }

        this._updatable = updatable;
        this._instanced = instanced;
        this._divisor = divisor || 1;

        this._data = data;

        this.byteStride = useBytes ? stride : stride * Float32Array.BYTES_PER_ELEMENT;

        if (!postponeInternalCreation) { // by default
            this.create();
        }
    }

    /**
     * Create a new VertexBuffer based on the current buffer
     * @param kind defines the vertex buffer kind (position, normal, etc.)
     * @param offset defines offset in the buffer (0 by default)
     * @param size defines the size in floats of attributes (position is 3 for instance)
     * @param stride defines the stride size in floats in the buffer (the offset to apply to reach next value when data is interleaved)
     * @param instanced defines if the vertex buffer contains indexed data
     * @param useBytes defines if the offset and stride are in bytes     *
     * @param divisor sets an optional divisor for instances (1 by default)
     * @returns the new vertex buffer
     */
    public createVertexBuffer(kind: string, offset: number, size: number, stride?: number, instanced?: boolean, useBytes = false, divisor?: number): VertexBuffer {
        const byteOffset = useBytes ? offset : offset * Float32Array.BYTES_PER_ELEMENT;
        const byteStride = stride ? (useBytes ? stride : stride * Float32Array.BYTES_PER_ELEMENT) : this.byteStride;

        // a lot of these parameters are ignored as they are overriden by the buffer
        return new VertexBuffer(this._engine, this, kind, this._updatable, true, byteStride, instanced === undefined ? this._instanced : instanced, byteOffset, size, undefined, undefined, true, this._divisor || divisor);
    }

    // Properties

    /**
     * Gets a boolean indicating if the Buffer is updatable?
     * @returns true if the buffer is updatable
     */
    public isUpdatable(): boolean {
        return this._updatable;
    }

    /**
     * Gets current buffer's data
     * @returns a DataArray or null
     */
    public getData(): Nullable<DataArray> {
        return this._data;
    }

    /**
     * Gets underlying native buffer
     * @returns underlying native buffer
     */
    public getBuffer(): Nullable<DataBuffer> {
        return this._buffer;
    }

    /**
     * Gets the stride in float32 units (i.e. byte stride / 4).
     * May not be an integer if the byte stride is not divisible by 4.
     * @returns the stride in float32 units
     * @deprecated Please use byteStride instead.
     */
    public getStrideSize(): number {
        return this.byteStride / Float32Array.BYTES_PER_ELEMENT;
    }

    // Methods

    /**
     * Store data into the buffer. If the buffer was already used it will be either recreated or updated depending on isUpdatable property
     * @param data defines the data to store
     */
    public create(data: Nullable<DataArray> = null): void {
        if (!data && this._buffer) {
            return; // nothing to do
        }

        data = data || this._data;

        if (!data) {
            return;
        }

        if (!this._buffer) { // create buffer
            if (this._updatable) {
                this._buffer = this._engine.createDynamicVertexBuffer(data);
                this._data = data;
            } else {
                this._buffer = this._engine.createVertexBuffer(data);
            }
        } else if (this._updatable) { // update buffer
            this._engine.updateDynamicVertexBuffer(this._buffer, data);
            this._data = data;
        }
    }

    /** @hidden */
    public _rebuild(): void {
        this._buffer = null;
        this.create(this._data);
    }

    /**
     * Update current buffer data
     * @param data defines the data to store
     */
    public update(data: DataArray): void {
        this.create(data);
    }

    /**
     * Updates the data directly.
     * @param data the new data
     * @param offset the new offset
     * @param vertexCount the vertex count (optional)
     * @param useBytes set to true if the offset is in bytes
     */
    public updateDirectly(data: DataArray, offset: number, vertexCount?: number, useBytes: boolean = false): void {
        if (!this._buffer) {
            return;
        }

        if (this._updatable) { // update buffer
            this._engine.updateDynamicVertexBuffer(this._buffer, data, useBytes ? offset : offset * Float32Array.BYTES_PER_ELEMENT, (vertexCount ? vertexCount * this.byteStride : undefined));
            this._data = null;
        }
    }

    /**
     * Release all resources
     */
    public dispose(): void {
        if (!this._buffer) {
            return;
        }
        if (this._engine._releaseBuffer(this._buffer)) {
            this._buffer = null;
        }
    }
}

/**
     * Specialized buffer used to store vertex data
     */
export class VertexBuffer {
    /** @hidden */
    public _buffer: Buffer;
    private _kind: string;
    private _size: number;
    private _ownsBuffer: boolean;
    private _instanced: boolean;
    private _instanceDivisor: number;

    /**
     * The byte type.
     */
    public static readonly BYTE = 5120;

    /**
     * The unsigned byte type.
     */
    public static readonly UNSIGNED_BYTE = 5121;

    /**
     * The short type.
     */
    public static readonly SHORT = 5122;

    /**
     * The unsigned short type.
     */
    public static readonly UNSIGNED_SHORT = 5123;

    /**
     * The integer type.
     */
    public static readonly INT = 5124;

    /**
     * The unsigned integer type.
     */
    public static readonly UNSIGNED_INT = 5125;

    /**
     * The float type.
     */
    public static readonly FLOAT = 5126;

    /**
     * Gets or sets the instance divisor when in instanced mode
     */
    public get instanceDivisor(): number {
        return this._instanceDivisor;
    }

    public set instanceDivisor(value: number) {
        this._instanceDivisor = value;
        if (value == 0) {
            this._instanced = false;
        } else {
            this._instanced = true;
        }
    }

    /**
     * Gets the byte stride.
     */
    public readonly byteStride: number;

    /**
     * Gets the byte offset.
     */
    public readonly byteOffset: number;

    /**
     * Gets whether integer data values should be normalized into a certain range when being casted to a float.
     */
    public readonly normalized: boolean;

    /**
     * Gets the data type of each component in the array.
     */
    public readonly type: number;

    /**
     * Constructor
     * @param engine the engine
     * @param data the data to use for this vertex buffer
     * @param kind the vertex buffer kind
     * @param updatable whether the data is updatable
     * @param postponeInternalCreation whether to postpone creating the internal WebGL buffer (optional)
     * @param stride the stride (optional)
     * @param instanced whether the buffer is instanced (optional)
     * @param offset the offset of the data (optional)
     * @param size the number of components (optional)
     * @param type the type of the component (optional)
     * @param normalized whether the data contains normalized data (optional)
     * @param useBytes set to true if stride and offset are in bytes (optional)
     * @param divisor defines the instance divisor to use (1 by default)
     */
    constructor(engine: any, data: DataArray | Buffer, kind: string, updatable: boolean, postponeInternalCreation?: boolean, stride?: number,
        instanced?: boolean, offset?: number, size?: number, type?: number, normalized = false, useBytes = false, divisor = 1) {
        if (data instanceof Buffer) {
            this._buffer = data;
            this._ownsBuffer = false;
        } else {
            this._buffer = new Buffer(engine, data, updatable, stride, postponeInternalCreation, instanced, useBytes);
            this._ownsBuffer = true;
        }

        this._kind = kind;

        if (type == undefined) {
            const data = this.getData();
            this.type = VertexBuffer.FLOAT;
            if (data instanceof Int8Array) { this.type = VertexBuffer.BYTE; }
            else if (data instanceof Uint8Array) { this.type = VertexBuffer.UNSIGNED_BYTE; }
            else if (data instanceof Int16Array) { this.type = VertexBuffer.SHORT; }
            else if (data instanceof Uint16Array) { this.type = VertexBuffer.UNSIGNED_SHORT; }
            else if (data instanceof Int32Array) { this.type = VertexBuffer.INT; }
            else if (data instanceof Uint32Array) { this.type = VertexBuffer.UNSIGNED_INT; }
        }
        else {
            this.type = type;
        }

        const typeByteLength = VertexBuffer.GetTypeByteLength(this.type);

        if (useBytes) {
            this._size = size || (stride ? (stride / typeByteLength) : VertexBuffer.DeduceStride(kind));
            this.byteStride = stride || this._buffer.byteStride || (this._size * typeByteLength);
            this.byteOffset = offset || 0;
        }
        else {
            this._size = size || stride || VertexBuffer.DeduceStride(kind);
            this.byteStride = stride ? (stride * typeByteLength) : (this._buffer.byteStride || (this._size * typeByteLength));
            this.byteOffset = (offset || 0) * typeByteLength;
        }

        this.normalized = normalized;

        this._instanced = instanced !== undefined ? instanced : false;
        this._instanceDivisor = instanced ? divisor : 0;
    }

    /** @hidden */
    public _rebuild(): void {
        if (!this._buffer) {
            return;
        }

        this._buffer._rebuild();
    }

    /**
     * Returns the kind of the VertexBuffer (string)
     * @returns a string
     */
    public getKind(): string {
        return this._kind;
    }

    // Properties

    /**
     * Gets a boolean indicating if the VertexBuffer is updatable?
     * @returns true if the buffer is updatable
     */
    public isUpdatable(): boolean {
        return this._buffer.isUpdatable();
    }

    /**
     * Gets current buffer's data
     * @returns a DataArray or null
     */
    public getData(): Nullable<DataArray> {
        return this._buffer.getData();
    }

    /**
     * Gets underlying native buffer
     * @returns underlying native buffer
     */
    public getBuffer(): Nullable<DataBuffer> {
        return this._buffer.getBuffer();
    }

    /**
     * Gets the stride in float32 units (i.e. byte stride / 4).
     * May not be an integer if the byte stride is not divisible by 4.
     * @returns the stride in float32 units
     * @deprecated Please use byteStride instead.
     */
    public getStrideSize(): number {
        return this.byteStride / VertexBuffer.GetTypeByteLength(this.type);
    }

    /**
     * Returns the offset as a multiple of the type byte length.
     * @returns the offset in bytes
     * @deprecated Please use byteOffset instead.
     */
    public getOffset(): number {
        return this.byteOffset / VertexBuffer.GetTypeByteLength(this.type);
    }

    /**
     * Returns the number of components per vertex attribute (integer)
     * @returns the size in float
     */
    public getSize(): number {
        return this._size;
    }

    /**
     * Gets a boolean indicating is the internal buffer of the VertexBuffer is instanced
     * @returns true if this buffer is instanced
     */
    public getIsInstanced(): boolean {
        return this._instanced;
    }

    /**
     * Returns the instancing divisor, zero for non-instanced (integer).
     * @returns a number
     */
    public getInstanceDivisor(): number {
        return this._instanceDivisor;
    }

    // Methods

    /**
     * Store data into the buffer. If the buffer was already used it will be either recreated or updated depending on isUpdatable property
     * @param data defines the data to store
     */
    public create(data?: DataArray): void {
        this._buffer.create(data);
    }

    /**
     * Updates the underlying buffer according to the passed numeric array or Float32Array.
     * This function will create a new buffer if the current one is not updatable
     * @param data defines the data to store
     */
    public update(data: DataArray): void {
        this._buffer.update(data);
    }

    /**
     * Updates directly the underlying WebGLBuffer according to the passed numeric array or Float32Array.
     * Returns the directly updated WebGLBuffer.
     * @param data the new data
     * @param offset the new offset
     * @param useBytes set to true if the offset is in bytes
     */
    public updateDirectly(data: DataArray, offset: number, useBytes: boolean = false): void {
        this._buffer.updateDirectly(data, offset, undefined, useBytes);
    }

    /**
     * Disposes the VertexBuffer and the underlying WebGLBuffer.
     */
    public dispose(): void {
        if (this._ownsBuffer) {
            this._buffer.dispose();
        }
    }

    /**
     * Enumerates each value of this vertex buffer as numbers.
     * @param count the number of values to enumerate
     * @param callback the callback function called for each value
     */
    public forEach(count: number, callback: (value: number, index: number) => void): void {
        VertexBuffer.ForEach(this._buffer.getData()!, this.byteOffset, this.byteStride, this._size, this.type, count, this.normalized, callback);
    }

    // Enums
    /**
     * Positions
     */
    public static readonly PositionKind = "position";
    /**
     * Normals
     */
    public static readonly NormalKind = "normal";
    /**
     * Tangents
     */
    public static readonly TangentKind = "tangent";
    /**
     * Texture coordinates
     */
    public static readonly UVKind = "uv";
    /**
     * Texture coordinates 2
     */
    public static readonly UV2Kind = "uv2";
    /**
     * Texture coordinates 3
     */
    public static readonly UV3Kind = "uv3";
    /**
     * Texture coordinates 4
     */
    public static readonly UV4Kind = "uv4";
    /**
     * Texture coordinates 5
     */
    public static readonly UV5Kind = "uv5";
    /**
     * Texture coordinates 6
     */
    public static readonly UV6Kind = "uv6";
    /**
     * Colors
     */
    public static readonly ColorKind = "color";
    /**
     * Matrix indices (for bones)
     */
    public static readonly MatricesIndicesKind = "matricesIndices";
    /**
     * Matrix weights (for bones)
     */
    public static readonly MatricesWeightsKind = "matricesWeights";
    /**
     * Additional matrix indices (for bones)
     */
    public static readonly MatricesIndicesExtraKind = "matricesIndicesExtra";
    /**
     * Additional matrix weights (for bones)
     */
    public static readonly MatricesWeightsExtraKind = "matricesWeightsExtra";

    /**
     * Deduces the stride given a kind.
     * @param kind The kind string to deduce
     * @returns The deduced stride
     */
    public static DeduceStride(kind: string): number {
        switch (kind) {
            case VertexBuffer.UVKind:
            case VertexBuffer.UV2Kind:
            case VertexBuffer.UV3Kind:
            case VertexBuffer.UV4Kind:
            case VertexBuffer.UV5Kind:
            case VertexBuffer.UV6Kind:
                return 2;
            case VertexBuffer.NormalKind:
            case VertexBuffer.PositionKind:
                return 3;
            case VertexBuffer.ColorKind:
            case VertexBuffer.MatricesIndicesKind:
            case VertexBuffer.MatricesIndicesExtraKind:
            case VertexBuffer.MatricesWeightsKind:
            case VertexBuffer.MatricesWeightsExtraKind:
            case VertexBuffer.TangentKind:
                return 4;
            default:
                throw new Error("Invalid kind '" + kind + "'");
        }
    }

    /**
     * Gets the byte length of the given type.
     * @param type the type
     * @returns the number of bytes
     */
    public static GetTypeByteLength(type: number): number {
        switch (type) {
            case VertexBuffer.BYTE:
            case VertexBuffer.UNSIGNED_BYTE:
                return 1;
            case VertexBuffer.SHORT:
            case VertexBuffer.UNSIGNED_SHORT:
                return 2;
            case VertexBuffer.INT:
            case VertexBuffer.UNSIGNED_INT:
            case VertexBuffer.FLOAT:
                return 4;
            default:
                throw new Error(`Invalid type '${type}'`);
        }
    }

    /**
     * Enumerates each value of the given parameters as numbers.
     * @param data the data to enumerate
     * @param byteOffset the byte offset of the data
     * @param byteStride the byte stride of the data
     * @param componentCount the number of components per element
     * @param componentType the type of the component
     * @param count the number of values to enumerate
     * @param normalized whether the data is normalized
     * @param callback the callback function called for each value
     */
    public static ForEach(data: DataArray, byteOffset: number, byteStride: number, componentCount: number, componentType: number, count: number, normalized: boolean, callback: (value: number, index: number) => void): void {
        if (data instanceof Array) {
            let offset = byteOffset / 4;
            const stride = byteStride / 4;
            for (let index = 0; index < count; index += componentCount) {
                for (let componentIndex = 0; componentIndex < componentCount; componentIndex++) {
                    callback(data[offset + componentIndex], index + componentIndex);
                }
                offset += stride;
            }
        }
        else {
            const dataView = data instanceof ArrayBuffer ? new DataView(data) : new DataView(data.buffer, data.byteOffset, data.byteLength);
            const componentByteLength = VertexBuffer.GetTypeByteLength(componentType);
            for (let index = 0; index < count; index += componentCount) {
                let componentByteOffset = byteOffset;
                for (let componentIndex = 0; componentIndex < componentCount; componentIndex++) {
                    const value = VertexBuffer._GetFloatValue(dataView, componentType, componentByteOffset, normalized);
                    callback(value, index + componentIndex);
                    componentByteOffset += componentByteLength;
                }
                byteOffset += byteStride;
            }
        }
    }

    private static _GetFloatValue(dataView: DataView, type: number, byteOffset: number, normalized: boolean): number {
        switch (type) {
            case VertexBuffer.BYTE: {
                let value = dataView.getInt8(byteOffset);
                if (normalized) {
                    value = Math.max(value / 127, -1);
                }
                return value;
            }
            case VertexBuffer.UNSIGNED_BYTE: {
                let value = dataView.getUint8(byteOffset);
                if (normalized) {
                    value = value / 255;
                }
                return value;
            }
            case VertexBuffer.SHORT: {
                let value = dataView.getInt16(byteOffset, true);
                if (normalized) {
                    value = Math.max(value / 32767, -1);
                }
                return value;
            }
            case VertexBuffer.UNSIGNED_SHORT: {
                let value = dataView.getUint16(byteOffset, true);
                if (normalized) {
                    value = value / 65535;
                }
                return value;
            }
            case VertexBuffer.INT: {
                return dataView.getInt32(byteOffset, true);
            }
            case VertexBuffer.UNSIGNED_INT: {
                return dataView.getUint32(byteOffset, true);
            }
            case VertexBuffer.FLOAT: {
                return dataView.getFloat32(byteOffset, true);
            }
            default: {
                throw new Error(`Invalid component type ${type}`);
            }
        }
    }
}