//Copyright (c) 2009 The Chromium Authors. All rights reserved.
//Use of this source code is governed by a BSD-style license that can be
//found in the LICENSE file.

// Various functions for helping debug WebGL apps.

type FunctionKeys<T> = {
	[P in keyof T]: T[P] extends Function ? P : never;
}[keyof T];
type DebugContextProp = { [x: number]: boolean };
type WebGLContextFuncKey = FunctionKeys<WebGLRenderingContext>;
type GLValidEnumContext = {
	[prop in WebGLContextFuncKey]?: DebugContextProp;
};
type GLPartialContext = {
	-readonly [prop in keyof WebGLRenderingContext]?: WebGLRenderingContext[prop];
};
type WebGLResource = (
	| WebGLBuffer
	| WebGLFramebuffer
	| WebGLProgram
	| WebGLRenderbuffer
	| WebGLShader
	| WebGLTexture
) & { __webglDebugContextLostId__: number };

export const WebGLDebugUtils = (function () {
	/**
	 * Wrapped logging function.
	 * @param {string} msg Message to log.
	 */
	const log = function (msg: string) {
		if (window.console && window.console.log) {
			window.console.log(msg);
		}
	};

	/**
	 * Which arguments are enums.
	 * @type {!Object.<number, string>}
	 */
	const glValidEnumContexts: GLValidEnumContext = {
		// Generic setters and getters

		enable: { 0: true },
		disable: { 0: true },
		getParameter: { 0: true },

		// Rendering

		drawArrays: { 0: true },
		drawElements: { 0: true, 2: true },

		// Shaders

		createShader: { 0: true },
		getShaderParameter: { 1: true },
		getProgramParameter: { 1: true },

		// Vertex attributes

		getVertexAttrib: { 1: true },
		vertexAttribPointer: { 2: true },

		// Textures

		bindTexture: { 0: true },
		activeTexture: { 0: true },
		getTexParameter: { 0: true, 1: true },
		texParameterf: { 0: true, 1: true },
		texParameteri: { 0: true, 1: true, 2: true },
		texImage2D: { 0: true, 2: true, 6: true, 7: true },
		texSubImage2D: { 0: true, 6: true, 7: true },
		copyTexImage2D: { 0: true, 2: true },
		copyTexSubImage2D: { 0: true },
		generateMipmap: { 0: true },

		// Buffer objects

		bindBuffer: { 0: true },
		bufferData: { 0: true, 2: true },
		bufferSubData: { 0: true },
		getBufferParameter: { 0: true, 1: true },

		// Renderbuffers and framebuffers

		pixelStorei: { 0: true, 1: true },
		readPixels: { 4: true, 5: true },
		bindRenderbuffer: { 0: true },
		bindFramebuffer: { 0: true },
		checkFramebufferStatus: { 0: true },
		framebufferRenderbuffer: { 0: true, 1: true, 2: true },
		framebufferTexture2D: { 0: true, 1: true, 2: true },
		getFramebufferAttachmentParameter: { 0: true, 1: true, 2: true },
		getRenderbufferParameter: { 0: true, 1: true },
		renderbufferStorage: { 0: true, 1: true },

		// Frame buffer operations (clear, blend, depth test, stencil)

		clear: { 0: true },
		depthFunc: { 0: true },
		blendFunc: { 0: true, 1: true },
		blendFuncSeparate: { 0: true, 1: true, 2: true, 3: true },
		blendEquation: { 0: true },
		blendEquationSeparate: { 0: true, 1: true },
		stencilFunc: { 0: true },
		stencilFuncSeparate: { 0: true, 1: true },
		stencilMaskSeparate: { 0: true },
		stencilOp: { 0: true, 1: true, 2: true },
		stencilOpSeparate: { 0: true, 1: true, 2: true, 3: true },

		// Culling

		cullFace: { 0: true },
		frontFace: { 0: true },
	};

	/**
	 * Map of numbers to names.
	 * @type {Object}
	 */
	let glEnums: Record<string | number, any> | null = null;

	/**
	 * Initializes this module. Safe to call more than once.
	 * @param {!WebGLRenderingContext} ctx A WebGL context. If
	 *    you have more than one context it doesn't matter which one
	 *    you pass in, it is only used to pull out constants.
	 */
	function init(ctx: WebGLRenderingContext) {
		if (glEnums == null) {
			glEnums = {};
			for (const propertyName in ctx) {
				if (typeof (ctx as any)[propertyName] == 'number') {
					glEnums[(ctx as any)[propertyName]] = propertyName;
				}
			}
		}
	}

	/**
	 * Checks the utils have been initialized.
	 */
	function checkInit() {
		if (glEnums == null) {
			throw 'WebGLDebugUtils.init(ctx) not called';
		}
	}

	/**
	 * Returns true or false if value matches any WebGL enum
	 * @param {*} glEnumKey Value to check if it might be an enum.
	 * @return {boolean} True if value matches one of the WebGL defined enums
	 */
	function mightBeEnum(glEnumKey: string | number) {
		checkInit();
		return !!glEnums && glEnums[glEnumKey] !== undefined;
	}

	/**
	 * Gets an string version of an WebGL enum.
	 *
	 * Example:
	 *   const str = WebGLDebugUtil.glEnumToString(ctx.getError());
	 *
	 * @param {number} glEnumKey Value to return an enum for
	 * @return {string} The string version of the enum.
	 */
	function glEnumToString(glEnumKey: string | number) {
		checkInit();
		const name = glEnums && glEnums[glEnumKey];
		return name !== undefined ? name : '*UNKNOWN WebGL ENUM (0x' + glEnumKey.toString(16) + ')';
	}

	/**
	 * Returns the string version of a WebGL argument.
	 * Attempts to convert enum arguments to strings.
	 * @param {string} functionName the name of the WebGL function.
	 * @param {number} argumentIndx the index of the argument.
	 * @param {*} value The value of the argument.
	 * @return {string} The value as a string.
	 */
	function glFunctionArgToString(functionName: WebGLContextFuncKey, argumentIndex: number, value: string | number) {
		const funcInfo = glValidEnumContexts[functionName];
		if (funcInfo !== undefined) {
			if (funcInfo[argumentIndex]) {
				return glEnumToString(value);
			}
		}
		return value.toString();
	}

	/**
	 * Given a WebGL context returns a wrapped context that calls
	 * gl.getError after every command and calls a function if the
	 * result is not gl.NO_ERROR.
	 *
	 * @param {!WebGLRenderingContext} ctx The webgl context to
	 *        wrap.
	 * @param {!function(err, funcName, args): void} opt_onErrorFunc
	 *        The function to call when gl.getError returns an
	 *        error. If not specified the default function calls
	 *        console.log with a message.
	 */
	function makeDebugContext(
		ctx: WebGLRenderingContext,
		opt_onErrorFunc?: (err: any, funcName: keyof typeof glValidEnumContexts, args: any[]) => void,
	) {
		init(ctx);
		opt_onErrorFunc =
			opt_onErrorFunc ||
			function (err, functionName, args) {
				// apparently we can't do args.join(",");
				let argStr = '';
				for (let ii = 0; ii < args.length; ++ii) {
					argStr += (ii == 0 ? '' : ', ') + glFunctionArgToString(functionName, ii as never, args[ii]);
				}
				log('WebGL error ' + glEnumToString(err) + ' in ' + functionName + '(' + argStr + ')');
			};

		// Holds booleans for each GL error so after we get the error ourselves
		// we can still return it to the client app.
		const glErrorShadow: Record<string | number, any> = {};

		// Makes a function that calls a WebGL function and then calls getError.
		function makeErrorWrapper(ctx: WebGLRenderingContext, functionName: WebGLContextFuncKey) {
			return function () {
				const result = (ctx as any)[functionName].apply(ctx, arguments);
				const err = ctx.getError();
				if (err != 0) {
					glErrorShadow[err] = true;
					opt_onErrorFunc!(err, functionName, arguments as any);
				}
				return result;
			};
		}

		// Make a an object that has a copy of every property of the WebGL context
		// but wraps all functions.
		const wrapper: GLPartialContext = {};
		for (const propertyName in ctx) {
			const funcKey = propertyName as WebGLContextFuncKey;
			if (typeof ctx[funcKey] === 'function') {
				wrapper[funcKey] = makeErrorWrapper(ctx, funcKey);
			} else {
				wrapper[funcKey] = (ctx as any)[funcKey];
			}
		}

		// Override the getError function with one that returns our saved results.
		wrapper.getError = function () {
			for (const err in glErrorShadow) {
				if (glErrorShadow[err]) {
					glErrorShadow[err] = false;
					return +err;
				}
			}
			return ctx.NO_ERROR;
		};

		return wrapper;
	}

	function resetToInitialState(ctx: WebGLRenderingContext) {
		const numAttribs = ctx.getParameter(ctx.MAX_VERTEX_ATTRIBS);
		const tmp = ctx.createBuffer();
		ctx.bindBuffer(ctx.ARRAY_BUFFER, tmp);
		for (let ii = 0; ii < numAttribs; ++ii) {
			ctx.disableVertexAttribArray(ii);
			ctx.vertexAttribPointer(ii, 4, ctx.FLOAT, false, 0, 0);
			ctx.vertexAttrib1f(ii, 0);
		}
		ctx.deleteBuffer(tmp);

		const numTextureUnits = ctx.getParameter(ctx.MAX_TEXTURE_IMAGE_UNITS);
		for (let ii = 0; ii < numTextureUnits; ++ii) {
			ctx.activeTexture(ctx.TEXTURE0 + ii);
			ctx.bindTexture(ctx.TEXTURE_CUBE_MAP, null);
			ctx.bindTexture(ctx.TEXTURE_2D, null);
		}

		ctx.activeTexture(ctx.TEXTURE0);
		ctx.useProgram(null);
		ctx.bindBuffer(ctx.ARRAY_BUFFER, null);
		ctx.bindBuffer(ctx.ELEMENT_ARRAY_BUFFER, null);
		ctx.bindFramebuffer(ctx.FRAMEBUFFER, null);
		ctx.bindRenderbuffer(ctx.RENDERBUFFER, null);
		ctx.disable(ctx.BLEND);
		ctx.disable(ctx.CULL_FACE);
		ctx.disable(ctx.DEPTH_TEST);
		ctx.disable(ctx.DITHER);
		ctx.disable(ctx.SCISSOR_TEST);
		ctx.blendColor(0, 0, 0, 0);
		ctx.blendEquation(ctx.FUNC_ADD);
		ctx.blendFunc(ctx.ONE, ctx.ZERO);
		ctx.clearColor(0, 0, 0, 0);
		ctx.clearDepth(1);
		ctx.clearStencil(-1);
		ctx.colorMask(true, true, true, true);
		ctx.cullFace(ctx.BACK);
		ctx.depthFunc(ctx.LESS);
		ctx.depthMask(true);
		ctx.depthRange(0, 1);
		ctx.frontFace(ctx.CCW);
		ctx.hint(ctx.GENERATE_MIPMAP_HINT, ctx.DONT_CARE);
		ctx.lineWidth(1);
		ctx.pixelStorei(ctx.PACK_ALIGNMENT, 4);
		ctx.pixelStorei(ctx.UNPACK_ALIGNMENT, 4);
		ctx.pixelStorei(ctx.UNPACK_FLIP_Y_WEBGL, false);
		ctx.pixelStorei(ctx.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
		// TODO: Delete this IF.
		if (ctx.UNPACK_COLORSPACE_CONVERSION_WEBGL) {
			ctx.pixelStorei(ctx.UNPACK_COLORSPACE_CONVERSION_WEBGL, ctx.BROWSER_DEFAULT_WEBGL);
		}
		ctx.polygonOffset(0, 0);
		ctx.sampleCoverage(1, false);
		ctx.scissor(0, 0, ctx.canvas.width, ctx.canvas.height);
		ctx.stencilFunc(ctx.ALWAYS, 0, 0xffffffff);
		ctx.stencilMask(0xffffffff);
		ctx.stencilOp(ctx.KEEP, ctx.KEEP, ctx.KEEP);
		ctx.viewport(0, 0, (ctx.canvas as HTMLCanvasElement).clientWidth, (ctx.canvas as HTMLCanvasElement).clientHeight);
		ctx.clear(ctx.COLOR_BUFFER_BIT | ctx.DEPTH_BUFFER_BIT | ctx.STENCIL_BUFFER_BIT);

		// TODO: This should NOT be needed but Firefox fails with 'hint'
		while (ctx.getError());
	}

	function makeLostContextSimulatingContext(ctx: WebGLRenderingContext) {
		const wrapper_: GLPartialContext & {
			loseContext?: Function;
			restoreContext?: Function;
			registerOnContextLostListener?: Function;
			registerOnContextRestoredListener?: Function;
		} = {};
		let contextId_ = 1;
		let contextLost_ = false;
		const resourceDb_: WebGLResource[] = [];
		let onLost_: Function | undefined = undefined;
		let onRestored_: Function | undefined = undefined;
		let nextOnRestored_: Function | undefined = undefined;

		// Holds booleans for each GL error so can simulate errors.
		const glErrorShadow_: { [prop in number | string]: boolean } = {};

		function isWebGLResource(obj: WebGLResource) {
			//return false;
			return (
				obj instanceof WebGLBuffer ||
				obj instanceof WebGLFramebuffer ||
				obj instanceof WebGLProgram ||
				obj instanceof WebGLRenderbuffer ||
				obj instanceof WebGLShader ||
				obj instanceof WebGLTexture
			);
		}

		function checkResources(args: WebGLResource[]) {
			for (let ii = 0; ii < args.length; ++ii) {
				const arg = args[ii];
				if (isWebGLResource(arg)) {
					return arg.__webglDebugContextLostId__ == contextId_;
				}
			}
			return true;
		}

		function clearErrors() {
			const k = Object.keys(glErrorShadow_);
			for (let ii = 0; ii < k.length; ++ii) {
				delete glErrorShadow_[k[ii]];
			}
		}

		// Makes a function that simulates WebGL when out of context.
		function makeLostContextWrapper(ctx: WebGLRenderingContext, functionName: WebGLContextFuncKey) {
			const f = ctx[functionName];
			return function () {
				// Only call the functions if the context is not lost.
				if (!contextLost_) {
					if (!checkResources(arguments as unknown as WebGLResource[])) {
						glErrorShadow_[ctx.INVALID_OPERATION] = true;
						return;
					}
					const result = (f as (this: WebGLRenderingContext, mask: number) => any).apply(
						ctx,
						arguments as unknown as [number],
					);
					return result;
				}
			};
		}

		for (const propertyName in ctx) {
			const ctxFuncKey = propertyName as WebGLContextFuncKey;
			if (typeof ctx[propertyName as keyof WebGLRenderingContext] === 'function') {
				wrapper_[ctxFuncKey] = makeLostContextWrapper(ctx, ctxFuncKey);
			} else {
				wrapper_[ctxFuncKey] = ctx[ctxFuncKey] as any;
			}
		}

		function makeWebGLContextEvent(statusMessage: string) {
			return { statusMessage: statusMessage };
		}

		function freeResources() {
			for (let ii = 0; ii < resourceDb_.length; ++ii) {
				const resource = resourceDb_[ii];
				if (resource instanceof WebGLBuffer) {
					ctx.deleteBuffer(resource);
				} else if (resource instanceof WebGLFramebuffer) {
					ctx.deleteFramebuffer(resource);
				} else if (resource instanceof WebGLProgram) {
					ctx.deleteProgram(resource);
				} else if (resource instanceof WebGLRenderbuffer) {
					ctx.deleteRenderbuffer(resource);
				} else if (resource instanceof WebGLShader) {
					ctx.deleteShader(resource);
				} else if (resource instanceof WebGLTexture) {
					ctx.deleteTexture(resource);
				}
			}
		}

		wrapper_.loseContext = function () {
			if (!contextLost_) {
				contextLost_ = true;
				++contextId_;
				while (ctx.getError());
				clearErrors();
				glErrorShadow_[ctx.CONTEXT_LOST_WEBGL] = true;
				setTimeout(function () {
					if (onLost_) {
						onLost_(makeWebGLContextEvent('context lost'));
					}
				}, 0);
			}
		};

		wrapper_.restoreContext = function () {
			if (contextLost_) {
				if (onRestored_) {
					setTimeout(function () {
						freeResources();
						resetToInitialState(ctx);
						contextLost_ = false;
						if (onRestored_) {
							const callback = onRestored_;
							onRestored_ = nextOnRestored_;
							nextOnRestored_ = undefined;
							callback(makeWebGLContextEvent('context restored'));
						}
					}, 0);
				} else {
					throw 'You can not restore the context without a listener';
				}
			}
		};

		// Wrap a few functions specially.
		wrapper_.getError = function () {
			if (!contextLost_) {
				let err;
				while ((err = ctx.getError())) {
					glErrorShadow_[err] = true;
				}
			}
			for (const err in glErrorShadow_) {
				if (glErrorShadow_[err]) {
					delete glErrorShadow_[err];
					return +err;
				}
			}
			return ctx.NO_ERROR;
		};

		const creationFunctions: WebGLContextFuncKey[] = [
			'createBuffer',
			'createFramebuffer',
			'createProgram',
			'createRenderbuffer',
			'createShader',
			'createTexture',
		];
		for (let ii = 0; ii < creationFunctions.length; ++ii) {
			const functionName = creationFunctions[ii];
			wrapper_[functionName] = (function (f) {
				return function () {
					if (contextLost_) {
						return null;
					}
					const obj = (f as (this: WebGLRenderingContext, mask: number) => any).apply(
						ctx,
						arguments as unknown as [number],
					);
					obj.__webglDebugContextLostId__ = contextId_;
					resourceDb_.push(obj);
					return obj;
				};
			})(ctx[functionName]);
		}

		const functionsThatShouldReturnNull: WebGLContextFuncKey[] = [
			'getActiveAttrib',
			'getActiveUniform',
			'getBufferParameter',
			'getContextAttributes',
			'getAttachedShaders',
			'getFramebufferAttachmentParameter',
			'getParameter',
			'getProgramParameter',
			'getProgramInfoLog',
			'getRenderbufferParameter',
			'getShaderParameter',
			'getShaderInfoLog',
			'getShaderSource',
			'getTexParameter',
			'getUniform',
			'getUniformLocation',
			'getVertexAttrib',
		];
		for (let ii = 0; ii < functionsThatShouldReturnNull.length; ++ii) {
			const functionName = functionsThatShouldReturnNull[ii];
			wrapper_[functionName] = (function (f) {
				return function () {
					if (contextLost_) {
						return null;
					}
					return (f as (this: WebGLRenderingContext, mask: number) => any).apply(ctx, arguments as unknown as [number]);
				};
			})(wrapper_[functionName]);
		}

		const isFunctions: WebGLContextFuncKey[] = [
			'isBuffer',
			'isEnabled',
			'isFramebuffer',
			'isProgram',
			'isRenderbuffer',
			'isShader',
			'isTexture',
		];
		for (let ii = 0; ii < isFunctions.length; ++ii) {
			const functionName = isFunctions[ii];
			wrapper_[functionName] = (function (f) {
				return function () {
					if (contextLost_) {
						return false;
					}
					return (f as (this: WebGLRenderingContext, mask: number) => any).apply(ctx, arguments as unknown as [number]);
				};
			})(wrapper_[functionName]);
		}

		wrapper_.checkFramebufferStatus = (function (f) {
			return function () {
				if (contextLost_) {
					return ctx.FRAMEBUFFER_UNSUPPORTED;
				}
				return (f as (this: WebGLRenderingContext, mask: number) => any).apply(ctx, arguments as unknown as [number]);
			};
		})(wrapper_.checkFramebufferStatus);

		wrapper_.getAttribLocation = (function (f) {
			return function () {
				if (contextLost_) {
					return -1;
				}
				return (f as (this: WebGLRenderingContext, mask: number) => any).apply(ctx, arguments as unknown as [number]);
			};
		})(wrapper_.getAttribLocation);

		wrapper_.getVertexAttribOffset = (function (f) {
			return function () {
				if (contextLost_) {
					return 0;
				}
				return (f as (this: WebGLRenderingContext, mask: number) => any).apply(ctx, arguments as unknown as [number]);
			};
		})(wrapper_.getVertexAttribOffset);

		wrapper_.isContextLost = function () {
			return contextLost_;
		};
		function wrapEvent(listener: Function | { handleEvent: Function }) {
			if (typeof listener == 'function') {
				return listener;
			} else {
				return function (info: any) {
					listener.handleEvent(info);
				};
			}
		}

		wrapper_.registerOnContextLostListener = function (listener: Function) {
			onLost_ = wrapEvent(listener);
		};

		wrapper_.registerOnContextRestoredListener = function (listener: Function) {
			if (contextLost_) {
				nextOnRestored_ = wrapEvent(listener);
			} else {
				onRestored_ = wrapEvent(listener);
			}
		};

		return wrapper_;
	}

	return {
		/**
		 * Initializes this module. Safe to call more than once.
		 * @param {!WebGLRenderingContext} ctx A WebGL context. If
		 *    you have more than one context it doesn't matter which one
		 *    you pass in, it is only used to pull out constants.
		 */
		init: init,

		/**
		 * Returns true or false if value matches any WebGL enum
		 * @param {*} value Value to check if it might be an enum.
		 * @return {boolean} True if value matches one of the WebGL defined enums
		 */
		mightBeEnum: mightBeEnum,

		/**
		 * Gets an string version of an WebGL enum.
		 *
		 * Example:
		 *   WebGLDebugUtil.init(ctx);
		 *   const str = WebGLDebugUtil.glEnumToString(ctx.getError());
		 *
		 * @param {number} value Value to return an enum for
		 * @return {string} The string version of the enum.
		 */
		glEnumToString: glEnumToString,

		/**
		 * Converts the argument of a WebGL function to a string.
		 * Attempts to convert enum arguments to strings.
		 *
		 * Example:
		 *   WebGLDebugUtil.init(ctx);
		 *   const str = WebGLDebugUtil.glFunctionArgToString('bindTexture', 0, gl.TEXTURE_2D);
		 *
		 * would return 'TEXTURE_2D'
		 *
		 * @param {string} functionName the name of the WebGL function.
		 * @param {number} argumentIndx the index of the argument.
		 * @param {*} value The value of the argument.
		 * @return {string} The value as a string.
		 */
		glFunctionArgToString: glFunctionArgToString,

		/**
		 * Given a WebGL context returns a wrapped context that calls
		 * gl.getError after every command and calls a function if the
		 * result is not NO_ERROR.
		 *
		 * You can supply your own function if you want. For example, if you'd like
		 * an exception thrown on any GL error you could do this
		 *
		 *    function throwOnGLError(err, funcName, args) {
		 *      throw WebGLDebugUtils.glEnumToString(err) + " was caused by call to" +
		 *            funcName;
		 *    };
		 *
		 *    ctx = WebGLDebugUtils.makeDebugContext(
		 *        canvas.getContext("webgl"), throwOnGLError);
		 *
		 * @param {!WebGLRenderingContext} ctx The webgl context to wrap.
		 * @param {!function(err, funcName, args): void} opt_onErrorFunc The function
		 *     to call when gl.getError returns an error. If not specified the default
		 *     function calls console.log with a message.
		 */
		makeDebugContext: makeDebugContext,

		/**
		 * Given a WebGL context returns a wrapped context that adds 4
		 * functions.
		 *
		 * ctx.loseContext:
		 *   simulates a lost context event.
		 *
		 * ctx.restoreContext:
		 *   simulates the context being restored.
		 *
		 * ctx.registerOnContextLostListener(listener):
		 *   lets you register a listener for context lost. Use instead
		 *   of addEventListener('webglcontextlostevent', listener);
		 *
		 * ctx.registerOnContextRestoredListener(listener):
		 *   lets you register a listener for context restored. Use
		 *   instead of addEventListener('webglcontextrestored',
		 *   listener);
		 *
		 * @param {!WebGLRenderingContext} ctx The webgl context to wrap.
		 */
		makeLostContextSimulatingContext: makeLostContextSimulatingContext,

		/**
		 * Resets a context to the initial state.
		 * @param {!WebGLRenderingContext} ctx The webgl context to
		 *     reset.
		 */
		resetToInitialState: resetToInitialState,
	};
})();