/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

class HookCodeFactory {
	constructor(config) {
		this.config = config;
		this.options = undefined;
	}

	create(options) {
		this.init(options);
		switch(this.options.type) {
			case "sync":
				return new Function(this.args(), "\"use strict\";\n" + this.header() + this.content({
					onError: err => `throw ${err};\n`,
					onResult: result => `return ${result};\n`,
					onDone: () => "",
					rethrowIfPossible: true
				}));
			case "async":
				return new Function(this.args({
					after: "_callback"
				}), "\"use strict\";\n" + this.header() + this.content({
					onError: err => `_callback(${err});\n`,
					onResult: result => `_callback(null, ${result});\n`,
					onDone: () => "_callback();\n"
				}));
			case "promise":
				let code = "";
				code += "\"use strict\";\n";
				code += "return new Promise((_resolve, _reject) => {\n";
				code += "var _sync = true;\n";
				code += this.header();
				code += this.content({
					onError: err => {
						let code = "";
						code += "if(_sync)\n";
						code += `_resolve(Promise.resolve().then(() => { throw ${err}; }));\n`;
						code += "else\n";
						code += `_reject(${err});\n`;
						return code;
					},
					onResult: result => `_resolve(${result});\n`,
					onDone: () => "_resolve();\n"
				});
				code += "_sync = false;\n";
				code += "});\n";
				return new Function(this.args(), code);
		}
	}

	setup(instance, options) {
		instance._x = options.taps.map(t => t.fn);
	}

	/**
	 * @param {{ type: "sync" | "promise" | "async", taps: Array<Tap>, interceptors: Array<Interceptor> }} options
	 */
	init(options) {
		this.options = options;
		this._args = options.args.slice();
	}

	header() {
		let code = "";
		if(this.needContext()) {
			code += "var _context = {};\n";
		} else {
			code += "var _context;\n";
		}
		code += "var _x = this._x;\n";
		if(this.options.interceptors.length > 0) {
			code += "var _taps = this.taps;\n";
			code += "var _interceptors = this.interceptors;\n";
		}
		for(let i = 0; i < this.options.interceptors.length; i++) {
			const interceptor = this.options.interceptors[i];
			if(interceptor.call) {
				code += `${this.getInterceptor(i)}.call(${this.args({
					before: interceptor.context ? "_context" : undefined
				})});\n`;
			}
		}
		return code;
	}

	needContext() {
		for(const tap of this.options.taps)
			if(tap.context) return true;
		return false;
	}

	callTap(tapIndex, { onError, onResult, onDone, rethrowIfPossible }) {
		let code = "";
		let hasTapCached = false;
		for(let i = 0; i < this.options.interceptors.length; i++) {
			const interceptor = this.options.interceptors[i];
			if(interceptor.tap) {
				if(!hasTapCached) {
					code += `var _tap${tapIndex} = ${this.getTap(tapIndex)};\n`;
					hasTapCached = true;
				}
				code += `${this.getInterceptor(i)}.tap(${interceptor.context ? "_context, " : ""}_tap${tapIndex});\n`;
			}
		}
		code += `var _fn${tapIndex} = ${this.getTapFn(tapIndex)};\n`;
		const tap = this.options.taps[tapIndex];
		switch(tap.type) {
			case "sync":
				if(!rethrowIfPossible) {
					code += `var _hasError${tapIndex} = false;\n`;
					code += "try {\n";
				}
				if(onResult) {
					code += `var _result${tapIndex} = _fn${tapIndex}(${this.args({
						before: tap.context ? "_context" : undefined
					})});\n`;
				} else {
					code += `_fn${tapIndex}(${this.args({
						before: tap.context ? "_context" : undefined
					})});\n`;
				}
				if(!rethrowIfPossible) {
					code += "} catch(_err) {\n";
					code += `_hasError${tapIndex} = true;\n`;
					code += onError("_err");
					code += "}\n";
					code += `if(!_hasError${tapIndex}) {\n`;
				}
				if(onResult) {
					code += onResult(`_result${tapIndex}`);
				}
				if(onDone) {
					code += onDone();
				}
				if(!rethrowIfPossible) {
					code += "}\n";
				}
				break;
			case "async":
				let cbCode = "";
				if(onResult)
					cbCode += `(_err${tapIndex}, _result${tapIndex}) => {\n`;
				else
					cbCode += `_err${tapIndex} => {\n`;
				cbCode += `if(_err${tapIndex}) {\n`;
				cbCode += onError(`_err${tapIndex}`);
				cbCode += "} else {\n";
				if(onResult) {
					cbCode += onResult(`_result${tapIndex}`);
				}
				if(onDone) {
					cbCode += onDone();
				}
				cbCode += "}\n";
				cbCode += "}";
				code += `_fn${tapIndex}(${this.args({
					before: tap.context ? "_context" : undefined,
					after: cbCode
				})});\n`;
				break;
			case "promise":
				code += `var _hasResult${tapIndex} = false;\n`;
				code += `_fn${tapIndex}(${this.args({
					before: tap.context ? "_context" : undefined
				})}).then(_result${tapIndex} => {\n`;
				code += `_hasResult${tapIndex} = true;\n`;
				if(onResult) {
					code += onResult(`_result${tapIndex}`);
				}
				if(onDone) {
					code += onDone();
				}
				code += `}, _err${tapIndex} => {\n`;
				code += `if(_hasResult${tapIndex}) throw _err${tapIndex};\n`;
				code += onError(`_err${tapIndex}`);
				code += "});\n";
				break;
		}
		return code;
	}

	callTapsSeries({ onError, onResult, onDone, rethrowIfPossible }) {
		if(this.options.taps.length === 0)
			return onDone();
		const firstAsync = this.options.taps.findIndex(t => t.type !== "sync");
		const next = i => {
			if(i >= this.options.taps.length) {
				return onDone();
			}
			const done = () => next(i + 1);
			const doneBreak = (skipDone) => {
				if(skipDone) return "";
				return onDone();
			}
			return this.callTap(i, {
				onError: error => onError(i, error, done, doneBreak),
				onResult: onResult && ((result) => {
					return onResult(i, result, done, doneBreak);
				}),
				onDone: !onResult && (() => {
					return done();
				}),
				rethrowIfPossible: rethrowIfPossible && (firstAsync < 0 || i < firstAsync)
			});
		};
		return next(0);
	}

	callTapsLooping({ onError, onDone, rethrowIfPossible }) {
		if(this.options.taps.length === 0)
			return onDone();
		const syncOnly = this.options.taps.every(t => t.type === "sync");
		let code = "";
		if(!syncOnly) {
			code += "var _looper = () => {\n";
			code += "var _loopAsync = false;\n";
		}
		code += "var _loop;\n";
		code += "do {\n";
		code += "_loop = false;\n";
		for(let i = 0; i < this.options.interceptors.length; i++) {
			const interceptor = this.options.interceptors[i];
			if(interceptor.loop) {
				code += `${this.getInterceptor(i)}.loop(${this.args({
					before: interceptor.context ? "_context" : undefined
				})});\n`;
			}
		}
		code += this.callTapsSeries({
			onError,
			onResult: (i, result, next, doneBreak) => {
				let code = "";
				code += `if(${result} !== undefined) {\n`;
				code += "_loop = true;\n";
				if(!syncOnly)
					code += "if(_loopAsync) _looper();\n";
				code += doneBreak(true);
				code += `} else {\n`;
				code += next();
				code += `}\n`;
				return code;
			},
			onDone: onDone && (() => {
				let code = "";
				code += "if(!_loop) {\n";
				code += onDone();
				code += "}\n";
				return code;
			}),
			rethrowIfPossible: rethrowIfPossible && syncOnly
		})
		code += "} while(_loop);\n";
		if(!syncOnly) {
			code += "_loopAsync = true;\n";
			code += "};\n";
			code += "_looper();\n";
		}
		return code;
	}

	callTapsParallel({ onError, onResult, onDone, rethrowIfPossible, onTap = (i, run) => run() }) {
		if(this.options.taps.length <= 1) {
			return this.callTapsSeries({ onError, onResult, onDone, rethrowIfPossible })
		}
		let code = "";
		code += "do {\n";
		code += `var _counter = ${this.options.taps.length};\n`;
		if(onDone) {
			code += "var _done = () => {\n";
			code += onDone();
			code += "};\n";
		}
		for(let i = 0; i < this.options.taps.length; i++) {
			const done = () => {
				if(onDone)
					return "if(--_counter === 0) _done();\n";
				else
					return "--_counter;";
			};
			const doneBreak = (skipDone) => {
				if(skipDone || !onDone)
					return "_counter = 0;\n";
				else
					return "_counter = 0;\n_done();\n";
			}
			code += "if(_counter <= 0) break;\n";
			code += onTap(i, () => this.callTap(i, {
				onError: error => {
					let code = "";
					code += "if(_counter > 0) {\n";
					code += onError(i, error, done, doneBreak);
					code += "}\n";
					return code;
				},
				onResult: onResult && ((result) => {
					let code = "";
					code += "if(_counter > 0) {\n";
					code += onResult(i, result, done, doneBreak);
					code += "}\n";
					return code;
				}),
				onDone: !onResult && (() => {
					return done();
				}),
				rethrowIfPossible
			}), done, doneBreak);
		}
		code += "} while(false);\n";
		return code;
	}

	args({ before, after } = {}) {
		let allArgs = this._args;
		if(before) allArgs = [before].concat(allArgs);
		if(after) allArgs = allArgs.concat(after);
		if(allArgs.length === 0) {
			return "";
		} else {
			return allArgs.join(", ");
		}
	}

	getTapFn(idx) {
		return `_x[${idx}]`;
	}

	getTap(idx) {
		return `_taps[${idx}]`;
	}

	getInterceptor(idx) {
		return `_interceptors[${idx}]`;
	}
}

module.exports = HookCodeFactory;