"use strict";

let generateBytecode = require("./passes/generate-bytecode");
let generateJS = require("./passes/generate-js");
let removeProxyRules = require("./passes/remove-proxy-rules");
let reportDuplicateLabels = require("./passes/report-duplicate-labels");
let reportDuplicateRules = require("./passes/report-duplicate-rules");
let reportInfiniteRecursion = require("./passes/report-infinite-recursion");
let reportInfiniteRepetition = require("./passes/report-infinite-repetition");
let reportUndefinedRules = require("./passes/report-undefined-rules");
let visitor = require("./visitor");

function processOptions(options, defaults) {
	return Object.assign({}, defaults, options);
}

let compiler = {
	// AST node visitor builder. Useful mainly for plugins which manipulate the
	// AST.
	visitor: visitor,

	// Compiler passes.
	//
	// Each pass is a function that is passed the AST. It can perform checks on it
	// or modify it as needed. If the pass encounters a semantic error, it throws
	// |peg.GrammarError|.
	passes: {
		check: {
			reportUndefinedRules: reportUndefinedRules,
			reportDuplicateRules: reportDuplicateRules,
			reportDuplicateLabels: reportDuplicateLabels,
			reportInfiniteRecursion: reportInfiniteRecursion,
			reportInfiniteRepetition: reportInfiniteRepetition
		},
		transform: {
			removeProxyRules: removeProxyRules
		},
		generate: {
			generateBytecode: generateBytecode,
			generateJS: generateJS
		}
	},

	// Generates a parser from a specified grammar AST. Throws |peg.GrammarError|
	// if the AST contains a semantic error. Note that not all errors are detected
	// during the generation and some may protrude to the generated parser and
	// cause its malfunction.
	compile(ast, passes, options = {}) {
		let processedOptions = processOptions(options, {
			allowedStartRules: [ast.rules[0].name],
			cache: false,
			dependencies: {},
			exportVar: null,
			format: "bare",
			optimize: "speed",
			output: "parser",
			trace: false
		});

		Object.values(passes).forEach((stagePasses) => {
			stagePasses.forEach(pass => { pass(ast, processedOptions); });
		});

		switch (processedOptions.output) {
			case "parser":
				return eval(ast.code);
				
			case "source":
				return ast.code;
				
			// FIXME: Move to Validatem code at entrypoint
			default:
				throw new Error("Invalid output format: " + processedOptions.output + ".");
		}
	}
};

module.exports = compiler;