"use strict";

function parseCodepoint(input, nullValue) {
	if (input === null) {
		return nullValue;
	} else if (typeof input === "number") {
		return input;
	} else if (typeof input === "string") {
		return input.codePointAt(0);
	} else {
		// FIXME: Better validation here
		throw new Error(`Invalid codepoint input`);
	}
}

module.exports = {
	zeroOrMore: (rule) => {
		return {
			__protocolKitInstruction: true,
			type: "zeroOrMore",
			rule: rule
		};
	},
	oneOrMore: (rule) => {
		return {
			__protocolKitInstruction: true,
			type: "oneOrMore",
			rule: rule
		};
	},
	either: (options) => {
		return {
			__protocolKitInstruction: true,
			type: "either",
			options: options
		};
	},
	until: (rule, allowEnd = true) => {
		return {
			__protocolKitInstruction: true,
			type: "until",
			rule: rule,
			// FIXME: Should allowEnd have a different default?
			allowEnd: allowEnd
		};
	},
	optional: (rule) => {
		return {
			__protocolKitInstruction: true,
			type: "optional",
			rule: rule
		};
	},
	peek: (rule) => {
		return {
			__protocolKitInstruction: true,
			type: "peek",
			rule: rule
		};
	},
	test: (rule) => {
		return {
			__protocolKitInstruction: true,
			type: "test",
			rule: rule
		};
	},
	wholeMatch: (rule) => {
		return {
			__protocolKitInstruction: true,
			type: "wholeMatch",
			rule: rule
		};
	},
	trackPosition: (rule) => {
		return {
			__protocolKitInstruction: true,
			type: "trackPosition",
			rule: rule
		};
	},
	EndOfInput: {
		__protocolKitInstruction: true,
		type: "endOfInput"
	},
	characterRange: (start, end) => {
		// NOTE: Both inclusive!
		let startCodepoint = parseCodepoint(start, 0);
		let endCodepoint = parseCodepoint(end, Infinity);

		return {
			__protocolKitInstruction: true,
			type: "characterRange",
			start: startCodepoint,
			end: endCodepoint
		};
	}
};