"use strict";

// FIXME: Move this into its own package!

const execall = require("execall");
const defaultValue = require("default-value");

// I'm so, so sorry...
let lineRegex = /\s+at\s+(?:(?:([^\[$\n]+)\[as ([^\]]+)\] |([^\($\n]+))\(([^\)\n]+)\)|([^\n]+))(?:\n|$)/gm;
let positionRegex = /(.+):(\d+):(\d+)/;

function maybeTrim(value) {
	if (value != null) {
		return value.trim();
	} else {
		return value;
	}
}

function parseLocation(locationString) {
	let match = positionRegex.exec(locationString);

	if (match != null) {
		return {
			path: match[1],
			line: parseInt(match[2]),
			column: parseInt(match[3])
		};
	} else {
		throw new Error(`Could not parse location from string: ${locationString}`);
	}
}

function extractFrames(stack) {
	// TODO: Maybe make this code even more cautious, and match each stacktrace line individually, aborting as soon as any one line cannot be parsed?
	let matches = execall(lineRegex, stack);

	return matches.map((match) => {
		let groups = match.subMatches;

		return {
			functionName: maybeTrim(defaultValue(groups[0], groups[2])),
			alias: groups[1],
			location: parseLocation(defaultValue(groups[3], groups[4]))
		};
	});
}

module.exports = function parseStackTrace(error) {
	let stack = error.stack;
	let lines = stack.split("\n");

	let firstStackLine = lines
		.map((line) => line.trim())
		.findIndex((line) => line.startsWith("at ") && positionRegex.test(line));

	if (firstStackLine !== -1) {
		let cleanStack = lines
			.slice(firstStackLine)
			.join("\n");

		return extractFrames(cleanStack);
	} else {
		throw new Error(`Could not find a stacktrace frame`);
	}
};