import * as path from 'path';

export interface Frame {
	functionName?: string;
	fileName: string;
	line?: number;
	column?: number;
}

/** Converts an error into a list of frames based on the error stack */
export function parse(err: Error): Frame[] {
	if (!err.stack) {
		return [];
	}
	
	const lines = err.stack.split('\n').slice(1);
	return lines
		.map(function(line: string): Frame {
			if (line.match(/^\s*[-]{4,}$/)) {
				return { fileName: line };
			}

			let pieces = line.trim().split(' ');
			// pieces[0] will always be 'at'
			function parseData(fileUri: string, functionName?: string): Frame {
				let pieces = fileUri.split(':');
				let column: number | undefined = parseInt(pieces[pieces.length - 1]); if (Number.isNaN(column)) column = undefined;
				let line:   number | undefined = parseInt(pieces[pieces.length - 2]); if (Number.isNaN(line)) line = undefined;
				let colLinePieces = (column ? 1 : 0) + (line ? 1 : 0)
				let fileName = pieces.slice(0, pieces.length - colLinePieces).join(':');
				return { fileName: fileName, line: line, column: column, functionName: functionName };
			}
			if (pieces.length === 2) {
				return parseData(pieces[1]);
			} else {
				//               chop of parenthesis                     chop off 'at' and file path
				return parseData(pieces[pieces.length - 1].slice(1, -1), pieces.slice(1, -1).join(' '));
			}
		});
}

export function relativizeFilePath(frame: Frame, baseDir: string): Frame {
	if (frame.fileName && frame.fileName[0] === '/') {
		let relativeFileName = path.relative(baseDir, frame.fileName);
		return Object.assign({}, frame, { fileName: relativeFileName });
	}
	return frame;
}

/** Converts a parsed frame into a line that "could have come from an Error" */
export function getFrameLine(frame: Frame): string {
	if (frame.functionName) {
		if (frame.line) {
			if (frame.column) {
				return `    at ${frame.functionName} (${frame.fileName}:${frame.line}:${frame.column})`;
			} else {
				return `    at ${frame.functionName} (${frame.fileName}:${frame.line})`;
			}
		} else {
			return `    at ${frame.functionName} (${frame.fileName})`;
		}
	} else {
		if (frame.line) {
			if (frame.column) {
				return `    at ${frame.fileName}:${frame.line}:${frame.column}`;
			} else {
				return `    at ${frame.fileName}:${frame.line}`;
			}
		} else {
			return `    at ${frame.fileName}`;
		}
	}
}