#!/usr/bin/env node

/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

'use strict';

// MODULES //

var resolve = require( 'path' ).resolve;
var stdin = require( '@stdlib/process/read-stdin' );
var readFileSync = require( '@stdlib/fs/read-file' ).sync;
var CLI = require( '@stdlib/cli/ctor' );
var stdinStream = require( '@stdlib/streams/node/stdin' );
var nextTick = require( '@stdlib/utils/next-tick' );
var timeit = require( './../lib' );


// FUNCTIONS //

/**
* Prints results as JSON.
*
* @private
* @param {Object} results - results
*/
function printJSON( results ) {
	console.log( JSON.stringify( results ) ); // eslint-disable-line no-console
}

/**
* Prints results as CSV.
*
* @private
* @param {Object} results - results
*/
function printCSV( results ) {
	var times = results.times;
	var i;

	console.log( '%s,%s', 'seconds', 'nanoseconds' ); // eslint-disable-line no-console
	for ( i = 0; i < times.length; i++ ) {
		console.log( '%d,%d', times[i][0], times[i][1] ); // eslint-disable-line no-console
	}
}

/**
* Pretty prints results.
*
* @private
* @param {Object} results - results
*/
function prettyPrint( results ) {
	var unit;
	var r;

	r = results.elapsed*1e6 / results.iterations;
	if ( r < 1000 ) {
		unit = 'usec';
	} else {
		r /= 1000;
		if ( r < 1000 ) {
			unit = 'msec';
		} else {
			r /= 1000;
			unit = 'sec';
		}
	}
	/* eslint-disable no-console */

	console.log( '' );
	console.log( 'iterations: %d', results.iterations );
	console.log( 'repeats: %d', results.repeats );
	console.log( 'iterations/s: %d', results.rate );
	console.log( 'elapsed time: %d sec', results.elapsed );
	console.log( 'lower bound: %d %s/iteration', r, unit );
	console.log( '' );

	/* eslint-enable no-console */
}


// MAIN //

/**
* Main execution sequence.
*
* @private
* @returns {void}
*/
function main() {
	var flags;
	var args;
	var code;
	var opts;
	var cli;

	// Create a command-line interface:
	cli = new CLI({
		'pkg': require( './../package.json' ),
		'options': require( './../etc/cli_opts.json' ),
		'help': readFileSync( resolve( __dirname, '..', 'docs', 'usage.txt' ), {
			'encoding': 'utf8'
		})
	});

	// Get any provided command-line options:
	flags = cli.flags();
	if ( flags.help || flags.version ) {
		return;
	}

	// Get any provided command-line arguments:
	args = cli.args();

	opts = {};
	if ( flags.iterations ) {
		opts.iterations = parseInt( flags.iterations, 10 );
	} else {
		opts.iterations = null;
	}
	if ( flags.repeats ) {
		opts.repeats = parseInt( flags.repeats, 10 );
	}
	if ( flags.before ) {
		opts.before = flags.before;
	}
	if ( flags.after ) {
		opts.after = flags.after;
	}
	if ( flags.async ) {
		opts.asynchronous = flags.async;
	}

	// Check if we are receiving data from `stdin`...
	if ( !stdinStream.isTTY ) {
		return stdin( onRead );
	}
	code = args[ 0 ];
	nextTick( next );

	/**
	* Callback invoked upon reading from `stdin`.
	*
	* @private
	* @param {(Error|null)} error - error object
	* @param {Buffer} data - data
	* @returns {void}
	*/
	function onRead( error, data ) {
		if ( error ) {
			return done( error );
		}
		code = data.toString();
		next();
	}

	/**
	* Times a snippet.
	*
	* @private
	*/
	function next() {
		timeit( code, opts, done );
	}

	/**
	* Callback invoked upon completion.
	*
	* @private
	* @param {(Error|null)} error - error object
	* @param {Object} results - results
	* @returns {void}
	*/
	function done( error, results ) {
		if ( error ) {
			return cli.error( error );
		}
		if ( flags.format === 'json' ) {
			printJSON( results );
		} else if ( flags.format === 'csv' ) {
			printCSV( results );
		} else {
			prettyPrint( results );
		}
	}
}

main();