/**
* @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 tape = require( 'tape' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var abs = require( '@stdlib/math/base/special/abs' );
var PINF = require( '@stdlib/constants/float64/pinf' );
var NINF = require( '@stdlib/constants/float64/ninf' );
var EPS = require( '@stdlib/constants/float64/eps' );
var exp2 = require( './../lib' );


// FIXTURES //

var mediumNegative = require( './fixtures/julia/medium_negative.json' );
var mediumPositive = require( './fixtures/julia/medium_positive.json' );
var smallNegative = require( './fixtures/julia/small_negative.json' );
var smallPositive = require( './fixtures/julia/small_positive.json' );
var tiny = require( './fixtures/julia/tiny.json' );


// TESTS //

tape( 'main export is a function', function test( t ) {
	t.ok( true, __filename );
	t.equal( typeof exp2, 'function', 'main export is a function' );
	t.end();
});

tape( 'the function accurately computes `2**x` for negative medium numbers', function test( t ) {
	var expected;
	var delta;
	var tol;
	var x;
	var v;
	var i;

	x = mediumNegative.x;
	expected = mediumNegative.expected;

	for ( i = 0; i < x.length; i++ ) {
		v = exp2( x[ i ] );
		delta = abs( v - expected[ i ] );
		tol = EPS * abs( expected[ i ] );
		t.ok( delta <= tol, 'within tolerance. x: ' + x[ i ] + '. Value: ' + v + '. Expected: ' + expected[ i ] + '. Delta: ' + delta + '. Tolerance: ' + tol + '.' );
	}
	t.end();
});

tape( 'the function accurately computes `2**x` for positive medium numbers', function test( t ) {
	var expected;
	var delta;
	var tol;
	var x;
	var v;
	var i;

	x = mediumPositive.x;
	expected = mediumPositive.expected;

	for ( i = 0; i < x.length; i++ ) {
		v = exp2( x[ i ] );
		delta = abs( v - expected[ i ] );
		tol = EPS * abs( expected[ i ] );
		t.ok( delta <= tol, 'within tolerance. x: ' + x[ i ] + '. Value: ' + v + '. Expected: ' + expected[ i ] + '. Delta: ' + delta + '. Tolerance: ' + tol + '.' );
	}
	t.end();
});

tape( 'the function accurately computes `2**x` for negative small numbers', function test( t ) {
	var expected;
	var delta;
	var tol;
	var x;
	var v;
	var i;

	x = smallNegative.x;
	expected = smallNegative.expected;

	for ( i = 0; i < x.length; i++ ) {
		v = exp2( x[ i ] );
		delta = abs( v - expected[ i ] );
		tol = EPS * abs( expected[ i ] );
		t.ok( delta <= tol, 'within tolerance. x: ' + x[ i ] + '. Value: ' + v + '. Expected: ' + expected[ i ] + '. Delta: ' + delta + '. Tolerance: ' + tol + '.' );
	}
	t.end();
});

tape( 'the function accurately computes `2**x` for positive small numbers', function test( t ) {
	var expected;
	var delta;
	var tol;
	var x;
	var v;
	var i;

	x = smallPositive.x;
	expected = smallPositive.expected;

	for ( i = 0; i < x.length; i++ ) {
		v = exp2( x[ i ] );
		delta = abs( v - expected[ i ] );
		tol = EPS * abs( expected[ i ] );
		t.ok( delta <= tol, 'within tolerance. x: ' + x[ i ] + '. Value: ' + v + '. Expected: ' + expected[ i ] + '. Delta: ' + delta + '. Tolerance: ' + tol + '.' );
	}
	t.end();
});

tape( 'the function accurately computes `2**x` for very small `x`', function test( t ) {
	var expected;
	var delta;
	var tol;
	var x;
	var v;
	var i;

	x = tiny.x;
	expected = tiny.expected;

	for ( i = 0; i < x.length; i++ ) {
		v = exp2( x[ i ] );
		delta = abs( v - expected[ i ] );
		tol = EPS * abs( expected[ i ] );
		t.ok( delta <= tol, 'within tolerance. x: ' + x[ i ] + '. Value: ' + v + '. Expected: ' + expected[ i ] + '. Delta: ' + delta + '. Tolerance: ' + tol + '.' );
	}
	t.end();
});

tape( 'the function returns `+infinity` for very large `x`', function test( t ) {
	t.equal( exp2( 1100.0 ), PINF, 'equals +infinity' );
	t.equal( exp2( 1200.0 ), PINF, 'equals +infinity' );
	t.equal( exp2( 1300.0 ), PINF, 'equals +infinity' );
	t.end();
});

tape( 'the function returns `0.0` for negative large `x`', function test( t ) {
	t.equal( exp2( -1100.0 ), 0.0, 'equals 0' );
	t.equal( exp2( -1200.0 ), 0.0, 'equals 0' );
	t.equal( exp2( -1300.0 ), 0.0, 'equals 0' );
	t.end();
});

tape( 'the function returns `0.0` if provided `-infinity`', function test( t ) {
	t.equal( exp2( NINF ), 0.0, 'equals 0' );
	t.end();
});

tape( 'the function returns `+infinity` if provided `+infinity`', function test( t ) {
	t.equal( exp2( PINF ), PINF, 'equals +infinity' );
	t.end();
});

tape( 'the function returns `1` if provided `0`', function test( t ) {
	var v = exp2( 0.0 );
	t.equal( v, 1.0, 'equals 1' );
	t.end();
});

tape( 'the function returns `NaN` if provided `NaN`', function test( t ) {
	var val = exp2( NaN );
	t.equal( isnan( val ), true, 'equals NaN' );
	t.end();
});
