// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
import math.big
import math.fractions

// (Old) results are verified using https://www.calculatorsoup.com/calculators/math/fractions.php
// Newer ones are contrived for corner cases or prepared by hand.
fn bi(s string) big.Integer {
    return big.integer_from_string(s) or { panic(err) }
}

fn test_4_by_8_f64_and_str() {
    f := fractions.fraction(4, 8)
    assert f.f64() == 0.5
    assert f.str() == '4/8'
}

fn test_10_by_5_f64_and_str() {
    f := fractions.fraction(10, 5)
    assert f.f64() == 2.0
    assert f.str() == '10/5'
}

fn test_9_by_3_f64_and_str() {
    f := fractions.fraction(9, 3)
    assert f.f64() == 3.0
    assert f.str() == '9/3'
}

fn test_4_by_minus_5_f64_and_str() {
    f := fractions.fraction(4, -5)
    assert f.f64() == -0.8
    assert f.str() == '-4/5'
}

fn test_minus_7_by_minus_92_str() {
    f := fractions.fraction(-7, -5)
    assert f.str() == '7/5'
}

fn test_4_by_8_plus_5_by_10() {
    f1 := fractions.fraction(4, 8)
    f2 := fractions.fraction(5, 10)
    sum := f1 + f2
    assert sum.f64() == 1.0
    assert sum.str() == '1/1'
    assert sum == fractions.fraction(1, 1)
}

fn test_5_by_5_plus_8_by_8() {
    f1 := fractions.fraction(5, 5)
    f2 := fractions.fraction(8, 8)
    sum := f1 + f2
    assert sum.f64() == 2.0
    assert sum.str() == '2/1'
    assert sum == fractions.fraction(2, 1)
}

fn test_9_by_3_plus_1_by_3() {
    f1 := fractions.fraction(9, 3)
    f2 := fractions.fraction(1, 3)
    sum := f1 + f2
    assert sum.str() == '10/3'
    assert sum == fractions.fraction(10, 3)
}

fn test_3_by_7_plus_1_by_4() {
    f1 := fractions.fraction(3, 7)
    f2 := fractions.fraction(1, 4)
    sum := f1 + f2
    assert sum.str() == '19/28'
    assert sum == fractions.fraction(19, 28)
}

fn test_36529_by_12409100000_plus_418754901_by_9174901000() {
    f1 := fractions.fraction(i64(36529), i64(12409100000))
    f2 := fractions.fraction(i64(418754901), i64(9174901000))
    sum := f1 + f2
    assert sum.str() == '5196706591957729/113852263999100000'
}

fn test_4_by_8_plus_minus_5_by_10() {
    f1 := fractions.fraction(4, 8)
    f2 := fractions.fraction(-5, 10)
    diff := f2 + f1
    assert diff.f64() == 0
    assert diff.str() == '0/1'
}

fn test_4_by_8_minus_5_by_10() {
    f1 := fractions.fraction(4, 8)
    f2 := fractions.fraction(5, 10)
    diff := f2 - f1
    assert diff.f64() == 0
    assert diff.str() == '0/1'
}

fn test_5_by_5_minus_8_by_8() {
    f1 := fractions.fraction(5, 5)
    f2 := fractions.fraction(8, 8)
    diff := f2 - f1
    assert diff.f64() == 0
    assert diff.str() == '0/1'
}

fn test_9_by_3_minus_1_by_3() {
    f1 := fractions.fraction(9, 3)
    f2 := fractions.fraction(1, 3)
    diff := f1 - f2
    assert diff.str() == '8/3'
}

fn test_3_by_7_minus_1_by_4() {
    f1 := fractions.fraction(3, 7)
    f2 := fractions.fraction(1, 4)
    diff := f1 - f2
    assert diff.str() == '5/28'
}

fn test_36529_by_12409100000_minus_418754901_by_9174901000() {
    f1 := fractions.fraction(i64(36529), i64(12409100000))
    f2 := fractions.fraction(i64(418754901), i64(9174901000))
    sum := f1 - f2
    assert sum.str() == '-5196036292040471/113852263999100000'
}

fn test_4_by_8_times_5_by_10() {
    f1 := fractions.fraction(4, 8)
    f2 := fractions.fraction(5, 10)
    product := f1 * f2
    assert product.f64() == 0.25
    assert product.str() == '1/4'
}

fn test_5_by_5_times_8_by_8() {
    f1 := fractions.fraction(5, 5)
    f2 := fractions.fraction(8, 8)
    product := f1 * f2
    assert product.f64() == 1.0
    assert product.str() == '1/1'
}

fn test_9_by_3_times_1_by_3() {
    f1 := fractions.fraction(9, 3)
    f2 := fractions.fraction(1, 3)
    product := f1 * f2
    assert product.f64() == 1.0
    assert product.str() == '1/1'
}

fn test_3_by_7_times_1_by_4() {
    f1 := fractions.fraction(3, 7)
    f2 := fractions.fraction(1, 4)
    product := f2 * f1
    assert product.f64() == (3.0 / 28.0)
    assert product.str() == '3/28'
}

fn test_4_by_8_over_5_by_10() {
    f1 := fractions.fraction(4, 8)
    f2 := fractions.fraction(5, 10)
    q := f1 / f2
    assert q.f64() == 1.0
    assert q.str() == '1/1'
}

fn test_5_by_5_over_8_by_8() {
    f1 := fractions.fraction(5, 5)
    f2 := fractions.fraction(8, 8)
    q := f1 / f2
    assert q.f64() == 1.0
    assert q.str() == '1/1'
}

fn test_9_by_3_over_1_by_3() {
    f1 := fractions.fraction(9, 3)
    f2 := fractions.fraction(1, 3)
    q := f1 / f2
    assert q.f64() == 9.0
    assert q.str() == '9/1'
}

fn test_3_by_7_over_1_by_4() {
    f1 := fractions.fraction(3, 7)
    f2 := fractions.fraction(1, 4)
    q := f1 / f2
    assert q.str() == '12/7'
}

fn test_reciprocal_4_by_8() {
    f := fractions.fraction(4, 8)
    assert f.reciprocal().str() == '8/4'
}

fn test_reciprocal_5_by_10() {
    f := fractions.fraction(5, 10)
    assert f.reciprocal().str() == '10/5'
}

fn test_reciprocal_5_by_5() {
    f := fractions.fraction(5, 5)
    assert f.reciprocal().str() == '5/5'
}

fn test_reciprocal_8_by_8() {
    f := fractions.fraction(8, 8)
    assert f.reciprocal().str() == '8/8'
}

fn test_reciprocal_9_by_3() {
    f := fractions.fraction(9, 3)
    assert f.reciprocal().str() == '3/9'
}

fn test_reciprocal_1_by_3() {
    f := fractions.fraction(1, 3)
    assert f.reciprocal().str() == '3/1'
}

fn test_reciprocal_7_by_3() {
    f := fractions.fraction(7, 3)
    assert f.reciprocal().str() == '3/7'
}

fn test_reciprocal_1_by_4() {
    f := fractions.fraction(1, 4)
    assert f.reciprocal().str() == '4/1'
}

fn test_4_by_8_equals_5_by_10() {
    f1 := fractions.fraction(4, 8)
    f2 := fractions.fraction(5, 10)
    assert f1 == f2
}

fn test_1_by_2_does_not_equal_3_by_4() {
    f1 := fractions.fraction(1, 2)
    f2 := fractions.fraction(3, 4)
    assert f1 != f2
}

fn test_reduce_3_by_9() {
    f := fractions.fraction(3, 9)
    assert f.reduce() == fractions.fraction(1, 3)
}

fn test_1_by_3_less_than_2_by_4() {
    f1 := fractions.fraction(1, 3)
    f2 := fractions.fraction(2, 4)
    assert f1 < f2
    assert f1 <= f2
}

fn test_2_by_3_greater_than_2_by_4() {
    f1 := fractions.fraction(2, 3)
    f2 := fractions.fraction(2, 4)
    assert f1 > f2
    assert f1 >= f2
}

fn test_5_by_7_not_less_than_2_by_4() {
    f1 := fractions.fraction(5, 7)
    f2 := fractions.fraction(2, 4)
    assert !(f1 < f2)
    assert !(f1 <= f2)
}

fn test_49_by_75_not_greater_than_2_by_3() {
    f1 := fractions.fraction(49, 75)
    f2 := fractions.fraction(2, 3)
    assert !(f1 > f2)
    assert !(f1 >= f2)
}

fn test_i32_rational_addition() {
    f1 := fractions.rational(i32(4), i32(8))
    f2 := fractions.rational(i32(5), i32(10))
    sum := f1 + f2
    assert sum.str() == '1/1'
    assert sum == fractions.rational(i32(1), i32(1))
}

fn test_big_fraction_normalizes_and_reduces() {
    f := fractions.big_fraction(bi('-14'), bi('-21'))
    assert f.str() == '14/21'
    assert f.reciprocal().str() == '21/14'
    assert f.reduce().str() == '2/3'
}

fn test_big_fraction_addition() {
    f1 := fractions.big_fraction(bi('100000000000000000000000000000000000000'), bi('3'))
    f2 := fractions.big_fraction(bi('5'), bi('6'))
    sum := f1 + f2
    assert sum.str() == '200000000000000000000000000000000000005/6'
    assert sum > f1
}

fn test_big_fraction_exact_comparison_beyond_i64() {
    huge := bi('9223372036854775808123456789')
    f1 := fractions.big_fraction(huge + big.one_int, huge)
    f2 := fractions.big_fraction(huge, huge + big.one_int)
    assert f1 > f2
    assert f1 != f2
}