<?php

namespace Tests\Unit;

use App\Services\EducationGapCalculator;
use InvalidArgumentException;
use PHPUnit\Framework\TestCase;

class EducationGapCalculatorTest extends TestCase
{
    public function test_unknown_supply_is_not_zero_and_invalid_comparisons_are_not_gaps(): void
    {
        $calculator = new EducationGapCalculator;
        $this->assertSame(['state' => 'insufficient_data', 'people' => null], $calculator->observed(100, null, true, true));
        $this->assertSame(['state' => 'insufficient_data', 'people' => null], $calculator->observed(null, 10, true, true));
        $this->assertSame(['state' => 'incomparable', 'people' => null], $calculator->observed(100, 10, false, true));
        $this->assertSame(['state' => 'expired', 'people' => null], $calculator->observed(100, 10, true, false));
    }

    public function test_comparable_people_produce_only_an_unvalidated_nonnegative_gap(): void
    {
        $calculator = new EducationGapCalculator;
        $this->assertSame(['state' => 'observed_unvalidated', 'people' => 60], $calculator->observed(100, 40, true, true));
        $this->assertSame(0, $calculator->observed(10, 40, true, true)['people']);
        $this->assertSame(10, $calculator->observed(10, 0, true, true)['people']);
    }

    public function test_negative_quantities_are_rejected(): void
    {
        $this->expectException(InvalidArgumentException::class);
        (new EducationGapCalculator)->observed(10, -1, true, true);
    }
}