using AfterHours.Economy;
using NUnit.Framework;

namespace AfterHours.Tests
{
    public sealed class PricingServiceTests
    {
        [Test]
        public void AtOrBelowRecommendedPrice_EveryoneBuys()
        {
            Assert.AreEqual(1f, PricingService.PurchaseProbability(10f, 12f), 0.0001f);
            Assert.AreEqual(1f, PricingService.PurchaseProbability(12f, 12f), 0.0001f);
        }

        [Test]
        public void AtRejectionThreshold_NobodyBuys()
        {
            float price = 12f * PricingService.RejectionThreshold;
            Assert.AreEqual(0f, PricingService.PurchaseProbability(price, 12f), 0.0001f);
        }

        [Test]
        public void DemandFallsMonotonically()
        {
            float previous = 1f;
            for (float price = 12f; price < 21f; price += 0.5f)
            {
                float current = PricingService.PurchaseProbability(price, 12f);
                Assert.LessOrEqual(current, previous);
                previous = current;
            }
        }

        [Test]
        public void SmallMarkupHurtsLessThanLargeOne()
        {
            float small = 1f - PricingService.PurchaseProbability(13f, 12f);
            float large = 1f - PricingService.PurchaseProbability(19f, 12f);
            Assert.Less(small, large * 0.5f);
        }

        [Test]
        public void ExpectedProfitPeaksAboveWholesale()
        {
            float best = 0f, bestPrice = 0f;
            for (float price = 5f; price < 21f; price += 0.25f)
            {
                float profit = PricingService.ExpectedProfitPerUnit(price, 12f, 5f);
                if (profit > best) { best = profit; bestPrice = price; }
            }
            Assert.Greater(bestPrice, 5f);
            Assert.Greater(best, 0f);
        }
    }
}