using System;
using NUnit.Framework;
using SVSim.BattleEngine.Rng;

namespace SVSim.BattleEngine.Tests
{
    [TestFixture]
    public class RngSeamTests
    {
        // RandomSourceBridge.Range must mirror the engine's exact roll arithmetic:
        // BattleManagerBase.StableRandom does `(int)Math.Floor((double)val * unit)`.
        [Test]
        public void Bridge_Range_mirrors_engine_floor_arithmetic()
        {
            Assert.That(RandomSourceBridge.Range(7, 0.0), Is.EqualTo(0));   // floor(7*0)   = 0
            Assert.That(RandomSourceBridge.Range(7, 0.999), Is.EqualTo(6)); // floor(6.993) = 6 (never == val)
            Assert.That(RandomSourceBridge.Range(3, 0.5), Is.EqualTo(1));   // floor(1.5)   = 1 (middle of 3)
            Assert.That(RandomSourceBridge.Range(1, 0.5), Is.EqualTo(0));   // floor(0.5)   = 0
        }

        // SeededRandomSource(seed) must reproduce the engine's own generators EXACTLY: BattleManagerBase
        // seeds both _stableRandom and _stableRandomOnlySelf as `new System.Random(RandomSeed)`
        // (BattleManagerBase.cs:721-722). NextUnit() == synced.NextDouble(); NextSelf(max) == self.Next(max).
        [Test]
        public void SeededSource_reproduces_two_System_Random_streams()
        {
            const int seed = 12345;
            var src = new SeededRandomSource(seed);

            var refSynced = new System.Random(seed); // mirrors _stableRandom
            var refSelf   = new System.Random(seed); // mirrors _stableRandomOnlySelf (separate stream)

            for (int i = 0; i < 8; i++)
                Assert.That(src.NextUnit(), Is.EqualTo(refSynced.NextDouble()), $"NextUnit drift at {i}");
            for (int i = 0; i < 8; i++)
                Assert.That(src.NextSelf(100), Is.EqualTo(refSelf.Next(100)), $"NextSelf drift at {i}");
        }
    }
}