using System;
using CounterDrone.Core.Algorithms;
using Xunit;

namespace CounterDrone.Core.Tests
{
    public class DamageAssessmentTests
    {
        [Fact]
        public void SingleSegment_ThroughCenter_DiameterExposure()
        {
            // 无人机穿过球心：路径=2R
            float len = DamageAssessment.PathInSphere(0, 0, 0, 40, 0, 0, 20, 0, 0, 20);
            Assert.Equal(40, len, 1);
        }

        [Fact]
        public void TwoAdjacentClouds_FullCoverage()
        {
            // 20段×4m步长=80m，经过R=20的两朵相邻云（中心在20和60）
            float total = 0;
            float prevX = 0;
            for (int s = 0; s < 20; s++)
            {
                float nextX = prevX + 4;
                total += DamageAssessment.PathInSphere(prevX, 0, 0, nextX, 0, 0, 20, 0, 0, 20);
                total += DamageAssessment.PathInSphere(prevX, 0, 0, nextX, 0, 0, 60, 0, 0, 20);
                prevX = nextX;
            }
            // 每朵云直径40m，两朵共80m
            Assert.True(Math.Abs(total - 80f) < 1f, $"total={total:F2}, expected=80");
        }

        [Fact]
        public void NineCloudChain_CoverageMatchesTheory()
        {
            // 9朵云，间距40m，R=20m，无人机段长22.2m(55.6m/s×0.4s)
            float[] cloudX = { 9840, 9880, 9920, 9960, 10000, 10040, 10080, 10120, 10160 };
            float radius = 20;
            float total = 0;
            float prevX = 9800;
            for (int t = 0; t < 20; t++)
            {
                float nextX = prevX + 22.22f;
                foreach (float cx in cloudX)
                    total += DamageAssessment.PathInSphere(prevX, 0, 0, nextX, 0, 0, cx, 0, 0, radius);
                prevX = nextX;
            }
            // 理论: 9×40m = 360m
            Assert.True(Math.Abs(total - 360f) < 10f, $"total={total:F1}, expected=360");
        }
        [Fact]
        public void TwoCloudsWithGap_GapYieldsNoExposure()
        {
            // 两朵云中心在20和80, R=20: 云1=[0,40], 云2=[60,100], 间隙=[40,60]
            float total = 0;
            float prevX = 0;
            for (int s = 0; s < 25; s++) // 100m / 4m = 25段
            {
                float nextX = prevX + 4;
                total += DamageAssessment.PathInSphere(prevX, 0, 0, nextX, 0, 0, 20, 0, 0, 20);
                total += DamageAssessment.PathInSphere(prevX, 0, 0, nextX, 0, 0, 80, 0, 0, 20);
                prevX = nextX;
            }
            // 每朵云直径40m，两朵共80m，间隙无暴露
            Assert.True(Math.Abs(total - 80f) < 1f, $"total={total:F2}, expected=80");
        }
        [Fact]
        public void TwoPointsInDifferentClouds_GapExcluded()
        {
            // 两朵云R=10, 边间距50: 云1中心(0), 云2中心(70)
            // 两点: 云1内(0)→云2内(70)
            float len1 = DamageAssessment.PathInSphere(0, 0, 0, 70, 0, 0, 0, 0, 0, 10);
            float len2 = DamageAssessment.PathInSphere(0, 0, 0, 70, 0, 0, 70, 0, 0, 10);
            float total = len1 + len2;
            Assert.True(Math.Abs(total - 20f) < 1f, $"total={total:F2}, expected=20 (10+10)");
        }
    }
}