using System;
using IvfTl.AutoFocus.Layout;
using Xunit;

namespace IvfTl.AutoFocus.Tests
{
    /// <summary>
    /// M2-02 PhotoLayerCalculator 单元测试(重建被删单测)。
    /// 覆盖 §2.4 层位置公式 + §2.5 就近优先/钳位/异常/边界。
    /// 所有期望值均按 PhotoLayerCalculator.cs 当前公式现算,并在注释里写出推导:
    ///   start = focusZ - LayerDown*spacing;  第 i 层 = start + i*spacing。
    /// </summary>
    public class PhotoLayerCalculatorTests
    {
        // 小工具:构造一个已解析好的有效配置。
        private static FocusLayerConfig Cfg(int spacing, int count, int down) =>
            new FocusLayerConfig
            {
                LayerSpacingPulse = spacing,
                LayerCount = count,
                LayerDown = down,
            };

        // 小工具:构造原始就近优先入参。
        private static FocusLayerRawConfig Raw(
            int? wellSpacing = null, int? deviceSpacing = null,
            int? wellCount = null, int? deviceCount = null,
            int? wellDown = null, int? deviceDown = null,
            string tlSn = "TL-TEST", int houseSn = 4, int wellSn = 1) =>
            new FocusLayerRawConfig
            {
                TlSn = tlSn,
                HouseSn = houseSn,
                WellSn = wellSn,
                WellSpacingPulse = wellSpacing,
                DeviceSpacingPulse = deviceSpacing,
                WellLayerCount = wellCount,
                DeviceLayerCount = deviceCount,
                WellMoveDownLayer = wellDown,
                DeviceLayerDown = deviceDown,
            };

        // ===== ① 层公式:期望值如 [88178,88306,88434,88562,88690] =====
        // 推导(按代码公式现算):
        //   focusZ=88434, down=2, spacing=128, count=5
        //   start = 88434 - 2*128 = 88434 - 256 = 88178
        //   层: 88178, 88178+128=88306, +128=88434, +128=88562, +128=88690
        //   (清晰层 FocusZ=88434 恰落在第 down=2 层 — 符合设计语义)
        [Fact]
        public void 层公式_计划样例_应得88178到88690()
        {
            var cfg = Cfg(spacing: 128, count: 5, down: 2);
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(88434, cfg, pulseMax: 0);

            Assert.Equal(new[] { 88178, 88306, 88434, 88562, 88690 }, pos);
            // 清晰层(第 down 层)必须 == focusZ
            Assert.Equal(88434, pos[2]);
        }

        // 通用公式校验:任意取值,逐层与 start + i*spacing 对齐。
        [Theory]
        [InlineData(50000, 200, 7, 3)]   // start=50000-3*200=49400
        [InlineData(0, 10, 4, 0)]        // down=0 → start=focusZ=0
        [InlineData(-100, 50, 3, 1)]     // 负 focusZ(纯算术,不钳位)→ start=-150
        public void 层公式_逐层等于起点加i乘间距(int focusZ, int spacing, int count, int down)
        {
            var cfg = Cfg(spacing, count, down);
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(focusZ, cfg, pulseMax: 0);

            int start = focusZ - down * spacing;
            Assert.Equal(count, pos.Length);
            for (int i = 0; i < count; i++)
                Assert.Equal(start + i * spacing, pos[i]);
            // 第 down 层永远等于 focusZ(锚点语义)
            if (down < count) Assert.Equal(focusZ, pos[down]);
        }

        // ===== ② 层间距双空(well 级和设备级都没配)→ FocusConfigMissingException =====
        [Fact]
        public void 间距双空_应抛FocusConfigMissingException_默认消息为层间距未配置()
        {
            var raw = Raw(wellSpacing: null, deviceSpacing: null,
                          deviceCount: 5, deviceDown: 2, tlSn: "TL-9", houseSn: 4, wellSn: 1);

            var ex = Assert.Throws<FocusConfigMissingException>(() => PhotoLayerCalculator.Resolve(raw));
            Assert.Equal("TL-9", ex.TlSn);
            Assert.Equal(4, ex.HouseSn);
            Assert.Equal(1, ex.WellSn);
            Assert.Contains("层间距未配置", ex.Message);   // 默认消息
        }

        // 层数双空 / 下移双空 也各自抛(带定制消息),验证不会兜底魔法数。
        [Fact]
        public void 层数双空_应抛异常且消息为层数未配置()
        {
            var raw = Raw(deviceSpacing: 128, wellCount: null, deviceCount: null, deviceDown: 2);
            var ex = Assert.Throws<FocusConfigMissingException>(() => PhotoLayerCalculator.Resolve(raw));
            Assert.Contains("层数未配置", ex.Message);
        }

        [Fact]
        public void 下移双空_应抛异常且消息为下移层数未配置()
        {
            var raw = Raw(deviceSpacing: 128, deviceCount: 5, wellDown: null, deviceDown: null);
            var ex = Assert.Throws<FocusConfigMissingException>(() => PhotoLayerCalculator.Resolve(raw));
            Assert.Contains("下移层数未配置", ex.Message);
        }

        // ===== ③ 就近优先:well 级覆盖设备级 =====
        [Fact]
        public void 就近优先_well级间距覆盖设备级()
        {
            var raw = Raw(wellSpacing: 200, deviceSpacing: 128, deviceCount: 5, deviceDown: 2);
            var cfg = PhotoLayerCalculator.Resolve(raw);
            Assert.Equal(200, cfg.LayerSpacingPulse);   // well 赢
        }

        [Fact]
        public void 就近优先_well级层数与下移覆盖设备级()
        {
            var raw = Raw(deviceSpacing: 128,
                          wellCount: 9, deviceCount: 5,
                          wellDown: 3, deviceDown: 2);
            var cfg = PhotoLayerCalculator.Resolve(raw);
            Assert.Equal(9, cfg.LayerCount);   // well 赢
            Assert.Equal(3, cfg.LayerDown);    // well 赢
        }

        [Fact]
        public void 就近优先_well级为空时回退设备级()
        {
            var raw = Raw(wellSpacing: null, deviceSpacing: 128,
                          wellCount: null, deviceCount: 5,
                          wellDown: null, deviceDown: 2);
            var cfg = PhotoLayerCalculator.Resolve(raw);
            Assert.Equal(128, cfg.LayerSpacingPulse);
            Assert.Equal(5, cfg.LayerCount);
            Assert.Equal(2, cfg.LayerDown);
        }

        // well 级下移 = 0 必须被当成"有效覆盖"(0 是合法 down,不能被当 null)。
        [Fact]
        public void 就近优先_well级下移为0应视为有效覆盖而非回退()
        {
            var raw = Raw(deviceSpacing: 128, deviceCount: 5,
                          wellDown: 0, deviceDown: 2);
            var cfg = PhotoLayerCalculator.Resolve(raw);
            Assert.Equal(0, cfg.LayerDown);   // 不应回退成设备级 2
        }

        // ===== ④ 下移层数 down 覆盖 — 改变起点位置 =====
        // down 越大,起点越往下(Z 越小),整组层整体下移。
        [Theory]
        [InlineData(0)]   // start = focusZ
        [InlineData(2)]   // start = focusZ - 2*spacing
        [InlineData(4)]   // start = focusZ - 4*spacing (= 末层之外,清晰层落最末)
        public void 下移层数_控制起点为focusZ减down乘间距(int down)
        {
            int focusZ = 90000, spacing = 100, count = 5;
            var cfg = Cfg(spacing, count, down);
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(focusZ, cfg, 0);
            Assert.Equal(focusZ - down * spacing, pos[0]);   // 第0层=起点
        }

        // ===== ⑤ pulseMax 钳位 =====
        // 起点为负 → 第0层钳到 0;末层超上限 → 钳到 pulseMax。
        [Fact]
        public void 钳位_下越界钳到0_上越界钳到pulseMax()
        {
            // focusZ=150, down=2, spacing=100 → start=150-200=-50(负,会被钳)
            // 原始层: -50, 50, 150, 250, 350 ; pulseMax=300
            // 钳后:    0,  50, 150, 250, 300
            var cfg = Cfg(spacing: 100, count: 5, down: 2);
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(150, cfg, pulseMax: 300);
            Assert.Equal(new[] { 0, 50, 150, 250, 300 }, pos);
        }

        [Fact]
        public void 钳位_pulseMax为0时不钳位允许负值()
        {
            var cfg = Cfg(spacing: 100, count: 3, down: 2);
            // start = 150 - 200 = -50 → 不钳位
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(150, cfg, pulseMax: 0);
            Assert.Equal(new[] { -50, 50, 150 }, pos);
        }

        [Fact]
        public void 钳位_全部在范围内时不改变()
        {
            var cfg = Cfg(spacing: 100, count: 3, down: 1);
            // start=88434-100=88334 → 88334,88434,88534 ; pulseMax=100000 不触发
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(88434, cfg, pulseMax: 100000);
            Assert.Equal(new[] { 88334, 88434, 88534 }, pos);
        }

        // ===== ⑥ 边界 / 防御性 =====
        [Fact]
        public void 边界_单层count1_只返回起点一层()
        {
            var cfg = Cfg(spacing: 128, count: 1, down: 0);
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(5000, cfg, 0);
            Assert.Single(pos);
            Assert.Equal(5000, pos[0]);
        }

        [Fact]
        public void 边界_LayerCount为0应抛ArgumentOutOfRange()
        {
            var cfg = Cfg(spacing: 128, count: 0, down: 0);
            Assert.Throws<ArgumentOutOfRangeException>(
                () => PhotoLayerCalculator.ComputeLayerPositions(5000, cfg, 0));
        }

        [Fact]
        public void 边界_负LayerCount应抛ArgumentOutOfRange()
        {
            var cfg = Cfg(spacing: 128, count: -3, down: 0);
            Assert.Throws<ArgumentOutOfRangeException>(
                () => PhotoLayerCalculator.ComputeLayerPositions(5000, cfg, 0));
        }

        [Fact]
        public void 边界_cfg为null应抛ArgumentNull()
        {
            Assert.Throws<ArgumentNullException>(
                () => PhotoLayerCalculator.ComputeLayerPositions(5000, null, 0));
        }

        [Fact]
        public void 边界_Resolve入参null应抛ArgumentNull()
        {
            Assert.Throws<ArgumentNullException>(() => PhotoLayerCalculator.Resolve(null));
        }

        // 可疑边界探针:down >= count(清晰层落在拍摄范围之外)。
        // 注:down<count 校验现已下沉到 Resolve(配置非法时抛 FocusConfigMissingException)；
        // ComputeLayerPositions 作为纯公式仍不校验 down<count(此处直接喂 cfg 绕过 Resolve),
        // 这里断言"公式计算不抛、但第 down 层不在返回数组里",把绕过解析时的隐患钉成事实。
        [Fact]
        public void 可疑边界_down等于count时计算不抛但清晰层不在拍摄层内()
        {
            // down=5, count=5 → start=focusZ-5*spacing,层 index 0..4,
            // 清晰层(第5层)= focusZ 本身,却不在返回的 5 层(0..4)里。
            int focusZ = 90000, spacing = 100, count = 5, down = 5;
            var cfg = Cfg(spacing, count, down);
            int[] pos = PhotoLayerCalculator.ComputeLayerPositions(focusZ, cfg, 0);
            Assert.Equal(count, pos.Length);
            // 末层 = start + (count-1)*spacing = (focusZ-500)+400 = focusZ-100 < focusZ
            Assert.Equal(focusZ - 100, pos[count - 1]);
            Assert.DoesNotContain(focusZ, pos);   // 清晰层落在拍摄层之外 — 设计隐患佐证
        }
    }
}