namespace LivingVillage.Desktop.Tests

open Microsoft.VisualStudio.TestTools.UnitTesting
open LivingVillage.Kernel
open LivingVillage.Desktop

/// P20 第一步回归：确定性生成器 + 尺寸参数化 + 30 spawn 核心可达 + 视口裁剪。
[<TestClass>]
type MapGenTests () =

    let tilesEqual (a: MapGen.Result) (b: MapGen.Result) (message: string) =
        if a.Tiles.Length <> b.Tiles.Length then
            Assert.Fail(sprintf "%s: tile count %d <> %d" message a.Tiles.Length b.Tiles.Length)
        for i in 0 .. a.Tiles.Length - 1 do
            if a.Tiles.[i] <> b.Tiles.[i] then
                Assert.Fail(sprintf "%s: tile %d = %d, expected %d" message i a.Tiles.[i] b.Tiles.[i])

    let checksum (map: MapGen.Result) : int64 =
        map.Tiles |> Array.mapi (fun i v -> int64 i * int64 (v + 1)) |> Array.sum

    [<TestMethod>]
    member _.SameSeedGeneratesByteIdenticalTerrain () =
        let a = MapGen.generateWithSize 64 48 (uint64 4242)
        let b = MapGen.generateWithSize 64 48 (uint64 4242)
        tilesEqual a b "64x48 same seed"
        Assert.AreEqual<uint64>(a.Seed, b.Seed)
        Assert.AreEqual<int64>(checksum a, checksum b)

        let large1 = MapGen.generateWithSize 256 192 (uint64 7)
        let large2 = MapGen.generateWithSize 256 192 (uint64 7)
        tilesEqual large1 large2 "256x192 same seed"
        Assert.AreEqual<int64>(checksum large1, checksum large2)

    [<TestMethod>]
    member _.DifferentSeedsProduceDifferentTerrain () =
        let a = MapGen.generateWithSize 256 192 (uint64 1)
        let b = MapGen.generateWithSize 256 192 (uint64 2)
        Assert.AreNotEqual<int64>(checksum a, checksum b, "different seeds must differ")

    [<TestMethod>]
    member _.LargeMapThirtySpawnsAllReachCore () =
        let map = MapGen.generateWithSize 256 192 (uint64 4242)
        Assert.AreEqual<int>(256, map.Width)
        Assert.AreEqual<int>(192, map.Height)
        Assert.AreEqual<int>(30, map.Spawns.Length)
        Assert.IsTrue(map.ReachabilityOk, "all 30 spawns must reach the core")
        Assert.IsTrue(map.ReachableTiles > 30, "core region must be walkable")
        for (x, y) in map.Spawns do
            Assert.AreNotEqual<int>(int MapGen.GroundTile.Water, map.Tiles.[y * map.Width + x], sprintf "spawn (%d,%d) must be walkable" x y)

    [<TestMethod>]
    member _.DefaultSizeMatchesLegacyBounds () =
        let map = MapGen.generate (MapGen.defaultParams (uint64 4242))
        Assert.AreEqual<int>(64, map.Width)
        Assert.AreEqual<int>(48, map.Height)
        Assert.AreEqual<int>(64 * 48, map.Tiles.Length)
        Assert.IsTrue(map.ReachabilityOk)
        Assert.AreEqual<int>(30, map.Spawns.Length)

    [<TestMethod>]
    member _.VisibleRangeCullsLargeMapToViewport () =
        let total = 256 * 192
        let x0, y0, x1, y1 = MapGen.visibleTileRange 256 192 1000 1000 1280 720
        let count = MapGen.visibleTileCount 256 192 1000 1000 1280 720
        Assert.AreEqual<int>((x1 - x0 + 1) * (y1 - y0 + 1), count)
        Assert.IsTrue(count < total, "viewport culling must draw strictly fewer tiles than the whole map")

        let ox0, oy0, ox1, oy1 = MapGen.visibleTileRange 256 192 0 0 1280 720
        Assert.AreEqual<int>(0, ox0)
        Assert.AreEqual<int>(0, oy0)
        Assert.AreEqual<int>(1280 / Sim.tilePixels + 1, ox1)
        Assert.AreEqual<int>(720 / Sim.tilePixels + 1, oy1)

    [<TestMethod>]
    member _.VisibleRangeClampsAtLegacyMapEdges () =
        let x0, y0, x1, y1 = MapGen.visibleTileRange 64 48 0 0 2048 1536
        Assert.AreEqual<int>(0, x0)
        Assert.AreEqual<int>(0, y0)
        Assert.AreEqual<int>(63, x1)
        Assert.AreEqual<int>(47, y1)
        Assert.AreEqual<int>(64 * 48, MapGen.visibleTileCount 64 48 0 0 2048 1536)