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

    let waterRunsInColumn (map: MapGen.Result) (x: int) : int list =
        let runs = ResizeArray<int>()
        let mutable run = 0
        for y in 0 .. map.Height - 1 do
            if map.Tiles.[y * map.Width + x] = int MapGen.GroundTile.Water then
                run <- run + 1
            elif run > 0 then
                runs.Add run
                run <- 0
        if run > 0 then runs.Add run
        List.ofSeq runs

    let waterNeighbourCount (map: MapGen.Result) (x: int) (y: int) : int =
        [ (1, 0); (-1, 0); (0, 1); (0, -1) ]
        |> List.sumBy (fun (dx, dy) ->
            let nx, ny = x + dx, y + dy
            if nx >= 0 && nx < map.Width && ny >= 0 && ny < map.Height && map.Tiles.[ny * map.Width + nx] = int MapGen.GroundTile.Water then 1 else 0)

    /// P30：把民居按「足迹邻近（两轴间隙 <=2 格）」聚成组团，返回各组规模。
    let houseGroups (houses: MapGen.Building list) : int list =
        let arr = houses |> List.sortBy (fun b -> b.Top, b.Left) |> Array.ofList
        let n = arr.Length
        let parent = Array.init n id
        let rec find i = if parent.[i] = i then i else (parent.[i] <- find parent.[i]; parent.[i])
        let union a b =
            let ra = find a
            let rb = find b
            if ra <> rb then parent.[ra] <- rb
        let near (a: MapGen.Building) (b: MapGen.Building) =
            let xGap = max (a.Left - (b.Left + b.Width - 1)) (b.Left - (a.Left + a.Width - 1))
            let yGap = max (a.Top - (b.Top + b.Height - 1)) (b.Top - (a.Top + a.Height - 1))
            xGap <= 2 && yGap <= 2
        for i in 0 .. n - 1 do
            for j in i + 1 .. n - 1 do
                if near arr.[i] arr.[j] then union i j
        [ for i in 0 .. n - 1 -> find i ] |> List.groupBy id |> List.map (fun (_, group) -> group.Length)

    [<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)

    // ---- P20 第二步：河道连续性 + 桥/路/建筑 + 交通可达 ----

    [<TestMethod>]
    member _.RiversAreContinuousWithoutGapsOrIsolatedTiles () =
        let map = MapGen.generateWithSize 256 192 (uint64 4242)
        Assert.IsTrue(map.Rivers.Length >= 1, "at least one river band")
        let minWidth = map.Rivers |> List.map (fun river -> river.Width) |> List.min
        Assert.IsTrue(minWidth >= 3, "river width lower bound")
        for x in 1 .. map.Width - 2 do
            let runs = waterRunsInColumn map x
            if runs.Length <> map.Rivers.Length then
                Assert.Fail(sprintf "column %d must hold exactly %d contiguous runs, saw %d" x map.Rivers.Length runs.Length)
            for run in runs do
                Assert.IsTrue(run >= minWidth, sprintf "column %d has a run of %d < min width %d" x run minWidth)
        for y in 0 .. map.Height - 1 do
            for x in 0 .. map.Width - 1 do
                if map.Tiles.[y * map.Width + x] = int MapGen.GroundTile.Water then
                    Assert.IsTrue(waterNeighbourCount map x y >= 2, sprintf "water tile (%d,%d) is isolated" x y)

    [<TestMethod>]
    member _.StructuresContainBridgesRoadsAndBuildingsAlongRivers () =
        let map = MapGen.generateWithSize 256 192 (uint64 4242)
        Assert.IsTrue(map.Bridges.Length >= map.Rivers.Length, "at least one bridge per river")
        Assert.IsTrue(map.Paths.Length > 0, "stone road network exists")
        Assert.IsTrue(map.Buildings.Length >= 4, "at least four riverside building blocks")
        for building in map.Buildings do
            Assert.IsTrue(MapGen.isWalkable map building.DoorX building.DoorY, sprintf "door (%d,%d) must be walkable" building.DoorX building.DoorY)
            let nearWater =
                [ for y in max 0 (building.Top - 12) .. min (map.Height - 1) (building.Top + building.Height + 12) do
                    for x in max 0 (building.Left - 12) .. min (map.Width - 1) (building.Left + building.Width + 12) ->
                        map.Tiles.[y * map.Width + x] = int MapGen.GroundTile.Water ]
                |> List.exists id
            Assert.IsTrue(nearWater, "building block must sit along a river")

    [<TestMethod>]
    member _.BridgesKeepBothRiverBanksReachableFromSpawns () =
        let map = MapGen.generateWithSize 256 192 (uint64 4242)
        let startX, startY = map.Spawns.Head
        let visited = MapGen.floodFill map startX startY
        for (x, y) in map.Spawns do
            Assert.IsTrue(visited.[y * map.Width + x], sprintf "spawn (%d,%d) unreachable" x y)
        for building in map.Buildings do
            Assert.IsTrue(visited.[building.DoorY * map.Width + building.DoorX], "building door unreachable via bridge/road")
        for (x, y) in map.Bridges do
            Assert.IsTrue(visited.[y * map.Width + x], sprintf "bridge tile (%d,%d) unreachable" x y)
        Assert.IsTrue(map.BridgeCrossingsOk, "each bridge must connect both river banks")

    [<TestMethod>]
    member _.StructuresAreDeterministicAcrossRuns () =
        let a = MapGen.generateWithSize 256 192 (uint64 4242)
        let b = MapGen.generateWithSize 256 192 (uint64 4242)
        Assert.IsTrue(a.Rivers = b.Rivers)
        Assert.IsTrue(a.Bridges = b.Bridges)
        Assert.IsTrue(a.Paths = b.Paths)
        Assert.IsTrue(a.Buildings = b.Buildings)
        let c = MapGen.generateWithSize 256 192 (uint64 7)
        Assert.IsTrue(a.Buildings <> c.Buildings || a.Bridges <> c.Bridges, "different seeds must relocate structures")

    // ---- P20 第三步：序列化确定性 + 默认可玩世界接入生成器站位 ----

    [<TestMethod>]
    member _.SameSeedSerializationIsByteIdentical () =
        let a = MapGen.generateWithSize 256 192 (uint64 4242)
        let b = MapGen.generateWithSize 256 192 (uint64 4242)
        Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)
        let c = MapGen.generateWithSize 256 192 (uint64 7)
        Assert.AreNotEqual<string>(MapGen.serialize a, MapGen.serialize c)

    [<TestMethod>]
    member _.MapWorldPlacementUsesReachableCoreSpawns () =
        let map = MapGen.generateWithSize 256 192 (uint64 4242)
        let world = WorldBootstrap.initialWorldInMap false 42UL Sim.npcCount map
        Assert.AreEqual<int>(Sim.npcCount, world.Npcs.Length)
        let visited = MapGen.floodFill map (fst map.Spawns.Head) (snd map.Spawns.Head)
        for npc in world.Npcs do
            let tx = int npc.Pos.X / Sim.tilePixels
            let ty = int npc.Pos.Y / Sim.tilePixels
            Assert.IsTrue(visited.[ty * map.Width + tx], sprintf "npc tile (%d,%d) must be reachable from the core" tx ty)
        let ax = int world.Avatar.Pos.X / Sim.tilePixels
        let ay = int world.Avatar.Pos.Y / Sim.tilePixels
        Assert.IsTrue(visited.[ay * map.Width + ax], "avatar spawn must sit in the reachable core")
        Assert.IsTrue(ax >= map.Core.MinX && ax <= map.Core.MaxX && ay >= map.Core.MinY && ay <= map.Core.MaxY, "avatar spawn must sit in the core")

    // ---- P23：512x384 扩程（尺寸自适应参数 + 连续性/可达性 + 默认图锁定） ----

    [<TestMethod>]
    member _.SizeAdaptiveParamsScaleRiversWithHeight () =
        Assert.AreEqual<int>(2, (MapGen.paramsForSize 64 48 (uint64 1)).RiverCount)
        Assert.AreEqual<int>(2, (MapGen.paramsForSize 256 192 (uint64 1)).RiverCount)
        Assert.AreEqual<int>(4, (MapGen.paramsForSize 512 384 (uint64 1)).RiverCount)

    [<TestMethod>]
    member _.HugeMap512SameSeedIsByteIdentical () =
        let a = MapGen.generateWithSize 512 384 (uint64 4242)
        let b = MapGen.generateWithSize 512 384 (uint64 4242)
        tilesEqual a b "512x384 same seed"
        Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)
        Assert.AreEqual<int>(512, a.Width)
        Assert.AreEqual<int>(384, a.Height)
        Assert.AreEqual<int>(30, a.Spawns.Length)
        Assert.IsTrue(a.ReachabilityOk, "512x384 must keep the core reachable")
        Assert.IsTrue(a.BridgeCrossingsOk, "512x384 bridges must connect both banks")

    [<TestMethod>]
    member _.HugeMap512DifferentSeedsDiverge () =
        let a = MapGen.generateWithSize 512 384 (uint64 4242)
        let b = MapGen.generateWithSize 512 384 (uint64 7)
        Assert.AreNotEqual<int64>(checksum a, checksum b, "different seeds must differ at 512x384")
        Assert.AreNotEqual<string>(MapGen.serialize a, MapGen.serialize b)

    [<TestMethod>]
    member _.HugeMap512RiversStayContinuousAcrossAllBands () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.AreEqual<int>(4, map.Rivers.Length)
        let minWidth = map.Rivers |> List.map (fun river -> river.Width) |> List.min
        Assert.IsTrue(minWidth >= 3, "river width lower bound holds at 512x384")
        for x in 1 .. map.Width - 2 do
            let runs = waterRunsInColumn map x
            if runs.Length <> map.Rivers.Length then
                Assert.Fail(sprintf "column %d must hold exactly %d contiguous runs, saw %d" x map.Rivers.Length runs.Length)
            for run in runs do
                Assert.IsTrue(run >= minWidth, sprintf "column %d has a run of %d < min width %d" x run minWidth)
        for y in 0 .. map.Height - 1 do
            for x in 0 .. map.Width - 1 do
                if map.Tiles.[y * map.Width + x] = int MapGen.GroundTile.Water then
                    Assert.IsTrue(waterNeighbourCount map x y >= 2, sprintf "water tile (%d,%d) is isolated" x y)

    [<TestMethod>]
    member _.HugeMap512ThirtySpawnsReachCoreAndBothBanks () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let startX, startY = map.Spawns.Head
        let visited = MapGen.floodFill map startX startY
        for (x, y) in map.Spawns do
            Assert.IsTrue(visited.[y * map.Width + x], sprintf "spawn (%d,%d) unreachable at 512x384" x y)
        for building in map.Buildings do
            Assert.IsTrue(visited.[building.DoorY * map.Width + building.DoorX], "building door unreachable at 512x384")
        for (x, y) in map.Bridges do
            Assert.IsTrue(visited.[y * map.Width + x], sprintf "bridge tile (%d,%d) unreachable at 512x384" x y)
        Assert.IsTrue(map.Buildings.Length >= map.Rivers.Length, "riverside building per band at 512x384")

    // ---- P24：512x384 沿河民居加密（默认图不受影响） ----

    [<TestMethod>]
    member _.ExtraHouseDensityOnlyEnabledForLargeMaps () =
        Assert.AreEqual<int>(0, (MapGen.paramsForSize 64 48 (uint64 1)).ExtraRiversideHouses)
        Assert.AreEqual<int>(0, (MapGen.paramsForSize 256 192 (uint64 1)).ExtraRiversideHouses)
        Assert.IsTrue((MapGen.paramsForSize 512 384 (uint64 1)).ExtraRiversideHouses > 0)

    [<TestMethod>]
    member _.LargeMapHasAtLeastTwelveHousesWithReachableDoors () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.IsTrue(map.Buildings.Length >= 12, sprintf "512x384 must place >=12 houses, saw %d" map.Buildings.Length)
        let startX, startY = map.Spawns.Head
        let visited = MapGen.floodFill map startX startY
        for building in map.Buildings do
            Assert.IsTrue(MapGen.isWalkable map building.DoorX building.DoorY, sprintf "door (%d,%d) must be walkable" building.DoorX building.DoorY)
            Assert.IsTrue(visited.[building.DoorY * map.Width + building.DoorX], sprintf "door (%d,%d) unreachable" building.DoorX building.DoorY)
        Assert.IsTrue(map.ReachabilityOk, "512x384 reachability must hold with extra houses")

    [<TestMethod>]
    member _.LargeMapHousePlacementIsDeterministic () =
        let a = MapGen.generateWithSize 512 384 (uint64 4242)
        let b = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.AreEqual<int>(a.Buildings.Length, b.Buildings.Length)
        Assert.IsTrue(a.Buildings = b.Buildings)
        Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)

    /// P28/P30：512 沿河民居增密并出现 2/3/4 三档宽度（附属小筑/民居/大宅），形成聚落层次；
    /// 默认图仍为 0，不消耗 RNG，故 64/256 checksum 锁定不变。
    [<TestMethod>]
    member _.LargeMapHouseDensityHierarchyOnlyGrowsLargeMaps () =
        Assert.AreEqual<int>(30, (MapGen.paramsForSize 512 384 (uint64 1)).ExtraRiversideHouses)
        Assert.AreEqual<int>(0, (MapGen.paramsForSize 64 48 (uint64 1)).ExtraRiversideHouses)
        Assert.AreEqual<int>(0, (MapGen.paramsForSize 256 192 (uint64 1)).ExtraRiversideHouses)
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.IsTrue(map.Buildings.Length >= 28, sprintf "P30 512 must place >=28 houses, saw %d" map.Buildings.Length)
        let widths = map.Buildings |> List.map (fun b -> b.Width) |> Set.ofList
        Assert.IsTrue(widths.Contains 2, "outbuilding width 2 must appear")
        Assert.IsTrue(widths.Contains 3, "house width 3 must appear")
        Assert.IsTrue(widths.Contains 4, "hall width 4 must appear")
        Assert.IsTrue(map.Buildings.Length + map.Farmhouses.Length >= 32, "total houses (clusters + farmsteads) must be >=32")

    [<TestMethod>]
    member _.DefaultSizeHouseCountUnchanged () =
        Assert.AreEqual<int>(4, (MapGen.generateWithSize 64 48 (uint64 4242)).Buildings.Length)
        Assert.AreEqual<int>(4, (MapGen.generateWithSize 256 192 (uint64 4242)).Buildings.Length)

    // ---- P29：512 聚落组团（group seeding 仅大图启用；行内成组、组间留档） ----

    [<TestMethod>]
    member _.ClusterSeedOnlyEnabledForLargeMaps () =
        Assert.AreEqual<uint64>(0UL, (MapGen.paramsForSize 64 48 (uint64 4242)).ClusterSeed)
        Assert.AreEqual<uint64>(0UL, (MapGen.paramsForSize 256 192 (uint64 4242)).ClusterSeed)
        Assert.AreNotEqual<uint64>(0UL, (MapGen.paramsForSize 512 384 (uint64 4242)).ClusterSeed)
        Assert.AreEqual<uint64>(0UL, (MapGen.defaultParams (uint64 4242)).ClusterSeed)

    [<TestMethod>]
    member _.LargeMapHousesFormClusteredRowsWithControlledGaps () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let rowClusters (row: MapGen.Building list) =
            let sorted = row |> List.sortBy (fun b -> b.Left)
            let clusters = ResizeArray<MapGen.Building list>()
            let mutable current: MapGen.Building list = []
            let mutable previousEnd = System.Int32.MinValue
            for building in sorted do
                if current <> [] && building.Left - previousEnd <= 2 then
                    current <- building :: current
                else
                    if current <> [] then clusters.Add(List.rev current)
                    current <- [ building ]
                previousEnd <- building.Left + building.Width - 1
            if current <> [] then clusters.Add(List.rev current)
            List.ofSeq clusters
        let clusteredRows = map.Buildings |> List.groupBy (fun b -> b.Top) |> List.map (snd >> rowClusters)
        let clusterSizes = clusteredRows |> List.collect (List.map List.length)
        Assert.IsTrue(clusterSizes |> List.exists (fun n -> n >= 3), "at least one row-sized house cluster")
        // 行内出现多个簇 => 组间留有可控空档，而不是一整排等距。
        let rowCount = map.Buildings |> List.map (fun b -> b.Top) |> List.distinct |> List.length
        Assert.IsTrue(clusterSizes.Length > rowCount, "rows must split into separated groups")
        for clustersInRow in clusteredRows do
            match clustersInRow with
            | first :: rest ->
                let mutable previous = first
                for cluster in rest do
                    let prevEnd = previous |> List.map (fun b -> b.Left + b.Width - 1) |> List.max
                    let nextStart = cluster |> List.map (fun b -> b.Left) |> List.min
                    Assert.IsTrue(nextStart - prevEnd >= 3, "groups must be separated by a controlled gap")
                    previous <- cluster
            | [] -> ()

    /// 组团参数下，512 world 同 seed 两次生成逐字节一致（checksum 且序列化 diff 为空）。
    [<TestMethod>]
    member _.LargeMapClusterLayoutChecksumIsEmptyDiffAcrossRuns () =
        let a = MapGen.generateWithSize 512 384 (uint64 4242)
        let b = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.IsTrue(a.Tiles = b.Tiles, "tiles must be byte-identical across runs")
        Assert.AreEqual<int64>(checksum a, checksum b)
        Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)
        Assert.IsTrue(a.Buildings = b.Buildings)
        Assert.IsTrue(a.Decorations = b.Decorations)

    /// P29 垂柳成丛：岸边出现相邻 2-3 株的柳丛，且不再是均匀逐格散布。
    [<TestMethod>]
    member _.LargeMapWillowsGrowInGroves () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let willows = map.Decorations |> List.filter (fun d -> d.Kind = MapGen.Willow)
        Assert.IsTrue(willows.Length > 0, "large map must place willows")
        let groveSizes =
            willows
            |> List.groupBy (fun d -> d.Y)
            |> List.collect (fun (_, row) ->
                let xs = row |> List.map (fun d -> d.X) |> List.sort
                let sizes = ResizeArray<int>()
                let mutable current = 0
                let mutable previous = System.Int32.MinValue
                for x in xs do
                    if previous >= 0 && x - previous = 1 then
                        current <- current + 1
                    else
                        if current > 0 then sizes.Add current
                        current <- 1
                    previous <- x
                if current > 0 then sizes.Add current
                List.ofSeq sizes)
        Assert.IsTrue(groveSizes |> List.exists (fun n -> n >= 2), "willows must form groves of adjacent trunks")

    // ---- P25：大图不产孤立石板 tile（装饰石块默认开启仅限小图） ----

    [<TestMethod>]
    member _.DecorativeStonesDisabledOnLargeMaps () =
        Assert.IsTrue((MapGen.paramsForSize 64 48 (uint64 1)).DecorativeStones)
        Assert.IsTrue((MapGen.paramsForSize 256 192 (uint64 1)).DecorativeStones)
        Assert.IsFalse((MapGen.paramsForSize 512 384 (uint64 1)).DecorativeStones)

    [<TestMethod>]
    member _.LargeMapHasNoIsolatedStoneTiles () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let pathSet = System.Collections.Generic.HashSet<int>(map.Paths |> List.map (fun (x, y) -> y * map.Width + x))
        let stone x y = map.Tiles.[y * map.Width + x] = int MapGen.GroundTile.Stone
        let mutable isolated = 0
        for y in 0 .. map.Height - 1 do
            for x in 0 .. map.Width - 1 do
                if stone x y && not (pathSet.Contains(y * map.Width + x)) then
                    let neighbours =
                        [ (x + 1, y); (x - 1, y); (x, y + 1); (x, y - 1) ]
                        |> List.filter (fun (nx, ny) -> nx >= 0 && nx < map.Width && ny >= 0 && ny < map.Height)
                        |> List.filter (fun (nx, ny) -> stone nx ny)
                        |> List.length
                    if neighbours = 0 then isolated <- isolated + 1
        Assert.AreEqual<int>(0, isolated)
        // 装饰关闭后，大图所有石板都应属于路网。
        let stonesOutsidePaths =
            [ for y in 0 .. map.Height - 1 do
                  for x in 0 .. map.Width - 1 do
                      if stone x y && not (pathSet.Contains(y * map.Width + x)) then yield (x, y) ]
        Assert.AreEqual<int>(0, stonesOutsidePaths.Length)

    /// 锁定当前默认尺寸的生成结果，防止 P23 参数适配无意改变 64x48 / 256x192。
    [<TestMethod>]
    member _.DefaultSizeChecksumsArePinned () =
        Assert.AreEqual<int64>(6042052L, checksum (MapGen.generateWithSize 64 48 (uint64 4242)))
        Assert.AreEqual<int64>(1284656962L, checksum (MapGen.generateWithSize 256 192 (uint64 4242)))

    // ---- P26：河岸装饰（护岸石垒/芦苇/垂柳）仅大图、落在岸格且不挡通行 ----

    [<TestMethod>]
    member _.RiverDecorationsOnlyEnabledOnLargeMaps () =
        Assert.IsFalse((MapGen.paramsForSize 64 48 (uint64 1)).RiverDecorations)
        Assert.IsFalse((MapGen.paramsForSize 256 192 (uint64 1)).RiverDecorations)
        Assert.IsTrue((MapGen.paramsForSize 512 384 (uint64 1)).RiverDecorations)
        Assert.AreEqual<int>(0, (MapGen.generateWithSize 64 48 (uint64 4242)).Decorations.Length)
        Assert.AreEqual<int>(0, (MapGen.generateWithSize 256 192 (uint64 4242)).Decorations.Length)

    [<TestMethod>]
    member _.RiverbankDecorationsSitOnBanksAndNeverBlockPathsOrBridges () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.IsTrue(map.Decorations.Length > 0, "512x384 must place riverbank decorations")
        let pathSet = System.Collections.Generic.HashSet<int>(map.Paths |> List.map (fun (x, y) -> y * map.Width + x))
        let bridgeSet = System.Collections.Generic.HashSet<int>(map.Bridges |> List.map (fun (x, y) -> y * map.Width + x))
        let water x y = map.Tiles.[y * map.Width + x] = int MapGen.GroundTile.Water
        let inCore x y = x >= map.Core.MinX && x <= map.Core.MaxX && y >= map.Core.MinY && y <= map.Core.MaxY
        for decoration in map.Decorations do
            let footprint =
                match decoration.Kind with
                | MapGen.Willow -> [ decoration.Y; decoration.Y + 1 ]
                | _ -> [ decoration.Y ]
            for y in footprint do
                let i = y * map.Width + decoration.X
                Assert.AreNotEqual<int>(int MapGen.GroundTile.Water, map.Tiles.[i], "decoration must sit on land")
                Assert.IsFalse(pathSet.Contains i, "decoration must not block a path tile")
                Assert.IsFalse(bridgeSet.Contains i, "decoration must not block a bridge tile")
                Assert.IsFalse(inCore decoration.X y, "decoration must stay outside the core")
            // Bank adjacency: at least one footprint tile must touch the river orthogonally.
            let touchesWater =
                footprint
                |> List.exists (fun y ->
                    [ (decoration.X + 1, y); (decoration.X - 1, y); (decoration.X, y + 1); (decoration.X, y - 1) ]
                    |> List.exists (fun (nx, ny) ->
                        nx >= 0 && nx < map.Width && ny >= 0 && ny < map.Height && water nx ny))
            Assert.IsTrue(touchesWater, "decoration must line the riverbank, not float inland")

    [<TestMethod>]
    member _.LargeMapRiverDecorationsAreDeterministic () =
        let a = MapGen.generateWithSize 512 384 (uint64 4242)
        let b = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.IsTrue(a.Decorations = b.Decorations)
        Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)
        let c = MapGen.generateWithSize 512 384 (uint64 7)
        Assert.AreNotEqual<string>(MapGen.serialize a, MapGen.serialize c)

    // ---- P30：512 民居增密 + 组团规模 + 乡村空区填充 + 主路柔化 ----

    [<TestMethod>]
    member _.LargeMapGroupsAreTwoToFiveWithFewIsolated () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let groups = houseGroups map.Buildings
        Assert.IsTrue(groups.Length > 0, "512 must form house groups")
        let singletons = groups |> List.filter (fun n -> n < 2) |> List.length
        Assert.IsTrue(singletons <= 2, sprintf "isolated single-house groups must be <=2, saw %d" singletons)
        let inRange = groups |> List.filter (fun n -> n >= 2 && n <= 5) |> List.length
        Assert.IsTrue(inRange * 2 >= groups.Length, "most groups must hold 2-5 houses")
        // 另一 seed 同样不产孤立组，验证不是对 4242 的过拟合。
        let other = houseGroups (MapGen.generateWithSize 512 384 (uint64 7)).Buildings
        Assert.IsTrue((other |> List.filter (fun n -> n < 2) |> List.length) <= 2)

    [<TestMethod>]
    member _.LargeMapCountrysideFillsEmptyBandsWithMatureTiles () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let isField code = code = int MapGen.GroundTile.PaddyField || code = int MapGen.GroundTile.VegetablePlot
        let paddy = map.Tiles |> Array.filter (fun c -> c = int MapGen.GroundTile.PaddyField) |> Array.length
        let veg = map.Tiles |> Array.filter (fun c -> c = int MapGen.GroundTile.VegetablePlot) |> Array.length
        Assert.IsTrue(paddy > 0, "paddy fields must appear on 512")
        Assert.IsTrue(veg > 0, "vegetable plots must appear on 512")
        Assert.IsTrue(paddy + veg > 4000, sprintf "fields must cover a meaningful share, saw %d" (paddy + veg))
        Assert.IsTrue(map.Groves.Length > 0, "tree groves must appear")
        Assert.IsTrue(map.Farmhouses.Length > 0, "scattered farmsteads must appear")
        // 上部/下部空带都要有田块，避免大面积纯草。
        let topBand = [ for y in 0 .. 90 do for x in 0 .. map.Width - 1 -> map.Tiles.[y * map.Width + x] ] |> List.filter isField |> List.length
        let bottomBand = [ for y in 296 .. map.Height - 1 do for x in 0 .. map.Width - 1 -> map.Tiles.[y * map.Width + x] ] |> List.filter isField |> List.length
        Assert.IsTrue(topBand > 100, sprintf "top band must contain fields, saw %d" topBand)
        Assert.IsTrue(bottomBand > 100, sprintf "bottom band must contain fields, saw %d" bottomBand)
        // 默认图完全不进入乡村分支。
        let small = MapGen.generateWithSize 256 192 (uint64 4242)
        Assert.AreEqual<int>(0, small.Groves.Length)
        Assert.AreEqual<int>(0, small.Farmhouses.Length)
        Assert.AreEqual<int>(0, small.Tiles |> Array.filter isField |> Array.length)

    [<TestMethod>]
    member _.FieldsStayOnLandAwayFromWaterPathsAndCore () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let pathSet = System.Collections.Generic.HashSet<int>(map.Paths |> List.map (fun (x, y) -> y * map.Width + x))
        let isField code = code = int MapGen.GroundTile.PaddyField || code = int MapGen.GroundTile.VegetablePlot
        for y in 0 .. map.Height - 1 do
            for x in 0 .. map.Width - 1 do
                let i = y * map.Width + x
                if isField map.Tiles.[i] then
                    Assert.AreNotEqual<int>(int MapGen.GroundTile.Water, map.Tiles.[i])
                    Assert.IsFalse(pathSet.Contains i, sprintf "field (%d,%d) must not sit on a path" x y)
                    let inCore = x >= map.Core.MinX && x <= map.Core.MaxX && y >= map.Core.MinY && y <= map.Core.MaxY
                    Assert.IsFalse(inCore, sprintf "field (%d,%d) must stay outside the core" x y)

    [<TestMethod>]
    member _.LargeMapFarmsteadDoorsAreReachableAndDeterministic () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.IsTrue(map.ReachabilityOk, "512 reachability must hold with farmsteads")
        let visited = MapGen.floodFill map (fst map.Spawns.Head) (snd map.Spawns.Head)
        for farmhouse in map.Farmhouses do
            Assert.IsTrue(MapGen.isWalkable map farmhouse.DoorX farmhouse.DoorY, sprintf "farmstead door (%d,%d) must be walkable" farmhouse.DoorX farmhouse.DoorY)
            Assert.IsTrue(visited.[farmhouse.DoorY * map.Width + farmhouse.DoorX], sprintf "farmstead door (%d,%d) unreachable" farmhouse.DoorX farmhouse.DoorY)
        let other = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.IsTrue(map.Farmhouses = other.Farmhouses)
        Assert.IsTrue(map.Groves = other.Groves)
        Assert.IsTrue(map.Tiles = other.Tiles)
        Assert.AreEqual<string>(MapGen.serialize map, MapGen.serialize other)

    [<TestMethod>]
    member _.LargeMapMainRoadIsDeterministicSerpentine () =
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let other = MapGen.generateWithSize 512 384 (uint64 4242)
        // 同 seed 两次逐字节一致（含主路中心线）。
        Assert.IsTrue(map.MainRoadCenter = other.MainRoadCenter, "road centerline must be byte-identical across runs")
        Assert.AreEqual<string>(MapGen.serialize map, MapGen.serialize other)
        // 逐点微扰：相邻列步长 <=1，且相对中段基准确有 >=2 格弯曲。
        map.MainRoadCenter
        |> Array.pairwise
        |> Array.iter (fun (a, b) -> Assert.IsTrue(abs (b - a) <= 1, sprintf "road step must be <=1, saw %d -> %d" a b))
        let baseY = map.MainRoadCenter.[map.Width / 2]
        Assert.IsTrue(map.MainRoadCenter |> Array.exists (fun y -> abs (y - baseY) >= 2), "main road must bend by >=2 tiles")
        // 默认图主街仍笔直（不进入新分支）。
        let small = MapGen.generateWithSize 256 192 (uint64 4242)
        let smallBase = small.MainRoadCenter.[small.Width / 2]
        Assert.IsTrue(small.MainRoadCenter |> Array.forall (fun y -> y = smallBase), "default map road must stay straight")

    [<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)