namespace LivingVillage.Desktop

open Microsoft.Xna.Framework
open Microsoft.Xna.Framework.Graphics

/// P45 角色动画帧：全部原创手绘点阵，用像素代码内嵌生成图集，不依赖任何外部素材。
/// 布局与既有 `characterSourceRectangle` 完全一致：cell 32x48，
/// cellIndex = (variant*4 + direction)*6 + frame，共 5 变体 x 4 向 x 6 帧。
/// direction 顺序 North/South/West/East（0..3），frame 顺序 走1/走2/走3/走4/待机1/待机2（0..5）。
module CharacterArt =

    let sourceWidth = 16
    let sourceHeight = 24
    let pixelScale = 2
    let cellWidth = sourceWidth * pixelScale
    let cellHeight = sourceHeight * pixelScale
    let variantCount = 5
    let directionCount = 4
    let frameCount = 6
    let walkFrameCount = 4
    let idleFrameCount = 2
    let atlasWidth = cellWidth * variantCount * directionCount * frameCount

    // ---- 点阵字母：. 透明，其余为调色板索引 ----
    // H 头发 S 皮肤 E 眼睛 K 描边 T 草帽 R 外衣 r 外衣暗部 B 腰带 F 鞋

    /// 头部（10 行）按朝向：North 后脑、South 正面、West 左侧脸、East 右侧脸（镜像）。
    let private headNorth : string list =
        [ "................"
          "....HHHHHHHH...."
          "...HHHHHHHHHH..."
          "...HHHHHHHHHH..."
          "...HHHHHHHHHH..."
          "...HHHHHHHHHH..."
          "....HHHHHHHH...."
          "....HHHHHHHH...."
          ".....HHHHHH....."
          "......KKKK......" ]

    let private headSouth : string list =
        [ "................"
          "....HHHHHHHH...."
          "...HHHHHHHHHH..."
          "...HSSSSSSSSH..."
          "...HSSESSESSH..."
          "...HSSSSSSSSH..."
          "...HSSSSSSSSH..."
          "....SSSSSSSS...."
          ".....SSSSSS....."
          "......KKKK......" ]

    let private headWest : string list =
        [ "................"
          "....HHHHHHHH...."
          "...HHHHHHHHHH..."
          "...HHHSSSSHHH..."
          "...HHSESSSHHH..."
          "...HHSSSSSHHH..."
          "....HHSSSSHH...."
          "....HSSSSSSH...."
          ".....SSSSS......"
          "......KKKK......" ]

    /// 躯干（8 行，行 10..17）：走/待机的左右手臂高度不同，形成摆臂。
    let private torsoWalk0 : string list =
        [ "...RRRRRRRRRS..."
          "...RRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRR..."
          "...SRRRRRRRRR..."
          "....RRRRRRRR...."
          "....BBBBBBBB...."
          "....RRRRRRRR...." ]

    let private torsoWalk1 : string list =
        [ "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "....RRRRRRRR...."
          "....BBBBBBBB...."
          "....RRRRRRRR...." ]

    let private torsoWalk2 : string list =
        [ "...SRRRRRRRRR..."
          "...SRRRRRRRRR..."
          "...SRRRRRRRRS..."
          "...RRRRRRRRRS..."
          "...RRRRRRRRRS..."
          "....RRRRRRRR...."
          "....BBBBBBBB...."
          "....RRRRRRRR...." ]

    let private torsoWalk3 : string list =
        [ "...SRRRRRRRRR..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...RRRRRRRRRS..."
          "....RRRRRRRR...."
          "....BBBBBBBB...."
          "....RRRRRRRR...." ]

    let private torsoIdle1 : string list =
        [ "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "....RRRRRRRR...."
          "....BBBBBBBB...."
          "....RRRRRRRR...." ]

    /// 待机第二帧：手臂收短、腰带整体上提 2 行，读作呼吸起伏。
    let private torsoIdle2 : string list =
        [ "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "...SRRRRRRRRS..."
          "....RRRRRRRR...."
          "....BBBBBBBB...."
          "....RRRRRRRR...."
          "....RRRRRRRR...."
          "....RRRRRRRR...." ]

    /// 腿（6 行，行 18..23）：四帧行走跨步姿态各不相同，待机两帧双脚并拢。
    let private legsWalk0 : string list =
        [ "....RRRRRRRR...."
          "...RRRRRRRRRR..."
          "..RRR......RRR.."
          "..RRR......RRR.."
          "..FFF......FFF.."
          "..FFF......FFF.." ]

    let private legsWalk1 : string list =
        [ "....RRRRRRRR...."
          "....RRRRRRRR...."
          ".....RRRRRR....."
          ".....RR.RRR....."
          ".....FF.RRR....."
          "........FFF....." ]

    let private legsWalk2 : string list =
        [ "....RRRRRRRR...."
          "...RRRRRRRRR...."
          "...RRR....RRR..."
          "...RRR....RR...."
          "...FFF....FF...."
          "...FFF.........." ]

    let private legsWalk3 : string list =
        [ "....RRRRRRRR...."
          "....RRRRRRRR...."
          ".....RRRRRR....."
          ".....RRR.RR....."
          ".....RRR.FF....."
          ".....FFF........" ]

    let private legsIdle : string list =
        [ "....RRRRRRRR...."
          "....RRRRRRRR...."
          ".....RRRRRR....."
          ".....RRR.RR....."
          ".....FFF.FF....."
          ".....FFF.FF....." ]

    let private torsoByFrame : string list list =
        [ torsoWalk0; torsoWalk1; torsoWalk2; torsoWalk3; torsoIdle1; torsoIdle2 ]

    let private legsByFrame : string list list =
        [ legsWalk0; legsWalk1; legsWalk2; legsWalk3; legsIdle; legsIdle ]

    let private mirrorRow (row: string) : string =
        System.String(row.ToCharArray() |> Array.rev)

    let private headByDirection : string list list =
        [ headNorth; headSouth; headWest; headWest |> List.map mirrorRow ]

    /// 某个 (变体, 朝向, 帧) 的 24 行点阵字母；草帽变体在头部叠加草帽。
    let frameLetters (variantIndex: int) (directionIndex: int) (frameIndex: int) : string list =
        let head = headByDirection.[((directionIndex % directionCount) + directionCount) % directionCount]
        let torso = torsoByFrame.[((frameIndex % frameCount) + frameCount) % frameCount]
        let legs = legsByFrame.[((frameIndex % frameCount) + frameCount) % frameCount]
        let composed = head @ torso @ legs
        if (variantIndex % variantCount + variantCount) % variantCount = 4 then
            composed
            |> List.mapi (fun row line ->
                if row = 1 || row = 2 then
                    line |> Seq.map (fun c -> if c = '.' then '.' else 'T') |> System.String.Concat
                elif row = 3 then
                    line.ToCharArray()
                    |> Array.mapi (fun column c -> if column >= 2 && column <= 13 then 'T' else c)
                    |> System.String
                else line)
        else composed

    /// 变体外衣主色 / 暗部 / 腰带；决定 5 个村民的观感差异。
    let variantColors (variantIndex: int) : Color * Color * Color =
        match ((variantIndex % variantCount) + variantCount) % variantCount with
        | 0 -> Color(66, 84, 148), Color(44, 58, 110), Color(214, 198, 150)   // 靛蓝长衫
        | 1 -> Color(178, 132, 66), Color(128, 92, 44), Color(70, 60, 50)     // 赭黄马甲
        | 2 -> Color(74, 150, 128), Color(48, 110, 92), Color(232, 214, 160)  // 青碧束带
        | 3 -> Color(118, 124, 134), Color(84, 90, 100), Color(58, 62, 70)    // 灰帽
        | _ -> Color(146, 96, 70), Color(108, 70, 52), Color(90, 74, 48)      // 斗笠农夫

    let private colorOf (variantIndex: int) (letter: char) : Color option =
        let robe, robeShade, belt = variantColors variantIndex
        match letter with
        | 'H' -> Some(Color(44, 36, 34))
        | 'S' -> Some(Color(234, 194, 152))
        | 'E' -> Some(Color(24, 22, 28))
        | 'K' -> Some(Color(28, 30, 38))
        | 'T' -> Some(Color(216, 190, 120))
        | 'R' -> Some robe
        | 'r' -> Some robeShade
        | 'B' -> Some belt
        | 'F' -> Some(Color(58, 42, 34))
        | _ -> None

    let private cellIndex (variantIndex: int) (directionIndex: int) (frameIndex: int) : int =
        (variantIndex * directionCount + directionIndex) * frameCount + frameIndex

    /// 像素点阵 -> 直通 alpha 图集纹理。仅用 SetData，无外部素材。
    let buildAtlas (device: GraphicsDevice) : Texture2D =
        let pixels = Array.zeroCreate<Color> (atlasWidth * cellHeight)
        for variant in 0 .. variantCount - 1 do
            for direction in 0 .. directionCount - 1 do
                for frame in 0 .. frameCount - 1 do
                    let originX = cellIndex variant direction frame * cellWidth
                    let rows = frameLetters variant direction frame
                    for y in 0 .. sourceHeight - 1 do
                        let row = rows.[y]
                        for x in 0 .. sourceWidth - 1 do
                            match colorOf variant row.[x] with
                            | Some color ->
                                for sy in 0 .. pixelScale - 1 do
                                    for sx in 0 .. pixelScale - 1 do
                                        pixels.[(y * pixelScale + sy) * atlasWidth + originX + x * pixelScale + sx] <- color
                            | None -> ()
        let texture = new Texture2D(device, atlasWidth, cellHeight)
        texture.SetData pixels
        texture