namespace LivingVillage.Desktop

open Microsoft.Xna.Framework

/// P44 对话框/文字弹层：纯模型组件。
/// 负责完整背景框几何、中文正确断行的自动换行、分页(下一页)与关闭语义、
/// 开启时对世界交互的隔离判定，以及原创 32x64 点阵头像。
/// 只做确定性纯计算，实际绘制在 Game.fs。
module DialogOverlay =

    let textScale = 2
    let lineHeight = 18
    let linesPerPage = 4
    let paddingX = 16
    let paddingY = 12
    let titleGap = 6
    let avatarWidth = 32
    let avatarHeight = 64
    let avatarGap = 12
    let pageMarkerHeight = 20
    let minFrameWidth = 480
    let maxFrameWidth = 900
    let bottomMargin = 24

    type Layout =
        { X: int
          Y: int
          Width: int
          Height: int }

    type Model =
        { Title: string
          Pages: string list list
          Page: int
          ShowAvatar: bool }

    type View =
        { Lines: string list
          PageNumber: int
          PageCount: int
          HasPrev: bool
          HasNext: bool }

    // ---- 中文正确断行 ----

    let private isWide (c: char) : bool = (CjkGlyphAtlas.sourceRectangle c).IsSome

    /// 分词：CJK/可见字形单字成词，空格单独成词，拉丁/数字连续成词。
    /// 这样中文可在任意字间断行，拉丁词不会被从中间劈开。
    let private tokenize (paragraph: string) : string list =
        let tokens = System.Collections.Generic.List<string>()
        let buffer = System.Text.StringBuilder()
        let flush () =
            if buffer.Length > 0 then
                tokens.Add(buffer.ToString())
                buffer.Clear() |> ignore
        for c in paragraph do
            if isWide c then
                flush ()
                tokens.Add(string c)
            elif c = ' ' then
                flush ()
                tokens.Add " "
            else
                buffer.Append(c) |> ignore
        flush ()
        List.ofSeq tokens

    /// 把一段文字按像素宽度换行；显式 \n 强制换行。返回行列表。
    let wrapText (maxWidth: int) (text: string) : string list =
        let maxWidth = max 1 maxWidth
        text.Split('\n')
        |> Array.toList
        |> List.collect (fun paragraph ->
            let lines = System.Collections.Generic.List<string>()
            let current = System.Text.StringBuilder()
            let mutable currentWidth = 0
            let flushLine () =
                lines.Add(current.ToString().TrimEnd([| ' ' |]))
                current.Clear() |> ignore
                currentWidth <- 0
            for token in tokenize paragraph do
                let tokenWidth = FloatingPrompt.measureWidth token textScale
                if current.Length > 0 && currentWidth + tokenWidth > maxWidth then
                    flushLine ()
                if not (token = " " && current.Length = 0) then
                    current.Append(token) |> ignore
                    currentWidth <- currentWidth + tokenWidth
            if current.Length > 0 then flushLine ()
            if lines.Count = 0 then [ "" ] else List.ofSeq lines)

    // ---- 分页 ----

    let frameWidth (viewportWidth: int) : int =
        max minFrameWidth (min maxFrameWidth (viewportWidth - 64))

    let textWidth (viewportWidth: int) (showAvatar: bool) : int =
        frameWidth viewportWidth - 2 * paddingX - (if showAvatar then avatarWidth + avatarGap else 0)

    let create (title: string) (texts: string list) (viewportWidth: int) (showAvatar: bool) : Model =
        let maxWidth = textWidth viewportWidth showAvatar
        let body = texts |> List.collect (wrapText maxWidth)
        let pages = if body.IsEmpty then [ [] ] else List.chunkBySize linesPerPage body
        { Title = title
          Pages = pages
          Page = 0
          ShowAvatar = showAvatar }

    let pageCount (model: Model) : int = max 1 model.Pages.Length

    let private clampPage (model: Model) : int =
        if model.Pages.IsEmpty then 0 else max 0 (min (model.Pages.Length - 1) model.Page)

    let view (model: Model) : View =
        let page = clampPage model
        let total = pageCount model
        { Lines = (if model.Pages.IsEmpty then [] else model.Pages.[page])
          PageNumber = page + 1
          PageCount = total
          HasPrev = page > 0
          HasNext = page < total - 1 }

    /// 下一页；已在最后一页时返回 None，调用方保持当前页（翻页边界不崩）。
    let nextPage (model: Model) : Model option =
        let page = clampPage model
        if page < pageCount model - 1 then Some { model with Page = page + 1 } else None

    /// 上一页；已在第一页时返回 None。
    let prevPage (model: Model) : Model option =
        let page = clampPage model
        if page > 0 then Some { model with Page = page - 1 } else None

    // ---- 关闭与隔离 ----

    /// 关闭当前弹层。
    let close (_: Model option) : Model option = None

    /// 弹层开启时禁止任何世界交互穿透。
    let blocksWorldInteraction (overlayOpen: bool) : bool = overlayOpen

    /// 世界交互提示在弹层开启时隐藏。
    let promptVisible (overlayOpen: bool) : bool = not overlayOpen

    // ---- 几何 ----

    let private headerHeight = 8 * textScale + titleGap

    let rect (viewportWidth: int) (viewportHeight: int) (model: Model) : Layout =
        let current = view model
        let width = frameWidth viewportWidth
        let bodyLines = max 1 current.Lines.Length
        let bodyHeight = bodyLines * lineHeight
        let contentHeight = headerHeight + max bodyHeight (if model.ShowAvatar then avatarHeight else 0)
        let height = contentHeight + 2 * paddingY + pageMarkerHeight
        { X = (viewportWidth - width) / 2
          Y = viewportHeight - height - bottomMargin
          Width = width
          Height = height }

    let textOriginX (layout: Layout) (showAvatar: bool) : int =
        layout.X + paddingX + (if showAvatar then avatarWidth + avatarGap else 0)

    let textOriginY (layout: Layout) : int = layout.Y + paddingY + headerHeight

    let avatarRect (layout: Layout) : Layout =
        { X = layout.X + paddingX
          Y = layout.Y + paddingY + headerHeight
          Width = avatarWidth
          Height = avatarHeight }

    // ---- 原创 32x64 点阵头像（8x16 @ scale 4）----

    let avatarColumns = 8
    let avatarRows = 16
    let avatarScale = 4

    let avatarPattern : string list =
        [ "00000000"
          "00111100"
          "01111110"
          "01111110"
          "01111110"
          "00111100"
          "00011000"
          "00011000"
          "00111100"
          "01111110"
          "11111111"
          "11111111"
          "11111111"
          "11011011"
          "10000001"
          "00000000" ]