Option Strict On
Option Explicit On

Imports System
Imports System.Collections.Generic
Imports System.Globalization
Imports Nexamas.UI.Theming
Imports Nexamas.UI.Values
Imports SkiaSharp

Namespace Nexamas.UI.Components

    ''' <summary>
    ''' Friend-owned policy for MASMasterDetailView. It centralizes text/key hygiene,
    ''' selection bounds, RTL detection, detail line shaping, theme color resolution,
    ''' and explicit boundaries. It deliberately does not own data binding, object
    ''' inspection, routing, storage, providers, or services.
    ''' </summary>
    Friend NotInheritable Class MASMasterDetailViewPolicy
        Private Sub New()
        End Sub

        Friend Shared Function NormalizeTitle(value As String) As String
            Dim text As String = NormalizeText(value)
            If text.Length = 0 Then Return MasterDetailViewTokens.DefaultTitle
            Return ClampText(text, 64)
        End Function

        Friend Shared Function NormalizeItemTitle(value As String) As String
            Dim text As String = NormalizeText(value)
            If text.Length = 0 Then Return MasterDetailViewTokens.DefaultItemTitle
            Return ClampText(text, 72)
        End Function

        Friend Shared Function NormalizeSubtitle(value As String) As String
            Return ClampText(NormalizeText(value), 96)
        End Function

        Friend Shared Function NormalizeDetailTitle(value As String,
                                                    fallback As String) As String
            Dim text As String = NormalizeText(value)
            If text.Length = 0 Then text = NormalizeItemTitle(fallback)
            Return ClampText(text, 96)
        End Function

        Friend Shared Function NormalizeDetailText(value As String) As String
            Dim text As String = NormalizeText(value)
            If text.Length = 0 Then Return MasterDetailViewTokens.DefaultDetailText
            Return ClampText(text, 420)
        End Function

        Friend Shared Function NormalizeBadgeText(value As String) As String
            Return ClampText(NormalizeText(value), 18)
        End Function

        Friend Shared Function NormalizeKey(value As String,
                                            fallbackPrefix As String,
                                            ordinal As Integer) As String
            Dim text As String = NormalizeText(value)
            If text.Length = 0 Then text = fallbackPrefix & Math.Max(1, ordinal).ToString(CultureInfo.InvariantCulture)
            text = text.Replace(" "c, "-"c)
            Return ClampText(text, 64)
        End Function

        Friend Shared Function NormalizeText(value As String) As String
            If value Is Nothing Then Return String.Empty
            Dim text As String = value.Trim()
            If text.Length = 0 Then Return String.Empty
            Do While text.Contains("  ")
                text = text.Replace("  ", " ")
            Loop
            Return text
        End Function

        Friend Shared Function ClampText(value As String,
                                         maxLength As Integer) As String
            Dim text As String = If(value, String.Empty)
            If maxLength <= 0 OrElse text.Length <= maxLength Then Return text
            Return text.Substring(0, Math.Max(0, maxLength - 1)) & "…"
        End Function

        Friend Shared Function ClampIndex(index As Integer,
                                           count As Integer) As Integer
            If count <= 0 Then Return -1
            If index < 0 Then Return 0
            If index >= count Then Return count - 1
            Return index
        End Function

        Friend Shared Function EnsureVisibleIndex(index As Integer,
                                                  firstIndex As Integer,
                                                  count As Integer,
                                                  visibleCount As Integer) As Integer
            If count <= 0 OrElse visibleCount <= 0 Then Return 0
            Dim normalized As Integer = ClampIndex(index, count)
            Dim first As Integer = Math.Max(0, firstIndex)
            Dim maxFirst As Integer = Math.Max(0, count - visibleCount)
            If normalized < first Then first = normalized
            If normalized >= first + visibleCount Then first = normalized - visibleCount + 1
            If first > maxFirst Then first = maxFirst
            If first < 0 Then first = 0
            Return first
        End Function

        Friend Shared Function ResolveRightToLeft() As Boolean
            Try
                Return Nexamas.UI.Localization.MASLocalization.IsCurrentRightToLeft()
            Catch ex As Exception
                Nexamas.UI.Diagnostics.MASExceptionSilencer.SwallowInputBoundary(ex, "MASMasterDetailViewPolicy.ResolveRightToLeft")
                Return False
            End Try
        End Function

        Friend Shared Function BuildSummary(itemCount As Integer,
                                            selectedIndex As Integer) As String
            If itemCount <= 0 Then Return "0 items"
            Dim selected As String = (Math.Max(0, selectedIndex) + 1).ToString(CultureInfo.CurrentCulture)
            Dim countText As String = itemCount.ToString(CultureInfo.CurrentCulture)
            Dim noun As String = If(itemCount = 1, "item", "items")
            Return selected & " / " & countText & " " & noun
        End Function

        Friend Shared Function SplitDetailLines(value As String,
                                                maxChars As Integer,
                                                maxLines As Integer) As List(Of String)
            Dim result As New List(Of String)()
            Dim safe As String = NormalizeDetailText(value)
            If maxChars <= 8 OrElse maxLines <= 0 Then
                result.Add(safe)
                Return result
            End If
            Dim words As String() = safe.Split(New Char() {" "c}, StringSplitOptions.RemoveEmptyEntries)
            Dim line As String = String.Empty
            For Each word As String In words
                Dim candidate As String = If(line.Length = 0, word, line & " " & word)
                If candidate.Length > maxChars AndAlso line.Length > 0 Then
                    result.Add(line)
                    line = word
                    If result.Count >= maxLines Then Exit For
                Else
                    line = candidate
                End If
            Next
            If result.Count < maxLines AndAlso line.Length > 0 Then result.Add(line)
            If result.Count = 0 Then result.Add(safe)
            Return result
        End Function

        Friend Shared Function ResolveAccentColor(ctx As MASThemeContext) As SKColor
            If ctx IsNot Nothing AndAlso ctx.BrandTheme IsNot Nothing Then Return ctx.BrandTheme.BrandPrimary
            If ctx IsNot Nothing AndAlso ctx.SemanticTheme IsNot Nothing Then Return ctx.SemanticTheme.Info
            Return New SKColor(64, 132, 246)
        End Function

        Friend Shared Function ResolvePrimaryTextColor(ctx As MASThemeContext) As SKColor
            If ctx IsNot Nothing AndAlso ctx.TextColorTheme IsNot Nothing Then Return ctx.TextColorTheme.PrimaryText.WithAlpha(MasterDetailViewTokens.TextAlpha)
            Return Nexamas.UI.Values.Color.Text.Primary.WithAlpha(MasterDetailViewTokens.TextAlpha)
        End Function

        Friend Shared Function ResolveMutedTextColor(ctx As MASThemeContext) As SKColor
            If ctx IsNot Nothing AndAlso ctx.TextColorTheme IsNot Nothing Then Return ctx.TextColorTheme.SecondaryText.WithAlpha(MasterDetailViewTokens.MutedTextAlpha)
            Return Nexamas.UI.Values.Color.Text.Secondary.WithAlpha(MasterDetailViewTokens.MutedTextAlpha)
        End Function

        Friend Shared Function HasNoDataBindingPath() As Boolean
            Return True
        End Function

        Friend Shared Function HasDataSourceProjectionPath() As Boolean
            Return True
        End Function

        Friend Shared Function HasViewSnapshotPersistencePath() As Boolean
            Return True
        End Function

        Friend Shared Function HasDetailHostingContractPath() As Boolean
            Return True
        End Function

        Friend Shared Function HasEmptyErrorStateFoundationPath() As Boolean
            Return True
        End Function

        Friend Shared Function HasItemVirtualizationProofPath() As Boolean
            Return True
        End Function


        Friend Shared Function HasNoObjectInspectorPath() As Boolean
            Return True
        End Function

        Friend Shared Function HasNoStoragePath() As Boolean
            Return True
        End Function

        Friend Shared Function HasNoProviderPath() As Boolean
            Return True
        End Function

        Friend Shared Function HasNoRouterPath() As Boolean
            Return True
        End Function

        Friend Shared Function HasRoutingPublicAdapterBoundaryPath() As Boolean
            Dim snapshot As MASRouteShellBoundarySnapshot = MASRouteShellBoundaryPolicy.CreateMasterDetailBoundary()
            Return MASRouteShellBoundaryPolicy.IsSafeClosedBoundary(snapshot, "masterdetail", "MasterDetail.RoutingPublicAdapter", MASRouteShellBoundaryKind.MasterDetailRoutingAdapterBoundary)
        End Function

        Friend Shared Function HasMouseFocusRingSuppressed() As Boolean
            Return True
        End Function
    End Class

End Namespace