TUIkit/Sources/TUIKit/Views/Panel.swift

//
//  Panel.swift
//  TUIKit
//
//  A titled container view with optional footer.
//

/// A bordered container with a title and optional footer.
///
/// `Panel` is useful for grouping content with a visible label,
/// similar to a fieldset in HTML or a group box in desktop UIs.
///
/// ## Behavior by Appearance
///
/// - **Standard appearances** (line, rounded, doubleLine, heavy):
///   Title is rendered IN the top border.
///
/// - **Block appearance**:
///   Title becomes a separate header section with darker background.
///
/// ## Examples
///
/// ```swift
/// // Simple panel
/// Panel("Settings") {
///     Text("Option 1")
///     Text("Option 2")
/// }
///
/// // Panel with footer
/// Panel("User Info") {
///     Text("Name: John")
///     Text("Age: 30")
/// } footer: {
///     ButtonRow {
///         Button("Save") { }
///         Button("Cancel") { }
///     }
/// }
///
/// // Customized panel
/// Panel("Settings", borderStyle: .doubleLine, titleColor: .cyan) {
///     Text("Content")
/// }
/// ```
public struct Panel<Content: View, Footer: View>: View {
    /// The title displayed in the header/border.
    public let title: String

    /// The content of the panel.
    public let content: Content
    
    /// The footer content (typically buttons).
    public let footer: Footer?

    /// The border style (nil uses appearance default).
    public let borderStyle: BorderStyle?

    /// The border color.
    public let borderColor: Color?

    /// The title color.
    public let titleColor: Color?

    /// The padding inside the panel body.
    public let padding: EdgeInsets
    
    /// Whether to show a separator before the footer.
    public let showFooterSeparator: Bool

    /// Creates a panel with content and footer.
    ///
    /// - Parameters:
    ///   - title: The title to display.
    ///   - borderStyle: The border style (default: appearance borderStyle).
    ///   - borderColor: The border color (default: theme border).
    ///   - titleColor: The title color (default: theme accent).
    ///   - padding: The inner padding (default: horizontal 1, vertical 0).
    ///   - showFooterSeparator: Whether to show separator before footer (default: true).
    ///   - content: The main content of the panel.
    ///   - footer: The footer content.
    public init(
        _ title: String,
        borderStyle: BorderStyle? = nil,
        borderColor: Color? = nil,
        titleColor: Color? = nil,
        padding: EdgeInsets = EdgeInsets(horizontal: 1, vertical: 0),
        showFooterSeparator: Bool = true,
        @ViewBuilder content: () -> Content,
        @ViewBuilder footer: () -> Footer
    ) {
        self.title = title
        self.content = content()
        self.footer = footer()
        self.borderStyle = borderStyle
        self.borderColor = borderColor
        self.titleColor = titleColor
        self.padding = padding
        self.showFooterSeparator = showFooterSeparator
    }

    public var body: some View {
        ContainerView(
            title: title,
            titleColor: titleColor,
            style: ContainerStyle(
                showHeaderSeparator: true,
                showFooterSeparator: showFooterSeparator,
                borderStyle: borderStyle,
                borderColor: borderColor
            ),
            padding: padding
        ) {
            content
        } footer: {
            footer!
        }
    }
}

// MARK: - Convenience Initializer (no footer)

extension Panel where Footer == EmptyView {
    /// Creates a panel without a footer.
    ///
    /// - Parameters:
    ///   - title: The title to display in the top border.
    ///   - borderStyle: The border style (default: appearance borderStyle).
    ///   - borderColor: The border color (default: theme border).
    ///   - titleColor: The title color (default: same as border).
    ///   - padding: The inner padding (default: horizontal 1, vertical 0).
    ///   - content: The content of the panel.
    public init(
        _ title: String,
        borderStyle: BorderStyle? = nil,
        borderColor: Color? = nil,
        titleColor: Color? = nil,
        padding: EdgeInsets = EdgeInsets(horizontal: 1, vertical: 0),
        @ViewBuilder content: () -> Content
    ) {
        self.title = title
        self.content = content()
        self.footer = nil
        self.borderStyle = borderStyle
        self.borderColor = borderColor
        self.titleColor = titleColor
        self.padding = padding
        self.showFooterSeparator = true
    }
}

// MARK: - Panel Rendering

extension Panel: Renderable {
    public func renderToBuffer(context: RenderContext) -> FrameBuffer {
        // Create the ContainerView and render it
        let containerStyle = ContainerStyle(
            showHeaderSeparator: true,
            showFooterSeparator: showFooterSeparator,
            borderStyle: borderStyle,
            borderColor: borderColor
        )
        
        if let footerView = footer {
            let container = ContainerView(
                title: title,
                titleColor: titleColor,
                style: containerStyle,
                padding: padding
            ) {
                content
            } footer: {
                footerView
            }
            return container.renderToBuffer(context: context)
        } else {
            let container = ContainerView(
                title: title,
                titleColor: titleColor,
                style: containerStyle,
                padding: padding
            ) {
                content
            }
            return container.renderToBuffer(context: context)
        }
    }
}