//
//  AspectContainer.swift
//
//  Copyright 2026 Brendan Szymanski <hello@bscubed.dev>
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
//
//  SPDX-License-Identifier: GPL-3.0-or-later
//

import Adwaita
import CGtkWidgets

/// A single‑child container that preserves a fixed aspect ratio.
///
/// Unlike GTK's built‑in `GtkAspectFrame`, this container overrides
/// `measure()` to report the correct height (`width × ratio`) during
/// the layout pass.  This makes it work correctly inside `ScrollView`,
/// `AdwCarousel`, and other flexible layouts where the parent needs
/// to know the child's preferred size.
///
/// ```swift
/// AspectContainer(aspectRatio: 16.0 / 9.0) {
///     .child {
///         Picture()
///             .data(imageData)
///             .halign(.fill)
///             .hexpand()
///     }
///     .maxWidth(800)
/// }
/// ```
///
/// Ported 1:1 from the Gelata project's `AspectRatioContainer` Rust widget.
public struct AspectContainer: Widget {

    #if exposeGeneratedAppearUpdateFunctions
        public var updateFunctions: [(ViewStorage, WidgetData, Bool) -> Void] = []
        public var appearFunctions: [(ViewStorage, WidgetData) -> Void] = []
    #else
        var updateFunctions: [(ViewStorage, WidgetData, Bool) -> Void] = []
        var appearFunctions: [(ViewStorage, WidgetData) -> Void] = []
    #endif

    /// The child widget.
    var child: Body?
    /// The desired width‑to‑height ratio.
    var aspectRatio: Float
    /// An optional maximum width in pixels (0 = no limit).
    var maxWidth: Int?

    /// Create an aspect‑ratio container.
    /// - Parameter aspectRatio: Desired `width / height` ratio.
    public init(aspectRatio: Float) {
        self.aspectRatio = aspectRatio
    }

    // MARK: - Widget

    public func container<Data>(data: WidgetData, type: Data.Type) -> ViewStorage
    where Data: ViewRenderData {
        let storage = ViewStorage(aspect_container_new(aspectRatio)?.opaque())
        for function in appearFunctions {
            function(storage, data)
        }
        if let childStorage = child?.storage(data: data, type: type) {
            storage.content["child"] = [childStorage]
            gtk_widget_set_parent(
                childStorage.opaquePointer?.cast(),
                storage.opaquePointer?.cast())
        }
        return storage
    }

    public func update<Data>(
        _ storage: ViewStorage,
        data: WidgetData,
        updateProperties: Bool,
        type: Data.Type
    ) where Data: ViewRenderData {
        storage.modify { widget in
            if let childStorage = storage.content["child"]?.first {
                child?.updateStorage(
                    childStorage,
                    data: data,
                    updateProperties: updateProperties,
                    type: type
                )
            }
            if let maxWidth,
                updateProperties,
                (storage.previousState as? Self)?.maxWidth != maxWidth
            {
                aspect_container_set_max_width(widget, maxWidth.cInt)
            }
            if updateProperties,
                (storage.previousState as? Self)?.aspectRatio != aspectRatio
            {
                aspect_container_set_aspect_ratio(widget, aspectRatio)
            }
        }
        for function in updateFunctions {
            function(storage, data, updateProperties)
        }
        if updateProperties {
            storage.previousState = self
        }
    }

}

// MARK: - Modifiers

extension AspectContainer {

    /// Set the child widget.
    public func child(@ViewBuilder _ child: () -> Body) -> Self {
        modify { $0.child = child() }
    }

    /// Set an optional maximum width in pixels.
    /// When set to a positive value, the container's width is clamped
    /// before computing the height from the aspect ratio.
    public func maxWidth(_ maxWidth: Int?) -> Self {
        modify { $0.maxWidth = maxWidth }
    }

}