//
//  FeedDetailGridView.swift
//  NewsBlur
//
//  Created by David Sinclair on 2023-01-19.
//  Copyright © 2023 NewsBlur. All rights reserved.
//

import SwiftUI

/// A protocol of interaction between a card in the grid, and the enclosing feed detail view controller.
protocol FeedDetailInteraction {
    func storyAppeared(_ story: Story)
    func storyTapped(_ story: Story)
    func storyHidden(_ story: Story)
}

/// A list or grid layout of story cards for the feed detail view.
struct FeedDetailGridView: View {
    var feedDetailInteraction: FeedDetailInteraction
    
    @ObservedObject var cache: StoryCache
    
    var columns: [GridItem] {
        if cache.isGrid {
            return Array(repeating: GridItem(.flexible(), spacing: 20), count: cache.settings.gridColumns)
        } else {
            return [GridItem(.flexible())]
        }
    }
    
    var isOS15OrLater: Bool {
        if #available(iOS 15.0, *) {
            return true
        } else {
            return false
        }
    }
    
    var cardHeight: CGFloat {
        return cache.settings.gridHeight
    }
    
    var storyHeight: CGFloat {
        //TODO: 🚧 determine ideal height of story view
        return 1000
    }
    
//    let stories: [Story] = StoryCache.stories
    
    var body: some View {
        ScrollView {
            LazyVGrid(columns: columns, spacing: cache.isGrid ? 20 : 0) {
                Section {
                    ForEach(cache.before) { story in
                        makeCardView(for: story, cache: cache)
                    }
                }
                    
                if !cache.isGrid, let story = cache.selected {
                    makeCardView(for: story, cache: cache)
                }
                
                Section(header: makeStoryView(cache: cache)) {
                    ForEach(cache.after) { story in
                        makeCardView(for: story, cache: cache)
                    }
                }
            }
            .if(cache.isGrid) { view in
                view.padding()
            }
        }
    }
    
    @ViewBuilder
    func makeCardView(for story: Story, cache: StoryCache) -> some View {
        CardView(cache: cache, story: loaded(story: story))
            .onAppear {
                feedDetailInteraction.storyAppeared(story)
            }
            .onTapGesture {
                feedDetailInteraction.storyTapped(story)
            }
            .if(cache.isGrid) { view in
                view.frame(height: cardHeight)
            }
    }
    
    @ViewBuilder
    func makeStoryView(cache: StoryCache) -> some View {
        if cache.isGrid, let story = cache.selected {
            StoryView(cache: cache, story: loaded(story: story), interaction: feedDetailInteraction)
                .frame(height: storyHeight)
        }
    }
    
    func loaded(story: Story) -> Story {
        story.load()
        return story
    }
}

//struct FeedDetailGridView_Previews: PreviewProvider {
//    static var previews: some View {
//        FeedDetailGridView(feedDetailInteraction: FeedDetailViewController(), storyCache: StoryCache())
//    }
//}