//
//  ComposeAttachmentImage.swift
//  Tusker
//
//  Created by Shadowfacts on 11/10/21.
//  Copyright © 2021 Shadowfacts. All rights reserved.
//

import SwiftUI
import Photos

struct ComposeAttachmentImage: View {
    let attachment: CompositionAttachment
    let fullSize: Bool
    
    @State private var image: UIImage? = nil
    @State private var imageContentMode: ContentMode = .fill
    @State private var imageBackgroundColor: Color = .black
    
    @Environment(\.colorScheme) private var colorScheme: ColorScheme
    
    var body: some View {
        if let image = image {
            Image(uiImage: image)
                .resizable()
                .aspectRatio(contentMode: imageContentMode)
                .background(imageBackgroundColor)
        } else {
            Image(systemName: placeholderImageName)
                .onAppear(perform: self.loadImage)
        }
    }
    
    private var placeholderImageName: String {
        switch colorScheme {
        case .light:
            return "photo"
        case .dark:
            return "photo.fill"
        @unknown default:
            return "photo"
        }
    }
    
    private func loadImage() {
        switch attachment.data {
        case let .image(image):
            self.image = image
        case let .asset(asset):
            let size: CGSize
            if fullSize {
                size = PHImageManagerMaximumSize
            } else {
                // currently only used as thumbnail in ComposeAttachmentRow
                size = CGSize(width: 80, height: 80)
            }
            PHImageManager.default().requestImage(for: asset, targetSize: size, contentMode: .aspectFill, options: nil) { (image, _) in
                DispatchQueue.main.async {
                    self.image = image
                }
            }
        case let .video(url):
            let asset = AVURLAsset(url: url)
            let imageGenerator = AVAssetImageGenerator(asset: asset)
            if let cgImage = try? imageGenerator.copyCGImage(at: .zero, actualTime: nil) {
                self.image = UIImage(cgImage: cgImage)
            }
        case let .drawing(drawing):
            image = drawing.imageInLightMode(from: drawing.bounds)
            imageContentMode = .fit
            imageBackgroundColor = .white
        }
    }
}

struct ComposeAttachmentImage_Previews: PreviewProvider {
    static var previews: some View {
        ComposeAttachmentImage(attachment: CompositionAttachment(data: .image(UIImage())), fullSize: false)
    }
}