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

import SwiftUI
import Photos
import TuskerComponents

struct AttachmentThumbnailView: View {
    let attachment: DraftAttachment
    let fullSize: Bool
    
    @State private var gifData: Data? = nil
    @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 gifData {
            GIFViewWrapper(gifData: gifData)
        } else if let 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(originalData, originalType: _):
            self.image = UIImage(data: originalData)
        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)
            }
            let isGIF = PHAssetResource.assetResources(for: asset).contains(where: { $0.uniformTypeIdentifier == UTType.gif.identifier })
            if isGIF {
                PHImageManager.default().requestImageDataAndOrientation(for: asset, options: nil) { data, typeIdentifier, orientation, info in
                    if typeIdentifier == UTType.gif.identifier {
                        self.gifData = data
                    } else if let data {
                        let image = UIImage(data: data)
                        DispatchQueue.main.async {
                            self.image = image
                        }
                    }
                }
            } else {
                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
        case let .gif(data):
            self.gifData = data
        }
    }
}

private struct GIFViewWrapper: UIViewRepresentable {
    typealias UIViewType = GIFImageView

    @State private var controller: GIFController

    init(gifData: Data) {
        self._controller = State(wrappedValue: GIFController(gifData: gifData))
    }

    func makeUIView(context: Context) -> GIFImageView {
        let view = GIFImageView()
        controller.attach(to: view)
        controller.startAnimating()
        view.contentMode = .scaleAspectFit
        view.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
        view.setContentCompressionResistancePriority(.defaultLow, for: .vertical)
        return view
    }

    func updateUIView(_ uiView: GIFImageView, context: Context) {
    }
}