import Photos
import SwiftUI

enum GalleryMediaType {
    case video
    case photo
}

struct GalleryItem: Identifiable {
    let id: String
    let type: GalleryMediaType
    var thumbnail: Image?
    var duration: String?
}

extension GalleryItem {
    static func fetchAll() async -> [GalleryItem] {
        await Task {
            let fetchOptions = PHFetchOptions()
            fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
            let assets = PHAsset.fetchAssets(with: fetchOptions)
            var tmpGalleryItems: [GalleryItem] = []
            assets.enumerateObjects { asset, _, _ in
                if asset.mediaType == .image {
                    let item = GalleryItem(id: asset.localIdentifier, type: .photo, thumbnail: nil, duration: nil)
                    tmpGalleryItems.append(item)
                }
                if asset.mediaType == .video {
                    let item = GalleryItem(id: asset.localIdentifier, type: .video, thumbnail: nil, duration: asset.duration.minAndSec)
                    tmpGalleryItems.append(item)
                }
            }
            return tmpGalleryItems
        }.value
    }

    mutating func fetchThumbnail() async throws {
        guard let asset = PHAsset.fetchAssets(withLocalIdentifiers: [id], options: nil).firstObject else { return }
        let size = CGSize(width: Const.galleryGridSize, height: Const.galleryGridSize)

        switch type {
        case .photo:
            let originalImage = try await PHImageManager.default().getPhoto(for: asset)
            let cropped = try await originalImage.scaleAndCropImage(size)
            thumbnail = Image(uiImage: cropped)

        case .video:
            let avAsset = try await PHImageManager.default().getVideo(for: asset)
            let cropped = try await avAsset.generateVideoThumbnail(size)
            thumbnail = Image(uiImage: cropped)
        }
    }
}