//
//  PhotoTumbnailView.swift
//  Swipe That Pic
//
//  Created by Amine Bou on 27/07/2024.
//

import Foundation
import Photos
import SwiftUI

struct BigPicture: View {
    private var image: Image

    @State var scale = 1.0
    @State var lastScale = 0.0
    @State var offset: CGSize = .zero
    @State var lastOffset: CGSize = .zero

    init(image: Image) {
        self.image = image
    }

    var body: some View {
        GeometryReader { proxy in
            image
                .resizable()
                .scaledToFill()
                .scaleEffect(scale)
                .offset(offset)
                .frame(width: proxy.size.width, height: proxy.size.height)
                .gesture(
                    MagnificationGesture(minimumScaleDelta: 0)
                        .onChanged({ value in
                            withAnimation(.interactiveSpring()) {
                                scale = handleScaleChange(value)
                            }
                        })
                        .onEnded({ _ in
                            lastScale = scale
                        }).simultaneously(
                            with: DragGesture(minimumDistance: 0)
                                .onChanged({ value in
                                    withAnimation(.interactiveSpring()) {
                                        offset = handleOffsetChange(value.translation)
                                    }
                                })
                                .onEnded({ _ in
                                    lastOffset = offset
                                })

                        ).simultaneously(with: TapGesture(count: 2).onEnded({ Void in
                            scale = 1.0
                            lastScale = 0.0
                            offset = .zero
                            lastOffset = .zero
                        }))
                )

        }
        // We'll also make sure that the photo will
        // be square
        .aspectRatio(1, contentMode: .fit)
        
    }

    private func handleScaleChange(_ zoom: CGFloat) -> CGFloat {
        lastScale + zoom - (lastScale == 0 ? 0 : 1)
    }

    private func handleOffsetChange(_ offset: CGSize) -> CGSize {
        var newOffset: CGSize = .zero

        newOffset.width = offset.width + lastOffset.width
        newOffset.height = offset.height + lastOffset.height

        return newOffset
    }
}