//
//  KMPDFThumbnialPageView.swift
//  PDF Reader Pro
//
//  Created by tangchao on 2022/11/24.
//

import Cocoa

class KMPDFThumbnialPageView: NSView {
    private var pendingWordItem: DispatchWorkItem?
    var page: CPDFPage? {
        didSet {
            let path = page?.document.documentURL.path ?? ""
            let id = "\(String(describing: self.page?.pageIndex())) + \(self.bounds)"
            let image = KMThumbnailCache.shared.thumbnail(for: path, id: id)
            if image != nil {
                self.pageImageIv.image = image
            } else {
                self.pageImageIv.image = NSImage()
                self.performTask()
            }
        }
    }
    
    var pageImageIv = NSImageView()
    
    var isThumb = false
    
    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
        self.setup();
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
    }
    
    func setup() {
        self.wantsLayer = true
        self.layer?.backgroundColor = NSColor.white.cgColor
        
        self.shadow = NSShadow()
        self.layer?.shadowColor = NSColor.black.cgColor
        self.layer?.shadowOpacity = 0.2
        self.layer?.shadowRadius = 3.0
        self.layer?.shadowOffset = CGSize(width: 0, height: -3)
        
        pageImageIv.wantsLayer = true;
        self.addSubview(self.pageImageIv)
        self.pageImageIv.autoresizingMask = [.width, .height];
        self.pageImageIv.frame = self.bounds
    }
    
    func performTask() {
        pendingWordItem?.cancel()
        let newWorkItem = DispatchWorkItem {
            self.updateThumbnial()
        }
        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.3, execute:newWorkItem)
        pendingWordItem = newWorkItem
    }
    
    func updateThumbnial(needReset: Bool = true) {
        let pageIndex = self.page?.pageIndex()
        let path = page?.document.documentURL.path ?? ""
        let id = "\(String(describing: pageIndex)) + \(self.bounds)"
        let image = KMThumbnailCache.shared.thumbnail(for: path, id: id)
        if image != nil && !needReset {
            self.pageImageIv.image = image
        } else {
            self.page?.thumbnail(of: self.bounds.size, needReset: needReset, completion: { [unowned self] image in
                if (image != nil) {
                    self.pageImageIv.image = image
                    KMThumbnailCache.shared.addThumbnail(for: path, id: id, image: image!)
                }
            })
        }
    }
}