elpha-ios/elpha-ios/AttachmentsView.swift

//
//  AttachmentsView.swift
//  elpha-ios
//
//  Created by Dwayne Harris on 11/28/18.
//  Copyright © 2018 Elpha. All rights reserved.
//

import UIKit

protocol AttachmentsViewDelegate: class {
    func attachmentTapped(_ sender: Any, index: Int)
}

class AttachmentsView: UIView {
    @IBOutlet var contentView: UIView!
    @IBOutlet var attachmentsCollectionView: UICollectionView!
    
    var attachments: [AttachmentMO]?
    weak var delegate: AttachmentsViewDelegate?
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setup()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }
    
    private func setup() {
        Bundle.main.loadNibNamed("AttachmentsView", owner: self, options: nil)
        addSubview(contentView)
        contentView.frame = self.bounds
        contentView.autoresizingMask = [.flexibleWidth]
        
        attachmentsCollectionView.dataSource = self
        attachmentsCollectionView.delegate = self
        
        attachmentsCollectionView.register(UINib(nibName: "ImageAttachmentCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "ImageAttachmentCollectionViewCell")
        attachmentsCollectionView.register(UINib(nibName: "VideoAttachmentCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "VideoAttachmentCollectionViewCell")
    }
    
    func update(withAttachments attachments: [AttachmentMO]) {
        self.attachments = Array(attachments.prefix(4))

        attachmentsCollectionView.reloadData()
        attachmentsCollectionView.collectionViewLayout.invalidateLayout()
    }
}

extension AttachmentsView: UICollectionViewDelegate, UICollectionViewDataSource {
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return attachments?.count ?? 0
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard let attachment = attachments?[indexPath.row] else {
            fatalError("")
        }
        
        let attachmentType = AttachmentType(rawValue: attachment.type!)!
        
        switch attachmentType {
        case .gifv, .video:
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "VideoAttachmentCollectionViewCell", for: indexPath) as! VideoAttachmentCollectionViewCell
            cell.update(withAttachment: attachment)
            return cell
        default:
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ImageAttachmentCollectionViewCell", for: indexPath) as! ImageAttachmentCollectionViewCell
            cell.update(withAttachment: attachment)
            return cell
        }
    }
    
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        delegate?.attachmentTapped(self, index: indexPath.row)
    }
}

extension AttachmentsView: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        print("collectionView sizeForItemAt indexPath: \(indexPath)")
        
        let halfWidth = (frame.size.width / 2) - 2
        let halfHeight = (frame.size.height / 2) - 2
        
        let tallSize = CGSize(width: halfWidth, height: frame.size.height)
        let smallSize = CGSize(width: halfWidth, height: halfHeight)
        
        switch attachments?.count ?? 0 {
        case 1: return CGSize(width: frame.size.width, height: frame.size.height)
        case 2: return tallSize
        case 3: return indexPath.row == 0 ? tallSize : smallSize
        case 4: return smallSize
        default: return CGSize.zero
        }
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 4
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets.zero
    }
}