gallery/Gallery/ReverseImageViewController.swift

import UIKit
import CoreData
import WebKit
import CoreServices

extension Data {

    /// Append string to Data
    ///
    /// Rather than littering my code with calls to `data(using: .utf8)` to convert `String` values to `Data`, this wraps it in a nice convenient little extension to Data. This defaults to converting using UTF-8.
    ///
    /// - parameter string:       The string to be added to the `Data`.

    mutating func append(_ string: String, using encoding: String.Encoding = .utf8) {
        if let data = string.data(using: encoding) {
            append(data)
        }
    }
}

class ReverseImageViewController: UIViewController {
    var post: Post?
    @IBOutlet weak var webView: WKWebView!
    
    let documentsPath : URL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].absoluteURL
    
    private func mimeType(for path: String) -> String {
        let url = URL(fileURLWithPath: path)
        let pathExtension = url.pathExtension

        if let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension as NSString, nil)?.takeRetainedValue() {
            if let mimetype = UTTypeCopyPreferredTagWithClass(uti, kUTTagClassMIMEType)?.takeRetainedValue() {
                return mimetype as String
            }
        }
        return "application/octet-stream"
    }
    
    private func createBody(with parameters: [String: String]?, filePathKey: String, paths: [String], boundary: String) throws -> Data {
        var body = Data()

        if parameters != nil {
            for (key, value) in parameters! {
                body.append("--\(boundary)\r\n")
                body.append("Content-Disposition: form-data; name=\"\(key)\"\r\n\r\n")
                body.append("\(value)\r\n")
            }
        }

        for path in paths {
            let url = URL(fileURLWithPath: path)
            let filename = url.lastPathComponent
            let data = try Data(contentsOf: url)
            let mimetype = mimeType(for: path)

            body.append("--\(boundary)\r\n")
            body.append("Content-Disposition: form-data; name=\"\(filePathKey)\"; filename=\"\(filename)\"\r\n")
            body.append("Content-Type: \(mimetype)\r\n\r\n")
            body.append(data)
            body.append("\r\n")
        }

        body.append("--\(boundary)--\r\n")
        return body
    }
    
    private func generateBoundaryString() -> String {
        return "Boundary-\(UUID().uuidString)"
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        var components = URLComponents(string: "https://iqdb.org")
        components?.queryItems = [URLQueryItem(name: "url", value: "true")]
        if let result = components?.url {
            let boundary = generateBoundaryString()

            var request = URLRequest(url: result)
            request.httpMethod = "POST"
            request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")

            let imagePath = documentsPath.appendingPathComponent(post!.value(forKey: "name") as! String).path

            do {
                request.httpBody = try createBody(with: nil, filePathKey: "file", paths: [imagePath], boundary: boundary)
            } catch let error as NSError {
                print(error)
            }

            webView!.load(request)
        }
    }
    
    @IBAction func cancelAction(_ sender: Any) {
        dismiss(animated: true, completion: nil)
    }
}

extension ReverseImageViewController {
    static func loadFromStoryboard(post: Post) -> ReverseImageViewController? {
        let storyboard = UIStoryboard(name: "Main", bundle: .main)
        let viewController = storyboard.instantiateViewController(withIdentifier: "ReverseImageViewController") as? ReverseImageViewController
        viewController!.post = post
        
        return viewController
    }
}