//
//  Service.swift
//  Juick
//
//  Created by Vitaly Takmazov on 16.09.2020.
//  Copyright © 2020 com.juick. All rights reserved.
//

import Foundation

class Service : NSObject, URLSessionDelegate, URLSessionTaskDelegate {
    let backgroundQueue = OperationQueue()
    
    let baseURL : URL?
    
    lazy var authorizationHeader : String? = {
        if let token = UserDefaults.standard.string(forKey: "token") {
            return "Juick \(token)"
        }
        return nil;
    }()
    
    override init() {
        let baseURLString = Bundle.main.object(forInfoDictionaryKey:"base_url") as! String
        debugPrint("Initializing with \(baseURLString) base URL")
        self.baseURL = URL(string: baseURLString)
        super.init()
    }
    func url(url:URL, params:[String: String]) -> URL {
        let parametersUrl = NSURLComponents(url: url, resolvingAgainstBaseURL: true)
        var items : [URLQueryItem] = []
        for (key, value) in params {
            items.append(URLQueryItem(name: key, value: value))
        }
        parametersUrl?.queryItems = items
        return (parametersUrl?.url!)!
    }
    func fetchData(url:URL, postData:Data?, boundary:String?, header:String?, callback: @escaping (Data?, Error?) -> Void) {
        var request = URLRequest(url: url)
        if (header != nil) {
            request.addValue(header!, forHTTPHeaderField:"Authorization")
        }
        if (boundary != nil) {
            request.httpMethod = "POST";
            request.httpBody = postData;
            let contentType = "multipart/form-data; boundary=\(boundary!)"
            request.setValue(contentType, forHTTPHeaderField:"Content-Type")
        } else if (postData != nil) {
            request.httpMethod = "PUT";
            request.httpBody = postData;
            request.setValue("application/json", forHTTPHeaderField:"Content-Type")
        } else {
            request.httpMethod = "GET";
        }
        
        let task = URLSession.shared.dataTask(with: request, completionHandler: { (data, response, error) in
            if (error != nil) {
                OperationQueue.main.addOperation {
                    callback(nil, error)
                }
            } else {
                let statusCode = (response as? HTTPURLResponse)?.statusCode ?? 457
                if (response == nil || statusCode != 200) {
                    let url = request.url
                    let err = NSError(domain: "JuickErrorDomain", code: statusCode, userInfo: ["url":url!.absoluteString])
                    OperationQueue.main.addOperation {
                        callback(nil, err)
                    }
                } else {
                    OperationQueue.main.addOperation {
                        callback(data, error)
                    }
                }
            }
        })
        self.backgroundQueue.addOperation {
            task.resume()
        }
    }
    private func multipartData(params:[String:String], boundary:String) -> Data {
        var body = Data()
        for (key, value) in params {
            body.append("--\(boundary)\r\n".data(using: .utf8)!)
            body.append("Content-Disposition: form-data; name=\(key)\r\n\r\n".data(using: .utf8)!)
            body.append("\(value)\r\n".data(using: .utf8)!)
        }
        body.append("--\(boundary)--".data(using: .utf8)!)
        return body;
    }
    private func get(path:String, params:[String:String], callback:@escaping (NSDictionary?, Error?) -> Void) {
        if let url = URL(string: path, relativeTo: self.baseURL) {
            let requestUrl = params.isEmpty ? url : self.url(url: url, params: params)
            fetchData(url: requestUrl, postData: nil, boundary: nil, header: self.authorizationHeader) {
                (responseData, err) in
                if (err != nil) {
                    callback(nil, err)
                } else {
                    if let data = responseData, let jsonData = try? JSONSerialization.jsonObject(with: data, options: []) {
                        callback(jsonData as? NSDictionary, nil)
                    } else {
                        callback(nil, NSError(domain: "JuickErrorDomain", code: 500, userInfo: ["message":"JSON error"]))
                    }
                }
            }
        }
    }
    
    func post(path: String, params:[String:String], callback:@escaping (NSDictionary?, Error?) -> Void) {
        if let url = URL(string: path, relativeTo: self.baseURL) {
            let boundary = "Boundary-\(UUID().uuidString)";
            fetchData(url: url, postData:multipartData(params: params, boundary: boundary), boundary: boundary, header: self.authorizationHeader) {
                (responseData, err) in
                if (err != nil) {
                    callback(nil, err)
                } else {
                    if let data = responseData, let jsonData = try? JSONSerialization.jsonObject(with: data, options: []) {
                        callback(jsonData as? NSDictionary, nil)
                    } else {
                        callback(nil, NSError(domain: "JuickErrorDomain", code: 500, userInfo: ["message":"JSON error"]))
                    }
                }
            }
        }
    }

    func fetchImage(url:URL, callback:@escaping(Data?)-> Void) {
        fetchData(url: url, postData: nil, boundary: nil, header: self.authorizationHeader) { (data, err) in
            if (err != nil) {
                callback(nil);
            } else {
                callback(data);
            }
        }
    }
}