import Foundation

class APIClient: ObservableObject {
    private let baseURL = "https://mkch.pooziqo.xyz"
    private let apiURL = "https://mkch.pooziqo.xyz/api"
    private let session = URLSession.shared
    private var authKey: String = ""
    private var passcode: String = ""
    private let userAgent = "MobileMkch/2.0.0-ios-alpha"
    
    func authenticate(authKey: String, completion: @escaping (Error?) -> Void) {
        self.authKey = authKey
        
        let url = URL(string: "\(baseURL)/key/auth/")!
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(error)
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(APIError(message: "Ошибка получения формы аутентификации", code: 0))
                    return
                }
                
                guard let data = data,
                      let html = String(data: data, encoding: .utf8) else {
                    completion(APIError(message: "Ошибка чтения формы аутентификации", code: 0))
                    return
                }
                
                let csrfToken = self.extractCSRFToken(from: html)
                
                guard !csrfToken.isEmpty else {
                    completion(APIError(message: "Не удалось извлечь CSRF токен", code: 0))
                    return
                }
                
                var formData = URLComponents()
                formData.queryItems = [
                    URLQueryItem(name: "csrfmiddlewaretoken", value: csrfToken),
                    URLQueryItem(name: "key", value: authKey)
                ]
                
                var postRequest = URLRequest(url: url)
                postRequest.httpMethod = "POST"
                postRequest.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
                postRequest.setValue("\(self.baseURL)/key/auth/", forHTTPHeaderField: "Referer")
                postRequest.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
                postRequest.httpBody = formData.query?.data(using: .utf8)
                
                self.session.dataTask(with: postRequest) { _, postResponse, postError in
                    DispatchQueue.main.async {
                        if let postError = postError {
                            completion(postError)
                            return
                        }
                        
                        guard let postHttpResponse = postResponse as? HTTPURLResponse,
                              (postHttpResponse.statusCode == 200 || postHttpResponse.statusCode == 302) else {
                            completion(APIError(message: "Ошибка аутентификации", code: 0))
                            return
                        }
                        
                        completion(nil)
                    }
                }.resume()
            }
        }.resume()
    }
    
    func loginWithPasscode(passcode: String, completion: @escaping (Error?) -> Void) {
        self.passcode = passcode
        
        let url = URL(string: "\(baseURL)/passcode/enter/")!
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(error)
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(APIError(message: "Ошибка получения формы passcode", code: 0))
                    return
                }
                
                guard let data = data,
                      let html = String(data: data, encoding: .utf8) else {
                    completion(APIError(message: "Ошибка чтения формы passcode", code: 0))
                    return
                }
                
                let csrfToken = self.extractCSRFToken(from: html)
                
                guard !csrfToken.isEmpty else {
                    completion(APIError(message: "Не удалось извлечь CSRF токен для passcode", code: 0))
                    return
                }
                
                var formData = URLComponents()
                formData.queryItems = [
                    URLQueryItem(name: "csrfmiddlewaretoken", value: csrfToken),
                    URLQueryItem(name: "passcode", value: passcode)
                ]
                
                var postRequest = URLRequest(url: url)
                postRequest.httpMethod = "POST"
                postRequest.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
                postRequest.setValue("\(self.baseURL)/passcode/enter/", forHTTPHeaderField: "Referer")
                postRequest.httpBody = formData.query?.data(using: .utf8)
                
                self.session.dataTask(with: postRequest) { _, postResponse, postError in
                    DispatchQueue.main.async {
                        if let postError = postError {
                            completion(postError)
                            return
                        }
                        
                        guard let postHttpResponse = postResponse as? HTTPURLResponse,
                              (postHttpResponse.statusCode == 200 || postHttpResponse.statusCode == 302) else {
                            completion(APIError(message: "Ошибка входа с passcode", code: 0))
                            return
                        }
                        
                        completion(nil)
                    }
                }.resume()
            }
        }.resume()
    }
    
    func getBoards(completion: @escaping (Result<[Board], Error>) -> Void) {
        if let cachedBoards = Cache.shared.getBoards() {
            completion(.success(cachedBoards))
            return
        }
        
        let url = URL(string: "\(apiURL)/boards/")!
        var request = URLRequest(url: url)
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(.failure(error))
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(.failure(APIError(message: "Ошибка получения досок", code: 0)))
                    return
                }
                
                guard let data = data else {
                    completion(.failure(APIError(message: "Нет данных", code: 0)))
                    return
                }
                
                do {
                    let boards = try JSONDecoder().decode([Board].self, from: data)
                    Cache.shared.setBoards(boards)
                    completion(.success(boards))
                } catch {
                    completion(.failure(error))
                }
            }
        }.resume()
    }
    
    func getThreads(forBoard boardCode: String, completion: @escaping (Result<[Thread], Error>) -> Void) {
        if let cachedThreads = Cache.shared.getThreads(forBoard: boardCode) {
            completion(.success(cachedThreads))
            return
        }
        
        let url = URL(string: "\(apiURL)/board/\(boardCode)")!
        var request = URLRequest(url: url)
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(.failure(error))
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(.failure(APIError(message: "Ошибка получения тредов", code: 0)))
                    return
                }
                
                guard let data = data else {
                    completion(.failure(APIError(message: "Нет данных", code: 0)))
                    return
                }
                
                do {
                    let threads = try JSONDecoder().decode([Thread].self, from: data)
                    Cache.shared.setThreads(threads, forBoard: boardCode)
                    completion(.success(threads))
                } catch {
                    completion(.failure(error))
                }
            }
        }.resume()
    }
    
    func getThreadDetail(boardCode: String, threadId: Int, completion: @escaping (Result<ThreadDetail, Error>) -> Void) {
        if let cachedThread = Cache.shared.getThreadDetail(forThreadId: threadId) {
            completion(.success(cachedThread))
            return
        }
        
        let url = URL(string: "\(apiURL)/board/\(boardCode)/thread/\(threadId)")!
        var request = URLRequest(url: url)
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(.failure(error))
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(.failure(APIError(message: "Ошибка получения треда", code: 0)))
                    return
                }
                
                guard let data = data else {
                    completion(.failure(APIError(message: "Нет данных", code: 0)))
                    return
                }
                
                do {
                    let thread = try JSONDecoder().decode(ThreadDetail.self, from: data)
                    Cache.shared.setThreadDetail(thread, forThreadId: threadId)
                    completion(.success(thread))
                } catch {
                    completion(.failure(error))
                }
            }
        }.resume()
    }
    
    func getComments(boardCode: String, threadId: Int, completion: @escaping (Result<[Comment], Error>) -> Void) {
        if let cachedComments = Cache.shared.getComments(forThreadId: threadId) {
            completion(.success(cachedComments))
            return
        }
        
        let url = URL(string: "\(apiURL)/board/\(boardCode)/thread/\(threadId)/comments")!
        var request = URLRequest(url: url)
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(.failure(error))
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(.failure(APIError(message: "Ошибка получения комментариев", code: 0)))
                    return
                }
                
                guard let data = data else {
                    completion(.failure(APIError(message: "Нет данных", code: 0)))
                    return
                }
                
                do {
                    let comments = try JSONDecoder().decode([Comment].self, from: data)
                    Cache.shared.setComments(comments, forThreadId: threadId)
                    completion(.success(comments))
                } catch {
                    completion(.failure(error))
                }
            }
        }.resume()
    }
    
    func getFullThread(boardCode: String, threadId: Int, completion: @escaping (Result<(ThreadDetail, [Comment]), Error>) -> Void) {
        let group = DispatchGroup()
        var threadDetail: ThreadDetail?
        var comments: [Comment]?
        var threadError: Error?
        var commentsError: Error?
        
        group.enter()
        getThreadDetail(boardCode: boardCode, threadId: threadId) { result in
            switch result {
            case .success(let detail):
                threadDetail = detail
            case .failure(let error):
                threadError = error
            }
            group.leave()
        }
        
        group.enter()
        getComments(boardCode: boardCode, threadId: threadId) { result in
            switch result {
            case .success(let commentList):
                comments = commentList
            case .failure(let error):
                commentsError = error
            }
            group.leave()
        }
        
        group.notify(queue: .main) {
            if let threadError = threadError {
                completion(.failure(threadError))
                return
            }
            
            if let commentsError = commentsError {
                completion(.failure(commentsError))
                return
            }
            
            guard let detail = threadDetail, let commentList = comments else {
                completion(.failure(APIError(message: "Не удалось загрузить данные", code: 0)))
                return
            }
            
            completion(.success((detail, commentList)))
        }
    }
    
    func createThread(boardCode: String, title: String, text: String, passcode: String, completion: @escaping (Error?) -> Void) {
        if !passcode.isEmpty {
            loginWithPasscode(passcode: passcode) { error in
                if let error = error {
                    completion(error)
                    return
                }
                self.performCreateThread(boardCode: boardCode, title: title, text: text, completion: completion)
            }
        } else {
            performCreateThread(boardCode: boardCode, title: title, text: text, completion: completion)
        }
    }
    
    private func performCreateThread(boardCode: String, title: String, text: String, completion: @escaping (Error?) -> Void) {
        let formURL = "\(baseURL)/boards/board/\(boardCode)/new"
        let url = URL(string: formURL)!
        
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(error)
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(APIError(message: "Ошибка получения формы", code: 0))
                    return
                }
                
                guard let data = data,
                      let html = String(data: data, encoding: .utf8) else {
                    completion(APIError(message: "Ошибка чтения формы", code: 0))
                    return
                }
                
                let csrfToken = self.extractCSRFToken(from: html)
                
                guard !csrfToken.isEmpty else {
                    completion(APIError(message: "Не удалось извлечь CSRF токен", code: 0))
                    return
                }
                
                var formData = URLComponents()
                formData.queryItems = [
                    URLQueryItem(name: "csrfmiddlewaretoken", value: csrfToken),
                    URLQueryItem(name: "title", value: title),
                    URLQueryItem(name: "text", value: text)
                ]
                
                var postRequest = URLRequest(url: url)
                postRequest.httpMethod = "POST"
                postRequest.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
                postRequest.setValue(formURL, forHTTPHeaderField: "Referer")
                postRequest.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
                postRequest.httpBody = formData.query?.data(using: .utf8)
                
                self.session.dataTask(with: postRequest) { _, postResponse, postError in
                    DispatchQueue.main.async {
                        if let postError = postError {
                            completion(postError)
                            return
                        }
                        
                        guard let postHttpResponse = postResponse as? HTTPURLResponse,
                              (postHttpResponse.statusCode == 200 || postHttpResponse.statusCode == 302) else {
                            completion(APIError(message: "Ошибка создания треда", code: 0))
                            return
                        }
                        
                        Cache.shared.delete("threads_\(boardCode)")
                        completion(nil)
                    }
                }.resume()
            }
        }.resume()
    }
    
    func addComment(boardCode: String, threadId: Int, text: String, passcode: String, completion: @escaping (Error?) -> Void) {
        if !passcode.isEmpty {
            loginWithPasscode(passcode: passcode) { error in
                if let error = error {
                    completion(error)
                    return
                }
                self.performAddComment(boardCode: boardCode, threadId: threadId, text: text, completion: completion)
            }
        } else {
            performAddComment(boardCode: boardCode, threadId: threadId, text: text, completion: completion)
        }
    }
    
    private func performAddComment(boardCode: String, threadId: Int, text: String, completion: @escaping (Error?) -> Void) {
        let formURL = "\(baseURL)/boards/board/\(boardCode)/thread/\(threadId)/comment"
        let url = URL(string: formURL)!
        
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(error)
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(APIError(message: "Ошибка получения формы", code: 0))
                    return
                }
                
                guard let data = data,
                      let html = String(data: data, encoding: .utf8) else {
                    completion(APIError(message: "Ошибка чтения формы", code: 0))
                    return
                }
                
                let csrfToken = self.extractCSRFToken(from: html)
                
                guard !csrfToken.isEmpty else {
                    completion(APIError(message: "Не удалось извлечь CSRF токен", code: 0))
                    return
                }
                
                var formData = URLComponents()
                formData.queryItems = [
                    URLQueryItem(name: "csrfmiddlewaretoken", value: csrfToken),
                    URLQueryItem(name: "text", value: text)
                ]
                
                var postRequest = URLRequest(url: url)
                postRequest.httpMethod = "POST"
                postRequest.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
                postRequest.setValue(formURL, forHTTPHeaderField: "Referer")
                postRequest.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
                postRequest.httpBody = formData.query?.data(using: .utf8)
                
                self.session.dataTask(with: postRequest) { _, postResponse, postError in
                    DispatchQueue.main.async {
                        if let postError = postError {
                            completion(postError)
                            return
                        }
                        
                        guard let postHttpResponse = postResponse as? HTTPURLResponse,
                              (postHttpResponse.statusCode == 200 || postHttpResponse.statusCode == 302) else {
                            completion(APIError(message: "Ошибка добавления комментария", code: 0))
                            return
                        }
                        
                        Cache.shared.delete("comments_\(threadId)")
                        completion(nil)
                    }
                }.resume()
            }
        }.resume()
    }
    
    private func extractCSRFToken(from html: String) -> String {
        let pattern = #"name=['"]csrfmiddlewaretoken['"]\s+value=['"]([^'"]+)['"]"#
        let regex = try? NSRegularExpression(pattern: pattern)
        
        guard let match = regex?.firstMatch(in: html, range: NSRange(html.startIndex..., in: html)) else {
            return ""
        }
        
        guard let range = Range(match.range(at: 1), in: html) else {
            return ""
        }
        
        return String(html[range])
    }
    
    func checkNewThreads(forBoard boardCode: String, lastKnownThreadId: Int, completion: @escaping (Result<[Thread], Error>) -> Void) {
        let url = URL(string: "\(apiURL)/board/\(boardCode)")!
        var request = URLRequest(url: url)
        request.setValue(self.userAgent, forHTTPHeaderField: "User-Agent")
        
        session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                if let error = error {
                    completion(.failure(error))
                    return
                }
                
                guard let httpResponse = response as? HTTPURLResponse,
                      httpResponse.statusCode == 200 else {
                    completion(.failure(APIError(message: "Ошибка получения тредов", code: 0)))
                    return
                }
                
                guard let data = data else {
                    completion(.failure(APIError(message: "Нет данных", code: 0)))
                    return
                }
                
                do {
                    let threads = try JSONDecoder().decode([Thread].self, from: data)
                    let newThreads = threads.filter { $0.id > lastKnownThreadId }
                    completion(.success(newThreads))
                } catch {
                    completion(.failure(error))
                }
            }
        }.resume()
    }
}