//
//  ChatAPI.swift
//  SimpleX
//
//  Created by Evgeny Poberezkin on 27/01/2022.
//  Copyright © 2022 SimpleX Chat. All rights reserved.
//

import Foundation
import UIKit

private var chatController: chat_ctrl?
private let jsonDecoder = getJSONDecoder()
private let jsonEncoder = getJSONEncoder()

enum ChatCommand {
    case showActiveUser
    case createActiveUser(profile: Profile)
    case startChat
    case apiGetChats
    case apiGetChat(type: ChatType, id: Int64)
    case apiSendMessage(type: ChatType, id: Int64, msg: MsgContent)
    case addContact
    case connect(connReq: String)
    case apiDeleteChat(type: ChatType, id: Int64)
    case updateProfile(profile: Profile)
    case createMyAddress
    case deleteMyAddress
    case showMyAddress
    case apiAcceptContact(contactReqId: Int64)
    case apiRejectContact(contactReqId: Int64)
    case string(String)

    var cmdString: String {
        get {
            switch self {
            case .showActiveUser: return "/u"
            case let .createActiveUser(profile): return "/u \(profile.displayName) \(profile.fullName)"
            case .startChat: return "/_start"
            case .apiGetChats: return "/_get chats"
            case let .apiGetChat(type, id): return "/_get chat \(type.rawValue)\(id) count=500"
            case let .apiSendMessage(type, id, mc): return "/_send \(type.rawValue)\(id) \(mc.cmdString)"
            case .addContact: return "/connect"
            case let .connect(connReq): return "/connect \(connReq)"
            case let .apiDeleteChat(type, id): return "/_delete \(type.rawValue)\(id)"
            case let .updateProfile(profile): return "/profile \(profile.displayName) \(profile.fullName)"
            case .createMyAddress: return "/address"
            case .deleteMyAddress: return "/delete_address"
            case .showMyAddress: return "/show_address"
            case let .apiAcceptContact(contactReqId): return "/_accept \(contactReqId)"
            case let .apiRejectContact(contactReqId): return "/_reject \(contactReqId)"
            case let .string(str): return str
            }
        }
    }
}

struct APIResponse: Decodable {
    var resp: ChatResponse
}

enum ChatResponse: Decodable, Error {
    case response(type: String, json: String)
    case activeUser(user: User)
    case chatStarted
    case apiChats(chats: [ChatData])
    case apiChat(chat: ChatData)
    case invitation(connReqInvitation: String)
    case sentConfirmation
    case sentInvitation
    case contactDeleted(contact: Contact)
    case userProfileNoChange
    case userProfileUpdated(fromProfile: Profile, toProfile: Profile)
    case userContactLink(connReqContact: String)
    case userContactLinkCreated(connReqContact: String)
    case userContactLinkDeleted
    case contactConnected(contact: Contact)
    case receivedContactRequest(contactRequest: UserContactRequest)
    case acceptingContactRequest(contact: Contact)
    case contactRequestRejected
    case contactUpdated(toContact: Contact)
    case contactSubscribed(contact: Contact)
    case contactDisconnected(contact: Contact)
    case contactSubError(contact: Contact, chatError: ChatError)
    case newChatItem(chatItem: AChatItem)
    case chatCmdError(chatError: ChatError)
    case chatError(chatError: ChatError)

    var responseType: String {
        get {
            switch self {
            case let .response(type, _): return "* \(type)"
            case .activeUser: return "activeUser"
            case .chatStarted: return "chatStarted"
            case .apiChats: return "apiChats"
            case .apiChat: return "apiChat"
            case .invitation: return "invitation"
            case .sentConfirmation: return "sentConfirmation"
            case .sentInvitation: return "sentInvitation"
            case .contactDeleted: return "contactDeleted"
            case .userProfileNoChange: return "userProfileNoChange"
            case .userProfileUpdated: return "userProfileNoChange"
            case .userContactLink: return "userContactLink"
            case .userContactLinkCreated: return "userContactLinkCreated"
            case .userContactLinkDeleted: return "userContactLinkDeleted"
            case .contactConnected: return "contactConnected"
            case .receivedContactRequest: return "receivedContactRequest"
            case .acceptingContactRequest: return "acceptingContactRequest"
            case .contactRequestRejected: return "contactRequestRejected"
            case .contactUpdated: return "contactUpdated"
            case .contactSubscribed: return "contactSubscribed"
            case .contactDisconnected: return "contactDisconnected"
            case .contactSubError: return "contactSubError"
            case .newChatItem: return "newChatItem"
            case .chatCmdError: return "chatCmdError"
            case .chatError: return "chatError"
            }
        }
    }
    
    var details: String {
        get {
            switch self {
            case let .response(_, json): return json
            case let .activeUser(user): return String(describing: user)
            case .chatStarted: return noDetails
            case let .apiChats(chats): return String(describing: chats)
            case let .apiChat(chat): return String(describing: chat)
            case let .invitation(connReqInvitation): return connReqInvitation
            case .sentConfirmation: return noDetails
            case .sentInvitation: return noDetails
            case let .contactDeleted(contact): return String(describing: contact)
            case .userProfileNoChange: return noDetails
            case let .userProfileUpdated(_, toProfile): return String(describing: toProfile)
            case let .userContactLink(connReq): return connReq
            case let .userContactLinkCreated(connReq): return connReq
            case .userContactLinkDeleted: return noDetails
            case let .contactConnected(contact): return String(describing: contact)
            case let .receivedContactRequest(contactRequest): return String(describing: contactRequest)
            case let .acceptingContactRequest(contact): return String(describing: contact)
            case .contactRequestRejected: return noDetails
            case let .contactUpdated(toContact): return String(describing: toContact)
            case let .contactSubscribed(contact): return String(describing: contact)
            case let .contactDisconnected(contact): return String(describing: contact)
            case let .contactSubError(contact, chatError): return "contact:\n\(String(describing: contact))\nerror:\n\(String(describing: chatError))"
            case let .newChatItem(chatItem): return String(describing: chatItem)
            case let .chatCmdError(chatError): return String(describing: chatError)
            case let .chatError(chatError): return String(describing: chatError)
            }
        }
    }

    private var noDetails: String { get { "\(responseType): no details" } }
}

enum TerminalItem: Identifiable {
    case cmd(Date, ChatCommand)
    case resp(Date, ChatResponse)

    var id: Date {
        get {
            switch self {
            case let .cmd(id, _): return id
            case let .resp(id, _): return id
            }
        }
    }

    var label: String {
        get {
            switch self {
            case let .cmd(_, cmd): return "> \(cmd.cmdString.prefix(30))"
            case let .resp(_, resp): return "< \(resp.responseType)"
            }
        }
    }

    var details: String {
        get {
            switch self {
            case let .cmd(_, cmd): return cmd.cmdString
            case let .resp(_, resp): return resp.details
            }
        }
    }
}

func chatSendCmd(_ cmd: ChatCommand) throws -> ChatResponse {
    var c = cmd.cmdString.cString(using: .utf8)!
    print("command", cmd.cmdString)
// TODO some mechanism to update model without passing it - maybe Publisher / Subscriber?
//    DispatchQueue.main.async {
//        termId += 1
//        chatModel.terminalItems.append(.cmd(termId, cmd))
//    }
    return chatResponse(chat_send_cmd(getChatCtrl(), &c)!)
}

func chatRecvMsg() throws -> ChatResponse {
    chatResponse(chat_recv_msg(getChatCtrl())!)
}

func apiGetActiveUser() throws -> User? {
    let r = try chatSendCmd(.showActiveUser)
    switch r {
    case let .activeUser(user): return user
    case .chatCmdError(.error(.noActiveUser)): return nil
    default: throw r
    }
}

func apiCreateActiveUser(_ p: Profile) throws -> User {
    let r = try chatSendCmd(.createActiveUser(profile: p))
    if case let .activeUser(user) = r { return user }
    throw r
}

func apiStartChat() throws {
    let r = try chatSendCmd(.startChat)
    if case .chatStarted = r { return }
    throw r
}

func apiGetChats() throws -> [Chat] {
    let r = try chatSendCmd(.apiGetChats)
    if case let .apiChats(chats) = r { return chats.map { Chat.init($0) } }
    throw r
}

func apiGetChat(type: ChatType, id: Int64) throws -> Chat {
    let r = try chatSendCmd(.apiGetChat(type: type, id: id))
    if case let .apiChat(chat) = r { return Chat.init(chat) }
    throw r
}

func apiSendMessage(type: ChatType, id: Int64, msg: MsgContent) throws -> ChatItem {
    let r = try chatSendCmd(.apiSendMessage(type: type, id: id, msg: msg))
    if case let .newChatItem(aChatItem) = r { return aChatItem.chatItem }
    throw r
}

func apiAddContact() throws -> String {
    let r = try chatSendCmd(.addContact)
    if case let .invitation(connReqInvitation) = r { return connReqInvitation }
    throw r
}

func apiConnect(connReq: String) throws {
    let r = try chatSendCmd(.connect(connReq: connReq))
    switch r {
    case .sentConfirmation: return
    case .sentInvitation: return
    default: throw r
    }
}

func apiDeleteChat(type: ChatType, id: Int64) throws {
    let r = try chatSendCmd(.apiDeleteChat(type: type, id: id))
    if case .contactDeleted = r { return }
    throw r
}

func apiUpdateProfile(profile: Profile) throws -> Profile? {
    let r = try chatSendCmd(.updateProfile(profile: profile))
    switch r {
    case .userProfileNoChange: return nil
    case let .userProfileUpdated(_, toProfile): return toProfile
    default: throw r
    }
}

func apiCreateUserAddress() throws -> String {
    let r = try chatSendCmd(.createMyAddress)
    if case let .userContactLinkCreated(connReq) = r { return connReq }
    throw r
}

func apiDeleteUserAddress() throws {
    let r = try chatSendCmd(.deleteMyAddress)
    if case .userContactLinkDeleted = r { return }
    throw r
}

func apiGetUserAddress() throws -> String? {
    let r = try chatSendCmd(.showMyAddress)
    switch r {
    case let .userContactLink(connReq):
        return connReq
    case .chatCmdError(chatError: .errorStore(storeError: .userContactLinkNotFound)):
        return nil
    default: throw r
    }
}

func apiAcceptContactRequest(contactReqId: Int64) throws -> Contact {
    let r = try chatSendCmd(.apiAcceptContact(contactReqId: contactReqId))
    if case let .acceptingContactRequest(contact) = r { return contact }
    throw r
}

func apiRejectContactRequest(contactReqId: Int64) throws {
    let r = try chatSendCmd(.apiRejectContact(contactReqId: contactReqId))
    if case .contactRequestRejected = r { return }
    throw r
}

func processReceivedMsg(_ chatModel: ChatModel, _ res: ChatResponse) {
    DispatchQueue.main.async {
        chatModel.terminalItems.append(.resp(.now, res))
        switch res {
        case let .contactConnected(contact):
            chatModel.updateContact(contact)
            chatModel.updateNetworkStatus(contact, .connected)
        case let .receivedContactRequest(contactRequest):
            chatModel.addChat(Chat(
                chatInfo: ChatInfo.contactRequest(contactRequest: contactRequest),
                chatItems: []
            ))
        case let .contactUpdated(toContact):
            let cInfo = ChatInfo.direct(contact: toContact)
            if chatModel.hasChat(toContact.id) {
                chatModel.updateChatInfo(cInfo)
            }
        case let .contactSubscribed(contact):
            chatModel.updateContact(contact)
            chatModel.updateNetworkStatus(contact, .connected)
        case let .contactDisconnected(contact):
            chatModel.updateContact(contact)
            chatModel.updateNetworkStatus(contact, .disconnected)
        case let .contactSubError(contact, chatError):
            chatModel.updateContact(contact)
            var err: String
            switch chatError {
            case .errorAgent(agentError: .BROKER(brokerErr: .NETWORK)): err = "network"
            case .errorAgent(agentError: .SMP(smpErr: .AUTH)): err = "contact deleted"
            default: err = String(describing: chatError)
            }
            chatModel.updateNetworkStatus(contact, .error(err))
        case let .newChatItem(aChatItem):
            chatModel.addChatItem(aChatItem.chatInfo, aChatItem.chatItem)
        default:
            print("unsupported response: ", res.responseType)
        }
    }
}

private struct UserResponse: Decodable {
    var user: User?
    var error: String?
}

private func chatResponse(_ cjson: UnsafePointer<CChar>) -> ChatResponse {
    let s = String.init(cString: cjson)
    let d = s.data(using: .utf8)!
// TODO is there a way to do it without copying the data? e.g:
//    let p = UnsafeMutableRawPointer.init(mutating: UnsafeRawPointer(cjson))
//    let d = Data.init(bytesNoCopy: p, count: strlen(cjson), deallocator: .free)

// TODO some mechanism to update model without passing it - maybe Publisher / Subscriber?

    do {
        let r = try jsonDecoder.decode(APIResponse.self, from: d)
        return r.resp
    } catch {
        print (error)
    }
        
    var type: String?
    var json: String?
    if let j = try? JSONSerialization.jsonObject(with: d) as? NSDictionary {
        if let j1 = j["resp"] as? NSDictionary, j1.count == 1 {
            type = j1.allKeys[0] as? String
        }
        json = prettyJSON(j)
    }
    return ChatResponse.response(type: type ?? "invalid", json: json ?? s)
}

func prettyJSON(_ obj: NSDictionary) -> String? {
    if let d = try? JSONSerialization.data(withJSONObject: obj, options: .prettyPrinted) {
        return String(decoding: d, as: UTF8.self)
    }
    return nil
}

private func getChatCtrl() -> chat_ctrl {
    if let controller = chatController { return controller }
    let dataDir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.path + "/mobile_v1"
    var cstr = dataDir.cString(using: .utf8)!
    chatController = chat_init(&cstr)
    return chatController!
}

private func decodeCJSON<T: Decodable>(_ cjson: UnsafePointer<CChar>) -> T? {
    let s = String.init(cString: cjson)
    let d = s.data(using: .utf8)!
//    let p = UnsafeMutableRawPointer.init(mutating: UnsafeRawPointer(cjson))
//    let d = Data.init(bytesNoCopy: p, count: strlen(cjson), deallocator: .free)
    return try? jsonDecoder.decode(T.self, from: d)
}

private func getJSONObject(_ cjson: UnsafePointer<CChar>) -> NSDictionary? {
    let s = String.init(cString: cjson)
    let d = s.data(using: .utf8)!
    return try? JSONSerialization.jsonObject(with: d) as? NSDictionary
}

private func encodeCJSON<T: Encodable>(_ value: T) -> [CChar] {
    let data = try! jsonEncoder.encode(value)
    let str = String(decoding: data, as: UTF8.self)
    return str.cString(using: .utf8)!
}

enum ChatError: Decodable {
    case error(errorType: ChatErrorType)
    case errorAgent(agentError: AgentErrorType)
    case errorStore(storeError: StoreError)
}

enum ChatErrorType: Decodable {
    case noActiveUser
    case activeUserExists
    case chatNotStarted
    case invalidConnReq
    case invalidChatMessage(message: String)
    case contactGroups(contact: Contact, groupNames: [GroupName])
    case groupUserRole
    case groupContactRole(contactName: ContactName)
    case groupDuplicateMember(contactName: ContactName)
    case groupDuplicateMemberId
    case groupNotJoined(groupInfo: GroupInfo)
    case groupMemberNotActive
    case groupMemberUserRemoved
    case groupMemberNotFound(contactName: ContactName)
    case groupMemberIntroNotFound(contactName: ContactName)
    case groupCantResendInvitation(groupInfo: GroupInfo, contactName: ContactName)
    case groupInternal(message: String)
    case fileNotFound(message: String)
    case fileAlreadyReceiving(message: String)
    case fileAlreadyExists(filePath: String)
    case fileRead(filePath: String, message: String)
    case fileWrite(filePath: String, message: String)
    case fileSend(fileId: Int64, agentError: String)
    case fileRcvChunk(message: String)
    case fileInternal(message: String)
    case agentVersion
    case commandError(message: String)
}

enum StoreError: Decodable {
    case duplicateName
    case contactNotFound(contactId: Int64)
    case contactNotFoundByName(contactName: ContactName)
    case contactNotReady(contactName: ContactName)
    case duplicateContactLink
    case userContactLinkNotFound
    case contactRequestNotFound(contactRequestId: Int64)
    case contactRequestNotFoundByName(contactName: ContactName)
    case groupNotFound(groupId: Int64)
    case groupNotFoundByName(groupName: GroupName)
    case groupWithoutUser
    case duplicateGroupMember
    case groupAlreadyJoined
    case groupInvitationNotFound
    case sndFileNotFound(fileId: Int64)
    case sndFileInvalid(fileId: Int64)
    case rcvFileNotFound(fileId: Int64)
    case fileNotFound(fileId: Int64)
    case rcvFileInvalid(fileId: Int64)
    case connectionNotFound(agentConnId: String)
    case introNotFound
    case uniqueID
    case internalError(message: String)
    case noMsgDelivery(connId: Int64, agentMsgId: String)
    case badChatItem(itemId: Int64)
    case chatItemNotFound(itemId: Int64)
}

enum AgentErrorType: Decodable {
    case CMD(cmdErr: CommandErrorType)
    case CONN(connErr: ConnectionErrorType)
    case SMP(smpErr: SMPErrorType)
    case BROKER(brokerErr: BrokerErrorType)
    case AGENT(agentErr: SMPAgentError)
    case INTERNAL(internalErr: String)
}

enum CommandErrorType: Decodable {
    case PROHIBITED
    case SYNTAX
    case NO_CONN
    case SIZE
    case LARGE
}

enum ConnectionErrorType: Decodable {
    case NOT_FOUND
    case DUPLICATE
    case SIMPLEX
    case NOT_ACCEPTED
    case NOT_AVAILABLE
}

enum BrokerErrorType: Decodable {
    case RESPONSE(smpErr: SMPErrorType)
    case UNEXPECTED
    case NETWORK
    case TRANSPORT(transportErr: SMPTransportError)
    case TIMEOUT
}

enum SMPErrorType: Decodable {
    case BLOCK
    case SESSION
    case CMD(cmdErr: SMPCommandError)
    case AUTH
    case QUOTA
    case NO_MSG
    case LARGE_MSG
    case INTERNAL
}

enum SMPCommandError: Decodable {
    case UNKNOWN
    case SYNTAX
    case NO_AUTH
    case HAS_AUTH
    case NO_QUEUE
}

enum SMPTransportError: Decodable {
    case TEBadBlock
    case TELargeMsg
    case TEBadSession
    case TEHandshake(handshakeErr: SMPHandshakeError)
}

enum SMPHandshakeError: Decodable {
    case PARSE
    case VERSION
    case IDENTITY
}

enum SMPAgentError: Decodable {
    case A_MESSAGE
    case A_PROHIBITED
    case A_VERSION
    case A_ENCRYPTION
}