//
//  WCManager.swift
//  meterios
//
//  (c) 2025 Martin "maride" Dessauer
//

import SwiftUI
import WatchConnectivity

enum WCMeteriosMessageTypes: String {
    case ConnectionInfo
    case DrinkList
    case BookDrink
}

class WCManager: NSObject, WCSessionDelegate {
    @AppStorage("meteHostAddr") private var meteHostAddr = ""
    @AppStorage("meteUserID") private var meteUserID = -1
    
    private let session: WCSession = WCSession.default
    
    override init() {
        super.init()
        
        if (WCSession.isSupported()) {
            session.delegate = self
            session.activate()
            log("Activated session")
        }
    }
    
    // Functions required by WCSessionDelegate protocol, but not of interest for Meterios
#if os(iOS)
    func sessionDidBecomeInactive(_ session: WCSession) {}
    func sessionDidDeactivate(_ session: WCSession) {}
#endif // os(iOS)
    func session(_ session: WCSession, activationDidCompleteWith activationState: WCSessionActivationState, error: (any Error)?) {}
    
    // session(...) gets called for every incoming message through the WatchConnectivity channel
    // As Meterios currently only needs messages from watch to device and responses back to the watch, this function currently only implements device-related responses.
    func session(_ session: WCSession, didReceiveMessage message: [String : Any], replyHandler: @escaping ([String : Any]) -> Void) {
        // Check for the different possible message types
        if message.contains(where: { $0.key == "request" && $0.value as! String == WCMeteriosMessageTypes.ConnectionInfo.rawValue }) {
            // Request for ConnectionInfo
            replyHandler([
                "userID": meteUserID,
                "hostAddr": meteHostAddr
            ])
        } else if message.contains(where: { $0.key == "request" && $0.value as! String == WCMeteriosMessageTypes.DrinkList.rawValue }) {
            // Request for a list of available drinks
            Task {
                let drinks = try await BackendConnector().GetDrinks(baseAddr: meteHostAddr)
                let availableDrinks = drinks.filter({ $0.active })
                
                // Create a plist-compatible variant of the Drink object containing the required information
                var drinkArray: Array<String> = []
                for d in availableDrinks {
                    drinkArray.append(
                        try! JSONEncoder().encode(d).base64EncodedString()
                    )
                }
                
                replyHandler([
                    "drinks": drinkArray
                ])
            }
        } else if message.contains(where: { $0.key == "request" && $0.value as! String == WCMeteriosMessageTypes.BookDrink.rawValue }) {
            // Book the given drink at the backend
            Task {
                do {
                    // Book
                    let drinkID = message["drinkID"] as! Int
                    try await BackendConnector().BookDrink(baseAddr: meteHostAddr, userID: meteUserID, drinkID: drinkID)
                    replyHandler([
                        "salut": SalutManager.getSalute()
                    ])
                } catch {
                    // Error booking against the backend
                    replyHandler([
                        "error": error,
                        "salut": ""
                    ])
                }
            }
        } else {
            log("Error: received unknown request. \(message)")
        }
    }
    
    // requestConnectionInfo requests User ID and Host address from the paired device
    func requestConnectionInfo(replyHandler: @escaping (Int, String) -> Void, errorHandler: @escaping ((any Error)?) -> Void) {
        session.sendMessage([
            "request": WCMeteriosMessageTypes.ConnectionInfo.rawValue
        ], replyHandler: { reply in
            replyHandler(reply["userID"] as! Int, reply["hostAddr"] as! String)
        }, errorHandler: { error in
            errorHandler(error)
        })
    }
    
    // requestDrinksList requests the list of drinks available at the backend from the paired device
    func requestDrinksList(replyHandler: @escaping (Array<Drink>) -> Void, errorHandler: @escaping ((any Error)?) -> Void) {
        session.sendMessage([
            "request": WCMeteriosMessageTypes.DrinkList.rawValue
        ], replyHandler: { reply in
            let drinks = reply["drinks"] as! Array<String>
            
            // Create Drink objects from response
            var drinkArray: Array<Drink> = []
            for d in drinks {
                let jsonDecoded = Data(base64Encoded: d)
                let drink = try! JSONDecoder().decode(Drink.self, from: jsonDecoded!)
                drinkArray.append(drink)
            }
            
            // enjoy your drinks, replyHandler!
            replyHandler(drinkArray)
        }, errorHandler: { error in
            errorHandler(error)
        })
    }
    
    // bookDrink books the drink given by drinkID
    func bookDrink(drinkID: Int, replyHandler: @escaping (String) -> Void, errorHandler: @escaping ((any Error)?) -> Void) {
        session.sendMessage([
            "request": WCMeteriosMessageTypes.BookDrink.rawValue,
            "drinkID": drinkID,
        ], replyHandler: { reply in
            let salut = reply["salut"] as! String
            replyHandler(salut)
        }, errorHandler: { error in
            errorHandler(error)
        })
    }
    
    private func log(_ line: String) {
#if os(iOS)
        let prefix = "[WCM@iOS]"
#elseif os(watchOS)
        let prefix = "[WCM@wOS]"
#else
        let prefix = "[WCM@?OS]"
#endif // os(...)
        print("\(prefix) \(line)")
    }
}