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

import Foundation

enum MeteClientError: Error {
    case StatusCodeLooksBad(explanation: String)
}

/// **MeteClient** is the client-side implementation of the Space Market API. Pure Swift, no platform-specific frameworks used.
class MeteClient {
    private let address: String
    private let userID: Int

    init(address: String, userID: Int) {
        self.address = address
        self.userID = userID
    }
    
    func CanConnect() async throws -> Bool {
        // Send HTTP request to the drinks endpoint
        let url = URL(string: "https://\(address)/api/v1/users/stats.json")
        let (_, response) = try await URLSession.shared.data(from: url!)
        
        let statusCode = (response as? HTTPURLResponse)?.statusCode
        return statusCode == 200
    }

    // GetDrinks returns the list of drinks available at the backend
    func GetDrinks() async throws -> Array<MeteClientDrink> {
        // Send HTTP request to the drinks endpoint
        let url = URL(string: "https://\(address)/api/v1/drinks")
        let (data, _) = try await URLSession.shared.data(from: url!)
    
        // Decode JSON to array of drinks
        let decoder = JSONDecoder()
        let drinks = try decoder.decode([MeteClientDrink].self, from: data)

        return drinks
    }

    // GetUser returns the user object for the given ID
    func GetUser() async throws -> MeteClientUser {
        // Send HTTP request to the user endpoint
        let url = URL(string: "https://\(address)/api/v1/users/\(userID).json")
        let (data, _) = try await URLSession.shared.data(from: url!)
    
        // Decode JSON to array of drinks
        let decoder = JSONDecoder()
        let user = try decoder.decode(MeteClientUser.self, from: data)

        return user
    }

    // GetUsers returns all users registered at the backend
    func GetUsers() async throws -> Array<MeteClientUser> {
        // Send HTTP request to the user endpoint
        let url = URL(string: "https://\(address)/api/v1/users.json")
        let (data, _) = try await URLSession.shared.data(from: url!)

        // Decode JSON to array of drinks
        let decoder = JSONDecoder()
        let users = try decoder.decode([MeteClientUser].self, from: data)

        return users
    }

    // BookDrink subtracts the recommended price off the balance from the user given by ID
    func BookDrink(_ drinkID: Int) async throws {
        // Send HTTP request to the user endpoint
        let url = URL(string: "https://\(address)/api/v1/users/\(userID)/buy.json?drink=\(drinkID)")
        let (_, response) = try await URLSession.shared.data(from: url!)

        // Check status code
        let statusCode = (response as? HTTPURLResponse)?.statusCode
        if statusCode != 204 {
            throw MeteClientError.StatusCodeLooksBad(explanation: "Failed to book drink \(drinkID) for user \(userID)@\(address): HTTP status code \(statusCode ?? 0) received for \(url!)")
        }
    }
}