using RobotLib.Communication;
using System;
using System.Collections.Generic;
using System.Text.Json;

namespace RobotLib.Battery
{
    public class DevBattery : DevBase
    {
        private float voltage;

        private const string TOPIC_ROBO_REQ_BATTERY = "/mobile/cmd/battery/get_volt";
        private const string TOPIC_ROBO_RESP_BATTERY = "/mobile/state/battery/voltage";

        public event EventHandler<BatteryEventArgs> BatteryChanged;

        public float Voltage
        {
            get { return voltage; }
            private set
            {
                // value changed?
                if (voltage != value)
                {
                    // set new voltage and raise event
                    voltage = value;
                    BatteryChanged?.Invoke(this, new BatteryEventArgs(voltage));
                }
            }
        }

        public DevBattery(IPublisherSubscriber com) : base(com, new List<string>() { TOPIC_ROBO_RESP_BATTERY }) { }

        public override void Refresh()
        {
            this.RequestBatteryVoltage();
        }

        public void RequestBatteryVoltage()
        {
            base.SendMessage(TOPIC_ROBO_REQ_BATTERY, true.ToString());
        }

        protected override void ParseMessage(string fromTopic, string message)
        {
            if (fromTopic == TOPIC_ROBO_RESP_BATTERY)
            {
                var parsedString = GetValueFromMesage<string>("voltage", message);
                if (parsedString == null) parsedString = "?";

                // example message = "Battery: 1.25 V"
                var valueUnit = parsedString.Trim().Split(' ');
                string voltage = valueUnit[0].Trim();
                float fVoltage = float.NaN;

                if(float.TryParse(voltage, out fVoltage))
                {
                    this.Voltage = fVoltage;
                }
            }
        }

        private T GetValueFromMesage<T>(string parameter, string message)
        {
            var data = JsonSerializer.Deserialize<Dictionary<string, T>>(message);
            data.TryGetValue(parameter, out T value);
            return value;
        }
    }
}