// Copyright (C)2025, Philip Munts dba Munts Technologies.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// POSSIBILITY OF SUCH DAMAGE.

using System.Device.Gpio;
using System.Device.Gpio.Drivers;

namespace IO.Objects.IoT.GPIO
{
    /// <summary>
    /// Encapsulates Linux GPIO pins using <c>System.Device.Gpio</c>.
    /// </summary>
    public class Pin : IO.Interfaces.GPIO.Pin
    {
	// Cache GpioController instances in the following array:
        private static GpioController[] gpiochips = new GpioController[10];

        private readonly int chip;
        private readonly int line;
        private readonly PinMode mode;
        private bool mystate = false;

        /// <summary>
        /// Constructor for a single GPIO pin.
        /// </summary>
        /// <param name="desg">GPIO pin designator.</param>
        /// <param name="mode">Pin mode.</param>
        /// <param name="state">Initial GPIO output state.</param>
        public Pin(IO.Objects.SimpleIO.Device.Designator desg, PinMode mode, bool state = false)
        {
	    if (desg.chip >= gpiochips.Length)
              throw new System.Exception("GPIO chip number is out of range");

            if (gpiochips[desg.chip] == null)
              gpiochips[desg.chip] = new GpioController(new LibGpiodDriver((int) desg.chip));

            this.chip = (int) desg.chip;
            this.line = (int) desg.chan;
            this.mode = mode;

            gpiochips[this.chip].OpenPin(this.line, this.mode);

            if (mode == PinMode.Output) this.state = state;
        }

        /// <summary>
        /// Read/Write GPIO state property.
        /// </summary>
        public bool state
        {
            get
            {
                if (this.mode == PinMode.Output)
                    return this.mystate;
                else
                    return gpiochips[this.chip].Read(this.line) == PinValue.High ? true : false;
            }

            set
            {
                if (this.mode == PinMode.Output)
                {
                    gpiochips[this.chip].Write(this.line, value ? PinValue.High : PinValue.Low);
                    this.mystate = value;
                }
                else
                    throw new System.Exception("Cannot write to input pin");
            }
        }
    }
}