// Linux kernel I/O device common declartions

// Copyright (C)2020-2023, Philip Munts dba Munts Technologies.
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using System;

namespace IO.Objects.SimpleIO.Device
{
    /// <summary>
    /// Linux kernel I/O device designator.
    /// </summary>
    /// <remarks>
    /// Many Linux kernel I/O devices, including ADC inputs, DAC outputs,
    /// GPIO pins, I2C buses, PWM outputs, and SPI devices, are selected by a
    /// tuple of integers: chip and channel.
    /// </remarks>
    public struct Designator
    {
        /// <summary>
        /// Linux kernel I/O device chip number.
        /// </summary>
        public uint chip;

        /// <summary>
        /// Linux kernel I/O device channel number.
        /// </summary>
        public uint chan;

        /// <summary>
        /// Linux kernel I/O device designator constructor.
        /// </summary>
        /// <param name="chip">Linux kernel I/O device chip number.</param>
        /// <param name="chan">Linux kernel I/O device channel number.</param>
        public Designator(uint chip = uint.MaxValue, uint chan = uint.MaxValue)
        {
            this.chip = chip;
            this.chan = chan;
        }

        /// <summary>
        /// Linux kernel I/O device designator constructor.  The chip and
        /// channel numbers shall be obtained from the operator via
        /// <c>System.Console.ReadLine</c>
        /// </summary>
        /// <param name="prompt">Operator prompt string of the form
        /// "Enter XXX channel:".</param>
        /// <param name="chip">Linux kernel I/O device chip number.  If a
        /// value is supplied, the operator will not be prompted for for
        /// the chip number.</param>
        public Designator(string prompt, uint chip = uint.MaxValue)
        {
            if (chip == uint.MaxValue)
            {
                System.Console.Write(prompt.Replace("channel: ","chip:    "));
                this.chip = uint.Parse(System.Console.ReadLine());
            }
            else
            {
                this.chip = chip;
            }

            System.Console.Write(prompt);
            this.chan = uint.Parse(System.Console.ReadLine());
        }

        /// <summary>
        /// Linux kernel I/O device designator for an unavailable device.
        /// </summary>
        public static readonly Designator Unavailable =
            new Designator(uint.MaxValue, uint.MaxValue);

        /// <summary>
        /// Returns <c>true</c> if this device designator is not equal to
        /// <c>Unavailable</c>.
        /// </summary>
        public bool available
        {
            get { return !this.Equals(Unavailable); }
        }
    }
}