using System;
using System.Diagnostics;
using System.IO.Ports;

namespace BeeDevelopment.Sircs {

    /// <summary>
    /// Represents a command sent by a SIRCS remote control.
    /// </summary>
    public struct SircsCommand : IEquatable<SircsCommand> {

        #region Properties

        private byte command;
        /// <summary>
        /// Gets or sets the command value.
        /// </summary>
        public byte Command {
            get { return this.command; }
            set { this.command = value; }
        }

        private short device;
        /// <summary>
        /// Gets or sets the device identifier.
        /// </summary>
        public short Device {
            get { return this.device; }
            set { this.device = value; }
        }

        private int length;
        /// <summary>
        /// Gets or sets the length of the command in bits.
        /// </summary>
        public int Length {
            get { return this.length; }
            set { this.length = value; }
        }

        #endregion

        #region Construction

        /// <summary>
        /// Creates an instance of a <see cref="SircsCommand"/> structure.
        /// </summary>
        /// <param name="command">The command value.</param>
        /// <param name="device">The device identifier.</param>
        /// <param name="length">The length of the command in bits.</param>
        public SircsCommand(byte command, short device, int length) {
            this.command = command;
            this.device = device;
            this.length = length;
        }

        #endregion

        #region Methods

        /// <summary>
        /// Converts the <see cref="SircsCommand"/> into a string.
        /// </summary>
        /// <returns>A string representation of the <see cref="SircsCommand"/>.</returns>
        public override string ToString() {
            return string.Format("Command={0:X2}, Device={1:X4}, Length={2}", this.command, this.device, this.length);
        }

        /// <summary>
        /// Returns the hash code for this instance.
        /// </summary>
        /// <returns>The hash code for this instance.</returns>
        public override int GetHashCode() {
            return this.command ^ this.device ^ this.length;
        }

        /// <summary>
        /// Returns a value indicating whether this instance is equal to another <see cref="SircsCommand"/> instance.
        /// </summary>
        /// <param name="other">The instance to compare to this one for equality.</param>
        /// <returns>True if the instances are equal, false otherwise.</returns>
        public bool Equals(SircsCommand other) {
            return this.command == other.command && this.device == other.device && this.length == other.length;
        }

        /// <summary>
        /// Returns a value indicating whether this instance is equal to another <see cref="SircsCommand"/> instance.
        /// </summary>
        /// <param name="other">The instance to compare to this one for equality.</param>
        /// <returns>True if the instances are equal, false otherwise.</returns>
        public override bool Equals(object other) {
            return other != null && other is SircsCommand && ((SircsCommand)other).Equals(this);
        }

        #endregion

        #region Operators

        public static bool operator ==(SircsCommand a, SircsCommand b) { return a.Equals(b); }
        public static bool operator !=(SircsCommand a, SircsCommand b) { return !a.Equals(b); }

        #endregion

    }

    #region Events

    /// <summary>
    /// Represents the method that will handle the <c>SircsCommandReceived</c> event.
    /// </summary>
    /// <param name="sender">The object that fired the event.</param>
    /// <param name="e">Information about the event.</param>
    public delegate void SircsCommandReceivedEventHandler(object sender, SircsCommandReceivedEventArgs e);

    /// <summary>
    /// Provides data for the <c>SircsReceived.SircsCommandReceived</c> event.
    /// </summary>
    public class SircsCommandReceivedEventArgs : EventArgs {

        #region Properties

        /// <summary>
        /// Gets the <see cref="SircsCommand"/> that was received.
        /// </summary>
        public SircsCommand Command { get; private set; }

        /// <summary>
        /// Gets the number of times that the incoming command has been repeated when held.
        /// </summary>
        public int Repeat { get; private set; }

        #endregion

        #region Construction

        /// <summary>
        /// Creates a <see cref="SircsCommandReceivedEventArgs"/> instance.
        /// </summary>
        /// <param name="command">The <see cref="SircsCommand"/> that was recieved.</param>
        /// <param name="repeat">The number of times that the incoming command has been repeated when held.</param>
        public SircsCommandReceivedEventArgs(SircsCommand command, int repeat) {
            this.Command = command;
            this.Repeat = repeat;
        }

        #endregion

        #region Methods

        /// <summary>
        /// Converts the <see cref="SircsCommandReceivedEventArgs"/> into a string.
        /// </summary>
        /// <returns>A string representation of the <see cref="SircsCommandReceivedEventArgs"/>.</returns>
        public override string ToString() {
            return string.Format("{0}, Repeat={1}", this.Command, this.Repeat);
        }

        #endregion
    }

    #endregion

    /// <summary>
    /// Provides a way to receive SIRCS commands from a simple receiver attached to a serial port.
    /// </summary>
    public class SircsReceiver : IDisposable {

        #region Constants

        /// <summary>
        /// The minimum time length for a start bit (nominally 2.4ms).
        /// </summary>
        private const double StartBitMinLength = 2.0E-3;

        /// <summary>
        /// Threshold time length between a "low" (0.6ms) and a "high" (1.2ms) bit.
        /// </summary>
        private const double DataBitLengthThreshold = 0.9E-3;

        /// <summary>
        /// The maximum time length between data bits. If this is exceeded, any data command transfer is cancelled.
        /// </summary>
        private const double IntraBitMaxLength = 0.8E-3;

        /// <summary>
        /// The maximum time length between repeating commands. Commands are supposed to repeat every 45ms.
        /// </summary>
        private const double RepeatCommandMaxLength = 120.0E-3;

        #endregion

        #region Private Fields

        /// <summary>
        /// The <see cref="SerialPort"/> that the receiver is connected to.
        /// </summary>
        private SerialPort Port = null;

        /// <summary>
        /// The last time that the pin state changed in ticks.
        /// </summary>
        private long LastPinChangedTime = 0;

        /// <summary>
        /// A <see cref="Stopwatch"/> instance used to time incoming bits.
        /// </summary>
        private Stopwatch BitTimer = null;

        /// <summary>
        /// Set to <c>true</c> when receiving a command, <c>false</c> otherwise.
        /// </summary>
        private bool ReceivingCommand = false;

        /// <summary>
        /// Counts the number of bits currently received.
        /// </summary>
        private int BitsReceived = 0;

        /// <summary>
        /// Stores the command as it gets built up.
        /// </summary>
        private uint Command = 0;

        /// <summary>
        /// Stores the last received command.
        /// </summary>
        private SircsCommand LastCommand = default(SircsCommand);

        /// <summary>
        /// Stores the number of times the received command has been repeated.
        /// </summary>
        private int LastCommandRepeatCount = 0;

        /// <summary>
        /// A <see cref="Stopwatch"/> instance used to time repeating commands.
        /// </summary>
        private Stopwatch RepeatTimer = null;

        #endregion

        #region Construction/Destruction

        /// <summary>
        /// Creates an instance of a <see cref="SircsReceiver"/> from a serial port name.
        /// </summary>
        /// <param name="portName">The name of the serial port the receiver is connected to.</param>
        public SircsReceiver(string portName) {

            // Set up the serial port.
            this.Port = new SerialPort(portName);
            this.Port.PinChanged += new SerialPinChangedEventHandler(PinChanged);

            // Open the port for access.
            this.Port.Open();
            this.Port.DtrEnable = true;
            this.Port.RtsEnable = true;

            // Get the timers running.
            this.BitTimer = new Stopwatch();
            this.BitTimer.Start();
            this.RepeatTimer = new Stopwatch();
            this.RepeatTimer.Start();
        }

        /// <summary>
        /// Releases the resources used by this <see cref="SircsReceiver"/> instance.
        /// </summary>
        public void Dispose() {
            if (this.Port != null) {
                this.Port.PinChanged -= new SerialPinChangedEventHandler(PinChanged);
                this.Port.Dispose();
                this.Port = null;
            }
        }

        ~SircsReceiver() {
            this.Dispose();
        }

        #endregion

        #region Events

        /// <summary>
        /// An event that is fired when a <see cref="SircsCommand"/> is received.
        /// </summary>
        public event SircsCommandReceivedEventHandler SircsCommandReceived;

        /// <summary>
        /// A method that is invoked when a <see cref="SircsCommand"/> is received.
        /// </summary>
        /// <param name="e"></param>
        protected virtual void OnSircsCommandReceived(SircsCommandReceivedEventArgs e) {
            if (this.SircsCommandReceived != null) this.SircsCommandReceived(this, e);
        }

        #endregion

        #region SIRCS protocol handling

        void PinChanged(object sender, SerialPinChangedEventArgs e) {

            // Respond to changes on the CTS pin.
            if (e.EventType == SerialPinChange.CtsChanged) {

                // Quickly grab the current time and current CTS level.
                long CurrentPinChangedTime = this.BitTimer.ElapsedTicks;
                bool CurrentLevel = this.Port.CtsHolding;

                // Calculate the time elapsed.
                long DeltaTime = CurrentPinChangedTime - this.LastPinChangedTime;
                double SecondsElapsed = (double)DeltaTime / (double)Stopwatch.Frequency;
                this.LastPinChangedTime = CurrentPinChangedTime;

                if (CurrentLevel) { // If the current signal level is high, we may assume that we've just timed a low pulse.

                    // Have we received a start bit?
                    if (SecondsElapsed > SircsReceiver.StartBitMinLength) {
                        this.ReceivingCommand = true;
                        this.BitsReceived = 0;
                        this.Command = 0;
                    } else if (this.ReceivingCommand) {
                        // Process incoming bit.
                        this.Command >>= 1;
                        if (SecondsElapsed > SircsReceiver.DataBitLengthThreshold) {
                            this.Command |= unchecked((uint)(1 << 31));
                        }

                        // Have we received enough bits?
                        switch (++this.BitsReceived) {
                            case 12:
                            case 15:
                            case 20:
                                // We've received enough bits to handle the input as a received command.
                                // Check to see if there's any more data forthcoming.
                                long EndTime = CurrentPinChangedTime + (long)(Stopwatch.Frequency * SircsReceiver.IntraBitMaxLength);
                                while (BitTimer.ElapsedTicks < EndTime) {
                                    if (!(CurrentLevel = this.Port.CtsHolding)) break;
                                }
                                // The input is still high - there's no more data coming in; we've received a command.
                                if (CurrentLevel) {
                                    // Construct a struct to hold information about the recieved data.
                                    SircsCommand ReceivedCommand = new SircsCommand(
                                        (byte)((this.Command >> (32 - this.BitsReceived)) & 0x7F),
                                        (short)(this.Command >> ((32 + 7) - this.BitsReceived)),
                                        this.BitsReceived
                                    );
                                    
                                    // Reset the timer.
                                    this.ReceivingCommand = false;
                                    this.BitTimer.Reset();
                                    this.BitTimer.Start();
                                    this.LastPinChangedTime = 0;
                                    
                                    // Calculate the repeat count.

                                    // Quickly grab the current time and current CTS level.
                                    long RepeatTimeTicks = this.RepeatTimer.ElapsedTicks;
                                    this.RepeatTimer.Reset();
                                    this.RepeatTimer.Start();

                                    // Calculate the repeat time elapsed.
                                    double RepeatTimeSeconds = (double)RepeatTimeTicks / (double)Stopwatch.Frequency;

                                    // Is the command repeating?
                                    if (ReceivedCommand == this.LastCommand && RepeatTimeSeconds < SircsReceiver.RepeatCommandMaxLength) {
                                        ++this.LastCommandRepeatCount;
                                    } else {
                                        this.LastCommandRepeatCount = 1;
                                        this.LastCommand = ReceivedCommand;
                                    }
                                    
                                    // Fire the event.
                                    this.OnSircsCommandReceived(new SircsCommandReceivedEventArgs(ReceivedCommand, this.LastCommandRepeatCount));
                                }
                                break;
                        }
                    }
                } else { // If the current signal level is low, we may assume that we've just timed a high pulse.
                    // If a high pulse is too long, cancel any incoming commands.
                    if (SecondsElapsed > SircsReceiver.IntraBitMaxLength) {
                        this.ReceivingCommand = false;
                        this.BitTimer.Reset();
                        this.BitTimer.Start();
                        this.LastPinChangedTime = 0;
                    }
                }
            }
        }

        #endregion

    }
}

// Table of commands.
var Commands = [
    { Command : 0x00, Device : 0x093A, Length : 20, Shortcut : '1' },         // 1
    { Command : 0x01, Device : 0x093A, Length : 20, Shortcut : '2' },         // 2
    { Command : 0x02, Device : 0x093A, Length : 20, Shortcut : '3' },         // 3
    { Command : 0x03, Device : 0x093A, Length : 20, Shortcut : '4' },         // 4
    { Command : 0x04, Device : 0x093A, Length : 20, Shortcut : '5' },         // 5
    { Command : 0x05, Device : 0x093A, Length : 20, Shortcut : '6' },         // 6
    { Command : 0x06, Device : 0x093A, Length : 20, Shortcut : '7' },         // 7
    { Command : 0x07, Device : 0x093A, Length : 20, Shortcut : '8' },         // 8
    { Command : 0x08, Device : 0x093A, Length : 20, Shortcut : '9' },         // 9
    { Command : 0x09, Device : 0x093A, Length : 20, Shortcut : '0' },         // 0
    { Command : 0x0B, Device : 0x093A, Length : 20, Shortcut : '{ENTER}' },   // Enter
    { Command : 0x0E, Device : 0x093A, Length : 20, Shortcut : '{ESC}' },     // Return
    { Command : 0x1A, Device : 0x093A, Length : 20, Shortcut : 'lt' },        // Title
    { Command : 0x2A, Device : 0x093A, Length : 20, Shortcut : 'x' },         // A<->B
    { Command : 0x28, Device : 0x093A, Length : 20, Shortcut : 'd' },         // Time
    { Command : 0x2C, Device : 0x093A, Length : 20, Shortcut : '^r' },        // Repeat
    { Command : 0x30, Device : 0x093A, Length : 20, Shortcut : 'p' },         // Previous
    { Command : 0x31, Device : 0x093A, Length : 20, Shortcut : 'n' },         // Next
    { Command : 0x32, Device : 0x093A, Length : 20, Shortcut : '{ENTER}' },   // Play
    { Command : 0x33, Device : 0x093A, Length : 20, Shortcut : 'b' },         // Scan <<
    { Command : 0x34, Device : 0x093A, Length : 20, Shortcut : 'f' },         // Scan >>
    { Command : 0x38, Device : 0x093A, Length : 20, Shortcut : 's' },         // Stop
    { Command : 0x39, Device : 0x093A, Length : 20, Shortcut : ' ' },         // Pause
    { Command : 0x54, Device : 0x093A, Length : 20, Shortcut : 'z' },         // Display
    { Command : 0x60, Device : 0x093A, Length : 20, Shortcut : '^b' },        // Slow <<
    { Command : 0x61, Device : 0x093A, Length : 20, Shortcut : 't' },         // Slow >>
    { Command : 0x63, Device : 0x093A, Length : 20, Shortcut : 'u' },         // Subtitle
    { Command : 0x64, Device : 0x093A, Length : 20, Shortcut : 'h' },         // Audio
    { Command : 0x65, Device : 0x093A, Length : 20, Shortcut : 'a' },         // Angle
    { Command : 0x79, Device : 0x093A, Length : 20, Shortcut : '{UP}' },      // Up
    { Command : 0x7A, Device : 0x093A, Length : 20, Shortcut : '{DOWN}' },    // Down
    { Command : 0x7B, Device : 0x093A, Length : 20, Shortcut : '{LEFT}' },    // Left
    { Command : 0x7C, Device : 0x093A, Length : 20, Shortcut : '{RIGHT}' },   // Right
];

// Search for the matching command.
var Command = null;
for (var enumerator = new Enumerator(Commands); !enumerator.atEnd(); enumerator.moveNext()) {
    var TestCommand = enumerator.item();
    if (TestCommand.Command == WScript.Arguments(1) && TestCommand.Device == WScript.Arguments(2) && TestCommand.Length == WScript.Arguments(3)) {
        Command = TestCommand;
        break;
    }
}

// No command.
if (!Command) WScript.Quit(1);

// Find the PowerDVD process ID.
var PowerDvdId = null;
var WmiService = GetObject('winmgmts://./root/cimv2');
var Processes = WmiService.ExecQuery('Select ProcessId From Win32_Process Where Name="PowerDVD.exe"');
for (var enumerator = new Enumerator(Processes); !enumerator.atEnd(); enumerator.moveNext()) {
    PowerDvdId = enumerator.item().ProcessId;
    break;
}

// If we haven't found the process ID, quit with an error.
if (!PowerDvdId) WScript.Quit(1);

// Activate the PowerDVD instance.
var WshShell = new ActiveXObject('WScript.Shell');
WshShell.AppActivate(PowerDvdId);

// Send the shortcut keys.
WshShell.SendKeys(Command.Shortcut);

WScript.Quit(0);