using System;
using System.Linq;

namespace Unosquare.Swan {
  /// <summary>
  /// A console terminal helper to create nicer output and receive input from the user
  /// This class is thread-safe :).
  /// </summary>
  public static partial class Terminal {
    #region Helper Methods

    /// <summary>
    /// Prints all characters in the current code page.
    /// This is provided for debugging purposes only.
    /// </summary>
    public static void PrintCurrentCodePage() {
      if(!IsConsolePresent) {
        return;
      }

      lock(SyncLock) {
        $"Output Encoding: {OutputEncoding}".WriteLine();
        for(Byte byteValue = 0; byteValue < Byte.MaxValue; byteValue++) {
          Char charValue = OutputEncoding.GetChars(new[] { byteValue })[0];

          switch(byteValue) {
            case 8: // Backspace
            case 9: // Tab
            case 10: // Line feed
            case 13: // Carriage return
              charValue = '.';
              break;
          }

          $"{byteValue:000} {charValue}   ".Write();

          // 7 is a beep -- Console.Beep() also works
          if(byteValue == 7) {
            " ".Write();
          }

          if((byteValue + 1) % 8 == 0) {
            WriteLine();
          }
        }

        WriteLine();
      }
    }

    #endregion

    #region Write Methods

    /// <summary>
    /// Writes a character a number of times, optionally adding a new line at the end.
    /// </summary>
    /// <param name="charCode">The character code.</param>
    /// <param name="color">The color.</param>
    /// <param name="count">The count.</param>
    /// <param name="newLine">if set to <c>true</c> [new line].</param>
    /// <param name="writerFlags">The writer flags.</param>
    public static void Write(this Byte charCode, ConsoleColor? color = null, Int32 count = 1, Boolean newLine = false, TerminalWriters writerFlags = TerminalWriters.StandardOutput) {
      lock(SyncLock) {
        Byte[] bytes = new Byte[count];
        for(Int32 i = 0; i < bytes.Length; i++) {
          bytes[i] = charCode;
        }

        if(newLine) {
          Byte[] newLineBytes = OutputEncoding.GetBytes(Environment.NewLine);
          bytes = bytes.Union(newLineBytes).ToArray();
        }

        Char[] buffer = OutputEncoding.GetChars(bytes);
        OutputContext context = new OutputContext {
          OutputColor = color ?? Settings.DefaultColor,
          OutputText = buffer,
          OutputWriters = writerFlags,
        };

        EnqueueOutput(context);
      }
    }

    /// <summary>
    /// Writes the specified character in the default color.
    /// </summary>
    /// <param name="charCode">The character code.</param>
    /// <param name="color">The color.</param>
    /// <param name="writerFlags">The writer flags.</param>
    public static void Write(this Char charCode, ConsoleColor? color = null, TerminalWriters writerFlags = TerminalWriters.StandardOutput) {
      lock(SyncLock) {
        OutputContext context = new OutputContext {
          OutputColor = color ?? Settings.DefaultColor,
          OutputText = new[] { charCode },
          OutputWriters = writerFlags,
        };

        EnqueueOutput(context);
      }
    }

    /// <summary>
    /// Writes the specified text in the given color.
    /// </summary>
    /// <param name="text">The text.</param>
    /// <param name="color">The color.</param>
    /// <param name="writerFlags">The writer flags.</param>
    public static void Write(this String text, ConsoleColor? color = null, TerminalWriters writerFlags = TerminalWriters.StandardOutput) {
      if(text == null) {
        return;
      }

      lock(SyncLock) {
        Byte[] buffer = OutputEncoding.GetBytes(text);
        OutputContext context = new OutputContext {
          OutputColor = color ?? Settings.DefaultColor,
          OutputText = OutputEncoding.GetChars(buffer),
          OutputWriters = writerFlags,
        };

        EnqueueOutput(context);
      }
    }

    #endregion

    #region WriteLine Methods

    /// <summary>
    /// Writes a New Line Sequence to the standard output.
    /// </summary>
    /// <param name="writerFlags">The writer flags.</param>
    public static void WriteLine(TerminalWriters writerFlags = TerminalWriters.StandardOutput)
        => Environment.NewLine.Write(Settings.DefaultColor, writerFlags);

    /// <summary>
    /// Writes a line of text in the current console foreground color
    /// to the standard output.
    /// </summary>
    /// <param name="text">The text.</param>
    /// <param name="color">The color.</param>
    /// <param name="writerFlags">The writer flags.</param>
    public static void WriteLine(this String text, ConsoleColor? color = null, TerminalWriters writerFlags = TerminalWriters.StandardOutput)
        => Write($"{text ?? String.Empty}{Environment.NewLine}", color, writerFlags);

    /// <summary>
    /// As opposed to WriteLine methods, it prepends a Carriage Return character to the text
    /// so that the console moves the cursor one position up after the text has been written out.
    /// </summary>
    /// <param name="text">The text.</param>
    /// <param name="color">The color.</param>
    /// <param name="writerFlags">The writer flags.</param>
    public static void OverwriteLine(this String text, ConsoleColor? color = null, TerminalWriters writerFlags = TerminalWriters.StandardOutput) {
      Write($"\r{text ?? String.Empty}", color, writerFlags);
      Flush();
      CursorLeft = 0;
    }

    #endregion
  }
}