#region Apache License 2.0
/*
Nuclex .NET Framework
Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#endregion // Apache License 2.0

using System;

namespace Nuclex.Support.Parsing {

  partial class CommandLine {

    /// <summary>Argument being specified on an application's command line</summary>
    public class Argument {

      /// <summary>Initializes a new option with only a name</summary>
      /// <param name="raw">
      ///   String segment with the entire argument as it was given on the command line
      /// </param>
      /// <param name="nameStart">Absolute index the argument name starts at</param>
      /// <param name="nameLength">Number of characters in the option name</param>
      /// <returns>The newly created option</returns>
      internal static Argument OptionOnly(
        StringSegment raw,
        int nameStart, int nameLength
      ) {
        return new Argument(raw, nameStart, nameLength, -1, -1);
      }

      /// <summary>Initializes a new argument with only a value</summary>
      /// <param name="raw">
      ///   String segment with the entire argument as it was given on the command line
      /// </param>
      /// <param name="valueStart">Absolute index the value starts at</param>
      /// <param name="valueLength">Number of characters in the value</param>
      /// <returns>The newly created option</returns>
      internal static Argument ValueOnly(
        StringSegment raw,
        int valueStart, int valueLength
      ) {
        return new Argument(raw, -1, -1, valueStart, valueLength);
      }

      /// <summary>Creates a new option with a name and an assigned value</summary>
      /// <param name="raw">
      ///   String segment containing the entire option as it was given on the command line
      /// </param>
      /// <param name="nameStart">Absolute index the option name starts at</param>
      /// <param name="nameLength">Number of characters in the option name</param>
      /// <param name="valueStart">Absolute index the value starts at</param>
      /// <param name="valueLength">Number of characters in the value</param>
      /// <returns>The newly created option</returns>
      internal Argument(
        StringSegment raw,
        int nameStart, int nameLength,
        int valueStart, int valueLength
      ) {
        this.raw = raw;
        this.nameStart = nameStart;
        this.nameLength = nameLength;
        this.valueStart = valueStart;
        this.valueLength = valueLength;
      }

      /// <summary>Contains the raw string the command line argument was parsed from</summary>
      public string Raw {
        get { return this.raw.ToString(); }
      }

      /// <summary>Characters used to initiate this option</summary>
      public string Initiator {
        get {
          if(this.nameStart == -1) {
            return null;
          } else {
            return this.raw.Text.Substring(
              this.raw.Offset, this.nameStart - this.raw.Offset
            );
          }
        }
      }

      /// <summary>Name of the command line option</summary>
      public string Name {
        get {
          if(this.nameStart == -1) {
            return null;
          } else {
            return this.raw.Text.Substring(this.nameStart, this.nameLength);
          }
        }
      }

      /// <summary>Characters used to associate a value to this option</summary>
      public string Associator {
        get {
          if(this.nameStart == -1) {
            return null;
          } else {
            int associatorStart = this.nameStart + this.nameLength;

            if(this.valueStart == -1) {
              int characterCount = (this.raw.Offset + this.raw.Count) - associatorStart;
              if(characterCount == 0) {
                return null;
              }
            } else if(this.valueStart == associatorStart) {
              return null;
            }

            return this.raw.Text.Substring(associatorStart, 1);
          }
        }
      }

      /// <summary>Name of the command line option</summary>
      public string Value {
        get {
          if(this.valueStart == -1) {
            return null;
          } else {
            return this.raw.Text.Substring(this.valueStart, this.valueLength);
          }
        }
      }

      /// <summary>The raw length of the command line argument</summary>
      internal int RawLength {
        get { return this.raw.Count; }
      }

      /// <summary>
      ///   Contains the entire option as it was specified on the command line
      /// </summary>
      private StringSegment raw;

      /// <summary>Absolute index in the raw string the option name starts at</summary>
      private int nameStart;
      /// <summary>Number of characters in the option name</summary>
      private int nameLength;
      /// <summary>Absolute index in the raw string the value starts at</summary>
      private int valueStart;
      /// <summary>Number of characters in the value</summary>
      private int valueLength;

    }

  }

} // namespace Nuclex.Support.Parsing