using System;

using System.Collections;

using System.Collections.Generic;



namespace HttpServer

{

  /// <summary>

  /// represents a HTTP input item. Each item can have multiple sub items, a sub item

  /// is made in a HTML form by using square brackets

  /// </summary>

  /// <example>

  ///   // <input type="text" name="user[FirstName]" value="jonas" /> becomes:

  ///   Console.WriteLine("Value: {0}", form["user"]["FirstName"].Value);

  /// </example>

  /// <remarks>

  /// All names in a form SHOULD be in lowercase.

  /// </remarks>

  public class HttpInputItem : IHttpInput

  {

    /// <summary> Representation of a non-initialized <see cref="HttpInputItem"/>.</summary>

    public static readonly HttpInputItem Empty = new HttpInputItem(string.Empty, true);



    private readonly IDictionary<string, HttpInputItem> _items = new Dictionary<string, HttpInputItem>();

    private readonly List<string> _values = new List<string>();

    private string _name;

    private readonly bool _ignoreChanges;



    /// <summary>

    /// Initializes an input item setting its name/identifier and value

    /// </summary>

    /// <param name="name">Parameter name/id</param>

    /// <param name="value">Parameter value</param>

    public HttpInputItem(string name, string value)

    {

      Name = name;

      Add(value);

    }



    private HttpInputItem(string name, bool ignore)

    {

      Name = name;

      _ignoreChanges = ignore;

    }



    /// <summary>Creates a deep copy of the item specified</summary>

    /// <param name="item">The item to copy</param>

    /// <remarks>The function makes a deep copy of quite a lot which can be slow</remarks>

    public HttpInputItem(HttpInputItem item)

    {

      foreach (KeyValuePair<string, HttpInputItem> pair in item._items)

        _items.Add(pair.Key, pair.Value);



      foreach (string value in item._values)

        _values.Add(value);



      _ignoreChanges = item._ignoreChanges;

      _name = item.Name;

    }



    /// <summary>

    /// Number of values

    /// </summary>

    public int Count

    {

      get { return _values.Count; }

    }



    /// <summary>

    /// Get a sub item

    /// </summary>

    /// <param name="name">name in lower case.</param>

    /// <returns><see cref="HttpInputItem.Empty"/> if no item was found.</returns>

    public HttpInputItem this[string name]

    {

      get { return _items.ContainsKey(name) ? _items[name] : Empty; }

    }



    /// <summary>

    /// Name of item (in lower case).

    /// </summary>

    public string Name

    {

      get { return _name; }

      set { _name = value; }

    }



    /// <summary>

    /// Returns the first value, or null if no value exist.

    /// </summary>

    public string Value

    {

      get { return _values.Count == 0 ? null : _values[0]; }

      set

      {

        if (_values.Count == 0)

          _values.Add(value);

        else

          _values[0] = value;

      }

    }



    /// <summary>

    /// Returns the last value, or null if no value exist.

    /// </summary>

    public string LastValue

    {

      get { return _values.Count == 0 ? null : _values[_values.Count - 1]; }

    }



    /// <summary>

    /// Returns the list with values.

    /// </summary>

    public IList<string> Values

    {

      get { return _values.AsReadOnly(); }

    }





    /// <summary>

    /// Add another value to this item

    /// </summary>

    /// <param name="value">Value to add.</param>

    /// <exception cref="InvalidOperationException">Cannot add stuff to <see cref="HttpInput.Empty"/>.</exception>

    public void Add(string value)

    {

      if (value == null)

        return;

      if (_ignoreChanges)

        throw new InvalidOperationException("Cannot add stuff to HttpInput.Empty.");



      _values.Add(value);

    }



    /// <summary>

    /// checks if a sub-item exists (and has a value).

    /// </summary>

    /// <param name="name">name in lower case</param>

    /// <returns>true if the sub-item exists and has a value; otherwise false.</returns>

    public bool Contains(string name)

    {

      return _items.ContainsKey(name) && _items[name].Value != null;

    }



    /// <summary> Returns a formatted representation of the instance with the values of all contained parameters </summary>

    public override string ToString()

    {

      return ToString(string.Empty);

    }



    /// <summary>

    /// Outputs the string in a formatted manner

    /// </summary>

    /// <param name="prefix">A prefix to append, used internally</param>

    /// <param name="asQuerySting">produce a query string</param>

    public string ToString(string prefix, bool asQuerySting)

    {

      string name;

      if (string.IsNullOrEmpty(prefix))

        name = Name;

      else

        name = prefix + "[" + Name + "]";



      if (asQuerySting)

      {

        string temp;

        if (_values.Count == 0 && _items.Count > 0)

          temp = string.Empty;

        else

          temp = name;



        if (_values.Count > 0)

        {

          temp += '=';

          foreach (string value in _values)

            temp += value + ',';

          temp = temp.Remove(temp.Length - 1, 1);

        }



        foreach (KeyValuePair<string, HttpInputItem> item in _items)

          temp += item.Value.ToString(name, true) + '&';



        return _items.Count > 0 ? temp.Substring(0, temp.Length - 1) : temp;

      }

      else

      {

        string temp = name;

        if (_values.Count > 0)

        {

          temp += " = ";

          foreach (string value in _values)

            temp += value + ", ";

          temp = temp.Remove(temp.Length - 2, 2);

        }

        temp += Environment.NewLine;



        foreach (KeyValuePair<string, HttpInputItem> item in _items)

          temp += item.Value.ToString(name, false);

        return temp;

      }

    }



    #region IHttpInput Members



    /// <summary>

    /// 

    /// </summary>

    /// <param name="name">name in lower case</param>

    /// <returns></returns>

    HttpInputItem IHttpInput.this[string name]

    {

      get { return _items.ContainsKey(name) ? _items[name] : Empty; }

    }



    /// <summary>

    /// Add a sub item.

    /// </summary>

    /// <param name="name">Can contain array formatting, the item is then parsed and added in multiple levels</param>

    /// <param name="value">Value to add.</param>

    /// <exception cref="ArgumentNullException">Argument is null.</exception>

    /// <exception cref="InvalidOperationException">Cannot add stuff to <see cref="HttpInput.Empty"/>.</exception>

    public void Add(string name, string value)

    {

      if (name == null && value != null)

        throw new ArgumentNullException("name");

      if (name == null)

        return;

      if (_ignoreChanges)

        throw new InvalidOperationException("Cannot add stuff to HttpInput.Empty.");



      int pos = name.IndexOf('[');

      if (pos != -1)

      {

        string name1 = name.Substring(0, pos);

        string name2 = HttpInput.ExtractOne(name);

        if (!_items.ContainsKey(name1))

          _items.Add(name1, new HttpInputItem(name1, null));

        _items[name1].Add(name2, value);

        /*

        HttpInputItem item = HttpInput.ParseItem(name, value);



        // Add the value to an existing sub item

        if (_items.ContainsKey(item.Name))

          _items[item.Name].Add(item.Value);

        else

          _items.Add(item.Name, item);

        */

      }

      else

      {

        if (_items.ContainsKey(name))

          _items[name].Add(value);

        else

          _items.Add(name, new HttpInputItem(name, value));

      }

    }



    #endregion



    ///<summary>

    ///Returns an enumerator that iterates through the collection.

    ///</summary>

    ///

    ///<returns>

    ///A <see cref="T:System.Collections.Generic.IEnumerator`1"></see> that can be used to iterate through the collection.

    ///</returns>

    ///<filterpriority>1</filterpriority>

    IEnumerator<HttpInputItem> IEnumerable<HttpInputItem>.GetEnumerator()

    {

      return _items.Values.GetEnumerator();

    }



    #region IEnumerable Members



    ///<summary>

    ///Returns an enumerator that iterates through a collection.

    ///</summary>

    ///

    ///<returns>

    ///An <see cref="T:System.Collections.IEnumerator"></see> object that can be used to iterate through the collection.

    ///</returns>

    ///<filterpriority>2</filterpriority>

    public IEnumerator GetEnumerator()

    {

      return _items.Values.GetEnumerator();

    }



    #endregion



    /// <summary>

    /// Outputs the string in a formatted manner

    /// </summary>

    /// <param name="prefix">A prefix to append, used internally</param>

    /// <returns></returns>

    public string ToString(string prefix)

    {

      return ToString(prefix, false);

    }

  }

}