?/********************************************************
 * ADO.NET 2.0 Data Provider for SQLite Version 3.X
 * Written by Robert Simpson (robert@blackcastlesoft.com)
 * 
 * Released to the public domain, use at your own risk!
 ********************************************************/

namespace System.Data.SQLite
{
  using System;
  using System.Runtime.InteropServices;
  using System.Collections.Generic;
  using System.ComponentModel;
  using System.Globalization;
  using System.Text;

#if !PLATFORM_COMPACTFRAMEWORK 
  using System.ComponentModel.Design;
#endif

  /// <summary>
  /// SQLite has very limited types, and is inherently text-based.  The first 5 types below represent the sum of all types SQLite
  /// understands.  The DateTime extension to the spec is for internal use only.
  /// </summary>
  public enum TypeAffinity
  {
    /// <summary>
    /// Not used
    /// </summary>
    Uninitialized = 0,
    /// <summary>
    /// All integers in SQLite default to Int64
    /// </summary>
    Int64 = 1,
    /// <summary>
    /// All floating point numbers in SQLite default to double
    /// </summary>
    Double = 2,
    /// <summary>
    /// The default data type of SQLite is text
    /// </summary>
    Text = 3,
    /// <summary>
    /// Typically blob types are only seen when returned from a function
    /// </summary>
    Blob = 4,
    /// <summary>
    /// Null types can be returned from functions
    /// </summary>
    Null = 5,
    /// <summary>
    /// Used internally by this provider
    /// </summary>
    DateTime = 10,
    /// <summary>
    /// Used internally
    /// </summary>
    None = 11,
  }

  /// <summary>
  /// This implementation of SQLite for ADO.NET can process date/time fields in databases in only one of two formats.  Ticks and ISO8601.
  /// Ticks is inherently more accurate, but less compatible with 3rd party tools that query the database, and renders the DateTime field
  /// unreadable without post-processing.
  /// ISO8601 is more compatible, readable, fully-processable, but less accurate as it doesn't provide time down to fractions of a second.
  /// </summary>
  public enum SQLiteDateFormats
  {
    /// <summary>
    /// Using ticks is more accurate but less compatible with other viewers and utilities that access your database.
    /// </summary>
    Ticks = 0,
    /// <summary>
    /// The default format for this provider.
    /// </summary>
    ISO8601 = 1,
  }

  /// <summary>
  /// Struct used internally to determine the datatype of a column in a resultset
  /// </summary>
  internal struct SQLiteType
  {
    /// <summary>
    /// The DbType of the column, or DbType.Object if it cannot be determined
    /// </summary>
    internal DbType Type;
    /// <summary>
    /// The affinity of a column, used for expressions or when Type is DbType.Object
    /// </summary>
    internal TypeAffinity Affinity;
  }

  internal struct SQLiteTypeNames
  {
    internal SQLiteTypeNames(string newtypeName, DbType newdataType)
    {
      typeName = newtypeName;
      dataType = newdataType;
    }

    internal string typeName;
    internal DbType dataType;
  }

  /// <summary>
  /// This base class provides datatype conversion services for the SQLite provider.
  /// </summary>
  public abstract class SQLiteConvert
  {
    /// <summary>
    /// An array of ISO8601 datetime formats we support conversion from
    /// </summary>
    private static string[] _datetimeFormats = new string[] {
      "yyyy-MM-dd HH:mm:ss.fffffff",
      "yyyy-MM-dd HH:mm:ss",
      "yyyy-MM-dd HH:mm",                               
      "yyyyMMddHHmmss",
      "yyyyMMddHHmm",
      "yyyyMMddTHHmmssfffffff",
      "yyyy-MM-dd",
      "yy-MM-dd",
      "yyyyMMdd",
      "HH:mm:ss",
      "HH:mm",
      "THHmmss",
      "THHmm",
      "yyyy-MM-dd HH:mm:ss.fff",
      "yyyy-MM-ddTHH:mm",
      "yyyy-MM-ddTHH:mm:ss",
      "yyyy-MM-ddTHH:mm:ss.fff",
      "yyyy-MM-ddTHH:mm:ss.ffffff",
      "HH:mm:ss.fff"
    };

    /// <summary>
    /// An UTF-8 Encoding instance, so we can convert strings to and from UTF-8
    /// </summary>
    private Encoding _utf8 = new UTF8Encoding();
    /// <summary>
    /// The default DateTime format for this instance
    /// </summary>
    internal SQLiteDateFormats _datetimeFormat;
    /// <summary>
    /// Initializes the conversion class
    /// </summary>
    /// <param name="fmt">The default date/time format to use for this instance</param>
    internal SQLiteConvert(SQLiteDateFormats fmt)
    {
      _datetimeFormat = fmt;
    }

    #region UTF-8 Conversion Functions
    /// <summary>
    /// Converts a string to a UTF-8 encoded byte array sized to include a null-terminating character.
    /// </summary>
    /// <param name="sourceText">The string to convert to UTF-8</param>
    /// <returns>A byte array containing the converted string plus an extra 0 terminating byte at the end of the array.</returns>
    public byte[] ToUTF8(string sourceText)
    {
      Byte[] byteArray;
      int nlen = _utf8.GetByteCount(sourceText) + 1;

      byteArray = new byte[nlen];
      nlen = _utf8.GetBytes(sourceText, 0, sourceText.Length, byteArray, 0);
      byteArray[nlen] = 0;

      return byteArray;
    }

    /// <summary>
    /// Convert a DateTime to a UTF-8 encoded, zero-terminated byte array.
    /// </summary>
    /// <remarks>
    /// This function is a convenience function, which first calls ToString() on the DateTime, and then calls ToUTF8() with the
    /// string result.
    /// </remarks>
    /// <param name="dateTimeValue">The DateTime to convert.</param>
    /// <returns>The UTF-8 encoded string, including a 0 terminating byte at the end of the array.</returns>
    public byte[] ToUTF8(DateTime dateTimeValue)
    {
      return ToUTF8(ToString(dateTimeValue));
    }

    /// <summary>
    /// Converts a UTF-8 encoded IntPtr of the specified length into a .NET string
    /// </summary>
    /// <param name="nativestring">The pointer to the memory where the UTF-8 string is encoded</param>
    /// <param name="nativestringlen">The number of bytes to decode</param>
    /// <returns>A string containing the translated character(s)</returns>
    public virtual string ToString(IntPtr nativestring, int nativestringlen)
    {
      return UTF8ToString(nativestring, nativestringlen);
    }

    /// <summary>
    /// Converts a UTF-8 encoded IntPtr of the specified length into a .NET string
    /// </summary>
    /// <param name="nativestring">The pointer to the memory where the UTF-8 string is encoded</param>
    /// <param name="nativestringlen">The number of bytes to decode</param>
    /// <returns>A string containing the translated character(s)</returns>
    public virtual string UTF8ToString(IntPtr nativestring, int nativestringlen)
    {
      if (nativestringlen == 0) return "";

      byte[] byteArray = new byte[nativestringlen];

      Marshal.Copy(nativestring, byteArray, 0, nativestringlen);

      return _utf8.GetString(byteArray, 0, nativestringlen);
    }


    #endregion

    #region DateTime Conversion Functions
    /// <summary>
    /// Converts a string into a DateTime, using the current DateTimeFormat specified for the connection when it was opened.
    /// </summary>
    /// <remarks>
    /// Acceptable ISO8601 DateTime formats are:
    ///   yyyy-MM-dd HH:mm:ss
    ///   yyyyMMddHHmmss
    ///   yyyyMMddTHHmmssfffffff
    ///   yyyy-MM-dd
    ///   yy-MM-dd
    ///   yyyyMMdd
    ///   HH:mm:ss
    ///   THHmmss
    /// </remarks>
    /// <param name="dateText">The string containing either a Tick value or an ISO8601-format string</param>
    /// <returns>A DateTime value</returns>
    public DateTime ToDateTime(string dateText)
    {
      switch (_datetimeFormat)
      {
        case SQLiteDateFormats.Ticks:
          return new DateTime(Convert.ToInt64(dateText, CultureInfo.InvariantCulture));
        default:
          return DateTime.ParseExact(dateText, _datetimeFormats, DateTimeFormatInfo.InvariantInfo, DateTimeStyles.None);
      }
    }

    /// <summary>
    /// Converts a DateTime to a string value, using the current DateTimeFormat specified for the connection when it was opened.
    /// </summary>
    /// <param name="dateValue">The DateTime value to convert</param>
    /// <returns>Either a string consisting of the tick count for DateTimeFormat.Ticks, or a date/time in ISO8601 format.</returns>
    public string ToString(DateTime dateValue)
    {
      switch (_datetimeFormat)
      {
        case SQLiteDateFormats.Ticks:
          return dateValue.Ticks.ToString(CultureInfo.InvariantCulture);
        default:
          return dateValue.ToString(_datetimeFormats[0], CultureInfo.InvariantCulture);
      }
    }

    /// <summary>
    /// Internal function to convert a UTF-8 encoded IntPtr of the specified length to a DateTime.
    /// </summary>
    /// <remarks>
    /// This is a convenience function, which first calls ToString() on the IntPtr to convert it to a string, then calls
    /// ToDateTime() on the string to return a DateTime.
    /// </remarks>
    /// <param name="ptr">A pointer to the UTF-8 encoded string</param>
    /// <param name="len">The length in bytes of the string</param>
    /// <returns>The parsed DateTime value</returns>
    internal DateTime ToDateTime(IntPtr ptr, int len)
    {
      return ToDateTime(ToString(ptr, len));
    }
    #endregion

    /// <summary>
    /// Smart method of splitting a string.  Skips quoted elements, removes the quotes.
    /// </summary>
    /// <remarks>
    /// This split function works somewhat like the String.Split() function in that it breaks apart a string into
    /// pieces and returns the pieces as an array.  The primary differences are:
    /// <list type="bullet">
    /// <item><description>Only one character can be provided as a separator character</description></item>
    /// <item><description>Quoted text inside the string is skipped over when searching for the separator, and the quotes are removed.</description></item>
    /// </list>
    /// Thus, if splitting the following string looking for a comma:<br/>
    /// One,Two, "Three, Four", Five<br/>
    /// <br/>
    /// The resulting array would contain<br/>
    /// [0] One<br/>
    /// [1] Two<br/>
    /// [2] Three, Four<br/>
    /// [3] Five<br/>
    /// <br/>
    /// Note that the leading and trailing spaces were removed from each item during the split.
    /// </remarks>
    /// <param name="source">Source string to split apart</param>
    /// <param name="separator">Separator character</param>
    /// <returns>A string array of the split up elements</returns>
    public static string[] Split(string source, char separator)
    {
      char[] toks = new char[2] { '\"', separator };
      char[] quot = new char[1] { '\"' };