/*
* Copyright 2007 ZXing authors
*
* 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.
*/

using System;

namespace ZXing.QrCode.Internal
{
    /// <summary>
    /// <p>See ISO 18004:2006, 6.4.1, Tables 2 and 3. This enum encapsulates the various modes in which
    /// data can be encoded to bits in the QR code standard.</p>
    /// </summary>
    /// <author>Sean Owen</author>
    public sealed class Mode
    {
        /// <summary>
        /// Gets the name.
        /// </summary>
        public Names Name { get; private set; }

        /// <summary>
        /// enumeration for encoding modes
        /// </summary>
        public enum Names
        {
            /// <summary>
            /// 
            /// </summary>
            TERMINATOR,
            /// <summary>
            /// numeric encoding
            /// </summary>
            NUMERIC,
            /// <summary>
            /// alpha-numeric encoding
            /// </summary>
            ALPHANUMERIC,
            /// <summary>
            /// structured append
            /// </summary>
            STRUCTURED_APPEND,
            /// <summary>
            /// byte mode encoding
            /// </summary>
            BYTE,
            /// <summary>
            /// ECI segment
            /// </summary>
            ECI,
            /// <summary>
            /// Kanji mode
            /// </summary>
            KANJI,
            /// <summary>
            /// FNC1 char, first position
            /// </summary>
            FNC1_FIRST_POSITION,
            /// <summary>
            /// FNC1 char, second position
            /// </summary>
            FNC1_SECOND_POSITION,
            /// <summary>
            /// Hanzi mode
            /// </summary>
            HANZI
        }

        // No, we can't use an enum here. J2ME doesn't support it.

        /// <summary>
        /// 
        /// </summary>
        public static readonly Mode TERMINATOR = new Mode(new int[] { 0, 0, 0 }, 0x00, Names.TERMINATOR); // Not really a mode...
                                                                                                          /// <summary>
                                                                                                          /// 
                                                                                                          /// </summary>
        public static readonly Mode NUMERIC = new Mode(new int[] { 10, 12, 14 }, 0x01, Names.NUMERIC);
        /// <summary>
        /// 
        /// </summary>
        public static readonly Mode ALPHANUMERIC = new Mode(new int[] { 9, 11, 13 }, 0x02, Names.ALPHANUMERIC);
        /// <summary>
        /// 
        /// </summary>
        public static readonly Mode STRUCTURED_APPEND = new Mode(new int[] { 0, 0, 0 }, 0x03, Names.STRUCTURED_APPEND); // Not supported
                                                                                                                        /// <summary>
                                                                                                                        /// 
                                                                                                                        /// </summary>
        public static readonly Mode BYTE = new Mode(new int[] { 8, 16, 16 }, 0x04, Names.BYTE);
        /// <summary>
        /// 
        /// </summary>
        public static readonly Mode ECI = new Mode(null, 0x07, Names.ECI); // character counts don't apply
                                                                           /// <summary>
                                                                           /// 
                                                                           /// </summary>
        public static readonly Mode KANJI = new Mode(new int[] { 8, 10, 12 }, 0x08, Names.KANJI);
        /// <summary>
        /// 
        /// </summary>
        public static readonly Mode FNC1_FIRST_POSITION = new Mode(null, 0x05, Names.FNC1_FIRST_POSITION);
        /// <summary>
        /// 
        /// </summary>
        public static readonly Mode FNC1_SECOND_POSITION = new Mode(null, 0x09, Names.FNC1_SECOND_POSITION);
        /// <summary>See GBT 18284-2000; "Hanzi" is a transliteration of this mode name.</summary>
        public static readonly Mode HANZI = new Mode(new int[] { 8, 10, 12 }, 0x0D, Names.HANZI);

        private readonly int[] characterCountBitsForVersions;

        private Mode(int[] characterCountBitsForVersions, int bits, Names name)
        {
            this.characterCountBitsForVersions = characterCountBitsForVersions;
            Bits = bits;
            Name = name;
        }

        /// <summary>
        /// Fors the bits.
        /// </summary>
        /// <param name="bits">four bits encoding a QR Code data mode</param>
        /// <returns>
        ///   <see cref="Mode"/> encoded by these bits
        /// </returns>
        /// <exception cref="ArgumentException">if bits do not correspond to a known mode</exception>
        public static Mode forBits(int bits)
        {
            switch (bits)
            {
                case 0x0:
                    return TERMINATOR;
                case 0x1:
                    return NUMERIC;
                case 0x2:
                    return ALPHANUMERIC;
                case 0x3:
                    return STRUCTURED_APPEND;
                case 0x4:
                    return BYTE;
                case 0x5:
                    return FNC1_FIRST_POSITION;
                case 0x7:
                    return ECI;
                case 0x8:
                    return KANJI;
                case 0x9:
                    return FNC1_SECOND_POSITION;
                case 0xD:
                    // 0xD is defined in GBT 18284-2000, may not be supported in foreign country
                    return HANZI;
                default:
                    throw new ArgumentException();
            }
        }

        /// <param name="version">version in question
        /// </param>
        /// <returns> number of bits used, in this QR Code symbol {@link Version}, to encode the
        /// count of characters that will follow encoded in this {@link Mode}
        /// </returns>
        public int getCharacterCountBits(Version version)
        {
            if (characterCountBitsForVersions == null)
            {
                throw new ArgumentException("Character count doesn't apply to this mode");
            }
            int number = version.VersionNumber;
            int offset;
            if (number <= 9)
            {
                offset = 0;
            }
            else if (number <= 26)
            {
                offset = 1;
            }
            else
            {
                offset = 2;
            }
            return characterCountBitsForVersions[offset];
        }

        /// <summary>
        /// Gets the bits.
        /// </summary>
        public int Bits { get; private set; }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override String ToString()
        {
            return Name.ToString();
        }
    }
}