using System;
using System.Text;
using I18N.Common;

namespace I18N.CJK
{
	// FIXME:
	// find out what is the difference between 50220, 50221 and 50222.

	public class CP50220 : ISO2022JPEncoding
	{
		public CP50220 ()
			: base (50220, false, false)
		{
		}

		public override string EncodingName {
			get { return "Japanese (JIS)"; }
		}
	}

	public class CP50221 : ISO2022JPEncoding
	{
		public CP50221 ()
			: base (50221, true, false)
		{
		}

		public override string EncodingName {
			get { return "Japanese (JIS-Allow 1 byte Kana)"; }
		}
	}

	public class CP50222 : ISO2022JPEncoding
	{
		public CP50222 ()
			: base (50222, true, true)
		{
		}

		public override string EncodingName {
			get { return "Japanese (JIS-Allow 1 byte Kana - SO/SI)"; }
		}
	}

	public class ISO2022JPEncoding : MonoEncoding
	{
		static JISConvert convert = JISConvert.Convert;

		public ISO2022JPEncoding (int codePage, bool allow1ByteKana, bool allowShiftIO)
			: base (codePage)
		{
			this.allow_1byte_kana = allow1ByteKana;
			this.allow_shift_io = allowShiftIO;
		}

		readonly bool allow_1byte_kana, allow_shift_io;

		public override string BodyName {
			get { return "iso-2022-jp"; }
		}

		public override string HeaderName {
			get { return "iso-2022-jp"; }
		}

		public override string WebName {
			get { return "csISO2022JP"; }
		}

		public override int GetMaxByteCount (int charCount)
		{
			// ESC w ESC s ESC w ... (even number) ESC s
			return charCount / 2 * 5 + 4;
		}

		public override int GetMaxCharCount (int byteCount)
		{
			// no escape sequence
			return byteCount;
		}

		public override int GetByteCount (char [] chars, int charIndex, int charCount)
		{
			return new ISO2022JPEncoder (this, allow_1byte_kana, allow_shift_io).GetByteCount (chars, charIndex, charCount, true);
		}

		public unsafe override int GetBytesImpl (char* chars, int charCount, byte* bytes, int byteCount)
		{
			return new ISO2022JPEncoder (this, allow_1byte_kana, allow_shift_io).GetBytesImpl (chars, charCount, bytes, byteCount, true);
		}

		public override int GetCharCount (byte [] bytes, int index, int count)
		{
			return new ISO2022JPDecoder (allow_1byte_kana, allow_shift_io).GetCharCount (bytes, index, count);
		}

		public override int GetChars (byte [] bytes, int byteIndex, int byteCount, char [] chars, int charIndex)
		{
			return new ISO2022JPDecoder (allow_1byte_kana, allow_shift_io).GetChars (bytes, byteIndex, byteCount, chars, charIndex);
		}
	}

	internal enum ISO2022JPMode {
		ASCII,
		JISX0208,
		JISX0201
	}

	internal class ISO2022JPEncoder : MonoEncoding.MonoEncoder
	{
		static JISConvert convert = JISConvert.Convert;

		readonly bool allow_1byte_kana, allow_shift_io;

		ISO2022JPMode m = ISO2022JPMode.ASCII;
		bool shifted_in;

		public ISO2022JPEncoder (MonoEncoding owner, bool allow1ByteKana, bool allowShiftIO)
			: base (owner)
		{
			this.allow_1byte_kana = allow1ByteKana;
			this.allow_shift_io = allowShiftIO;
		}

		public override int GetByteCount (char [] chars, int charIndex, int charCount, bool flush)
		{
			int end = charIndex + charCount;
			int value;
			int byteCount = 0;

			for (int i = charIndex; i < end; i++) {
				char ch = chars [i];
				// When half-kana is not allowed and it is
				// actually in the input, convert to full width
				// kana.
				if (!allow_1byte_kana &&
					ch >= 0xFF60 && ch <= 0xFFA0)
					ch = full_width_map [ch - 0xFF60];

				if (ch >= 0x2010 && ch <= 0x9FA5)
				{
					if (shifted_in) {
						shifted_in = false;
						byteCount++; // shift_out
					}
					if (m != ISO2022JPMode.JISX0208)
						byteCount += 3;
					m = ISO2022JPMode.JISX0208;
					// This range contains the bulk of the CJK set.
					value = (ch - 0x2010) * 2;
					value = ((int)(convert.cjkToJis[value])) |
							(((int)(convert.cjkToJis[value + 1])) << 8);
				} else if (ch >= 0xFF01 && ch <= 0xFF60) {
					if (shifted_in) {
						shifted_in = false;
						byteCount++;
					}
					if (m != ISO2022JPMode.JISX0208)
						byteCount += 3;
					m = ISO2022JPMode.JISX0208;

					// This range contains extra characters,
					value = (ch - 0xFF01) * 2;
					value = ((int)(convert.extraToJis[value])) |
							(((int)(convert.extraToJis[value + 1])) << 8);
				} else if(ch >= 0xFF60 && ch <= 0xFFA0) {
					if (allow_shift_io) {
						if (!shifted_in) {
							byteCount++;
							shifted_in = true;
						}
					}
					else if (m != ISO2022JPMode.JISX0201) {
						byteCount += 3;
						m = ISO2022JPMode.JISX0201;
					}
					value = ch - 0xFF60 + 0xA0;
				} else if (ch < 128) {
					if (shifted_in) {
						shifted_in = false;
						byteCount++;
					}
					if (m != ISO2022JPMode.ASCII)
						byteCount += 3;
					m = ISO2022JPMode.ASCII;
					value = (int) ch;
				} else
					// skip non-convertible character
					continue;

				if (value > 0x100)
					byteCount += 2;
				else
					byteCount++;
			}
			// must end in ASCII mode
			if (flush) {
				if (shifted_in) {
					shifted_in = false;
					byteCount++;
				}
				if (m != ISO2022JPMode.ASCII)
					byteCount += 3;
				m = ISO2022JPMode.ASCII;
			}
			return byteCount;
		}

		// returns false if it failed to add required ESC.
		private unsafe void SwitchMode (byte* bytes, ref int byteIndex,
			ref int byteCount, ref ISO2022JPMode cur, ISO2022JPMode next)
		{
			if (cur == next)
				return;

			if (byteCount <= 3)
				throw new ArgumentOutOfRangeException ("Insufficient byte buffer.");
			bytes [byteIndex++] = 0x1B;
			bytes [byteIndex++] = (byte) (next == ISO2022JPMode.JISX0208 ? 0x24 : 0x28);
			bytes [byteIndex++] = (byte) (next == ISO2022JPMode.JISX0201 ? 0x49 : 0x42);
			cur = next;
		}

		static readonly char [] full_width_map = new char [] {
			'\0', '\u3002', '\u300C', '\u300D', '\u3001', '\u30FB', // to nakaguro
			'\u30F2', '\u30A1', '\u30A3', '\u30A5', '\u30A7', '\u30A9', '\u30E3', '\u30E5', '\u30E7', '\u30C3', // to small tsu
			'\u30FC', '\u30A2', '\u30A4', '\u30A6', '\u30A8', '\u30AA', // A-O
			'\u30AB', '\u30AD', '\u30AF', '\u30B1', '\u30B3',
			'\u30B5', '\u30B7', '\u30B9', '\u30BB', '\u30BD',
			'\u30BF', '\u30C1', '\u30C4', '\u30C6', '\u30C8',
			'\u30C9', '\u30CA', '\u30CB', '\u30CC', '\u30CD',
			'\u30CF', '\u30D2', '\u30D5', '\u30D8', '\u30DB',
			'\u30DE', '\u30DF', '\u30E0', '\u30E1', '\u30E2',
			'\u30E4', '\u30E6', '\u30E8', // Ya-Yo
			'\u30E9', '\u30EA', '\u30EB', '\u30EC', '\u30ED',
			'\u30EF', '\u30F1', '\u30F3', '\u309B', '\u309C'};

		public unsafe override int GetBytesImpl (
			char* chars, int charCount,
			byte* bytes, int byteCount, bool flush)
		{
			int charIndex = 0;
			int byteIndex = 0;
#if NET_2_0
			EncoderFallbackBuffer buffer = null;
#endif

			int start = byteIndex;
			int end = charIndex + charCount;
			int value;

			for (int i = charIndex; i < end; i++, charCount--) {
				char ch = chars [i];

				// When half-kana is not allowed and it is
				// actually in the input, convert to full width
				// kana.
				if (!allow_1byte_kana &&
					ch >= 0xFF60 && ch <= 0xFFA0)
					ch = full_width_map [ch - 0xFF60];

				if (ch >= 0x2010 && ch <= 0x9FA5)
				{
					if (shifted_in) {
						bytes [byteIndex++] = 0x0F;
						shifted_in = false;
						byteCount--;
					}
					switch (m) {
					case ISO2022JPMode.JISX0208:
						break;
					default:
						SwitchMode (bytes, ref byteIndex, ref byteCount, ref m, ISO2022JPMode.JISX0208);
						break;
					}
					// This range contains the bulk of the CJK set.
					value = (ch - 0x2010) * 2;
					value = ((int)(convert.cjkToJis[value])) |
							(((int)(convert.cjkToJis[value + 1])) << 8);
				} else if (ch >= 0xFF01 && ch <= 0xFF60) {
					if (shifted_in) {
						bytes [byteIndex++] = 0x0F;
						shifted_in = false;
						byteCount--;
					}
					switch (m) {
					case ISO2022JPMode.JISX0208:
						break;
					default:
						SwitchMode (bytes, ref byteIndex, ref byteCount, ref m, ISO2022JPMode.JISX0208);
						break;
					}

					// This range contains extra characters,
					value = (ch - 0xFF01) * 2;
					value = ((int)(convert.extraToJis[value])) |
							(((int)(convert.extraToJis[value + 1])) << 8);
				} else if (ch >= 0xFF60 && ch <= 0xFFA0) {
					// disallowed half-width kana is
					// already converted to full-width kana
					// so here we don't have to consider it.

					if (allow_shift_io) {
						if (!shifted_in) {
							bytes [byteIndex++] = 0x0E;
							shifted_in = true;
							byteCount--;
						}
					} else {
						switch (m) {
						case ISO2022JPMode.JISX0201:
							break;
						default:
							SwitchMode (bytes, ref byteIndex, ref byteCount, ref m, ISO2022JPMode.JISX0201);
							break;
						}
					}
					value = ch - 0xFF40;
				} else if (ch < 128) {
					if (shifted_in) {
						bytes [byteIndex++] = 0x0F;
						shifted_in = false;
						byteCount--;
					}
					SwitchMode (bytes, ref byteIndex, ref byteCount, ref m, ISO2022JPMode.ASCII);
					value = (int) ch;
				} else {
#if NET_2_0
					HandleFallback (
						chars, ref i, ref charCount,
						bytes, ref byteIndex, ref byteCount);
#endif
					// skip non-convertible character
					continue;
				}

//Console.WriteLine ("{0:X04} : {1:x02} {2:x02}", v, (int) v / 94 + 33, v % 94 + 33);
				if (value > 0x100) {
					value -= 0x0100;
					bytes [byteIndex++] = (byte) (value / 94 + 33);
					bytes [byteIndex++] = (byte) (value % 94 + 33);
					byteCount -= 2;
				}
				else {
					bytes [byteIndex++] = (byte) value;
					byteCount--;
				}
			}
			if (flush) {
				// must end in ASCII mode
				if (shifted_in) {
					bytes [byteIndex++] = 0x0F;
					shifted_in = false;
					byteCount--;
				}
				if (m != ISO2022JPMode.ASCII)
					SwitchMode (bytes, ref byteIndex, ref byteCount, ref m, ISO2022JPMode.ASCII);
			}
			return byteIndex - start;
		}

#if NET_2_0
		public override void Reset ()
		{
			m = ISO2022JPMode.ASCII;
			shifted_in = false;
		}
#endif
	}

	internal class ISO2022JPDecoder : Decoder
	{
		static JISConvert convert = JISConvert.Convert;

		readonly bool allow_shift_io;
		ISO2022JPMode m = ISO2022JPMode.ASCII;
		bool shifted_in;

		public ISO2022JPDecoder (bool allow1ByteKana, bool allowShiftIO)
		{
			this.allow_shift_io = allowShiftIO;
		}

		// GetCharCount
		public override int GetCharCount (byte [] bytes, int index, int count)
		{
			int ret = 0;

			int end = index + count;
			for (int i = index; i < end; i++) {
				if (allow_shift_io) {
					switch (bytes [i]) {
					case 0x0F:
						shifted_in = false;
						continue;
					case 0x0E:
						shifted_in = true;
						continue;
					}
				}
				if (bytes [i] != 0x1B) {
					if (!shifted_in && m == ISO2022JPMode.JISX0208) {
						if (i + 1 == end)
							break; // incomplete head of wide char
						else
							ret++;
						i++; // 2 byte char
					}
					else
						ret++; // half-kana or ASCII
				} else {
					if (i + 2 >= end)
						break; // incomplete escape sequence
					i++;
					bool wide = false;
					if (bytes [i] == 0x24)
						wide = true;
					else if (bytes [i] == 0x28)
						wide = false;
					else
						throw new ArgumentException ("Unexpected ISO-2022-JP escape sequence.");
					i++;
					if (bytes [i] == 0x42)
						m = wide ? ISO2022JPMode.JISX0208 : ISO2022JPMode.ASCII;
					else if (bytes [i] == 0x49)
						m = ISO2022JPMode.JISX0201;
					else
						throw new ArgumentException (String.Format ("Unexpected ISO-2022-JP escape sequence. Ended with 0x{0:X04}", bytes [i]));
				}
			}
			return ret;
		}

		private int ToChar (int value)
		{
			value <<= 1;
			return value + 1 >= convert.jisx0208ToUnicode.Length ?
				-1 :
				((int) (convert.jisx0208ToUnicode [value])) |
					(((int) (convert.jisx0208ToUnicode [value + 1])) << 8);
		}

		public override int GetChars (byte [] bytes, int byteIndex, int byteCount, char [] chars, int charIndex)
		{
			int start = charIndex;
			int end = byteIndex + byteCount;
			for (int i = byteIndex; i < end && charIndex < chars.Length; i++) {
				if (allow_shift_io) {
					switch (bytes [i]) {
					case 0x0F:
						shifted_in = false;
						continue;
					case 0x0E:
						shifted_in = true;
						continue;
					}
				}

				if (bytes [i] != 0x1B) {
					if (shifted_in || m == ISO2022JPMode.JISX0201) {
						// half-kana
						if (bytes [i] < 0x60)
							chars [charIndex++] = (char) (bytes [i] + 0xFF40);
						else
							// invalid
							chars [charIndex++] = '?';
					}
					else if (m == ISO2022JPMode.JISX0208) {
						if (i + 1 == end)
							break; // incomplete head of wide char

						// am so lazy, so reusing jis2sjis
						int s1 = ((bytes [i] - 1) >> 1) + ((bytes [i] <= 0x5e) ? 0x71 : 0xb1);
						int s2 = bytes [i + 1] + (((bytes [i] & 1) != 0) ? 0x20 : 0x7e);
						int v = (s1 - 0x81) * 0xBC;
						v += s2 - 0x41;

						int ch = ToChar (v);
						if (ch < 0)
							chars [charIndex++] = '?';
						else
							chars [charIndex++] = (char) ch;
						i++;
					}
					// LAMESPEC: actually this should not
					// be allowed when 1byte-kana is not
					// allowed, but MS.NET seems to allow
					// it in any mode.
					else if (bytes [i] > 0xA0 && bytes [i] < 0xE0) // half-width Katakana
						chars [charIndex++] = (char) (bytes [i] - 0xA0 + 0xFF60);
					else
						chars [charIndex++] = (char) bytes [i];
					continue;
				} else {
					if (i + 2 >= end)
						break; // incomplete escape sequence
					i++;
					bool wide = false;
					if (bytes [i] == 0x24)
						wide = true;
					else if (bytes [i] == 0x28)
						wide = false;
					else
						throw new ArgumentException ("Unexpected ISO-2022-JP escape sequence.");
					i++;
					if (bytes [i] == 0x42)
						m = wide ? ISO2022JPMode.JISX0208 : ISO2022JPMode.ASCII;
					else if (bytes [i] == 0x49)
						m = ISO2022JPMode.JISX0201;
					else
						throw new ArgumentException (String.Format ("Unexpected ISO-2022-JP escape sequence. Ended with 0x{0:X04}", bytes [i]));
				}
			}

			return charIndex - start;
		}

#if NET_2_0
		public override void Reset ()
		{
			m = ISO2022JPMode.ASCII;
			shifted_in = false;
		}
#endif
	}

	public class ENCiso_2022_jp : CP50220
	{
		public ENCiso_2022_jp () : base() {}

	}; // class ENCiso_2022_jp
}