using System;

namespace ComponentAce.Compression.Libs.zlib
{
    internal sealed class Tree
    {
    	private const int MAX_BITS = 15;

    	private const int BL_CODES = 19;

    	private const int D_CODES = 30;

    	private const int LITERALS = 256;

    	private const int LENGTH_CODES = 29;

    	private static readonly int L_CODES = 286;

    	private static readonly int HEAP_SIZE = 2 * L_CODES + 1;

    	internal const int MAX_BL_BITS = 7;

    	internal const int END_BLOCK = 256;

    	internal const int REP_3_6 = 16;

    	internal const int REPZ_3_10 = 17;

    	internal const int REPZ_11_138 = 18;

    	internal static readonly int[] extra_lbits = new int[29]
    	{
    		0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
    		1, 1, 2, 2, 2, 2, 3, 3, 3, 3,
    		4, 4, 4, 4, 5, 5, 5, 5, 0
    	};

    	internal static readonly int[] extra_dbits = new int[30]
    	{
    		0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
    		4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
    		9, 9, 10, 10, 11, 11, 12, 12, 13, 13
    	};

    	internal static readonly int[] extra_blbits = new int[19]
    	{
    		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    		0, 0, 0, 0, 0, 0, 2, 3, 7
    	};

    	internal static readonly byte[] bl_order = new byte[19]
    	{
    		16, 17, 18, 0, 8, 7, 9, 6, 10, 5,
    		11, 4, 12, 3, 13, 2, 14, 1, 15
    	};

    	internal const int Buf_size = 16;

    	internal const int DIST_CODE_LEN = 512;

    	internal static readonly byte[] _dist_code = new byte[512]
    	{
    		0, 1, 2, 3, 4, 4, 5, 5, 6, 6,
    		6, 6, 7, 7, 7, 7, 8, 8, 8, 8,
    		8, 8, 8, 8, 9, 9, 9, 9, 9, 9,
    		9, 9, 10, 10, 10, 10, 10, 10, 10, 10,
    		10, 10, 10, 10, 10, 10, 10, 10, 11, 11,
    		11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
    		11, 11, 11, 11, 12, 12, 12, 12, 12, 12,
    		12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
    		12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
    		12, 12, 12, 12, 12, 12, 13, 13, 13, 13,
    		13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
    		13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
    		13, 13, 13, 13, 13, 13, 13, 13, 14, 14,
    		14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
    		14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
    		14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
    		14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
    		14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
    		14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
    		14, 14, 15, 15, 15, 15, 15, 15, 15, 15,
    		15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
    		15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
    		15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
    		15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
    		15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
    		15, 15, 15, 15, 15, 15, 0, 0, 16, 17,
    		18, 18, 19, 19, 20, 20, 20, 20, 21, 21,
    		21, 21, 22, 22, 22, 22, 22, 22, 22, 22,
    		23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
    		24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
    		24, 24, 24, 24, 25, 25, 25, 25, 25, 25,
    		25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
    		26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
    		26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
    		26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
    		26, 26, 27, 27, 27, 27, 27, 27, 27, 27,
    		27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
    		27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
    		27, 27, 27, 27, 28, 28, 28, 28, 28, 28,
    		28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
    		28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
    		28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
    		28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
    		28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
    		28, 28, 28, 28, 28, 28, 28, 28, 29, 29,
    		29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
    		29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
    		29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
    		29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
    		29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
    		29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
    		29, 29
    	};

    	internal static readonly byte[] _length_code = new byte[256]
    	{
    		0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
    		9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
    		13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
    		15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
    		17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
    		18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
    		19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
    		20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
    		21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
    		21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
    		22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
    		22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
    		23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
    		24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
    		24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
    		24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
    		25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
    		25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
    		25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
    		25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
    		26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
    		26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
    		26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
    		27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
    		27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
    		27, 27, 27, 27, 27, 28
    	};

    	internal static readonly int[] base_length = new int[29]
    	{
    		0, 1, 2, 3, 4, 5, 6, 7, 8, 10,
    		12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
    		64, 80, 96, 112, 128, 160, 192, 224, 0
    	};

    	internal static readonly int[] base_dist = new int[30]
    	{
    		0, 1, 2, 3, 4, 6, 8, 12, 16, 24,
    		32, 48, 64, 96, 128, 192, 256, 384, 512, 768,
    		1024, 1536, 2048, 3072, 4096, 6144, 8192, 12288, 16384, 24576
    	};

    	internal short[] dyn_tree;

    	internal int max_code;

    	internal StaticTree stat_desc;

    	internal static int d_code(int dist)
    	{
    		return (dist < 256) ? _dist_code[dist] : _dist_code[256 + SupportClass.URShift(dist, 7)];
    	}

    	internal void gen_bitlen(Deflate s)
    	{
    		short[] array = dyn_tree;
    		short[] static_tree = stat_desc.static_tree;
    		int[] extra_bits = stat_desc.extra_bits;
    		int extra_base = stat_desc.extra_base;
    		int max_length = stat_desc.max_length;
    		int num = 0;
    		for (int i = 0; i <= 15; i++)
    		{
    			s.bl_count[i] = 0;
    		}
    		array[s.heap[s.heap_max] * 2 + 1] = 0;
    		int j;
    		for (j = s.heap_max + 1; j < HEAP_SIZE; j++)
    		{
    			int num2 = s.heap[j];
    			int i = array[array[num2 * 2 + 1] * 2 + 1] + 1;
    			if (i > max_length)
    			{
    				i = max_length;
    				num++;
    			}
    			array[num2 * 2 + 1] = (short)i;
    			if (num2 <= max_code)
    			{
    				s.bl_count[i]++;
    				int num3 = 0;
    				if (num2 >= extra_base)
    				{
    					num3 = extra_bits[num2 - extra_base];
    				}
    				short num4 = array[num2 * 2];
    				s.opt_len += num4 * (i + num3);
    				if (static_tree != null)
    				{
    					s.static_len += num4 * (static_tree[num2 * 2 + 1] + num3);
    				}
    			}
    		}
    		if (num == 0)
    		{
    			return;
    		}
    		do
    		{
    			int i = max_length - 1;
    			while (s.bl_count[i] == 0)
    			{
    				i--;
    			}
    			s.bl_count[i]--;
    			s.bl_count[i + 1] = (short)(s.bl_count[i + 1] + 2);
    			s.bl_count[max_length]--;
    			num -= 2;
    		}
    		while (num > 0);
    		for (int i = max_length; i != 0; i--)
    		{
    			int num2 = s.bl_count[i];
    			while (num2 != 0)
    			{
    				int num5 = s.heap[--j];
    				if (num5 <= max_code)
    				{
    					if (array[num5 * 2 + 1] != i)
    					{
    						s.opt_len = (int)(s.opt_len + ((long)i - (long)array[num5 * 2 + 1]) * array[num5 * 2]);
    						array[num5 * 2 + 1] = (short)i;
    					}
    					num2--;
    				}
    			}
    		}
    	}

    	internal void build_tree(Deflate s)
    	{
    		short[] array = dyn_tree;
    		short[] static_tree = stat_desc.static_tree;
    		int elems = stat_desc.elems;
    		int num = -1;
    		s.heap_len = 0;
    		s.heap_max = HEAP_SIZE;
    		for (int i = 0; i < elems; i++)
    		{
    			if (array[i * 2] != 0)
    			{
    				num = (s.heap[++s.heap_len] = i);
    				s.depth[i] = 0;
    			}
    			else
    			{
    				array[i * 2 + 1] = 0;
    			}
    		}
    		int num2;
    		while (s.heap_len < 2)
    		{
    			num2 = (s.heap[++s.heap_len] = ((num < 2) ? (++num) : 0));
    			array[num2 * 2] = 1;
    			s.depth[num2] = 0;
    			s.opt_len--;
    			if (static_tree != null)
    			{
    				s.static_len -= static_tree[num2 * 2 + 1];
    			}
    		}
    		max_code = num;
    		for (int i = s.heap_len / 2; i >= 1; i--)
    		{
    			s.pqdownheap(array, i);
    		}
    		num2 = elems;
    		do
    		{
    			int i = s.heap[1];
    			s.heap[1] = s.heap[s.heap_len--];
    			s.pqdownheap(array, 1);
    			int num3 = s.heap[1];
    			s.heap[--s.heap_max] = i;
    			s.heap[--s.heap_max] = num3;
    			array[num2 * 2] = (short)(array[i * 2] + array[num3 * 2]);
    			s.depth[num2] = (byte)(Math.Max(s.depth[i], s.depth[num3]) + 1);
    			array[i * 2 + 1] = (array[num3 * 2 + 1] = (short)num2);
    			s.heap[1] = num2++;
    			s.pqdownheap(array, 1);
    		}
    		while (s.heap_len >= 2);
    		s.heap[--s.heap_max] = s.heap[1];
    		gen_bitlen(s);
    		gen_codes(array, num, s.bl_count);
    	}

    	internal static void gen_codes(short[] tree, int max_code, short[] bl_count)
    	{
    		short[] array = new short[16];
    		short num = 0;
    		for (int i = 1; i <= 15; i++)
    		{
    			num = (array[i] = (short)(num + bl_count[i - 1] << 1));
    		}
    		for (int j = 0; j <= max_code; j++)
    		{
    			int num2 = tree[j * 2 + 1];
    			if (num2 != 0)
    			{
    				tree[j * 2] = (short)bi_reverse(array[num2]++, num2);
    			}
    		}
    	}

    	internal static int bi_reverse(int code, int len)
    	{
    		int num = 0;
    		do
    		{
    			num |= code & 1;
    			code = SupportClass.URShift(code, 1);
    			num <<= 1;
    		}
    		while (--len > 0);
    		return SupportClass.URShift(num, 1);
    	}
    }
}