/* Copyright (c) 2007-2008 CSIRO
   Copyright (c) 2007-2011 Xiph.Org Foundation
   Originally written by Jean-Marc Valin, Gregory Maxwell, Koen Vos,
   Timothy B. Terriberry, and the Opus open-source contributors
   Ported to C# by Logan Stromberg

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   - Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   - Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

   - Neither the name of Internet Society, IETF or IETF Trust, nor the
   names of specific contributors, may be used to endorse or promote
   products derived from this software without specific prior written
   permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

namespace Concentus.Celt
{
    using Concentus.Celt.Enums;
    using Concentus.Celt.Structs;
    using Concentus.Common;
    using Concentus.Common.CPlusPlus;
    using System.Diagnostics;

    internal static class Rate
    {
        private static readonly byte[] LOG2_FRAC_TABLE ={
           0,
           8,13,
          16,19,21,23,
          24,26,27,28,29,30,31,32,
          32,33,34,34,35,36,36,37,37
        };

        private const int ALLOC_STEPS = 6;

        internal static int get_pulses(int i)
        {
            return i < 8 ? i : (8 + (i & 7)) << ((i >> 3) - 1);
        }

        internal static int bits2pulses(CeltMode m, int band, int LM, int bits)
        {
            int i;
            int lo, hi;

            LM++;
            byte[] cache = m.cache.bits;
            int cache_ptr = m.cache.index[LM * m.nbEBands + band];

            lo = 0;
            hi = cache[cache_ptr];
            bits--;
            for (i = 0; i < CeltConstants.LOG_MAX_PSEUDO; i++)
            {
                int mid = (lo + hi + 1) >> 1;
                /* OPT: Make sure this is implemented with a conditional move */
                if ((int)cache[cache_ptr + mid] >= bits)
                    hi = mid;
                else
                    lo = mid;
            }
            if (bits - (lo == 0 ? -1 : (int)cache[cache_ptr + lo]) <= (int)cache[cache_ptr + hi] - bits)
                return lo;
            else
                return hi;
        }

        internal static int pulses2bits(CeltMode m, int band, int LM, int pulses)
        {
            LM++;
            return pulses == 0 ? 0 : m.cache.bits[m.cache.index[LM * m.nbEBands + band] + pulses] + 1;
        }

        internal static int interp_bits2pulses(CeltMode m, int start, int end, int skip_start,
              int[] bits1, int[] bits2, int[] thresh, int[] cap, int total, out int _balance,
              int skip_rsv, ref int intensity, int intensity_rsv, ref int dual_stereo, int dual_stereo_rsv, int[] bits,
              int[] ebits, int[] fine_priority, int C, int LM, EntropyCoder ec, int encode, int prev, int signalBandwidth)
        {
            int psum;
            int lo, hi;
            int i, j;
            int logM;
            int stereo;
            int codedBands = -1;
            int alloc_floor;
            int left, percoeff;
            int done;
            int balance;


            alloc_floor = C << EntropyCoder.BITRES;
            stereo = C > 1 ? 1 : 0;

            logM = LM << EntropyCoder.BITRES;
            lo = 0;
            hi = 1 << ALLOC_STEPS;
            for (i = 0; i < ALLOC_STEPS; i++)
            {
                int mid = (lo + hi) >> 1;
                psum = 0;
                done = 0;
                for (j = end; j-- > start;)
                {
                    int tmp = bits1[j] + (mid * (int)bits2[j] >> ALLOC_STEPS);
                    if (tmp >= thresh[j] || done != 0)
                    {
                        done = 1;
                        /* Don't allocate more than we can actually use */
                        psum += Inlines.IMIN(tmp, cap[j]);
                    }
                    else
                    {
                        if (tmp >= alloc_floor)
                            psum += alloc_floor;
                    }
                }
                if (psum > total)
                    hi = mid;
                else
                    lo = mid;
            }
            psum = 0;
            /*printf ("interp bisection gave %d\n", lo);*/
            done = 0;
            for (j = end; j-- > start;)
            {
                int tmp = bits1[j] + (lo * bits2[j] >> ALLOC_STEPS);
                if (tmp < thresh[j] && done == 0)
                {
                    if (tmp >= alloc_floor)
                        tmp = alloc_floor;
                    else
                        tmp = 0;
                }
                else
                {
                    done = 1;
                }

                /* Don't allocate more than we can actually use */
                tmp = Inlines.IMIN(tmp, cap[j]);
                bits[j] = tmp;
                psum += tmp;
            }

            /* Decide which bands to skip, working backwards from the end. */
            for (codedBands = end; ; codedBands--)
            {
                int band_width;
                int band_bits;
                int rem;
                j = codedBands - 1;
                /* Never skip the first band, nor a band that has been boosted by
                    dynalloc.
                   In the first case, we'd be coding a bit to signal we're going to waste
                    all the other bits.
                   In the second case, we'd be coding a bit to redistribute all the bits
                    we just signaled should be cocentrated in this band. */
                if (j <= skip_start)
                {
                    /* Give the bit we reserved to end skipping back. */
                    total += skip_rsv;
                    break;
                }

                /*Figure out how many left-over bits we would be adding to this band.
                  This can include bits we've stolen back from higher, skipped bands.*/
                left = total - psum;
                percoeff = Inlines.celt_udiv(left, m.eBands[codedBands] - m.eBands[start]);
                left -= (m.eBands[codedBands] - m.eBands[start]) * percoeff;
                rem = Inlines.IMAX(left - (m.eBands[j] - m.eBands[start]), 0);
                band_width = m.eBands[codedBands] - m.eBands[j];
                band_bits = (int)(bits[j] + percoeff * band_width + rem);
                /*Only code a skip decision if we're above the threshold for this band.
                  Otherwise it is force-skipped.
                  This ensures that we have enough bits to code the skip flag.*/
                if (band_bits >= Inlines.IMAX(thresh[j], alloc_floor + (1 << EntropyCoder.BITRES)))
                {
                    if (encode != 0)
                    {
                        /*This if() block is the only part of the allocation function that
                           is not a mandatory part of the bitstream: any bands we choose to
                           skip here must be explicitly signaled.*/
                        /*Choose a threshold with some hysteresis to keep bands from
                           fluctuating in and out.*/
#if FUZZING
            if ((new Random().Next() & 0x1) == 0)
#else
                        if (codedBands <= start + 2 || (band_bits > ((j < prev ? 7 : 9) * band_width << LM << EntropyCoder.BITRES) >> 4 && j <= signalBandwidth))
#endif
                        {
                            ec.enc_bit_logp(1, 1);
                            break;
                        }
                        ec.enc_bit_logp(0, 1);
                    }
                    else if (ec.dec_bit_logp(1) != 0)
                    {
                        break;
                    }
                    /*We used a bit to skip this band.*/
                    psum += 1 << EntropyCoder.BITRES;
                    band_bits -= 1 << EntropyCoder.BITRES;
                }
                /*Reclaim the bits originally allocated to this band.*/
                psum -= bits[j] + intensity_rsv;
                if (intensity_rsv > 0)
                    intensity_rsv = LOG2_FRAC_TABLE[j - start];
                psum += intensity_rsv;
                if (band_bits >= alloc_floor)
                {
                    /*If we have enough for a fine energy bit per channel, use it.*/
                    psum += alloc_floor;
                    bits[j] = alloc_floor;
                }
                else {
                    /*Otherwise this band gets nothing at all.*/
                    bits[j] = 0;
                }
            }

            Inlines.OpusAssert(codedBands > start);
            /* Code the intensity and dual stereo parameters. */
            if (intensity_rsv > 0)
            {
                if (encode != 0)
                {
                    intensity = Inlines.IMIN(intensity, codedBands);
                    ec.enc_uint((uint)(intensity - start), (uint)(codedBands + 1 - start));
                }
                else
                {
                    intensity = start + (int)ec.dec_uint((uint)(codedBands + 1 - start));
                }
            }
            else
            {
                intensity = 0;
            }

            if (intensity <= start)
            {
                total += dual_stereo_rsv;
                dual_stereo_rsv = 0;
            }
            if (dual_stereo_rsv > 0)
            {
                if (encode != 0)
                {
                    ec.enc_bit_logp(dual_stereo, 1);
                }
                else
                {
                    dual_stereo = ec.dec_bit_logp(1);
                }
            }
            else
            {
                dual_stereo = 0;
            }

            /* Allocate the remaining bits */
            left = total - psum;
            percoeff = Inlines.celt_udiv(left, m.eBands[codedBands] - m.eBands[start]);
            left -= (m.eBands[codedBands] - m.eBands[start]) * percoeff;
            for (j = start; j < codedBands; j++)
                bits[j] += ((int)percoeff * (m.eBands[j + 1] - m.eBands[j]));
            for (j = start; j < codedBands; j++)
            {
                int tmp = (int)Inlines.IMIN(left, m.eBands[j + 1] - m.eBands[j]);
                bits[j] += tmp;
                left -= tmp;
            }
            /*for (j=0;j<end;j++)printf("%d ", bits[j]);printf("\n");*/

            balance = 0;
            for (j = start; j < codedBands; j++)
            {
                int N0, N, den;
                int offset;
                int NClogN;
                int excess, bit;

                Inlines.OpusAssert(bits[j] >= 0);
                N0 = m.eBands[j + 1] - m.eBands[j];
                N = N0 << LM;
                bit = (int)bits[j] + balance;

                if (N > 1)
                {
                    excess = Inlines.MAX32(bit - cap[j], 0);
                    bits[j] = bit - excess;

                    /* Compensate for the extra DoF in stereo */
                    den = (C * N + ((C == 2 && N > 2 && (dual_stereo == 0) && j < intensity) ? 1 : 0));

                    NClogN = den * (m.logN[j] + logM);

                    /* Offset for the number of fine bits by log2(N)/2 + FINE_OFFSET
                       compared to their "fair share" of total/N */
                    offset = (NClogN >> 1) - den * CeltConstants.FINE_OFFSET;

                    /* N=2 is the only point that doesn't match the curve */
                    if (N == 2)
                        offset += den << EntropyCoder.BITRES >> 2;

                    /* Changing the offset for allocating the second and third
                        fine energy bit */
                    if (bits[j] + offset < den * 2 << EntropyCoder.BITRES)
                        offset += NClogN >> 2;
                    else if (bits[j] + offset < den * 3 << EntropyCoder.BITRES)
                        offset += NClogN >> 3;

                    /* Divide with rounding */
                    ebits[j] = Inlines.IMAX(0, (bits[j] + offset + (den << (EntropyCoder.BITRES - 1))));
                    ebits[j] = Inlines.celt_udiv(ebits[j], den) >> EntropyCoder.BITRES;

                    /* Make sure not to bust */
                    if (C * ebits[j] > (bits[j] >> EntropyCoder.BITRES))
                        ebits[j] = bits[j] >> stereo >> EntropyCoder.BITRES;

                    /* More than that is useless because that's about as far as PVQ can go */
                    ebits[j] = Inlines.IMIN(ebits[j], CeltConstants.MAX_FINE_BITS);

                    /* If we rounded down or capped this band, make it a candidate for the
                        final fine energy pass */
                    fine_priority[j] = (ebits[j] * (den << EntropyCoder.BITRES) >= bits[j] + offset) ? 1 : 0;

                    /* Remove the allocated fine bits; the rest are assigned to PVQ */
                    bits[j] -= C * ebits[j] << EntropyCoder.BITRES;

                }
                else {
                    /* For N=1, all bits go to fine energy except for a single sign bit */
                    excess = Inlines.MAX32(0, bit - (C << EntropyCoder.BITRES));
                    bits[j] = bit - excess;
                    ebits[j] = 0;
                    fine_priority[j] = 1;
                }

                /* Fine energy can't take advantage of the re-balancing in
                    quant_all_bands().
                   Instead, do the re-balancing here.*/
                if (excess > 0)
                {
                    int extra_fine;
                    int extra_bits;
                    extra_fine = Inlines.IMIN(excess >> (stereo + EntropyCoder.BITRES), CeltConstants.MAX_FINE_BITS - ebits[j]);
                    ebits[j] += extra_fine;
                    extra_bits = extra_fine * C << EntropyCoder.BITRES;
                    fine_priority[j] = (extra_bits >= excess - balance) ? 1 : 0;
                    excess -= extra_bits;
                }
                balance = excess;

                Inlines.OpusAssert(bits[j] >= 0);
                Inlines.OpusAssert(ebits[j] >= 0);
            }
            /* Save any remaining bits over the cap for the rebalancing in
                quant_all_bands(). */
            _balance = balance;

            /* The skipped bands use all their bits for fine energy. */
            for (; j < end; j++)
            {
                ebits[j] = bits[j] >> stereo >> EntropyCoder.BITRES;
                Inlines.OpusAssert(C * ebits[j] << EntropyCoder.BITRES == bits[j]);
                bits[j] = 0;
                fine_priority[j] = (ebits[j] < 1) ? 1 : 0;
            }

            return codedBands;
        }

        internal static int compute_allocation(CeltMode m, int start, int end, int[] offsets, int[] cap, int alloc_trim, ref int intensity, ref int dual_stereo,
              int total, out int balance, int[] pulses, int[] ebits, int[] fine_priority, int C, int LM, EntropyCoder ec, int encode, int prev, int signalBandwidth)
        {
            int lo, hi, len, j;
            int codedBands;
            int skip_start;
            int skip_rsv;
            int intensity_rsv;
            int dual_stereo_rsv;
            
            total = Inlines.IMAX(total, 0);
            len = m.nbEBands;
            skip_start = start;
            /* Reserve a bit to signal the end of manually skipped bands. */
            skip_rsv = total >= 1 << EntropyCoder.BITRES ? 1 << EntropyCoder.BITRES : 0;
            total -= skip_rsv;
            /* Reserve bits for the intensity and dual stereo parameters. */
            intensity_rsv = dual_stereo_rsv = 0;
            if (C == 2)
            {
                intensity_rsv = LOG2_FRAC_TABLE[end - start];
                if (intensity_rsv > total)
                    intensity_rsv = 0;
                else
                {
                    total -= intensity_rsv;
                    dual_stereo_rsv = total >= 1 << EntropyCoder.BITRES ? 1 << EntropyCoder.BITRES : 0;
                    total -= dual_stereo_rsv;
                }
            }

            int[] bits1 = new int[len];
            int[] bits2 = new int[len];
            int[] thresh = new int[len];
            int[] trim_offset = new int[len];

            for (j = start; j < end; j++)
            {
                /* Below this threshold, we're sure not to allocate any PVQ bits */
                thresh[j] = Inlines.IMAX((C) << EntropyCoder.BITRES, (3 * (m.eBands[j + 1] - m.eBands[j]) << LM << EntropyCoder.BITRES) >> 4);
                /* Tilt of the allocation curve */
                trim_offset[j] = C * (m.eBands[j + 1] - m.eBands[j]) * (alloc_trim - 5 - LM) * (end - j - 1)
                      * (1 << (LM + EntropyCoder.BITRES)) >> 6;
                /* Giving less resolution to single-coefficient bands because they get
                   more benefit from having one coarse value per coefficient*/
                if ((m.eBands[j + 1] - m.eBands[j]) << LM == 1)
                    trim_offset[j] -= C << EntropyCoder.BITRES;
            }
            lo = 1;
            hi = m.nbAllocVectors - 1;
            do
            {
                int done = 0;
                int psum = 0;
                int mid = (lo + hi) >> 1;
                for (j = end; j-- > start;)
                {
                    int bitsj;
                    int N = m.eBands[j + 1] - m.eBands[j];
                    bitsj = C * N * m.allocVectors[mid * len + j] << LM >> 2;

                    if (bitsj > 0)
                    {
                        bitsj = Inlines.IMAX(0, bitsj + trim_offset[j]);
                    }

                    bitsj += offsets[j];

                    if (bitsj >= thresh[j] || done != 0)
                    {
                        done = 1;
                        /* Don't allocate more than we can actually use */
                        psum += Inlines.IMIN(bitsj, cap[j]);
                    }
                    else
                    {
                        if (bitsj >= C << EntropyCoder.BITRES)
                        {
                            psum += C << EntropyCoder.BITRES;
                        }
                    }
                }
                if (psum > total)
                {
                    hi = mid - 1;
                }
                else
                {
                    lo = mid + 1;
                }
                /*printf ("lo = %d, hi = %d\n", lo, hi);*/
            } while (lo <= hi);

            hi = lo--;
            /*printf ("interp between %d and %d\n", lo, hi);*/

            for (j = start; j < end; j++)
            {
                int bits1j, bits2j;
                int N = m.eBands[j + 1] - m.eBands[j];
                bits1j = C * N * m.allocVectors[lo * len + j] << LM >> 2;
                bits2j = hi >= m.nbAllocVectors ?
                      cap[j] : C * N * m.allocVectors[hi * len + j] << LM >> 2;
                if (bits1j > 0)
                    bits1j = Inlines.IMAX(0, bits1j + trim_offset[j]);
                if (bits2j > 0)
                    bits2j = Inlines.IMAX(0, bits2j + trim_offset[j]);
                if (lo > 0)
                    bits1j += offsets[j];
                bits2j += offsets[j];
                if (offsets[j] > 0)
                    skip_start = j;
                bits2j = Inlines.IMAX(0, bits2j - bits1j);
                bits1[j] = bits1j;
                bits2[j] = bits2j;
            }

            codedBands = interp_bits2pulses(m, start, end, skip_start, bits1, bits2, thresh, cap,
                  total, out balance, skip_rsv, ref intensity, intensity_rsv, ref dual_stereo, dual_stereo_rsv,
                  pulses, ebits, fine_priority, C, LM, ec, encode, prev, signalBandwidth);

            return codedBands;
        }
    }
}