/*
  * Copyright (c) 2018 Paul B Mahol
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
  * as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public License
  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "libavutil/opt.h"
 #include "audio.h"
 #include "avfilter.h"
 #include "internal.h"
 #include "window_func.h"
 
 typedef struct HilbertContext {
     const AVClass *class;
 
     int sample_rate;
     int nb_taps;
     int nb_samples;
     int win_func;
 
     float *taps;
     int64_t pts;
 } HilbertContext;
 
 #define OFFSET(x) offsetof(HilbertContext, x)
 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption hilbert_options[] = {
     { "sample_rate", "set sample rate",    OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100},  1, INT_MAX,    FLAGS },
     { "r",           "set sample rate",    OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100},  1, INT_MAX,    FLAGS },
     { "taps",        "set number of taps", OFFSET(nb_taps),     AV_OPT_TYPE_INT, {.i64=22051}, 11, UINT16_MAX, FLAGS },
     { "t",           "set number of taps", OFFSET(nb_taps),     AV_OPT_TYPE_INT, {.i64=22051}, 11, UINT16_MAX, FLAGS },
     { "nb_samples",  "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, INT_MAX, FLAGS },
     { "n",           "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, INT_MAX, FLAGS },
     { "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64=WFUNC_BLACKMAN}, 0, NB_WFUNC-1, FLAGS, "win_func" },
     { "w",        "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64=WFUNC_BLACKMAN}, 0, NB_WFUNC-1, FLAGS, "win_func" },
         { "rect",     "Rectangular",      0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT},     0, 0, FLAGS, "win_func" },
         { "bartlett", "Bartlett",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BARTLETT}, 0, 0, FLAGS, "win_func" },
         { "hanning",  "Hanning",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING},  0, 0, FLAGS, "win_func" },
         { "hamming",  "Hamming",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HAMMING},  0, 0, FLAGS, "win_func" },
         { "blackman", "Blackman",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BLACKMAN}, 0, 0, FLAGS, "win_func" },
         { "welch",    "Welch",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_WELCH},    0, 0, FLAGS, "win_func" },
         { "flattop",  "Flat-top",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_FLATTOP},  0, 0, FLAGS, "win_func" },
         { "bharris",  "Blackman-Harris",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHARRIS},  0, 0, FLAGS, "win_func" },
         { "bnuttall", "Blackman-Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BNUTTALL}, 0, 0, FLAGS, "win_func" },
         { "bhann",    "Bartlett-Hann",    0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHANN},    0, 0, FLAGS, "win_func" },
         { "sine",     "Sine",             0, AV_OPT_TYPE_CONST, {.i64=WFUNC_SINE},     0, 0, FLAGS, "win_func" },
         { "nuttall",  "Nuttall",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_NUTTALL},  0, 0, FLAGS, "win_func" },
         { "lanczos",  "Lanczos",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_LANCZOS},  0, 0, FLAGS, "win_func" },
         { "gauss",    "Gauss",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_GAUSS},    0, 0, FLAGS, "win_func" },
         { "tukey",    "Tukey",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_TUKEY},    0, 0, FLAGS, "win_func" },
         { "dolph",    "Dolph-Chebyshev",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_DOLPH},    0, 0, FLAGS, "win_func" },
         { "cauchy",   "Cauchy",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_CAUCHY},   0, 0, FLAGS, "win_func" },
         { "parzen",   "Parzen",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_PARZEN},   0, 0, FLAGS, "win_func" },
         { "poisson",  "Poisson",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_POISSON},  0, 0, FLAGS, "win_func" },

         { "bohman" ,  "Bohman",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BOHMAN},   0, 0, FLAGS, "win_func" },

     {NULL}
 };
 
 AVFILTER_DEFINE_CLASS(hilbert);
 
 static av_cold int init(AVFilterContext *ctx)
 {
     HilbertContext *s = ctx->priv;
 
     if (!(s->nb_taps & 1)) {
         av_log(s, AV_LOG_ERROR, "Number of taps %d must be odd length.\n", s->nb_taps);
         return AVERROR(EINVAL);
     }
 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     HilbertContext *s = ctx->priv;
 
     av_freep(&s->taps);
 }
 
 static av_cold int query_formats(AVFilterContext *ctx)
 {
     HilbertContext *s = ctx->priv;
     static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
     int sample_rates[] = { s->sample_rate, -1 };
     static const enum AVSampleFormat sample_fmts[] = {
         AV_SAMPLE_FMT_FLT,
         AV_SAMPLE_FMT_NONE
     };
 
     AVFilterFormats *formats;
     AVFilterChannelLayouts *layouts;
     int ret;
 
     formats = ff_make_format_list(sample_fmts);
     if (!formats)
         return AVERROR(ENOMEM);
     ret = ff_set_common_formats (ctx, formats);
     if (ret < 0)
         return ret;
 
     layouts = avfilter_make_format64_list(chlayouts);
     if (!layouts)
         return AVERROR(ENOMEM);
     ret = ff_set_common_channel_layouts(ctx, layouts);
     if (ret < 0)
         return ret;
 
     formats = ff_make_format_list(sample_rates);
     if (!formats)
         return AVERROR(ENOMEM);
     return ff_set_common_samplerates(ctx, formats);
 }
 
 static av_cold int config_props(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     HilbertContext *s = ctx->priv;
     float overlap;
     int i;
 
     s->taps = av_malloc_array(s->nb_taps, sizeof(*s->taps));
     if (!s->taps)
         return AVERROR(ENOMEM);
 
     generate_window_func(s->taps, s->nb_taps, s->win_func, &overlap);
 
     for (i = 0; i < s->nb_taps; i++) {
         int k = -(s->nb_taps / 2) + i;
 
         if (k & 1) {
             float pk = M_PI * k;
 
             s->taps[i] *= (1.f - cosf(pk)) / pk;
         } else {
             s->taps[i] = 0.f;
         }
     }
 
     s->pts = 0;
 
     return 0;
 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     HilbertContext *s = ctx->priv;
     AVFrame *frame;
     int nb_samples;
 
     nb_samples = FFMIN(s->nb_samples, s->nb_taps - s->pts);
     if (!nb_samples)
         return AVERROR_EOF;
 
     if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
         return AVERROR(ENOMEM);
 
     memcpy(frame->data[0], s->taps + s->pts, nb_samples * sizeof(float));
 
     frame->pts = s->pts;
     s->pts    += nb_samples;
     return ff_filter_frame(outlink, frame);
 }
 
 static const AVFilterPad hilbert_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_AUDIO,
         .request_frame = request_frame,
         .config_props  = config_props,
     },
     { NULL }
 };
 
 AVFilter ff_asrc_hilbert = {
     .name          = "hilbert",
     .description   = NULL_IF_CONFIG_SMALL("Generate a Hilbert transform FIR coefficients."),
     .query_formats = query_formats,
     .init          = init,
     .uninit        = uninit,
     .priv_size     = sizeof(HilbertContext),
     .inputs        = NULL,
     .outputs       = hilbert_outputs,
     .priv_class    = &hilbert_class,
 };