%%
%% *SpHEAR Project
%% sphear_fir_render_directions: render impulse responses throught the FIR filter A2B matrix
%%
%% usage:
%%   [] = sphear_fir_render_directions(FIR, fmin, fmax, N, Npre, Fs, smooth)
%%
%% FIR: A2B matrix of FIR filters
%% fmin, fmax: range of frequencies to use
%% N: number of samples to filter
%% Npre: number of samples before the main impulse peak
%% Fs: sampling rate
%%
%% Copyright 2016, Fernando Lopez-Lezcano, All Rights Reserved
%% nando@ccrma.stanford.edu
%%
%%  This program is free software: you can redistribute it and/or modify
%%  it under the terms of the GNU General Public License as published by
%%  the Free Software Foundation, either version 3 of the License, or
%%  (at your option) any later version.
%%
%%  This program 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 General Public License for more details.
%%
%%  You should have received a copy of the GNU General Public License
%%  along with this program.  If not, see <http://www.gnu.org/licenses/>.

function [BFF] = sphear_fir_render_directions(FIR, fmin, fmax, N, Npre, Fs, smooth)

  [ref, Fs] = wavread('../cal/2016.04.20/export/reference-001-1.wav');
  %% find highest peak location and define sample range
  [index, value] = findmaxpeak(ref);
  r_start = index - Npre;
  r_end = r_start + N -1;
  range = r_start:r_end;
  ref_fft = fft(tukeywin(size(range)(2), 0.02) .* ref(range), N);
  printf("reference: peak %f at %d, sample range [%d %d]\n", value, index, r_start, r_end);
  
  capnames = cellstr(['LF'; 'RF'; 'LB'; 'RB']);

  minindex = N;
  maxpeak = 0;
  
  Nfft = 4096;

  f = figure;
  hold on;
  grid on;
  axis([fmin, fmax, -30, 0]);

  %% title(sprintf("azimuth = %05.1f degrees", angle));
  tics('y', [6, 0, -3, -6, -9, -12, -15, -20, -25, -30]);
  tics('x', [300, 500, 1000, 2000, 3000, 5000, 7000, 10000, 15000, 20000]);

  idx = 1;

  for m = [1, 5, 9, 13, 3, 7, 11, 15]
    %% render b format components
    bf(idx,:,:) = sphear_a_to_b(m, FIR, range, N);

    %% calculate B format frequency responses
    for b = 1:4
      bfft(idx,b,:) = fastsmooth(20*log10(abs(fft(bf(idx,b,:), Nfft))), smooth, 2, 1);
    end
    fr = (1:Nfft/2) * Fs/Nfft;
    semilogx(fr, bfft(idx,1,1:end/2), 'k');
    if (idx > 4)
      col = 'b';
    else
      col = 'r';
    end
    if (rem(idx, 2) == 1)
      semilogx(fr, bfft(idx,2,1:end/2), col);
    else
      semilogx(fr, bfft(idx,3,1:end/2), col);
    end

    idx = idx + 1;
  end

  print(f, '-deps','-color',["figures/sphear_directions.eps"]);
end


function [bf] = sphear_a_to_b(m, FIR, range, N);
  capnames = cellstr(['LF'; 'RF'; 'LB'; 'RB']);
  %% read in capsule signals and apply FIR filter
  for c = 1:4
    cs(c,:) = wavread(["../cal/2016.04.20/export/a-format-0" sprintf("%02.0f", m) "-" char(capnames(c)) ".wav"]);
    cr(c,:) = tukeywin(size(range)(2), 0.0) .* cs(c,:)'(range);
    for b = 1:4
      bs(c,b,:) = fftfilt(reshape(FIR(b,c,:), 1, [])', cr(c,:), N);
    end
  end
  %% add filtered capsule output to b format components
  for b = 1:4
    bf(b,:) = bs(1,b,:) + bs(2,b,:) + bs(3,b,:) + bs(4,b,:);
  end
end


function [i, v] = findmaxpeak(signal);
  [peaks, locs] = findpeaks(signal, "DoubleSided");
  [~, index] = max(peaks);
  i = locs(index);
  v = peaks(index);
end