%Minimum Error Rate Training For Statistical Machine Translation
%Copyright (2005) Ashish Venugopal

%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 2
%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, write to the Free
%  Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA

ALLDATA = load(feats_opt);
CANDS = load(cands_opt);

%init opt is now going to have ranges for each parameter
INIT = load(init_opt);

disp('Loaded translation data');
startEndIndices = zeros(size(CANDS,1), 2);
startIndex=1;
count = 0;
for s=1:1:size(CANDS,1)
  endIndex = startIndex + CANDS(s, 2)-1;
  count = count + 1;
  startEndIndices(count, :) = [startIndex, endIndex];
  startIndex=endIndex+1;
end



[nlines, NF] = size(INIT);
ALLFEAT = ALLDATA(:, 1:NF);

ALLSCORES = ALLDATA(:, NF+1:size(ALLDATA,2));
%clear ALLDATA;

%these variables are read in from the parameter restriction file
leftBound = INIT(1, :)
rightBound = INIT(2, :)
startingParams = INIT(3, :);

%when a lambda is within ExpansionMargin percentage ratio
%of either (symetric) bound, then multiply the bound by
%the ExpansionFactor
ExpansionMargin = 0.0;
ExpansionFactor = 1.2;

%number of times lambdas are randomly initialized for optimization
NumRandomTests = 5;
PermutationsEpsilon = 0.001;


%nist stats
ratio_x = 1.5;
score_x = 0.5;
beta = -log(score_x)/log(ratio_x)/log(ratio_x);
MAXNIST = 20.0;

%generate initial sums
initialScore = zeros(1, size(ALLSCORES,2));
numSentences = size(startEndIndices,1);


for s=1:numSentences
  
  sentStart = startEndIndices(s, 1);
  initialScore = initialScore+ALLSCORES(sentStart, :);;
  
end

numgrams = (size(initialScore,2)-1)/2.0;
referenceLength = initialScore(1, length(initialScore));
ngramData = initialScore(1, 1:length(initialScore)-1);

ngramData = reshape(ngramData, 2, numgrams);
basePrecision = ngramData(1,:)./ngramData(2,:);

%ngramData(2,1) is the number of unigrams suggested
lratio = ngramData(2,1)/referenceLength;
lpen = 1.0;
if lratio>=1.0
  %do nothing
else
  lpen = exp (-beta*log(lratio)*log(lratio));
end

bleuScore = (lpen*sum(basePrecision));
newError = MAXNIST-bleuScore;
str = 'InitialScore:';
str = sprintf('%s %f\n',str,bleuScore);

disp(str);


%saving the full optimization data after each complete iteration
%FullResults = zeros(NumRandomTests, NF+1);
FullResults = [];

%top level randomization of start values
for (topLevel=1:NumRandomTests)
  
  %generate random values in the restricted ranges, but dont
  %initialize the sampled values right next to the bounds, since then
  %the Expansion will always kick in. This way if the optimization
  %finds better parameters in the margin, only then will be have to
  %expand the range
  % if there are three rows in INIT and this is the first
  % iteration, then use the value from the last full run
  if (topLevel==1 && nlines==3)
    LAMBDAS = startingParams;
  else
    LAMBDAS = (leftBound+ExpansionMargin) + ((rightBound-ExpansionMargin)-(leftBound+ExpansionMargin)).*rand(1, NF);
  end
  str = 'Start Values:';
  disp(str);
  str = '';
  for i=1:length(LAMBDAS)
    str = sprintf('%s %f',str,LAMBDAS(i));
  end
  disp(str);
  
  
  %lastValue hold initial degenerate values of lambda
  lastValue = ones(1,size(LAMBDAS,2))*-1.0;
  %holds the degerate value for the error
  savedError = MAXNIST;
  lastError = MAXNIST;
  
  numIter = 1;
  ConvergedLimit = 3;
  
  converged = 0;
  IterationLimit = 100;
  
  
  %generate a random permutation of the dimension indices to vary
  %the search order, acrosss random initializations
  %ARV 06/20
  %oRange = randperm(NF); 
  oRange = 1:NF; 
  while (numIter<IterationLimit && converged<=ConvergedLimit);
    numIter = numIter + 1;
    lastValue = LAMBDAS;

    
    %go thru each dimension and save the best score that could be
    %achieved for that dimension in the variable called errorGain
    %dimension 1 of error gain is the lambda value, while row 2 
    %is the actual error gain (negative if there was a gain)
    errorGain = zeros(2, NF);
    for optiDim=oRange 
      %save the value of lambda in case the error increases
      %this error increase only happens due errors in precions
      %when differentiating between very close boundaries
      
      savedLambda = LAMBDAS(1, optiDim);
      %cancel out this dimension so that we can evaluate it at
      %different values
      LAMBDAS(1, optiDim) = 0;
      totalErrorDelta = [];
      
      %compute error boundaries for each sentence individually
      for s=1:numSentences
	
        sentStart = startEndIndices(s, 1);
        sentEnd = startEndIndices(s, 2);
        %s
	
        %prepare the sentence specific data
        FEAT = ALLFEAT(sentStart:sentEnd,:);
        SCORES = ALLSCORES(sentStart:sentEnd,:);
	
        [numCands, numFeats] = size(FEAT);

        %determine basic intercept and slope information for this sentence
        a = FEAT*LAMBDAS';
        slopes = FEAT(:, optiDim);

        [minLeftValue, minLeftCandidate] = min(a + slopes*leftBound(optiDim));
        [minRightValue, minRightCandidate] = min(a + slopes*rightBound(optiDim));

	originalMinLeftCandidate = minLeftCandidate;
	originalMinRightCandidate = minRightCandidate;
	

        slopeOfRightCandidate = slopes(minRightCandidate);
        slopeOfLeftCandidate = slopes(minLeftCandidate);
        relevantIndices = find (slopes < slopeOfLeftCandidate & slopes >= slopeOfRightCandidate);


        %initialize data that must be saved for this iteration
        %numIntersects starts at 1 since the first intersection point=leftBound
        numIntersects = 1;     
	intersectPoints = zeros(numCands+1, 2);
        intersectPoints(1, :) = [leftBound(optiDim) minLeftValue];

        %initialize the errorDelta that comes from crosssing the leftBound
        errorDeltas = zeros(numCands+1, size(SCORES,2)+1);
        errorDeltas(1, :) = [intersectPoints(1, 1) SCORES(minLeftCandidate, :)];
        %used to create error deltas across intersection boundaries
        workingError = SCORES(minLeftCandidate, :);
	


        %the relevant indices determine which candidate to consider for
        %evaluation. currently those sentences which have a slope lower
        %than the current sentence are chosen, becuase these
        %sentences have a chance of intersecting the current
        %sentence and becoming the lowest cost translation
        while (length(relevantIndices)>0)
	  
	  bestL = rightBound(optiDim);
	  bestValue = minRightValue;
	  bestSlope = slopeOfLeftCandidate;
	  
	  
	  %to save the new index of the min candidate
	  newMinCandidate = minLeftCandidate;
	  
	  for c=1:length(relevantIndices)
	    
	    x = relevantIndices(c);
	    
	    top = a(x,1)-a(minLeftCandidate,1);
	    bottom = slopes(minLeftCandidate,1)-slopes(x,1);
	    
	    if (bottom~=0)
	      newL = top/bottom;
	      
	      if (newL < bestL)
		candidateSlope = slopes(x);
		bestL = newL;
		bestValue = a(x)+ (newL*candidateSlope);
		newMinCandidate = c;
		bestSlope = candidateSlope;               
	      end
	      
	      %allows new intersections to be proposed that intersect at the
	      %same lambda. In this case consider only the one with the
	      %steeper slope since it will be lower in the next region
	      if (newL == bestL & (slopes(x)<bestSlope))
		candidateSlope = slopes(x);
		bestL = newL;
		bestValue = a(x)+ (newL*candidateSlope);
		newMinCandidate = c;
		bestSlope = candidateSlope;
	      end
	    end 
	  end
	  
	  %we have found a valid intersection point and a the candidate index
	  numIntersects = numIntersects + 1;
	  intersectPoints(numIntersects,:) =  [bestL bestValue];
	  
	  %reduce the data that is considered relevant for training
	  slopes = slopes(relevantIndices);
	  a = a(relevantIndices);
	  SCORES = SCORES(relevantIndices, :);
	  
	  minLeftCandidate= newMinCandidate;
	  slopeOfLeftCandidate = slopes(minLeftCandidate);

	  errorD = SCORES(minLeftCandidate, :) - workingError; 
	  errorDeltas(numIntersects, :) = [intersectPoints(numIntersects, 1) errorD];
	  workingError = SCORES(minLeftCandidate, :);
	  
	  relevantIndices = find (slopes < slopeOfLeftCandidate & slopes >= slopeOfRightCandidate);
	  
        end
	
        %ends the search for all relevant indices within this sentence
        %prunes the lists down to their actual lengths
        intersectPoints = intersectPoints(1:numIntersects, :);
        errorDeltas = errorDeltas(1:numIntersects, :);
	
        totalErrorDelta = [totalErrorDelta; errorDeltas];
      end %end of search thru each sentence

      totalErrorDelta = sortrows(totalErrorDelta);

      %generate bleu scores with length penalty for these boundaries
      lenTotalErrorDelta = length(totalErrorDelta);
      errorLineLen = size(totalErrorDelta, 2);
      numgrams = (size(ALLSCORES,2)-1)/2.0;
      
      % a 0 count line vector to compare against
      zeroLine = zeros(1, errorLineLen-1);
      
      totalErrorDelta = [totalErrorDelta; [rightBound(optiDim), zeroLine]];
      totalBaseError = zeroLine;
      
      %set the lowest error to the max possible error of this metric
      lowestError = MAXNIST;
      lowestLambda = leftBound(optiDim);
      
      for bIndex=1:lenTotalErrorDelta
        %increment the base count data
        incrementalError = totalErrorDelta(bIndex,2:errorLineLen);
	
        %no need to recalculate the error if there is no change in error count
	
        if (any(incrementalError))
	  
	  totalBaseError = totalBaseError + incrementalError;
	  
	  %if there are several boundary values that are the same we want to
	  %only consider a difference in score once they have all been
	  %accounted for
	  
	  if (totalErrorDelta(bIndex, 1)~=totalErrorDelta(bIndex+1, 1))
            
            
	    %calculate the new bleu score
	    referenceLength = totalBaseError(1, length(totalBaseError));
	    ngramData = totalBaseError(1, 1:length(totalBaseError)-1);

	    ngramData = reshape(ngramData, 2, numgrams);
	    basePrecision = ngramData(1,:)./ngramData(2,:);
            
	    
	    %ngramData(2,1) is the number of unigrams suggested
	    lratio = ngramData(2,1)/referenceLength;
	    lpen = 1.0;
	    if lratio>=1.0
	      %do nothing
	    else
	      lpen = exp (-beta*log(lratio)*log(lratio));
	    end
	    newError = MAXNIST-(lpen*sum(basePrecision));
	    

	    %see if an improvement has been made
	    if (newError < lowestError)
	      lowestError = newError;
	      lowestLambda = (totalErrorDelta(bIndex, 1)+totalErrorDelta(bIndex+1, 1))/2.0;

	    end
	    %use this to plot an error surface if you want
	    %errorSurface = [errorSurface; [totalErrorDelta(bIndex, 1) totalErrorDelta(bIndex+1, 1)  ((totalErrorDelta(bIndex, 1)+totalErrorDelta(bIndex+1, 1))/2.0) newError]];
            
	  end
	  
        end
      end
      
      
      %replace lambda with the old value
      LAMBDAS(1, optiDim) = savedLambda;

      %save the error values in the errorGain table
      errorGain(1, optiDim) = lowestLambda;
      errorGain(2, optiDim) = lowestError;
      
      %allows you to jump out and do temporarily worse for a bit
      savedError=lowestError;
      
      %dont lock in the error anymore
      %LAMBDAS(1,optiDim)=lowestLambda;
      
      %null out a parameter if it doesnt changes at all 
      %for i=1:length(LAMBDAS)
      %	if var(ALLFEAT(:,i))==0
      %	  LAMBDAS(i)=0;
      %	end
      %      end
      
      %display the lowest error if we had used the value of lambda
      %str = '';
      %str = sprintf('Dim %f', optiDim); 
      %LAMBDAS_COPY = LAMBDAS;
      %LAMBDAS_COPY(1, optiDim) = lowestLambda;
      %for i=1:length(LAMBDAS_COPY)
%	str = sprintf('%s %f',str,LAMBDAS_COPY(i));
      %end
      %str = sprintf('%s %f', str, lowestError);
      %disp(str);
      
      %at this point we have gone thru all dimensions
    end
    
    %disp('Iteration Completed, picking optimal lambda by gain');
    %errorGain
    [minError, minErrorDim] = min(errorGain(2, :));    
    %minError
    %minErrorDim
    if (minError <= savedError)
      LAMBDAS(1, minErrorDim) = errorGain(1, minErrorDim);
      str = '';
      str = sprintf('UsedDim(%f)', minErrorDim); 
      for i=1:length(LAMBDAS)
	if (i==minErrorDim)
	  str = sprintf('%s <%f>',str,LAMBDAS(i));
	else
	  str = sprintf('%s %f',str,LAMBDAS(i));
	end
	
	
      end
      str = sprintf('%s %f', str, minError);
      disp(str);
      
      savedError = minError;
    end

    % a mini convergence has happenned, lets save its value
    % in case the kickout cannot return back to the same value
    % this kickout move can only be done a limited number of
    % times, ie the converged limit
    if (abs(savedError-lastError)<PermutationsEpsilon)
      converged = converged+1;
      disp('Increment Convergence');
      
      %lock in the results for retrieval... this needs to be changed
      toAdd = [LAMBDAS, savedError];
      FullResults = [FullResults; toAdd];       
      
      %shake it out of its position a bit and keep going till
      %iteration limit ends, then lock it in again there
      LAMBDAS = LAMBDAS + (0.1).*rand(1,NF);
    
    else
      convergence = 0;
    end
    
    lastError = savedError;
  end
  

  %lock in the latest one as well in case we jumped out of this
  %because the IterationLimit ran out
  toAdd = [LAMBDAS, savedError];
  FullResults = [FullResults; toAdd];
  
  %find the result with the lowest error right now
  [mval, mRow] = min(FullResults(:, length(LAMBDAS)+1));
  str='';
  for i=1:length(LAMBDAS)
    str = sprintf('%s %f',str,FullResults(mRow, i));
  end
  str = sprintf('IntermediateParameters %s %f', str, mval);
  disp(str);
  str = sprintf('Itermediate Score %f',MAXNIST-mval);
  disp(str);
  %end of random initializations of LAMBDAS
end 


%pick the best performing scaling factors =================================
[mval, mRow] = min(FullResults(:, length(LAMBDAS)+1));
str='';
for i=1:length(LAMBDAS)
  str = sprintf('%s %f',str,FullResults(mRow, i));
end
str = sprintf('FinalParameters %s %f', str, mval);
disp(str);
str = sprintf('Final Score %f',MAXNIST-mval);
disp(str);
exit;