function submit(part)
%SUBMIT Submit your code and output to the ml-class servers
%   SUBMIT() will connect to the ml-class server and submit your solution

  fprintf('==\n== [ml-class] Submitting Solutions | Programming Exercise %s\n==\n', ...
          homework_id());
  if ~exist('part', 'var') || isempty(part)
    partId = promptPart();
  end
  
  % Check valid partId
  partNames = validParts();
  if ~isValidPartId(partId)
    fprintf('!! Invalid homework part selected.\n');
    fprintf('!! Expected an integer from 1 to %d.\n', numel(partNames) + 1);
    fprintf('!! Submission Cancelled\n');
    return
  end

  [login password] = loginPrompt();
  if isempty(login)
    fprintf('!! Submission Cancelled\n');
    return
  end

  fprintf('\n== Connecting to ml-class ... '); 
  if exist('OCTAVE_VERSION') 
    fflush(stdout);
  end
  
  % Setup submit list
  if partId == numel(partNames) + 1
    submitParts = 1:numel(partNames);
  else
    submitParts = [partId];
  end

  for s = 1:numel(submitParts)
    % Submit this part
    partId = submitParts(s);
    
    % Get Challenge
    [login, ch, signature] = getChallenge(login);
    if isempty(login) || isempty(ch) || isempty(signature)
      % Some error occured, error string in first return element.
      fprintf('\n!! Error: %s\n\n', login);
      return
    end
  
    % Attempt Submission with Challenge
    ch_resp = challengeResponse(login, password, ch);
    [result, str] = submitSolution(login, ch_resp, partId, output(partId), ...
                                 source(partId), signature);
                                 
    fprintf('\n== [ml-class] Submitted Homework %s - Part %d - %s\n', ...
            homework_id(), partId, partNames{partId});
    fprintf('== %s\n', strtrim(str));
    if exist('OCTAVE_VERSION') 
      fflush(stdout);
    end
  end
  
end

% ================== CONFIGURABLES FOR EACH HOMEWORK ==================

function id = homework_id() 
  id = '1';
end

function [partNames] = validParts()
  partNames = { 'Warm up exercise ', ...
                'Computing Cost (for one variable)', ...
                'Gradient Descent (for one variable)', ...
                'Feature Normalization', ...
                'Computing Cost (for multiple variables)', ...
                'Gradient Descent (for multiple variables)', ...
                'Normal Equations'};
end

function srcs = sources()
  % Separated by part
  srcs = { { 'warmUpExercise.m' }, ...
           { 'computeCost.m' }, ...
           { 'gradientDescent.m' }, ...
           { 'featureNormalize.m' }, ...
           { 'computeCostMulti.m' }, ...
           { 'gradientDescentMulti.m' }, ...
           { 'normalEqn.m' }, ...
         };
end

function out = output(partId)
  % Random Test Cases
  X1 = [ones(20,1) (exp(1) + exp(2) * (0.1:0.1:2))'];
  Y1 = X1(:,2) + sin(X1(:,1)) + cos(X1(:,2));
  X2 = [X1 X1(:,2).^0.5 X1(:,2).^0.25];
  Y2 = Y1.^0.5 + Y1;
  if partId == 1
    out = sprintf('%0.5f ', warmUpExercise());
  elseif partId == 2
    out = sprintf('%0.5f ', computeCost(X1, Y1, [0.5 -0.5]'));
  elseif partId == 3
    out = sprintf('%0.5f ', gradientDescent(X1, Y1, [0.5 -0.5]', 0.01, 10));
  elseif partId == 4
    out = sprintf('%0.5f ', featureNormalize(X2(:,2:4)));
  elseif partId == 5
    out = sprintf('%0.5f ', computeCostMulti(X2, Y2, [0.1 0.2 0.3 0.4]'));
  elseif partId == 6
    out = sprintf('%0.5f ', gradientDescentMulti(X2, Y2, [-0.1 -0.2 -0.3 -0.4]', 0.01, 10));
  elseif partId == 7
    out = sprintf('%0.5f ', normalEqn(X2, Y2));
  end 
end

function url = challenge_url()
  url = 'http://www.ml-class.org/course/homework/challenge';
end

function url = submit_url()
  url = 'http://www.ml-class.org/course/homework/submit';
end

% ========================= CHALLENGE HELPERS =========================

function src = source(partId)
  src = '';
  src_files = sources();
  if partId <= numel(src_files)
      flist = src_files{partId};
      for i = 1:numel(flist)
          fid = fopen(flist{i});
          while ~feof(fid)
            line = fgets(fid);
            src = [src line];
          end
          src = [src '||||||||'];
      end
  end
end

function ret = isValidPartId(partId)
  partNames = validParts();
  ret = (~isempty(partId)) && (partId >= 1) && (partId <= numel(partNames) + 1);
end

function partId = promptPart()
  fprintf('== Select which part(s) to submit:\n', ...
          homework_id());
  partNames = validParts();
  srcFiles = sources();
  for i = 1:numel(partNames)
    fprintf('==   %d) %s [', i, partNames{i});
    fprintf(' %s ', srcFiles{i}{:});
    fprintf(']\n');
  end
  fprintf('==   %d) All of the above \n==\nEnter your choice [1-%d]: ', ...
          numel(partNames) + 1, numel(partNames) + 1);
  selPart = input('', 's');
  partId = str2num(selPart);
  if ~isValidPartId(partId)
    partId = -1;
  end
end

function [email,ch,signature] = getChallenge(email)
  str = urlread(challenge_url(), 'post', {'email_address', email});

  str = strtrim(str);
  [email, str] = strtok (str, '|');
  [ch, str] = strtok (str, '|');
  [signature, str] = strtok (str, '|');
end


function [result, str] = submitSolution(email, ch_resp, part, output, ...
                                        source, signature)

  params = {'homework', homework_id(), ...
            'part', num2str(part), ...
            'email', email, ...
            'output', output, ...
            'source', source, ...
            'challenge_response', ch_resp, ...
            'signature', signature};

  str = urlread(submit_url(), 'post', params);
  
  % Parse str to read for success / failure
  result = 0;

end

% =========================== LOGIN HELPERS ===========================

function [login password] = loginPrompt()
  % Prompt for password
  [login password] = basicPrompt();
  
  if isempty(login) || isempty(password)
    login = []; password = [];
  end
end


function [login password] = basicPrompt()
  login = input('Login (Email address): ', 's');
  password = input('Password: ', 's');
end


function [str] = challengeResponse(email, passwd, challenge)
  salt = ')~/|]QMB3[!W`?OVt7qC"@+}';
  str = sha1([challenge sha1([salt email passwd])]);
  sel = randperm(numel(str));
  sel = sort(sel(1:16));
  str = str(sel);
end


% =============================== SHA-1 ================================

function hash = sha1(str)
  
  % Initialize variables
  h0 = uint32(1732584193);
  h1 = uint32(4023233417);
  h2 = uint32(2562383102);
  h3 = uint32(271733878);
  h4 = uint32(3285377520);
  
  % Convert to word array
  strlen = numel(str);

  % Break string into chars and append the bit 1 to the message
  mC = [double(str) 128];
  mC = [mC zeros(1, 4-mod(numel(mC), 4), 'uint8')];
  
  numB = strlen * 8;
  if exist('idivide')
    numC = idivide(uint32(numB + 65), 512, 'ceil');
  else
    numC = ceil(double(numB + 65)/512);
  end
  numW = numC * 16;
  mW = zeros(numW, 1, 'uint32');
  
  idx = 1;
  for i = 1:4:strlen + 1
    mW(idx) = bitor(bitor(bitor( ...
                  bitshift(uint32(mC(i)), 24), ...
                  bitshift(uint32(mC(i+1)), 16)), ...
                  bitshift(uint32(mC(i+2)), 8)), ...
                  uint32(mC(i+3)));
    idx = idx + 1;
  end
  
  % Append length of message
  mW(numW - 1) = uint32(bitshift(uint64(numB), -32));
  mW(numW) = uint32(bitshift(bitshift(uint64(numB), 32), -32));

  % Process the message in successive 512-bit chs
  for cId = 1 : double(numC)
    cSt = (cId - 1) * 16 + 1;
    cEnd = cId * 16;
    ch = mW(cSt : cEnd);
    
    % Extend the sixteen 32-bit words into eighty 32-bit words
    for j = 17 : 80
      ch(j) = ch(j - 3);
      ch(j) = bitxor(ch(j), ch(j - 8));
      ch(j) = bitxor(ch(j), ch(j - 14));
      ch(j) = bitxor(ch(j), ch(j - 16));
      ch(j) = bitrotate(ch(j), 1);
    end
  
    % Initialize hash value for this ch
    a = h0;
    b = h1;
    c = h2;
    d = h3;
    e = h4;
    
    % Main loop
    for i = 1 : 80
      if(i >= 1 && i <= 20)
        f = bitor(bitand(b, c), bitand(bitcmp(b), d));
        k = uint32(1518500249);
      elseif(i >= 21 && i <= 40)
        f = bitxor(bitxor(b, c), d);
        k = uint32(1859775393);
      elseif(i >= 41 && i <= 60)
        f = bitor(bitor(bitand(b, c), bitand(b, d)), bitand(c, d));
        k = uint32(2400959708);
      elseif(i >= 61 && i <= 80)
        f = bitxor(bitxor(b, c), d);
        k = uint32(3395469782);
      end
      
      t = bitrotate(a, 5);
      t = bitadd(t, f);
      t = bitadd(t, e);
      t = bitadd(t, k);
      t = bitadd(t, ch(i));
      e = d;
      d = c;
      c = bitrotate(b, 30);
      b = a;
      a = t;
      
    end
    h0 = bitadd(h0, a);
    h1 = bitadd(h1, b);
    h2 = bitadd(h2, c);
    h3 = bitadd(h3, d);
    h4 = bitadd(h4, e);

  end

  hash = reshape(dec2hex(double([h0 h1 h2 h3 h4]), 8)', [1 40]);
  
  hash = lower(hash);

end

function ret = bitadd(iA, iB)
  ret = double(iA) + double(iB);
  ret = bitset(ret, 33, 0);
  ret = uint32(ret);
end

function ret = bitrotate(iA, places)
  t = bitshift(iA, places - 32);
  ret = bitshift(iA, places);
  ret = bitor(ret, t);
end