function [obs] = parse_metar(metar_str)
% [obs] = parse_metar(metar_str)
% 
% Last modified:  Time-stamp: <2003-09-30 09:14:04 haines>
%
% Abstract: Function that loads, parses metar obs, appends new data, and saves with all data 
%
% Usage: [obs] = parse_metar(metar_str)
%   metar_str = string of coded metar data
%   [obs] = vector array of decoded data
%  

% 
% Author: Sara Haines, Sept 18, 2003
  
  

% Processing:
%   (1) break into words
%   (2) parse each word into categories 
%   (3) further extract each category and convert as necessary
%
% # Major parts and general idea of this subroutine courtesy of: 
% # wmk <wkowalsk@ii.pw.edu.pl>
% # www.ii.pw.edu.pl/~wkowalsk/metar2.cgi
% #  Thu May 20 21:34:39 CET 1999

% anything other than alph numeric or whitespace should be removed
metar_str = regexprep(metar_str, '[^A-Z|a-z|0-9|\-|\/|\s]', '');
  
% cell array of coded metar words
words = strread(metar_str, '%s', 'delimiter', ' ');
words(1) = [];

% for each word establish category
for i = 1:length(words)

  word = char(words(i));
  
  %   if regexp(word, 'RMK|TEMPO|BECMG|NOSIG')
  %     break; % break out of this loop
  %   else

  if regexp(word, 'COR|AUTO')
    if ~exist('obstype')
      obstype = word;
      continue;
    end
  elseif regexp(word, '^(\d{6})Z|^(\d{6})')
    if ~exist('rtime')
      rtime = word;
      continue;
    end
  elseif regexp(word, '(..)MPS|(..)KT')
    if ~exist('wind1')
      wind1 = word;
      continue;
    end
  elseif regexp(word, '^(\d{4})|(..)SM|CAVOK')
    if ~exist('visib')
      visib = word;
      continue;
    end
  elseif regexp(word, 'BR|DZ|DS|DU|RA|SN|SG|SA|SS|SQ|IC|PE|PY|GR|GS|FG|FC|FU|HZ')
     if ~exist('phenom')
       phenom{1} = word;
     else
       phenom{length(phenom)+1} = word;
     end
     continue;
  elseif regexp(word, 'FEW|SCT|BKN|OVC')
    if ~exist('clouds')
      clouds{1} = word;
    else
      clouds{length(clouds)+1} = word;
    end
    continue;
  elseif regexp(word, '^(\d{3})V(\d{3})')
     if ~exist('wind2')
       wind2 = word;
       continue;
     end
  elseif regexp(word, '^(M?\d{2})\/(M?\d{2})')
    if ~exist('tempr')
      tempr = word;
      continue;
    end
  elseif regexp(word, 'Q(\d{4})|A(\d{4})')
    if ~exist('press')
      press = word;
      continue;
    end
  elseif regexp(word, '^SLP')
    if ~exist('slpress')
      slpress = word;
      continue;
    end
  end

end % for

% process wind1, wind2, tempr, and press to get started
% to tease out wspd, wdir, peak_gusts, atemp, dewp, baro, slp
%
% eventually want to tease out higher precision temp and press 
% measurements from stations that have that (usually follows RMK,
% for example, RMK AO2 SLP133 T03110178)
%
% (still will need to handle visib, phenom, and clouds later)

% calm 00000KT
% variable VRBdd(d)KT or VRBdd(d)Gdd(d)KT
% wdir and wspd dddddKT
% wdir and wspd with gust factor ddddd(d)Gdd(d)KT
% (not worrying about direction variablility 350V040 assigned to wind2 word)

if exist('wind1')
  
  % split string between dir and speed
  wind1_dir = wind1(1:3);
  wind1_spd = wind1(4:end);
  
  if regexp(wind1, 'VRB')
    wdir = 999;
  else
    try 
      wdir = strread(wind1_dir, '%d'); 
    catch 
      wdir = -9999; 
    end
  end
  if regexp(wind1_spd, 'G')
    try 
      [wspd, maxwspd] = strread(wind1_spd, '%dG%d%*s'); 
    catch 
      wspd = -9999; 
      maxwspd = -9999; 
    end
  else
    try 
      [wspd] = strread(wind1_spd, '%d%*s');
      maxwspd = wspd;
    catch 
      wspd = -9999;
      maxwspd = -9999;
    end
  end
  
  if regexp(wind1_spd, 'KT')
    wspd = wspd*0.5141; % from knots to mps (m/sec)
    maxwspd = maxwspd*0.5141;
  elseif regexp(wind1_spd, 'MPS')
    % already in m/sec, don't do anything
  end
  
else
  wspd = -9999;
  wdir = -9999;
  maxwspd = -9999;
end

if exist('tempr')
  if length(tempr)>5
    tempr = tempr(1:5);
  end
  tempr = regexprep(tempr, 'M', '-');
  try
    [atemp,dewp] = strread(tempr, '%f/%f'); % deg C
  catch
    atemp = -9999;
    dewp = -9999;
  end
else
  atemp = -9999;
  dewp = -9999;
end

if exist('press')
  if length(press)>5
    press = press(1:5);
  end
  if regexp(press, '^Q')
    try
      baro = strread(press, 'Q%f'); % mbar
    catch
      baro = -9999;
    end
  elseif regexp(press, '^A')
    try
      baro = strread(press, 'A%f'); 
      baro = baro*0.33868; % from inHg*100 to mbar
    catch
      baro = -9999;
    end
  else
    baro = -9999;
  end
else
  baro = -9999;
end

if exist('slpress')
  if regexp(slpress, 'NO')
    slp = -9999;
  elseif length(slpress<4)
    slp = -9999;
  else
    try
      slp = strread(slpress, 'SLP%f');
      slp = slp/10;
      if slp >= 50
	slp = 900+slp;
      else
	slp = 1000+slp;
      end
    catch
      slp = -9999;
    end
  end
else
  slp = -9999;
end

obs.wspd = wspd;
obs.wdir = wdir;
obs.maxwspd = maxwspd;
obs.atemp = atemp;
obs.dewp = dewp;
obs.baro = baro;
obs.slp = slp;

% return;