sendTxt(params,msg)

function status = sendTxt(params,msg)
% status = sendTxt(params, msg)
%
% params: Parameter struct containing address and server info in fields:
%       params.domain       domain of smtp server (ex: 'uchicago.edu')
%       params.smtp         smtp server (ex: 'smtp.uchicago.edu')
%       params.phoneNumber  in string or numerical form with no dashes (ex: 7735551212)
%       params.provider     valid providers are:
%                           'verizon'
%                           'att'
%                           'tmobile'
%                           'sprint'
%       params.fromAddr     'from' address
%                           (ex: [e-mail])
%       params.exeLoc       location and filename of mailsend executable
%                           (ex: 'C:\mailsend.exe')
%
% msg:  String containing short text message to send.  If no string is
%       specified, the text of the most recent error is sent.
%
% status: returns message from mailsend or 0 if no error
%
% NOTE: 'msg' is automatically truncated to 158 chars 

% get lasterr

if nargin == 1
    msg = lasterr;
end

% input checking

err = [ ~isfield(params,'domain') ...
        ~isfield(params,'smtp') ...
        ~isfield(params,'phoneNumber') ...
        ~isfield(params,'provider') ...
        ~isfield(params,'fromAddr') ...
        ~isfield(params,'exeLoc') ];

if any(err)
    error('Params structure is missing fields.');
end

if ~isstr(msg)
    error('Msg input should be a short string');
end
      
% remove carriage returns and single quotes from msg and replace with spaces

ind = find(isspace(msg));
msg(ind)=' ';

ind = strfind(msg,'''');
msg(ind)=' ';

% truncate msg to sms length

if length(msg) > 158
    msg=msg(1:158);
end

% convert phone number to string if necessary

if isnumeric(params.phoneNumber)
    params.phoneNumber = num2str(params.phoneNumber);
end

% remove leading '1' from phone number if necessary

if params.phoneNumber(1) == '1'
    params.phoneNumber(1) = [];
end

% check for 10-digit number

if length(params.phoneNumber) ~= 10
    error('Must include full ten digit phone number.')
end

switch lowercase(params.provider)
    case 'verizon'
        toAddr = [params.phoneNumber '@vtext.com'];
    case 'att'
        toAddr = [params.phoneNumber '@txt.att.net'];
    case 'sprint'
        toAddr = [params.phoneNumber '@messaging.sprintpcs.com'];
    case 'tmobile'
        toAddr = [params.phoneNumber '@tmomail.net'];
    case 't-mobile'
        toAddr = [params.phoneNumber '@tmomail.net'];
    otherwise
        error('Carrier not recognized.');
end

% send it

status = eval([ 'system(''' params.exeLoc...
                ' -d '      params.domain...
                ' -smtp '   params.smtp...
                ' -t '      toAddr...
                ' -f '      params.fromAddr...
                ' -M "'     msg     '"'');']);