-- CSV Module
-- http://help.interfaceware.com/kb/parsing-csv-files

local function parseCsvLine (line,sep) 
   local res = {}
   local pos = 1
   sep = sep or ','
   while true do 
      local c = string.sub(line,pos,pos)
      if (c == "") then break end
      local posn = pos 
      local ctest = string.sub(line,pos,pos)
      trace(ctest)
      while ctest == ' ' do
         -- handle space(s) at the start of the line (with quoted values)
         posn = posn + 1
         ctest = string.sub(line,posn,posn) 
         if ctest == '"' then
            pos = posn
            c = ctest
         end
      end
      if (c == '"') then
         -- quoted value (ignore separator within)
         local txt = ""
         repeat
            local startp,endp = string.find(line,'^%b""',pos)
            txt = txt..string.sub(line,startp+1,endp-1)
            pos = endp + 1
            c = string.sub(line,pos,pos) 
            if (c == '"') then 
               txt = txt..'"' 
               -- check first char AFTER quoted string, if it is another
               -- quoted string without separator, then append it
               -- this is the way to "escape" the quote char in a quote. example:
               --   value1,"blub""blip""boing",value3  will result in blub"blip"boing  for the middle
            elseif c == ' ' then
               -- handle space(s) before the delimiter (with quoted values)
               while c == ' ' do
                  pos = pos + 1
                  c = string.sub(line,pos,pos) 
               end
            end
         until (c ~= '"')
         table.insert(res,txt)
         trace(c,pos,i)
         if not (c == sep or c == "") then 
            error("ERROR: Invalid CSV field - near character "..pos.." in this line of the CSV file: \n"..line, 3)
         end
         pos = pos + 1
         posn = pos 
         ctest = string.sub(line,pos,pos)
         trace(ctest)
         while ctest == ' ' do
            -- handle space(s) after the delimiter (with quoted values)
            posn = posn + 1
            ctest = string.sub(line,posn,posn) 
            if ctest == '"' then
               pos = posn
               c = ctest
            end
         end
      else    
         -- no quotes used, just look for the first separator
         local startp,endp = string.find(line,sep,pos)
         if (startp) then 
            table.insert(res,string.sub(line,pos,startp-1))
            pos = endp + 1
         else
            -- no separator found -> use rest of string and terminate
            table.insert(res,string.sub(line,pos))
            break
         end 
      end
   end
   return res
end

------------------------------------
---- Module Interface functions ----
------------------------------------
local csv = {}

function csv.parseCsv(Data, Separator)
   -- handle '\r\n\' as line separator
   Data = Data:gsub('\r\n','\n')
   -- handle '\r' (bad form) as line separator  
   Data = Data:gsub('\r','\n')
   local Result={}
   
   for Line in Data:gmatch("([^\n]+)") do
      local ParsedLine = parseCsvLine(Line, Separator)
      table.insert(Result, ParsedLine)
   end
   
   return Result
end

local csv_parseCsv = {
   Title="csv.parseCsv";
   Usage="csv.parseCsv(csv, delimiter)",
   SummaryLine=[[Parses a CSV data string into a table
   ]];
   Desc=[[Parses a CSV data string into a table.
   <p> CSV is used generally to refer any format with 
   character delimited fields, the delimiter defautls to
   a "," (comma) but you can specify any character(s) 
   ]];
   ["Returns"] = {
      {Desc="A table containing the parsed CSV data."},
   };
   ParameterTable= false,
   Parameters= {
      {csv= {Desc='A string containing CSV data <u>string</u>.'}},
      {separator= {Desc='One or more field separator characters <u>string</u>.'}},
   };
   Examples={
      [[   function main(Data)
   local Csv = csv.parseCsv( Data)         -- comma separated (default)
      --local Csv = csv.parseCsv(Data, '\t')
      --local Csv = csv.parseCsv(Data, '|') 
      trace(Csv)
   end]],
   };
   SeeAlso={
      {
         Title="csv_parse.lua - in our code repository.",
         Link="http://help.interfaceware.com/code/details/csv_parse-lua"
      },
      {
         Title="CSV Parser",
         Link="http://help.interfaceware.com/v6/csv-parser"
      }
   }
}

help.set{input_function=csv.parseCsv, help_data=csv_parseCsv}

return csv