convert: find/create the rules file automatically, allow comment lines

Commands/Convert.hs

@@ -5,6 +5,7 @@ format, and print it on stdout. See the manual for more details.
 
 module Commands.Convert where
 import Options (Opt(Debug))
+import Version (versionstr)
 import Ledger.Types (Ledger,AccountName,LedgerTransaction(..),Posting(..),PostingType(..))
 import Ledger.Utils (strip, spacenonewline, restofline)
 import Ledger.Parse (someamount, emptyCtx, ledgeraccountname)
@@ -19,27 +20,61 @@ import Locale (defaultTimeLocale)
 import Data.Time.Format (parseTime)
 import Control.Monad (when, guard)
 import Safe (readDef, readMay)
-import System.FilePath.Posix (takeBaseName)
+import System.Posix.Files (fileExist)
+import System.FilePath.Posix (takeBaseName, replaceExtension)
 import Text.ParserCombinators.Parsec
 
 
 convert :: [Opt] -> [String] -> Ledger -> IO ()
 convert opts args _ = do
-  when (length args /= 2) (error "please specify a csv data file and conversion rules file.")
-  let debug = Debug `elem` opts
-      [csvfile,rulesfile] = args
+  when (null args) $ error "please specify a csv data file."
+  let csvfile = head args
   csvparse <- parseCSVFromFile csvfile
   let records = case csvparse of
                   Left e -> error $ show e
                   Right rs -> reverse $ filter (/= [""]) rs
+  let debug = Debug `elem` opts
+      rulesfile = rulesFileFor csvfile
+  exists <- fileExist rulesfile
+  if (not exists) then do
+                  hPrintf stderr "creating conversion rules file %s, edit this file for better results\n" rulesfile
+                  writeFile rulesfile initialRulesFileContent
+   else
+      hPrintf stderr "using conversion rules file %s\n" rulesfile
   rulesstr <- readFile rulesfile
-  let rules = case parseCsvRules (takeBaseName csvfile) rulesstr of
+  let rules = case parseCsvRules rulesfile rulesstr of
                   Left e -> error $ show e
                   Right r -> r
-  when debug $ hPrintf stderr "using csv conversion rules file %s\n" rulesfile
-  when debug $ hPrintf stderr "%s\n" (show rules)
+  when debug $ hPrintf stderr "rules: %s\n" (show rules)
   mapM_ (printTxn debug rules) records
 
+rulesFileFor :: FilePath -> FilePath
+rulesFileFor csvfile = replaceExtension csvfile ".rules"
+
+initialRulesFileContent :: String
+initialRulesFileContent =
+    "# csv conversion rules file generated by hledger "++versionstr++"\n" ++
+    "# Add rules to this file for more accurate conversion, see\n"++
+    "# http://hledger.org/MANUAL.html#convert\n" ++
+    "\n" ++
+    "base-account assets:bank:checking\n" ++
+    "date-field 0\n" ++
+    "description-field 4\n" ++
+    "amount-field 1\n" ++
+    "currency $\n" ++
+    "\n" ++
+    "# account-assigning rules\n" ++
+    "\n" ++
+    "SPECTRUM\n" ++
+    "expenses:health:gym\n" ++
+    "\n" ++
+    "ITUNES\n" ++
+    "BLKBSTR=BLOCKBUSTER\n" ++
+    "expenses:entertainment\n" ++
+    "\n" ++
+    "(TO|FROM) SAVINGS\n" ++
+    "assets:bank:savings\n"
+
 {- |
 A set of data definitions and account-matching patterns sufficient to
 convert a particular CSV data file into meaningful ledger transactions. See above.
@@ -79,16 +114,16 @@ type CsvRecord = [String]
 
 -- rules file parser
 
-parseCsvRules :: String -> String -> Either ParseError CsvRules
-parseCsvRules basefilename s = runParser csvrulesP nullrules{baseAccount=basefilename} "" s
+parseCsvRules :: FilePath -> String -> Either ParseError CsvRules
+parseCsvRules rulesfile s = runParser csvrulesfile nullrules{baseAccount=takeBaseName rulesfile} rulesfile s
 
-csvrulesP :: GenParser Char CsvRules CsvRules
-csvrulesP = do
-  optional blanklines
+csvrulesfile :: GenParser Char CsvRules CsvRules
+csvrulesfile = do
+  many blankorcommentline
   many definitions
   r <- getState
   ars <- many accountrule
-  optional blanklines
+  many blankorcommentline
   eof
   return r{accountRules=ars}
 
@@ -106,6 +141,7 @@ definitions = do
    ,currencyfield
    ,basecurrency
    ,baseaccount
+   ,commentline
    ] <?> "definition"
   return ()
 
@@ -169,17 +205,26 @@ baseaccount = do
 accountrule :: GenParser Char CsvRules AccountRule
 accountrule = do
   blanklines
+  many blankorcommentline
   pats <- many1 matchreplacepattern
   guard $ length pats >= 2
   let pats' = init pats
       acct = either (fail.show) id $ runParser ledgeraccountname () "" $ fst $ last pats
+  many commentline
   return (pats',acct)
 
 blanklines = many1 blankline >> return ()
 
 blankline = many spacenonewline >> newline >> return () <?> "blank line"
 
+commentchar = oneOf ";#"
+
+commentline = many spacenonewline >> commentchar >> restofline >> return () <?> "comment line"
+
+blankorcommentline = choice' [blankline, commentline]
+
 matchreplacepattern = do
+  notFollowedBy commentchar
   matchpat <- many1 (noneOf "=\n")
   replpat <- optionMaybe $ do {char '='; many $ noneOf "\n"}
   newline

Options.hs

@@ -20,7 +20,7 @@ timeprogname  = "hours"
 usagehdr =
   "Usage: hledger [OPTIONS] [COMMAND [PATTERNS]]\n" ++
   "       hours   [OPTIONS] [COMMAND [PATTERNS]]\n" ++
-  "       hledger convert CSVFILE RULESFILE\n" ++
+  "       hledger convert CSVFILE\n" ++
   "\n" ++
   "hledger uses your ~/.ledger or $LEDGER file (or another specified with -f),\n" ++
   "while hours uses your ~/.timelog or $TIMELOG file.\n" ++

README

@@ -165,13 +165,13 @@ error, so keep an eye on them!)
 
 Use it like this::
 
- hledger convert FILE.csv FILE.rules >FILE.ledger
+ hledger convert FILE.csv >FILE.ledger
 
-This will convert the csv data in FILE.csv using the conversion hints in
-FILE.rules, and save the output into a temporary ledger file. Then you
-should review FILE.ledger for problems; update the rules and convert again
-if needed; and finally copy/paste transactions which are new into your
-main ledger.
+This will convert the csv data in FILE.csv, using conversion rules defined
+in FILE.rules, and save the output into a temporary ledger file. If
+FILE.rules does not exist it will be created. Then you should review
+FILE.ledger for problems; update the rules and convert again if needed;
+and finally copy/paste transactions which are new into your main ledger.
 
 rules file
 ''''''''''
@@ -187,6 +187,8 @@ file for converting the csv download from a Wells Fargo checking account::
  amount-field 1
  currency $
 
+ # account-assigning rules
+
  SPECTRUM
  expenses:health:gym
 
@@ -208,6 +210,8 @@ This says:
 
 Notes:
 
+- Lines beginning with # or ; are ignored (but avoid using inside an account rule)
+
 - Definitions must come first, one per line, all in one paragraph.  Each
   is a name and a value separated by whitespace. Supported names are:
   base-account, date-field, status-field, code-field, description-field,