{-# LANGUAGE OverloadedStrings #-}
module Moo.Main
    ( mainWithParameters
    , ExecutableParameters (..)
    , Configuration (..)
    , Args
    , usage
    , usageSpecific
    , procArgs
    )
where

import  Control.Monad.Reader (forM_, runReaderT, when)
import  Database.HDBC (SqlError, catchSql, seErrorMsg)
import  Prelude  hiding (lookup)
import  Data.Text (Text)
import  Data.String.Conversions (cs)
import  System.Environment (getProgName)
import  System.Exit (ExitCode (ExitFailure), exitWith)

import  Database.Schema.Migrations.Filesystem (filesystemStore, FilesystemStoreSettings(..))
import  Database.Schema.Migrations.Store
import  Moo.CommandInterface
import  Moo.Core

type Args = [String]

usage :: IO a
usage = do
  progName <- getProgName

  putStrLn $ "Usage: " ++ progName ++ " <command> [args]"
  putStrLn "Environment:"
  putStrLn $ "  " ++ envDatabaseName ++ ": database connection string"
  putStrLn $ "  " ++ envStoreName ++ ": path to migration store"
  putStrLn $ "  " ++ envLinearMigrations ++ ": whether to use linear migrations (defaults to False)"
  putStrLn "Commands:"
  forM_ commands $ \command -> do
          putStrLn $ "  " ++ usageString command
          putStrLn $ "  " ++ _cDescription command
          putStrLn ""

  putStrLn commandOptionUsage
  exitWith (ExitFailure 1)

usageSpecific :: Command -> IO a
usageSpecific command = do
  pn <- getProgName
  putStrLn $ "Usage: " ++ pn ++ " " ++ usageString command
  exitWith (ExitFailure 1)

procArgs :: Args -> IO (Command, CommandOptions, [String])
procArgs args = do
  when (null args) usage

  command <- case findCommand $ head args of
               Nothing -> usage
               Just c -> return c

  (opts, required) <- getCommandArgs $ tail args

  return (command, opts, required)

mainWithParameters :: Args -> ExecutableParameters -> IO ()
mainWithParameters args parameters = do
  (command, opts, required) <- procArgs args

  let storePathStr = _parametersMigrationStorePath parameters
      store = filesystemStore $ FSStore { storePath = storePathStr }
      linear = _parametersLinearMigrations parameters

  if length required < length ( _cRequired command) then
      usageSpecific command else
      do
        loadedStoreData <- loadMigrations store
        case loadedStoreData of
          Left es -> do
            putStrLn "There were errors in the migration store:"
            forM_ es $ \err -> putStrLn $ "  " ++ show err
          Right storeData -> do
            let st = AppState { _appOptions = opts
                              , _appCommand = command
                              , _appRequiredArgs = map cs required
                              , _appOptionalArgs = ["" :: Text]
                              , _appBackend = _parametersBackend parameters
                              , _appStore = store
                              , _appStoreData = storeData
                              , _appLinearMigrations = linear
                              , _appTimestampFilenames =
                                  _parametersTimestampFilenames parameters
                              }
            runReaderT (_cHandler command storeData) st `catchSql` reportSqlError

reportSqlError :: SqlError -> IO a
reportSqlError e = do
  putStrLn $ "\n" ++ "A database error occurred: " ++ seErrorMsg e
  exitWith (ExitFailure 1)