{-# LANGUAGE NamedFieldPuns  #-}
{-# LANGUAGE QuasiQuotes     #-}
{-# LANGUAGE RecordWildCards #-}
module PostgREST.CLI
  ( main
  , CLI (..)
  , Command (..)
  , readCLIShowHelp
  ) where

import qualified Data.Aeson                 as JSON
import qualified Data.ByteString.Char8      as BS
import qualified Data.ByteString.Lazy       as LBS
import qualified Hasql.Pool                 as SQL
import qualified Hasql.Transaction.Sessions as SQL
import qualified Options.Applicative        as O

import Data.Text.IO (hPutStrLn)
import Text.Heredoc (str)

import PostgREST.AppState    (AppState)
import PostgREST.Config      (AppConfig (..))
import PostgREST.DbStructure (queryDbStructure)
import PostgREST.Version     (prettyVersion)
import PostgREST.Workers     (reReadConfig)

import qualified PostgREST.App      as App
import qualified PostgREST.AppState as AppState
import qualified PostgREST.Config   as Config

import Protolude hiding (hPutStrLn)


main :: App.SignalHandlerInstaller -> Maybe App.SocketRunner -> CLI -> IO ()
main installSignalHandlers runAppWithSocket CLI{cliCommand, cliPath} = do
  conf@AppConfig{..} <-
    either panic identity <$> Config.readAppConfig mempty cliPath Nothing
  appState <- AppState.init conf

  -- Override the config with config options from the db
  -- TODO: the same operation is repeated on connectionWorker, ideally this
  -- would be done only once, but dump CmdDumpConfig needs it for tests.
  when configDbConfig $ reReadConfig True appState

  exec cliCommand appState
  where
    exec :: Command -> AppState -> IO ()
    exec CmdDumpConfig appState = putStr . Config.toText =<< AppState.getConfig appState
    exec CmdDumpSchema appState = putStrLn =<< dumpSchema appState
    exec CmdRun appState = App.run installSignalHandlers runAppWithSocket appState

-- | Dump DbStructure schema to JSON
dumpSchema :: AppState -> IO LBS.ByteString
dumpSchema appState = do
  AppConfig{..} <- AppState.getConfig appState
  actualPgVersion <- AppState.getPgVersion appState
  result <-
    let transaction = if configDbPreparedStatements then SQL.transaction else SQL.unpreparedTransaction in
    SQL.use (AppState.getPool appState) $
      transaction SQL.ReadCommitted SQL.Read $
        queryDbStructure
          (toList configDbSchemas)
          configDbExtraSearchPath
          actualPgVersion
          configDbPreparedStatements
  SQL.release $ AppState.getPool appState
  case result of
    Left e -> do
      hPutStrLn stderr $ "An error ocurred when loading the schema cache:\n" <> show e
      exitFailure
    Right dbStructure -> return $ JSON.encode dbStructure

-- | Command line interface options
data CLI = CLI
  { cliCommand :: Command
  , cliPath    :: Maybe FilePath
  }

data Command
  = CmdRun
  | CmdDumpConfig
  | CmdDumpSchema

-- | Read command line interface options. Also prints help.
readCLIShowHelp :: Bool -> IO CLI
readCLIShowHelp hasEnvironment =
  O.customExecParser prefs opts
  where
    prefs = O.prefs $ O.showHelpOnError <> O.showHelpOnEmpty
    opts = O.info parser $ O.fullDesc <> progDesc <> footer
    parser = O.helper <*> exampleParser <*> cliParser

    progDesc =
      O.progDesc $
        "PostgREST "
        <> BS.unpack prettyVersion
        <> " / create a REST API to an existing Postgres database"

    footer =
      O.footer $
        "To run PostgREST, please pass the FILENAME argument"
        <> " or set PGRST_ environment variables."

    exampleParser =
      O.infoOption exampleConfigFile $
        O.long "example"
        <> O.short 'e'
        <> O.help "Show an example configuration file"

    cliParser :: O.Parser CLI
    cliParser =
      CLI
        <$> (dumpConfigFlag <|> dumpSchemaFlag)
        <*> optionalIf hasEnvironment configFileOption

    configFileOption =
      O.strArgument $
        O.metavar "FILENAME"
        <> O.help "Path to configuration file (optional with PGRST_ environment variables)"

    dumpConfigFlag =
      O.flag CmdRun CmdDumpConfig $
        O.long "dump-config"
        <> O.help "Dump loaded configuration and exit"

    dumpSchemaFlag =
      O.flag CmdRun CmdDumpSchema $
        O.long "dump-schema"
        <> O.help "Dump loaded schema as JSON and exit (for debugging, output structure is unstable)"

    optionalIf :: Alternative f => Bool -> f a -> f (Maybe a)
    optionalIf True  = O.optional
    optionalIf False = fmap Just

exampleConfigFile :: [Char]
exampleConfigFile =
  [str|### REQUIRED:
      |db-uri = "postgres://user:pass@localhost:5432/dbname"
      |db-schema = "public"
      |db-anon-role = "postgres"
      |
      |### OPTIONAL:
      |## number of open connections in the pool
      |db-pool = 10
      |
      |## Time to live, in seconds, for an idle database pool connection.
      |db-pool-timeout = 10
      |
      |## extra schemas to add to the search_path of every request
      |db-extra-search-path = "public"
      |
      |## limit rows in response
      |# db-max-rows = 1000
      |
      |## stored proc to exec immediately after auth
      |# db-pre-request = "stored_proc_name"
      |
      |## stored proc that overrides the root "/" spec
      |## it must be inside the db-schema
      |# db-root-spec = "stored_proc_name"
      |
      |## Notification channel for reloading the schema cache
      |db-channel = "pgrst"
      |
      |## Enable or disable the notification channel
      |db-channel-enabled = true
      |
      |## Enable in-database configuration
      |db-config = true
      |
      |## Determine if GUC request settings for headers, cookies and jwt claims use the legacy names (string with dashes, invalid starting from PostgreSQL v14) with text values instead of the new names (string without dashes, valid on all PostgreSQL versions) with json values.
      |## For PostgreSQL v14 and up, this setting will be ignored.
      |db-use-legacy-gucs = true
      |
      |## how to terminate database transactions
      |## possible values are:
      |## commit (default)
      |##   transaction is always committed, this can not be overriden
      |## commit-allow-override
      |##   transaction is committed, but can be overriden with Prefer tx=rollback header
      |## rollback
      |##   transaction is always rolled back, this can not be overriden
      |## rollback-allow-override
      |##   transaction is rolled back, but can be overriden with Prefer tx=commit header
      |db-tx-end = "commit"
      |
      |## enable or disable prepared statements. disabling is only necessary when behind a connection pooler.
      |## when disabled, statements will be parametrized but won't be prepared.
      |db-prepared-statements = true
      |
      |server-host = "!4"
      |server-port = 3000
      |
      |## unix socket location
      |## if specified it takes precedence over server-port
      |# server-unix-socket = "/tmp/pgrst.sock"
      |
      |## unix socket file mode
      |## when none is provided, 660 is applied by default
      |# server-unix-socket-mode = "660"
      |
      |## determine if the OpenAPI output should follow or ignore role privileges or be disabled entirely
      |## admitted values: follow-privileges, ignore-privileges, disabled
      |openapi-mode = "follow-privileges"
      |
      |## base url for the OpenAPI output
      |openapi-server-proxy-uri = ""
      |
      |## choose a secret, JSON Web Key (or set) to enable JWT auth
      |## (use "@filename" to load from separate file)
      |# jwt-secret = "secret_with_at_least_32_characters"
      |# jwt-aud = "your_audience_claim"
      |jwt-secret-is-base64 = false
      |
      |## jspath to the role claim key
      |jwt-role-claim-key = ".role"
      |
      |## content types to produce raw output
      |# raw-media-types="image/png, image/jpg"
      |
      |## logging level, the admitted values are: crit, error, warn and info.
      |log-level = "error"
      |]