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{-| Implementation of the Ganeti Query2 functionality.

 -}

{-

Copyright (C) 2012 Google Inc.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.

-}

{-

TODO: problems with the current model:

1. There's nothing preventing a result such as ResultEntry RSNormal

Nothing, or ResultEntry RSNoData (Just ...); ideally, we would

separate the the RSNormal and other types; we would need a new data

type for this, though, with JSON encoding/decoding

2. We don't have a way to 'bind' a FieldDefinition's field type

(e.q. QFTBool) with the actual value that is returned from a

FieldGetter. This means that the various getter functions can return

divergent types for the same field when evaluated against multiple

items. This is bad; it only works today because we 'hide' everything

behind JSValue, but is not nice at all. We should probably remove the

separation between FieldDefinition and the FieldGetter, and introduce

a new abstract data type, similar to QFT*, that contains the values

too.

-}

module Ganeti.Query.Query

    ( query

    , queryFields

    , queryCompat

    , getRequestedNames

    , nameField

    ) where

import Control.DeepSeq

import Control.Monad (filterM, foldM)

import Control.Monad.Trans (lift)

import Data.List (intercalate)

import Data.Maybe (fromMaybe)

import qualified Data.Map as Map

import qualified Text.JSON as J

import Ganeti.BasicTypes

import Ganeti.Config

import Ganeti.Errors

import Ganeti.JQueue

import Ganeti.JSON

import Ganeti.Objects

import Ganeti.Query.Common

import Ganeti.Query.Filter

import qualified Ganeti.Query.Job as Query.Job

import Ganeti.Query.Group

import Ganeti.Query.Language

import Ganeti.Query.Node

import Ganeti.Query.Types

import Ganeti.Path

import Ganeti.Types

import Ganeti.Utils

-- * Helper functions

-- | Builds an unknown field definition.

mkUnknownFDef :: String -> FieldData a b

mkUnknownFDef name =

  ( FieldDefinition name name QFTUnknown ("Unknown field '" ++ name ++ "'")

  , FieldUnknown

  , QffNormal )

-- | Runs a field getter on the existing contexts.

execGetter :: ConfigData -> b -> a -> FieldGetter a b -> ResultEntry

execGetter _   _ item (FieldSimple getter)  = getter item

execGetter cfg _ item (FieldConfig getter)  = getter cfg item

execGetter _  rt item (FieldRuntime getter) = getter rt item

execGetter _   _ _    FieldUnknown          = rsUnknown

-- * Main query execution

-- | Helper to build the list of requested fields. This transforms the

-- list of string fields to a list of field defs and getters, with

-- some of them possibly being unknown fields.

getSelectedFields :: FieldMap a b  -- ^ Defined fields

                  -> [String]      -- ^ Requested fields

                  -> FieldList a b -- ^ Selected fields

getSelectedFields defined =

  map (\name -> fromMaybe (mkUnknownFDef name) $ name `Map.lookup` defined)

-- | Check whether list of queried fields contains live fields.

needsLiveData :: [FieldGetter a b] -> Bool

needsLiveData = any isRuntimeField

-- | Checks whether we have requested exactly some names. This is a

-- simple wrapper over 'requestedNames' and 'nameField'.

needsNames :: Query -> Maybe [FilterValue]

needsNames (Query kind _ qfilter) = requestedNames (nameField kind) qfilter

-- | Computes the name field for different query types.

nameField :: ItemType -> FilterField

nameField (ItemTypeLuxi QRJob) = "id"

nameField _ = "name"

-- | Extracts all quoted strings from a list, ignoring the

-- 'NumericValue' entries.

getAllQuotedStrings :: [FilterValue] -> [String]

getAllQuotedStrings =

  concatMap extractor

    where extractor (NumericValue _)   = []

          extractor (QuotedString val) = [val]

-- | Checks that we have either requested a valid set of names, or we

-- have a more complex filter.

getRequestedNames :: Query -> [String]

getRequestedNames qry =

  case needsNames qry of

    Just names -> getAllQuotedStrings names

    Nothing    -> []

-- | Compute the requested job IDs. This is custom since we need to

-- handle both strings and integers.

getRequestedJobIDs :: Filter FilterField -> Result [JobId]

getRequestedJobIDs qfilter =

  case requestedNames (nameField (ItemTypeLuxi QRJob)) qfilter of

    Nothing -> Ok []

    Just [] -> Ok []

    Just vals ->

      mapM (\e -> case e of

                    QuotedString s -> makeJobIdS s

                    NumericValue i -> makeJobId $ fromIntegral i

           ) vals

-- | Main query execution function.

query :: ConfigData   -- ^ The current configuration

      -> Bool         -- ^ Whether to collect live data

      -> Query        -- ^ The query (item, fields, filter)

      -> IO (ErrorResult QueryResult) -- ^ Result

query cfg live (Query (ItemTypeLuxi QRJob) fields qfilter) =

  queryJobs cfg live fields qfilter

query cfg live qry = queryInner cfg live qry $ getRequestedNames qry

-- | Inner query execution function.

queryInner :: ConfigData   -- ^ The current configuration

           -> Bool         -- ^ Whether to collect live data

           -> Query        -- ^ The query (item, fields, filter)

           -> [String]     -- ^ Requested names

           -> IO (ErrorResult QueryResult) -- ^ Result

queryInner cfg live (Query (ItemTypeOpCode QRNode) fields qfilter) wanted =

  runResultT $ do

  cfilter <- resultT $ compileFilter nodeFieldsMap qfilter

  let selected = getSelectedFields nodeFieldsMap fields

      (fdefs, fgetters, _) = unzip3 selected

      live' = live && needsLiveData fgetters

  nodes <- resultT $ case wanted of

             [] -> Ok . niceSortKey nodeName .

                   Map.elems . fromContainer $ configNodes cfg

             _  -> mapM (getNode cfg) wanted

  -- runs first pass of the filter, without a runtime context; this

  -- will limit the nodes that we'll contact for runtime data

  fnodes <- resultT $ filterM (\n -> evaluateFilter cfg Nothing n cfilter)

                      nodes

  -- here we would run the runtime data gathering, then filter again

  -- the nodes, based on existing runtime data

  nruntimes <- lift $ maybeCollectLiveData live' cfg fnodes

  let fdata = map (\(node, nrt) -> map (execGetter cfg nrt node) fgetters)

              nruntimes

  return QueryResult { qresFields = fdefs, qresData = fdata }

queryInner cfg _ (Query (ItemTypeOpCode QRGroup) fields qfilter) wanted =

  return $ do

  cfilter <- compileFilter groupFieldsMap qfilter

  let selected = getSelectedFields groupFieldsMap fields

      (fdefs, fgetters, _) = unzip3 selected

  groups <- case wanted of

              [] -> Ok . niceSortKey groupName .

                    Map.elems . fromContainer $ configNodegroups cfg

              _  -> mapM (getGroup cfg) wanted

  -- there is no live data for groups, so filtering is much simpler

  fgroups <- filterM (\n -> evaluateFilter cfg Nothing n cfilter) groups

  let fdata = map (\node ->

                       map (execGetter cfg GroupRuntime node) fgetters) fgroups

  return QueryResult {qresFields = fdefs, qresData = fdata }

queryInner _ _ (Query qkind _ _) _ =

  return . Bad . GenericError $ "Query '" ++ show qkind ++ "' not supported"

-- | Query jobs specific query function, needed as we need to accept

-- both 'QuotedString' and 'NumericValue' as wanted names.

queryJobs :: ConfigData                   -- ^ The current configuration

          -> Bool                         -- ^ Whether to collect live data

          -> [FilterField]                -- ^ Item

          -> Filter FilterField           -- ^ Filter

          -> IO (ErrorResult QueryResult) -- ^ Result

queryJobs cfg live fields qfilter =

  runResultT $ do

  rootdir <- lift queueDir

  let wanted_names = getRequestedJobIDs qfilter

      want_arch = Query.Job.wantArchived fields

  rjids <- case wanted_names of

             Bad msg -> resultT . Bad $ GenericError msg

             Ok [] -> if live

                        -- we can check the filesystem for actual jobs

                        then do

                          maybeJobIDs <-

                            lift (determineJobDirectories rootdir want_arch

                              >>= getJobIDs)

                          case maybeJobIDs of

                            Left e -> (resultT . Bad) . BlockDeviceError $

                              "Unable to fetch the job list: " ++ show e

                            Right jobIDs -> resultT . Ok $ sortJobIDs jobIDs

                        -- else we shouldn't look at the filesystem...

                        else return []

             Ok v -> resultT $ Ok v

  cfilter <- resultT $ compileFilter Query.Job.fieldsMap qfilter

  let selected = getSelectedFields Query.Job.fieldsMap fields

      (fdefs, fgetters, _) = unzip3 selected

      live' = live && needsLiveData fgetters

      disabled_data = Bad "live data disabled"

  -- runs first pass of the filter, without a runtime context; this

  -- will limit the jobs that we'll load from disk

  jids <- resultT $

          filterM (\jid -> evaluateFilter cfg Nothing jid cfilter) rjids

  -- here we run the runtime data gathering, filtering and evaluation,

  -- all in the same step, so that we don't keep jobs in memory longer

  -- than we need; we can't be fully lazy due to the multiple monad

  -- wrapping across different steps

  qdir <- lift queueDir

  fdata <- foldM

           -- big lambda, but we use many variables from outside it...

           (\lst jid -> do

              job <- lift $ if live'

                              then loadJobFromDisk qdir True jid

                              else return disabled_data

              pass <- resultT $ evaluateFilter cfg (Just job) jid cfilter

              let nlst = if pass

                           then let row = map (execGetter cfg job jid) fgetters

                                in rnf row `seq` row:lst

                           else lst

              -- evaluate nlst (to WHNF), otherwise we're too lazy

              return $! nlst

           ) [] jids

  return QueryResult { qresFields = fdefs, qresData = reverse fdata }

-- | Helper for 'queryFields'.

fieldsExtractor :: FieldMap a b -> [FilterField] -> QueryFieldsResult

fieldsExtractor fieldsMap fields =

  let selected = if null fields

                   then map snd $ Map.toAscList fieldsMap

                   else getSelectedFields fieldsMap fields

  in QueryFieldsResult (map (\(defs, _, _) -> defs) selected)

-- | Query fields call.

queryFields :: QueryFields -> ErrorResult QueryFieldsResult

queryFields (QueryFields (ItemTypeOpCode QRNode) fields) =

  Ok $ fieldsExtractor nodeFieldsMap fields

queryFields (QueryFields (ItemTypeOpCode QRGroup) fields) =

  Ok $ fieldsExtractor groupFieldsMap fields

queryFields (QueryFields (ItemTypeLuxi QRJob) fields) =

  Ok $ fieldsExtractor Query.Job.fieldsMap fields

queryFields (QueryFields qkind _) =

  Bad . GenericError $ "QueryFields '" ++ show qkind ++ "' not supported"

-- | Classic query converter. It gets a standard query result on input

-- and computes the classic style results.

queryCompat :: QueryResult -> ErrorResult [[J.JSValue]]

queryCompat (QueryResult fields qrdata) =

  case map fdefName $ filter ((== QFTUnknown) . fdefKind) fields of

    [] -> Ok $ map (map (maybe J.JSNull J.showJSON . rentryValue)) qrdata

    unknown -> Bad $ OpPrereqError ("Unknown output fields selected: " ++

                                    intercalate ", " unknown) ECodeInval