{-| Implementation of the iallocator interface.

-}

{-

Copyright (C) 2009 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.

-}

module Ganeti.HTools.IAlloc
    ( parseData
    , formatResponse
    ) where

import Data.Either ()
import Control.Monad
import Text.JSON (JSObject, JSValue(JSBool, JSString, JSArray),
                  makeObj, encodeStrict, decodeStrict,
                  fromJSObject, toJSString)
import qualified Ganeti.HTools.Container as Container
import qualified Ganeti.HTools.Node as Node
import qualified Ganeti.HTools.Instance as Instance
import Ganeti.HTools.Loader
import Ganeti.HTools.Utils
import Ganeti.HTools.Types

-- | Parse the basic specifications of an instance.
--
-- Instances in the cluster instance list and the instance in an
-- 'Allocate' request share some common properties, which are read by
-- this function.
parseBaseInstance :: String
                  -> [(String, JSValue)]
                  -> Result (String, Instance.Instance)
parseBaseInstance n a = do
  disk <- fromObj "disk_space_total" a
  mem <- fromObj "memory" a
  vcpus <- fromObj "vcpus" a
  tags <- fromObj "tags" a
  let running = "running"
  return (n, Instance.create n mem disk vcpus running tags 0 0)

-- | Parses an instance as found in the cluster instance listg.
parseInstance :: NameAssoc        -- ^ The node name-to-index association list
              -> String           -- ^ The name of the instance
              -> [(String, JSValue)] -- ^ The JSON object
              -> Result (String, Instance.Instance)
parseInstance ktn n a = do
  base <- parseBaseInstance n a
  nodes <- fromObj "nodes" a
  pnode <- readEitherString $ head nodes
  pidx <- lookupNode ktn n pnode
  let snodes = tail nodes
  sidx <- (if null snodes then return Node.noSecondary
           else readEitherString (head snodes) >>= lookupNode ktn n)
  return (n, Instance.setBoth (snd base) pidx sidx)

-- | Parses a node as found in the cluster node list.
parseNode :: String           -- ^ The node's name
          -> [(String, JSValue)] -- ^ The JSON object
          -> Result (String, Node.Node)
parseNode n a = do
  offline <- fromObj "offline" a
  drained <- fromObj "drained" a
  node <- (if offline || drained
           then return $ Node.create n 0 0 0 0 0 0 True
           else do
             mtotal <- fromObj "total_memory" a
             mnode  <- fromObj "reserved_memory" a
             mfree  <- fromObj "free_memory"  a
             dtotal <- fromObj "total_disk"   a
             dfree  <- fromObj "free_disk"    a
             ctotal <- fromObj "total_cpus"   a
             return $ Node.create n mtotal mnode mfree
                    dtotal dfree ctotal False)
  return (n, node)

-- | Top-level parser.
parseData :: String         -- ^ The JSON message as received from Ganeti
          -> Result Request -- ^ A (possible valid) request
parseData body = do
  decoded <- fromJResult $ decodeStrict body
  let obj = fromJSObject decoded
  -- request parser
  request <- liftM fromJSObject (fromObj "request" obj)
  rname <- fromObj "name" request
  -- existing node parsing
  nlist <- liftM fromJSObject (fromObj "nodes" obj)
  nobj <- mapM (\(x,y) -> asJSObject y >>= parseNode x . fromJSObject) nlist
  let (ktn, nl) = assignIndices nobj
  -- existing instance parsing
  ilist <- fromObj "instances" obj
  let idata = fromJSObject ilist
  iobj <- mapM (\(x,y) ->
                    asJSObject y >>= parseInstance ktn x . fromJSObject) idata
  let (kti, il) = assignIndices iobj
  -- cluster tags
  ctags <- fromObj "cluster_tags" obj
  (map_n, map_i, ptags, csf) <- mergeData [] [] (nl, il, ctags)
  req_nodes <- fromObj "required_nodes" request
  optype <- fromObj "type" request
  rqtype <-
      case optype of
        "allocate" ->
            do
              inew <- parseBaseInstance rname request
              let io = snd inew
              return $ Allocate io req_nodes
        "relocate" ->
            do
              ridx <- lookupInstance kti rname
              ex_nodes <- fromObj "relocate_from" request
              let ex_nodes' = map (stripSuffix $ length csf) ex_nodes
              ex_idex <- mapM (Container.findByName map_n) ex_nodes'
              return $ Relocate ridx req_nodes (map Node.idx ex_idex)
        other -> fail ("Invalid request type '" ++ other ++ "'")
  return $ Request rqtype map_n map_i ptags csf

-- | Formats the response into a valid IAllocator response message.
formatResponse :: Bool     -- ^ Whether the request was successful
               -> String   -- ^ Information text
               -> [String] -- ^ The list of chosen nodes
               -> String   -- ^ The JSON-formatted message
formatResponse success info nodes =
    let
        e_success = ("success", JSBool success)
        e_info = ("info", JSString . toJSString $ info)
        e_nodes = ("nodes", JSArray $ map (JSString . toJSString) nodes)
    in encodeStrict $ makeObj [e_success, e_info, e_nodes]