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{-| 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

                  -> JSObject JSValue

                  -> Result (String, Instance.Instance)

parseBaseInstance n a = do

  disk <- fromObj "disk_space_total" a

  mem <- fromObj "memory" a

  vcpus <- fromObj "vcpus" a

  let running = "running"

  return (n, Instance.create n mem disk vcpus running 0 0)

-- | Parses an instance as found in the cluster instance list.

parseInstance :: NameAssoc        -- ^ The node name-to-index association list

              -> String           -- ^ The name of the instance

              -> JSObject 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

          -> JSObject JSValue -- ^ The JSON object

          -> Result (String, Node.Node)

parseNode n a = do

    let name = n

    offline <- fromObj "offline" a

    drained <- fromObj "drained" a

    node <- (if offline || drained

             then return $ Node.create name 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 (name, 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 = decoded

  -- request parser

  request <- fromObj "request" obj

  rname <- fromObj "name" request

  -- existing node parsing

  nlist <- fromObj "nodes" obj

  let ndata = fromJSObject nlist

  nobj <- mapM (\(x,y) -> asJSObject y >>= parseNode x) ndata

  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) idata

  let (kti, il) = assignIndices iobj

  (map_n, map_i, csf) <- mergeData [] (nl, il)

  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 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]