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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

                  -> [(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 <- if null nodes

           then Bad $ "empty node list for instance " ++ n

           else 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

  guuid   <- fromObj "group" a

  node <- (if offline || drained

           then return $ Node.create n 0 0 0 0 0 0 True guuid

           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 guuid)

  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 "Parsing input IAllocator message" (decodeStrict body)

  let obj = fromJSObject decoded

  -- request parser

  request <- liftM fromJSObject (fromObj "request" obj)

  -- 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) <- mergeData [] [] [] (nl, il, ctags)

  optype <- fromObj "type" request

  rqtype <-

      case optype of

        "allocate" ->

            do

              rname <- fromObj "name" request

              req_nodes <- fromObj "required_nodes" request

              inew <- parseBaseInstance rname request

              let io = snd inew

              return $ Allocate io req_nodes

        "relocate" ->

            do

              rname <- fromObj "name" request

              ridx <- lookupInstance kti rname

              req_nodes <- fromObj "required_nodes" request

              ex_nodes <- fromObj "relocate_from" request

              ex_idex <- mapM (Container.findByName map_n) ex_nodes

              return $ Relocate ridx req_nodes (map Node.idx ex_idex)

        "multi-evacuate" ->

            do

              ex_names <- fromObj "evac_nodes" request

              ex_nodes <- mapM (Container.findByName map_n) ex_names

              let ex_ndx = map Node.idx ex_nodes

              return $ Evacuate ex_ndx

        other -> fail ("Invalid request type '" ++ other ++ "'")

  return $ Request rqtype map_n map_i ptags

-- | Format the result

formatRVal :: RqType -> [Node.AllocElement] -> JSValue

formatRVal _ [] = JSArray []

formatRVal (Evacuate _) elems =

    let sols = map (\(_, inst, nl) -> Instance.name inst : map Node.name nl)

               elems

        jsols = map (JSArray . map (JSString . toJSString)) sols

    in JSArray jsols

formatRVal _ elems =

    let (_, _, nodes) = head elems

        nodes' = map Node.name nodes

    in JSArray $ map (JSString . toJSString) nodes'

-- | Formats the response into a valid IAllocator response message.

formatResponse :: Bool     -- ^ Whether the request was successful

               -> String   -- ^ Information text

               -> RqType   -- ^ Request type

               -> [Node.AllocElement] -- ^ The resulting allocations

               -> String   -- ^ The JSON-formatted message

formatResponse success info rq elems =

    let

        e_success = ("success", JSBool success)

        e_info = ("info", JSString . toJSString $ info)

        e_nodes = ("nodes", formatRVal rq elems)

    in encodeStrict $ makeObj [e_success, e_info, e_nodes]