content: {-# LANGUAGE OverloadedStrings #-}
  {-| Logical Volumer information parser
  
  This module holds the definition of the parser that extracts status
  information about the logical volumes (LVs) of the system from the output of the
  @lvs@ command.
  
  -}
  {-
  
  Copyright (C) 2013 Google Inc.
  All rights reserved.
  
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:
  
  1. Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.
  
  2. Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  -}
  module Ganeti.Storage.Lvm.LVParser (lvParser, lvCommand, lvParams) where
  
  import qualified Data.Attoparsec.Text as A
  import qualified Data.Attoparsec.Combinator as AC
  import Data.Attoparsec.Text (Parser)
  import Data.Text (unpack)
  
  import Ganeti.Storage.Lvm.Types
  
  
  -- | The separator of the fields returned by @lvs@
  lvsSeparator :: Char
  lvsSeparator = ';'
  
  -- * Utility functions
  
  -- | Our own space-skipping function, because A.skipSpace also skips
  -- newline characters. It skips ZERO or more spaces, so it does not
  -- fail if there are no spaces.
  skipSpaces :: Parser ()
  skipSpaces = A.skipWhile A.isHorizontalSpace
  
  -- | A parser recognizing a number of bytes, represented as a number preceeded
  -- by a separator and followed by the "B" character.
  bytesP :: Parser Int
  bytesP = A.char lvsSeparator *> A.decimal <* A.char 'B'
  
  -- | A parser recognizing a number discarding the preceeding separator
  intP :: Parser Int
  intP = A.char lvsSeparator *> A.signed A.decimal
  
  -- | A parser recognizing a string starting with and closed by a separator (both
  -- are discarded)
  stringP :: Parser String
  stringP =
    A.char lvsSeparator *> fmap unpack (A.takeWhile (`notElem`
      [ lvsSeparator
      , '\n']
      ))
  
  -- * Parser implementation
  
  -- | The command providing the data, in the format the parser expects
  lvCommand :: String
  lvCommand = "lvs"
  
  -- | The parameters for getting the data in the format the parser expects
  lvParams :: [String]
  lvParams =
    [ "--noheadings"
    , "--units", "B"
    , "--separator", ";"
    , "-o", "lv_uuid,lv_name,lv_attr,lv_major,lv_minor,lv_kernel_major\
      \,lv_kernel_minor,lv_size,seg_count,lv_tags,modules,vg_uuid,vg_name,segtype\
      \,seg_start,seg_start_pe,seg_size,seg_tags,seg_pe_ranges,devices"
    ]
  
  -- | The parser for one line of the diskstatus file.
  oneLvParser :: Parser LVInfo
  oneLvParser =
    let uuidP = skipSpaces *> fmap unpack (A.takeWhile (/= lvsSeparator))
        nameP = stringP
        attrP = stringP
        majorP = intP
        minorP = intP
        kernelMajorP = intP
        kernelMinorP = intP
        sizeP = bytesP
        segCountP = intP
        tagsP = stringP
        modulesP = stringP
        vgUuidP = stringP
        vgNameP = stringP
        segtypeP = stringP
        segStartP = bytesP
        segStartPeP = intP
        segSizeP = bytesP
        segTagsP = stringP
        segPeRangesP = stringP
        devicesP = stringP
      in
        LVInfo
          <$> uuidP <*> nameP <*> attrP <*> majorP <*> minorP <*> kernelMajorP
          <*> kernelMinorP <*> sizeP <*> segCountP <*> tagsP <*> modulesP
          <*> vgUuidP <*> vgNameP <*> segtypeP <*> segStartP <*> segStartPeP
          <*> segSizeP <*> segTagsP <*> segPeRangesP <*> devicesP 
          <*> return Nothing <* A.endOfLine
  
  -- | The parser for a whole diskstatus file.
  lvParser :: Parser [LVInfo]
  lvParser = oneLvParser `AC.manyTill` A.endOfInput
  