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-- | Exports a datastructure for the top-level hakyll configuration
module Hakyll.Core.Configuration
    ( Configuration (..)
    , shouldIgnoreFile
    , shouldWatchIgnore
    , defaultConfiguration
    ) where


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import           Data.Default     (Default (..))
import           Data.List        (isPrefixOf, isSuffixOf)
import qualified Network.Wai.Application.Static as Static
import           System.Directory (canonicalizePath)
import           System.Exit      (ExitCode)
import           System.FilePath  (isAbsolute, makeRelative, normalise,
                                   takeExtension, takeFileName)
import           System.IO.Error  (catchIOError)
import           System.Process   (system)


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data Configuration = Configuration
    { -- | Directory in which the output written
      destinationDirectory :: FilePath
    , -- | Directory where hakyll's internal store is kept
      storeDirectory       :: FilePath
    , -- | Directory in which some temporary files will be kept
      tmpDirectory         :: FilePath
    , -- | Directory where hakyll finds the files to compile. This is @.@ by
      -- default.
      providerDirectory    :: FilePath
    , -- | Function to determine ignored files
      --
      -- In 'defaultConfiguration', the following files are ignored:
      --
      -- * files starting with a @.@
      --
      -- * files starting with a @#@
      --
      -- * files ending with a @~@
      --
      -- * files ending with @.swp@
      --
      -- Note that the files in 'destinationDirectory' and 'storeDirectory' will
      -- also be ignored. Note that this is the configuration parameter, if you
      -- want to use the test, you should use 'shouldIgnoreFile'.
      --
      ignoreFile           :: FilePath -> Bool
    , -- | Function to determine HTML files whose links are to be checked.
      --
      -- In 'defaultConfiguration', files with the @.html@ extension are checked.
      checkHtmlFile        :: FilePath -> Bool
    , -- | Function to determine files and directories that should not trigger
      -- a rebuild when touched in watch mode.
      --
      -- Paths are passed in relative to the providerDirectory.
      --
      -- All files that are ignored by 'ignoreFile' are also always ignored by
      -- 'watchIgnore'.
      watchIgnore          :: FilePath -> Bool
    , -- | Here, you can plug in a system command to upload/deploy your site.
      --
      -- Example:
      --
      -- > rsync -ave 'ssh -p 2217' _site jaspervdj@jaspervdj.be:hakyll
      --
      -- You can execute this by using
      --
      -- > ./site deploy
      --
      deployCommand        :: String
    , -- | Function to deploy the site from Haskell.
      --
      -- By default, this command executes the shell command stored in
      -- 'deployCommand'. If you override it, 'deployCommand' will not
      -- be used implicitely.
      --
      -- The 'Configuration' object is passed as a parameter to this
      -- function.
      --
      deploySite           :: Configuration -> IO ExitCode
    , -- | Use an in-memory cache for items. This is faster but uses more
      -- memory.
      inMemoryCache        :: Bool
    , -- | Override default host for preview server. Default is "127.0.0.1",
      -- which binds only on the loopback address.
      -- One can also override the host as a command line argument:
      -- ./site preview -h "0.0.0.0"
      previewHost          :: String
    , -- | Override default port for preview server. Default is 8000.
      -- One can also override the port as a command line argument:
      -- ./site preview -p 1234
      previewPort          :: Int
    , -- | Override other settings used by the preview server. Default is
      -- 'Static.defaultFileServerSettings'.
      previewSettings      :: FilePath -> Static.StaticSettings
    }

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instance Default Configuration where
    def = defaultConfiguration

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-- | Default configuration for a hakyll application
defaultConfiguration :: Configuration
defaultConfiguration = Configuration
    { destinationDirectory = "_site"
    , storeDirectory       = "_cache"
    , tmpDirectory         = "_cache/tmp"
    , providerDirectory    = "."
    , ignoreFile           = ignoreFile'
    , checkHtmlFile        = flip elem [".html", ".xhtml"] . takeExtension
    , watchIgnore          = const False
    , deployCommand        = "echo 'No deploy command specified' && exit 1"
    , deploySite           = system . deployCommand
    , inMemoryCache        = True
    , previewHost          = "127.0.0.1"
    , previewPort          = 8000
    , previewSettings      = Static.defaultFileServerSettings
    }
  where
    ignoreFile' path
        | "."    `isPrefixOf` fileName = True
        | "#"    `isPrefixOf` fileName = True
        | "~"    `isSuffixOf` fileName = True
        | ".swp" `isSuffixOf` fileName = True
        | otherwise                    = False
      where
        fileName = takeFileName path


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-- | Check if a file should be ignored
shouldIgnoreFile :: Configuration -> FilePath -> IO Bool
shouldIgnoreFile conf path = orM
    [ inDir (destinationDirectory conf)
    , inDir (storeDirectory conf)
    , inDir (tmpDirectory conf)
    , return (ignoreFile conf path')
    ]
  where
    path'    = normalise path
    absolute = isAbsolute path

    inDir dir
        | absolute  = do
            dir' <- catchIOError (canonicalizePath dir) (const $ return dir)
            return $ dir' `isPrefixOf` path'
        | otherwise = return $ dir `isPrefixOf` path'

    orM :: [IO Bool] -> IO Bool
    orM []       = return False
    orM (x : xs) = x >>= \b -> if b then return True else orM xs

-- | Returns a function to check if a file should be ignored in watch mode
shouldWatchIgnore :: Configuration -> IO (FilePath -> IO Bool)
shouldWatchIgnore conf = do
    fullProviderDir <- canonicalizePath $ providerDirectory conf
    return (\path ->
              let path' = makeRelative fullProviderDir path
              in (|| watchIgnore conf path') <$> shouldIgnoreFile conf path)