{- |
 Module      :  XMonad.Actions.Search
 Copyright   :  (C) 2007 Gwern Branwen
 License     :  None; public domain

 Maintainer  :  <gwern0@gmail.com>
 Stability   :  unstable
 Portability :  unportable

 A module for easily running Internet searches on web sites through XMonad.
 Modeled after the handy Surfraw CLI search tools

 Additional sites welcomed.
module XMonad.Actions.Search (      -- * Usage
                                 -- $usage

                          ) where

import Data.Char (chr, ord, isAlpha, isMark, isDigit)
import Numeric (showIntAtBase)
import XMonad (X(), MonadIO)
import XMonad.Prompt (XPrompt(showXPrompt), mkXPrompt, XPConfig())
import XMonad.Prompt.Shell (getShellCompl)
import XMonad.Util.Run (safeSpawn)
import XMonad.Util.XSelection (getSelection)

{- $usage

   This module is intended to allow easy access to databases on the Internet
   through XMonad's interface. The idea is that one wants to run a search but the
   query string and the browser to use must come from somewhere. There are two
   places the query string can come from - the user can type it into a prompt
   which pops up, or the query could be available already in the X Windows
   copy\/paste buffer (perhaps you just highlighted the string of interest).

   Thus, there are two main functions: 'promptSearch', and 'selectSearch'
   (implemented using the more primitive 'search'). To each of these is passed an
   engine function; this is a function that knows how to search a particular

   For example, the 'google' function knows how to search Google, and so on. You pass
   promptSearch and selectSearch the engine you want, the browser you want, and
   anything special they might need; this whole line is then bound to a key of
   you choosing in your xmonad.hs. For specific examples, see each function.
   This module is easily extended to new sites by using 'simpleEngine'.

-- A customized prompt.
data Search = Search
instance XPrompt Search where
    showXPrompt Search = "Search: "

-- | Escape the search string so search engines understand it.
-- Note that everything is escaped; we could be smarter and use 'isAllowedInURI'
-- but then that'd be hard enough to copy-and-paste we'd need to depend on 'network'.
escape :: String -> String
escape = escapeURIString (\c -> isAlpha c || isDigit c || isMark c)
         where -- Copied from Network.URI.
           escapeURIString ::
               (Char -> Bool)      -- a predicate which returns 'False' if should escape
               -> String           -- the string to process
               -> String           -- the resulting URI string
           escapeURIString p s = concatMap (escapeURIChar p) s
           escapeURIChar :: (Char->Bool) -> Char -> String
           escapeURIChar p c
               | p c       = [c]
               | otherwise = '%' : myShowHex (ord c) ""
                 myShowHex :: Int -> ShowS
                 myShowHex n r =  case showIntAtBase 16 (toChrHex) n r of
                                    []  -> "00"
                                    [ch] -> ['0',ch]
                                    cs  -> cs
                 toChrHex d
                   | d < 10    = chr (ord '0' + fromIntegral d)
                   | otherwise = chr (ord 'A' + fromIntegral (d - 10))

type Browser      = FilePath
type SearchEngine = String -> String

search :: MonadIO m => Browser -> SearchEngine -> String -> m ()
search browser site query = safeSpawn browser $ site query

{- | Given a base URL, create the SearchEngine that escapes the query and
   appends it to the base. You can easily define a new engine locally using simpleEngine
   without needing to modify Search.hs:

   > newEngine = simpleEngine "http://site.com/search="

   The important thing is that the site has a interface which accepts the query
   string as part of the URL. Alas, the exact URL to feed simpleEngine varies
   from site to site, often considerably. Generally, examining the resultant URL
   of a search will allow you to reverse-engineer it if you can't find the
   necessary URL already described in other projects such as Surfraw. -}
simpleEngine :: String -> SearchEngine
simpleEngine site query = site ++ escape query

-- The engines
amazon, google, hoogle, imdb, wayback, wikipedia :: SearchEngine
amazon    = simpleEngine "http://www.amazon.com/exec/obidos/external-search?index=all&keyword="
google    = simpleEngine "http://www.google.com/search?num=100&q="
hoogle    = simpleEngine "http://www.haskell.org/hoogle/?q="
imdb      = simpleEngine "http://www.imdb.com/Find?select=all&for="
wikipedia = simpleEngine "https://secure.wikimedia.org/wikipedia/en/wiki/Special:Search?go=Go&search="
wayback   = simpleEngine "http://web.archive.org/"
{- This doesn't seem to work, but nevertheless, it seems to be the official
   method at <http://web.archive.org/collections/web/advanced.html> to get the
   latest backup. -}

{- | Like 'search', but in this case, the string is not specified but grabbed
 from the user's response to a prompt. Example:

 > , ((modm,               xK_g     ), promptSearch greenXPConfig "firefox" google)

promptSearch :: XPConfig -> Browser -> SearchEngine -> X ()
promptSearch config browser site = mkXPrompt Search config (getShellCompl []) $ search browser site

{- | Like search, but for use with the X selection; it grabs the selection,
   passes it to a given searchEngine and opens it in the given browser. Example:

> , ((modm .|. shiftMask, xK_g     ), selectSearch "firefox" google)

selectSearch :: MonadIO m => Browser -> SearchEngine -> m ()
selectSearch browser searchEngine = search browser searchEngine =<< getSelection