summaryrefslogtreecommitdiff
path: root/src/Hakyll/Web/Urls.hs
blob: f41d323b0b58b8a0962ada3f68376c35314af6d1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
-- | Provides utilities to manipulate URL's
--
module Hakyll.Web.Urls
    ( withUrls
    , toUrl
    , toSiteRoot
    , isExternal
    ) where

import Data.List (isPrefixOf)
import System.FilePath (splitPath, takeDirectory, joinPath)
import qualified Data.Set as S

import qualified Text.HTML.TagSoup as TS

-- | Apply a function to each URL on a webpage
--
withUrls :: (String -> String) -> String -> String
withUrls f = TS.renderTagsOptions opts . map tag . TS.parseTags
  where
    tag (TS.TagOpen s a) = TS.TagOpen s $ map attr a
    tag x                = x
    attr (k, v)          = (k, if k `S.member` refs then f v else v)
    refs                 = S.fromList ["src", "href"]
    opts                 = TS.renderOptions {TS.optEscape = id}

-- | Convert a filepath to an URL starting from the site root
--
-- Example:
--
-- > toUrl "foo/bar.html"
--
-- Result:
--
-- > "/foo/bar.html"
--
toUrl :: FilePath -> String
toUrl ('/' : xs) = '/' : xs
toUrl url        = '/' : url

-- | Get the relative url to the site root, for a given (absolute) url
--
toSiteRoot :: String -> String
toSiteRoot = emptyException . joinPath . map parent
           . filter relevant . splitPath . takeDirectory
  where
    parent            = const ".."
    emptyException [] = "."
    emptyException x  = x
    relevant "."      = False
    relevant "/"      = False
    relevant _        = True

-- | Check if an URL links to an external HTTP(S) source
--
isExternal :: String -> Bool
isExternal url = any (flip isPrefixOf url) ["http://", "https://"]