From 79eb04e3c84bd9514659d0d52c2e862959647aa6 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Tue, 26 Jun 2012 19:52:27 -0400
Subject: [PATCH] Implement URL filename parsing (with tests) and the
 save_image function.

---
 src/LWN/HTTP.hs | 31 ++++++++++++++++++++++++++++
 src/LWN/URI.hs  | 55 ++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 83 insertions(+), 3 deletions(-)

diff --git a/src/LWN/HTTP.hs b/src/LWN/HTTP.hs
index 8b4c14d..c74248b 100644
--- a/src/LWN/HTTP.hs
+++ b/src/LWN/HTTP.hs
@@ -1,6 +1,7 @@
 module LWN.HTTP
 where
 
+import qualified Data.ByteString as B (hPut)
 import Network.Curl (
   CurlCode(..),
   CurlOption(..),
@@ -12,7 +13,12 @@ import Network.Curl (
   respCurlCode,
   withCurlDo               
   )
+import Network.Curl.Download (openURI)
+import System.Directory (getTemporaryDirectory)
 import System.IO (hPutStrLn, stderr)
+import System.IO.Temp (openBinaryTempFile)
+
+import LWN.URI (filename)
 
 login_url :: URLString
 login_url = "https://lwn.net/login"
@@ -118,3 +124,28 @@ log_in cookie_jar username password =
         
     curl_opts :: [CurlOption]
     curl_opts = default_curl_opts ++ post_opts
+
+
+-- | Save the image at 'url'. Saves to a temporary file, and
+--   returns the path to that file if successful. Otherwise,
+--   returns 'Nothing'.
+--
+--   We need to be able to parse the filename out of the URL
+--   so that when we stick our image in the document, the reader
+--   knows that type (jpg, png, etc.) it is.
+save_image :: URLString -> IO (Maybe FilePath)
+save_image url = do
+  let fn = filename url
+  case fn of
+    Nothing -> return Nothing
+    Just file -> do
+      temp_dir <- getTemporaryDirectory
+      (out_path, out_handle) <- openBinaryTempFile temp_dir file
+      result <- openURI url
+      case result of
+        Left err -> do
+          hPutStrLn stderr ("HTTP Error: " ++ err)
+          return Nothing
+        Right bs -> do
+          B.hPut out_handle bs
+          return $ Just out_path
diff --git a/src/LWN/URI.hs b/src/LWN/URI.hs
index 61ea6ca..0d01e19 100644
--- a/src/LWN/URI.hs
+++ b/src/LWN/URI.hs
@@ -2,9 +2,11 @@ module LWN.URI
 where
 
 import Data.Maybe (fromJust)
+import Data.String.Utils (split)
 import Network.URI (
   URI,
   parseAbsoluteURI,
+  parseURIReference,
   uriAuthority,
   uriPath,
   uriPort,
@@ -101,6 +103,23 @@ is_lwn_url s =
     parse_result = parseAbsoluteURI s
 
 
+
+filename :: URL -> Maybe String
+filename url =
+  case parse_result of
+    Nothing -> Nothing
+    Just uri ->
+      let components = split "/" (uriPath uri) in
+      -- Reverse them so that the filename comes first for easier
+      -- pattern-matching.
+      let reverse_components = reverse components in
+      case reverse_components of
+        []     -> Nothing
+        (x:xs) -> Just x
+  where
+    parse_result = parseURIReference url
+
+
 -- | A List of LWN URLs to use during testing.
 lwn_urls :: [URL]
 lwn_urls = [ proto ++ www ++ "lwn.net" ++ path ++ bigpage ++ query |
@@ -130,9 +149,39 @@ test_https_uris_matched =
     url = "https://lwn.net/Articles/500844/bigpage"
     uri = fromJust $ parseAbsoluteURI url
 
+
+test_bare_filename_parsed :: Assertion
+test_bare_filename_parsed =
+  assertEqual "Filename is 'example.jpg'" "example.jpg" actual_result
+  where
+    url = "example.jpg"
+    actual_result = fromJust $ filename url
+
+test_absolute_filename_parsed :: Assertion
+test_absolute_filename_parsed =
+  assertEqual "Filename is 'example.jpg'" "example.jpg" actual_result
+  where
+    url = "http://lwn.net/one/two/example.jpg"
+    actual_result = fromJust $ filename url
+
+test_relative_filename_parsed :: Assertion
+test_relative_filename_parsed =
+  assertEqual "Filename is 'example.jpg'" "example.jpg" actual_result
+  where
+    url = "/one/two/example.jpg"
+    actual_result = fromJust $ filename url
+
+
 uri_tests :: Test
 uri_tests =
   testGroup "URI Tests" [
-    testCase "HTTP URIs matched" test_http_uris_matched,
-    testCase "HTTPS URIs matched" test_https_uris_matched,
-    testCase "LWN URLs matched" test_lwn_urls_matched ]
+
+    testGroup "URI Matching" [
+      testCase "HTTP URIs matched" test_http_uris_matched,
+      testCase "HTTPS URIs matched" test_https_uris_matched,
+      testCase "LWN URLs matched" test_lwn_urls_matched ],
+
+    testGroup "Filename Parsing" [
+      testCase "Bare filename parsed" test_bare_filename_parsed,
+      testCase "Absolute filename parsed" test_absolute_filename_parsed,
+      testCase "Relative filename parsed" test_relative_filename_parsed ] ]
-- 
2.44.2