Add providing location for fetch

 -extends nexB#54
 -Added filename deduction (content-disposition/URL)
 -Fetch and its helper functions now use pathlib's Path

Signed-off-by: Mateusz Perc <m.perc@samsung.com>

requirements.txt

@@ -16,3 +16,4 @@ six==1.14.0
 urllib3==1.25.8
 wcwidth==0.1.8
 zipp==1.2.0
+kiss-headers==2.3.0

src/fetchcode/__init__.py

@@ -16,11 +16,12 @@
 
 from ftplib import FTP
 from mimetypes import MimeTypes
-import os
-import tempfile
 from urllib.parse import urlparse
+from kiss_headers import parse_it
+from pathlib import Path
 
 import requests
+import tempfile
 
 
 class Response:
@@ -41,14 +42,35 @@ def __init__(self, location, content_type, size, url):
 def fetch_http(url, location):
     """
     Return a `Response` object built from fetching the content at a HTTP/HTTPS based `url` URL string
-    saving the content in a file at `location`   
+    Saving the content in a file at `location`
+    If `location` is an existing directory - try to deduce the filename
+    If deduction failed, save the content in a temporary file created at a `location`
     """
     r = requests.get(url)
-    with open(location, 'wb') as f:
+
+    if Path.is_dir(location):
+        content_disposition = parse_it(r.headers).get("content-disposition") or {}
+        filename_priority = [
+            content_disposition.get("filename*"),
+            content_disposition.get("filename"),
+            Path(urlparse(url).path).name,
+        ]
+        filename_found = False
+        for filename in filename_priority:
+            if filename is not None and len(filename):
+                filename_found = True
+                location = location / filename
+                break
+        if not filename_found:
+            location = Path(
+                tempfile.NamedTemporaryFile(dir=location, delete=False).name
+            )
+
+    with open(location, "wb") as f:
         f.write(r.content)
 
-    content_type = r.headers.get('content-type')
-    size = r.headers.get('content-length')
+    content_type = r.headers.get("content-type")
+    size = r.headers.get("content-length")
     size = int(size) if size else None
 
     resp = Response(location=location, content_type=content_type, size=size, url=url)
@@ -59,49 +81,57 @@ def fetch_http(url, location):
 def fetch_ftp(url, location):
     """
     Return a `Response` object built from fetching the content at a FTP based `url` URL string
-    saving the content in a file at `location`  
+    Saving the content in a file at `location`
+    If `location` is an existing directory - deduce the filename from the URL
     """
     url_parts = urlparse(url)
 
     netloc = url_parts.netloc
-    path = url_parts.path
-    dir, file = os.path.split(path)
+    path = Path(url_parts.path)
+    directory = path.parent
+    filename = path.name
+
+    if Path.is_dir(location):
+        location /= filename
 
     ftp = FTP(netloc)
     ftp.login()
 
-    size = ftp.size(path)
+    size = ftp.size(str(path))
     mime = MimeTypes()
-    mime_type = mime.guess_type(file)
+    mime_type = mime.guess_type(filename)
     if mime_type:
         content_type = mime_type[0]
     else:
         content_type = None
 
-    ftp.cwd(dir)
-    file = 'RETR {}'.format(file)
-    with open(location, 'wb') as f:
-        ftp.retrbinary(file, f.write)
+    ftp.cwd(str(directory))
+    filename = "RETR {}".format(filename)
+    with open(location, "wb") as f:
+        ftp.retrbinary(filename, f.write)
     ftp.close()
 
     resp = Response(location=location, content_type=content_type, size=size, url=url)
     return resp
 
 
-def fetch(url):
+def fetch(url, location=None):
     """
-    Return a `Response` object built from fetching the content at the `url` URL string and store content at a temporary file.
+    Return a `Response` object built from fetching the content at the `url` URL string and store content at a provided `location`
+    If `location` is None, save the content in a newly created temporary file
+    If `location` is an existing directory - try to deduce the filename
     """
 
-    temp = tempfile.NamedTemporaryFile(delete=False)
-    location = temp.name
+    if location is None:
+        temp = tempfile.NamedTemporaryFile(delete=False)
+        location = temp.name
 
     url_parts = urlparse(url)
     scheme = url_parts.scheme
 
-    fetchers = {'ftp': fetch_ftp, 'http': fetch_http, 'https': fetch_http}
+    fetchers = {"ftp": fetch_ftp, "http": fetch_http, "https": fetch_http}
 
     if scheme in fetchers:
         return fetchers.get(scheme)(url, location)
 
-    raise Exception('Not a supported/known scheme.')
+    raise Exception("Not a supported/known scheme.")