mime: basic MIME type management

bebop/browser.py

@@ -131,10 +131,10 @@ class Browser:
                 elif char == ord("l"):
                     self.scroll_page_horizontally(1)
             self.screen.nodelay(False)
-
-        ctrl_char = curses.unctrl(char)
-        if ctrl_char == "a":
-            self.set_status("yup!")
+        # else:
+        #     unctrled = curses.unctrl(char)
+        #     if unctrled == b"^T":
+        #         self.set_status("test!")
 
     @property
     def page_pad_size(self):
@@ -281,13 +281,14 @@ class Browser:
             return
 
         if response.code == 20:
-            # TODO handle MIME type; assume it's gemtext for now.
-            text = response.content.decode("utf-8", errors="replace")
-            self.load_page(Page.from_gemtext(text))
+            handle_code = self.handle_response_content(response)
+            if handle_code == 0:
                 if self.current_url and history:
                     self.history.push(self.current_url)
                 self.current_url = url
                 self.set_status(url)
+            elif handle_code == 1:
+                self.set_status(f"Downloaded {url}.")
         elif response.generic_code == 30 and response.meta:
             self.open_url(response.meta, base_url=url, redirects=redirects + 1)
         elif response.generic_code in (40, 50):
@@ -299,6 +300,41 @@ class Browser:
             error = f"Unhandled response code {response.code}"
             self.set_status_error(error)
 
+    def handle_response_content(self, response: Response) -> int:
+        """Handle a response's content from a Gemini server.
+
+        According to the MIME type received or inferred, render or download the
+        response's content.
+
+        Currently only text/gemini content is rendered.
+
+        Arguments:
+        - response: a successful Response.
+
+        Returns:
+        An error code: 0 means a page has been loaded, so any book-keeping such
+        as history management can be applied; 1 means a content has been
+        successfully retrieved but has not been displayed (e.g. non-text
+        content) nor saved as a page; 2 means that the content could not be
+        handled, either due to bogus MIME type or MIME parameters.
+        """
+        mime_type = response.get_mime_type()
+        if mime_type.main_type == "text":
+            if mime_type.sub_type == "gemini":
+                encoding = mime_type.charset
+                try:
+                    text = response.content.decode(encoding, errors="replace")
+                except LookupError:
+                    self.set_status_error("Unknown encoding {encoding}.")
+                    return 2
+                self.load_page(Page.from_gemtext(text))
+                return 0
+            else:
+                pass  # TODO
+        else:
+            pass  # TODO
+        return 1
+
     def load_page(self, page: Page):
         """Load Gemtext data as the current page."""
         old_pad_height = self.page_pad.dim[0]

bebop/command_line.py

@@ -47,6 +47,7 @@ class CommandLine:
             command = ""
         except TerminateCommandInterrupt as exc:
             command = exc.command
+        else:
             command = command[1:].rstrip()
         curses.curs_set(0)
         self.clear()

bebop/mime.py

@@ -0,0 +1,40 @@
+"""Basic MIME utilities (RFC 2046)."""
+
+from dataclasses import dataclass
+from typing import Optional
+
+
+DEFAULT_CHARSET = "utf-8"
+
+
+@dataclass
+class MimeType:
+    main_type: str
+    sub_type: str
+    parameters: dict
+
+    @property
+    def charset(self):
+        return self.parameters.get("charset", DEFAULT_CHARSET)
+
+    @staticmethod
+    def from_str(mime_string) -> Optional["MimeType"]:
+        """Parse a MIME string into a MimeType instance, or None on error."""
+        if ";" in mime_string:
+            type_str, *parameters = mime_string.split(";")
+            parameters = {}
+            for param in map(lambda s: s.strip().lower(), parameters):
+                if param.count("=") != 1:
+                    return None
+                param_name, param_value = param.split("=")
+                parameters[param_name] = param_value
+        else:
+            type_str = mime_string.strip()
+            parameters = {}
+        if type_str.count("/") != 1:
+            return None
+        main_type, sub_type = type_str.split("/")
+        return MimeType(main_type, sub_type, parameters)
+
+
+DEFAULT_MIME_TYPE = MimeType("text", "gemini", {"charset": DEFAULT_CHARSET})

bebop/protocol.py

@@ -5,7 +5,9 @@ import socket
 import ssl
 from dataclasses import dataclass
 from enum import IntEnum
+from typing import Optional
 
+from bebop.mime import DEFAULT_MIME_TYPE, MimeType
 from bebop.tofu import CertStatus, CERT_STATUS_INVALID, validate_cert
 
 
@@ -190,11 +192,16 @@ class Response:
     MAX_META_LEN = 1024
 
     @property
-    def generic_code(self):
+    def generic_code(self) -> int:
+        """See `Response.get_generic_code`."""
         return Response.get_generic_code(self.code)
 
+    def get_mime_type(self) -> MimeType:
+        """Return the MIME type if possible, else the default MIME type."""
+        return MimeType.from_str(self.meta) or DEFAULT_MIME_TYPE
+
     @staticmethod
-    def parse(data):
+    def parse(data: bytes) -> Optional["Response"]:
         """Parse a received response."""
         try:
             response_header_len = data.index(LINE_TERM)
@@ -216,6 +223,6 @@ class Response:
         return response
 
     @staticmethod
-    def get_generic_code(code):
+    def get_generic_code(code) -> int:
         """Return the generic version (x0) of this code."""
         return code - (code % 10)