command_line: allow external editor for writing

bebop/browser/browser.py

@@ -4,7 +4,6 @@ import curses
 import curses.ascii
 import curses.textpad
 import os
-import subprocess
 import tempfile
 from math import inf
 
@@ -13,6 +12,7 @@ from bebop.bookmarks import (
 )
 from bebop.colors import ColorPair, init_colors
 from bebop.command_line import CommandLine
+from bebop.external import open_external_program
 from bebop.history import History
 from bebop.links import Links
 from bebop.mouse import ButtonState
@@ -428,15 +428,6 @@ class Browser:
                 save_bookmark(self.current_url, title)
         self.reset_status()
 
-    def open_external_program(self, command):
-        """Pauses the curses modes to open an external program."""
-        curses.nocbreak()
-        curses.echo()
-        subprocess.run(command)
-        curses.noecho()
-        curses.cbreak()
-        self.refresh_windows()
-
     def edit_page(self):
         """Open a text editor to edit the page source.
 
@@ -463,6 +454,7 @@ class Browser:
             delete_source_after = True
 
         command.append(source_filename)
-        self.open_external_program(command)
+        open_external_program(command)
         if delete_source_after:
             os.unlink(source_filename)
+        self.refresh_windows()

bebop/command_line.py

@@ -3,12 +3,21 @@
 import curses
 import curses.ascii
 import curses.textpad
+import os
+import tempfile
 
+from bebop.external import open_external_program
 from bebop.links import Links
 
 
 class CommandLine:
-    """Basic and flaky command-line à la Vim, using curses module's Textbox."""
+    """Basic and flaky command-line à la Vim, using curses module's Textbox.
+
+    I don't understand how to get proper pad-like behaviour, e.g. to scroll past
+    the window's right border when writing more content than the width allows.
+    Therefore I just added the M-e keybind to call an external editor and use
+    its content as result.
+    """
 
     def __init__(self, window):
         self.window = window
@@ -78,6 +87,9 @@ class CommandLine:
             ch = self.window.getch()
             if ch == -1:
                 raise EscapeCommandInterrupt()
+            else:  # ALT keybinds.
+                if ch == ord("e"):
+                    self.open_editor(self.gather())
             self.window.nodelay(False)
         return ch
 
@@ -151,6 +163,27 @@ class CommandLine:
         # Everything else could be a control character and should be processed.
         return ch
 
+    def open_editor(self, existing_content=None):
+        """Open an external editor and raise termination interrupt."""
+        try:
+            with tempfile.NamedTemporaryFile("w+t", delete=False) as temp_file:
+                if existing_content:
+                    temp_file.write(existing_content)
+                temp_filepath = temp_file.name
+        except OSError:
+            return
+
+        command = ["vi", temp_filepath]
+        open_external_program(command)
+
+        try:
+            with open(temp_filepath, "rt") as temp_file:
+                content = temp_file.read()
+            os.unlink(temp_filepath)
+        except OSError:
+            return
+        raise TerminateCommandInterrupt(content)
+
 
 class EscapeCommandInterrupt(Exception):
     """Signal that ESC has been pressed during command line."""

bebop/external.py

@@ -0,0 +1,17 @@
+"""Call external commands."""
+
+import curses
+import subprocess
+
+
+def open_external_program(command):
+    """Call command as a subprocess, suspending curses rendering.
+
+    The caller has to refresh whatever windows it manages after calling this
+    method or garbage may be left on the screen.
+    """
+    curses.nocbreak()
+    curses.echo()
+    subprocess.run(command)
+    curses.noecho()
+    curses.cbreak()