fix: rerun the command using python subprocess

When fixing a command, rerun the previously executed
command and capture the output in Python code. The
fish command for doing the same thing is broken.

functions/_fish_ai_autocomplete_or_fix.fish

@@ -3,11 +3,9 @@
 function _fish_ai_autocomplete_or_fix --description "Autocomplete the current command or fix the previous command using AI."
     set previous_status $status
     if test -z "$input" && test $previous_status -ne 0
-        # Fix the previous command. To give the AI a bit more context
-        # rerun the previous command and capture stdout and stderr
+        # Fix the previous command.
         set previous_command (history | head -1)
-        set error_message (eval "$previous_command" &| tail -10)
-        set fixed_command (_fish_ai_fix "$previous_command" "$error_message")
+        set fixed_command (_fish_ai_fix "$previous_command")
         commandline --replace "$fixed_command"
     else
         # Autocomplete the current command

functions/_fish_ai_fix.fish

@@ -1,7 +1,7 @@
 #!/usr/bin/env fish
 
-function _fish_ai_fix --description "Fix a command using AI." --argument-names "previous_command" "error_message"
+function _fish_ai_fix --description "Fix a command using AI." --argument-names "previous_command"
     set dir (dirname (status -f))
-    set output ("$dir/_fish_ai_fix.py" "$previous_command" "$error_message")
+    set output ("$dir/_fish_ai_fix.py" "$previous_command")
     echo -n "$output"
 end

functions/_fish_ai_fix.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 from sys import argv
+import subprocess
 import _fish_ai_engine as engine
 
 def get_instructions(command, error_message):
@@ -63,14 +64,26 @@ def get_instructions(command, error_message):
 def get_messages(command, error_message):
     return [ engine.get_system_prompt() ] + get_instructions(command, error_message)
 
-command = argv[1]
-# Cut lines in the error output exceeding 200 characters
-error_message = '\n'.join([line[:200] for line in argv[2].split('\n')])
+def get_error_message(previous_command):
+    """
+    There is no way to get the output of the previous command in fish, so
+    let's rerun the previous command and capture the output.
+    """
+    try:
+        subprocess.check_output(previous_command,
+            stderr = subprocess.STDOUT,
+            shell = True)
+    except subprocess.CalledProcessError as e:
+        # Get the last 10 lines of the output and truncate lines exceeding 200 characters
+        return '\n'.join([line[:200] for line in e.output.decode('utf-8').split('\n')[-10:]])
+
+previous_command = argv[1]
+error_message = get_error_message(previous_command)
 
 try:
-    engine.get_logger().debug('Fixing command: ' + command)
+    engine.get_logger().debug('Fixing command: ' + previous_command)
     engine.get_logger().debug('Command output: ' + error_message)
-    response = engine.get_response(messages = get_messages(command, error_message))
+    response = engine.get_response(messages = get_messages(previous_command, error_message))
     print(response)
 except Exception as e:
     engine.get_logger().exception(e)