From d5907a1bf9e04bb9d5215a3dafbd78231269cc1d Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Thu, 19 Apr 2018 10:26:14 +0530
Subject: [PATCH] More work on the diff kitten

---
 kittens/diff/git.py    |  3 +--
 kittens/diff/main.py   | 58 ++++++++++++++++++++++++++++++++++++++----
 kittens/tui/handler.py |  3 +++
 kittens/tui/loop.py    |  2 ++
 4 files changed, 59 insertions(+), 7 deletions(-)

diff --git a/kittens/diff/git.py b/kittens/diff/git.py
index d084b2a68..9efd6bf57 100644
--- a/kittens/diff/git.py
+++ b/kittens/diff/git.py
@@ -107,8 +107,7 @@ class Differ:
         key = file1, file2
         self.jobs.append(key)
 
-    def __call__(self):
-        context = 3
+    def __call__(self, context=3):
         ans = {}
         with concurrent.futures.ThreadPoolExecutor(max_workers=os.cpu_count()) as executor:
             jobs = {executor.submit(run_diff, key[0], key[1], context): key for key in self.jobs}
diff --git a/kittens/diff/main.py b/kittens/diff/main.py
index 6c471847b..2fc9b45b6 100644
--- a/kittens/diff/main.py
+++ b/kittens/diff/main.py
@@ -4,20 +4,38 @@
 
 import os
 import sys
+import traceback
 from functools import partial
+from gettext import gettext as _
+from threading import Thread
 
 from kitty.cli import parse_args
+from kitty.key_encoding import ESCAPE
 
 from ..tui.handler import Handler
 from ..tui.loop import Loop
-from ..tui.operations import set_line_wrapping, set_window_title
+from ..tui.operations import clear_screen, set_line_wrapping, set_window_title
 from .collect import create_collection
 
+INITIALIZING, READY, RENDERED = range(3)
+
 
 class DiffHandler(Handler):
 
-    def __init__(self, collection):
-        self.collection = collection
+    def __init__(self, left, right):
+        self.state = INITIALIZING
+        self.left, self.right = left, right
+        self.report_traceback_on_exit = None
+
+    def create_collection(self):
+        try:
+            self.collection = create_collection(self.left, self.right)
+        except Exception:
+            self.report_traceback_on_exit = traceback.format_exc()
+            self.quit_loop(1)
+        else:
+            self.state = READY
+        self.wakeup()
 
     def init_terminal_state(self):
         self.write(set_line_wrapping(False))
@@ -26,6 +44,35 @@ class DiffHandler(Handler):
     def initialize(self, *args):
         Handler.initialize(self, *args)
         self.init_terminal_state()
+        self.draw_screen()
+        t = Thread(target=self.create_collection, name='CreatingCollection')
+        t.daemon = True
+        t.start()
+
+    def draw_screen(self):
+        if self.state is INITIALIZING:
+            self.write(clear_screen())
+            self.write(_('Calculating diff, please wait...'))
+            return
+        if self.state is READY:
+            self.write(clear_screen())
+            self.state = RENDERED
+            return
+
+    def on_key(self, key_event):
+        if self.state is INITIALIZING:
+            if key_event.key is ESCAPE:
+                self.quit_loop(0)
+            return
+
+    def on_wakeup(self):
+        self.draw_screen()
+
+    def on_interrupt(self):
+        self.quit_loop(1)
+
+    def on_eot(self):
+        self.quit_loop(1)
 
 
 OPTIONS = partial('''\
@@ -40,12 +87,13 @@ def main(args):
     left, right = items
     if os.path.isdir(left) != os.path.isdir(right):
         raise SystemExit('The items to be diffed should both be either directories or files. Comparing a directory to a file is not valid.')
-    collection = create_collection(left, right)
 
     loop = Loop()
-    handler = DiffHandler(collection)
+    handler = DiffHandler(left, right)
     loop.loop(handler)
     if loop.return_code != 0:
+        if handler.report_traceback_on_exit:
+            print(handler.report_traceback_on_exit, file=sys.stderr)
         raise SystemExit(loop.return_code)
 
 
diff --git a/kittens/tui/handler.py b/kittens/tui/handler.py
index e5d9f3651..7d37544e9 100644
--- a/kittens/tui/handler.py
+++ b/kittens/tui/handler.py
@@ -30,6 +30,9 @@ class Handler:
     def on_eot(self):
         pass
 
+    def on_wakeup(self):
+        pass
+
     def write(self, data):
         if isinstance(data, str):
             data = data.encode('utf-8')
diff --git a/kittens/tui/loop.py b/kittens/tui/loop.py
index 6fc0a94b0..34efac78b 100644
--- a/kittens/tui/loop.py
+++ b/kittens/tui/loop.py
@@ -283,6 +283,8 @@ class Loop:
             handler.on_term()
         if b'i' in data:
             handler.on_interrupt()
+        if b'1' in data:
+            handler.on_wakeup()
 
     def _wakeup_write(self, val):
         while not os.write(self.wakeup_write_fd, val):