Move the focus from a surface: clicks, the wheel, point

Only the app's key handlers could move a list's focus. When the focus
view is a plain index position (`view tasks_list_focus = at.position`),
Vega now asks Pure for that index and moves it as a user pointing at a
row (pure_app_point), with no code in the app. The grid remembers which
item each line shows; in the TUI a click on a row focuses it and the
wheel moves the focus one row (SGR mouse reports, turned off on exit).
Scripts say point VIEW ROW or click LINE COLUMN on the last shown frame.
The focus is stored like any event, so the next run of any surface
starts from it.

The model now points too: random scripts with points (some past the
end) and TUI clicks still match it on every surface, a mouse click on a
real pseudo-terminal moves the focus, and the stored session keeps it.

1 files changed, 41 insertions, 10 deletions

diff --git a/tests/check.py b/tests/check.py
index d46698d..e0d5996 100644
--- a/tests/check.py
+++ b/tests/check.py
@@ -61,7 +61,13 @@ class Todo:
         self.tasks, self.at = [], 0
 
     def event(self, name, text=None):
-        """Returns False when the event fails (a missing item)."""
+        """Returns False when the event fails (a missing item). point takes
+        the row as text: a surface focusing it, as a click would."""
+        if name == 'point':
+            if not 0 <= text < len(self.tasks):
+                return False
+            self.at = text
+            return True
         if name == 'add':
             self.tasks.append({'title': text, 'done': 0, 'urgent': 0})
             self.at = len(self.tasks) - 1
@@ -127,7 +133,12 @@ def cli_and_say(vega, module, seeds, steps=300):
         rng = random.Random(seed)
         model, script, expected_cli, expected_say = Todo(), [], [], []
         for _ in range(steps):
-            if rng.random() < 0.25:
+            roll = rng.random()
+            if roll < 0.1:
+                row = rng.randrange(len(model.tasks) + 2)
+                script.append(f'point tasks_list {row}')
+                ok, name = model.event('point', row), 'point'
+            elif roll < 0.35:
                 word = rng.choice(WORDS)
                 script.append('text ' + (word.encode().hex() or '-'))
                 ok, name = model.event('add', word), 'add'
@@ -164,7 +175,12 @@ def stored_surfaces(vega, module, work, seeds, steps=240):
             surface = ['cli', 'say'][number % 2]
             script, expected = [], []
             for _ in range(start, end):
-                if rng.random() < 0.3:
+                roll = rng.random()
+                if roll < 0.1:
+                    row = rng.randrange(len(model.tasks) + 1)
+                    script.append(f'point tasks_list {row}')
+                    ok, name = model.event('point', row), 'point'
+                elif roll < 0.4:
                     word = rng.choice(WORDS)
                     script.append('text ' + (word.encode().hex() or '-'))
                     ok, name = model.event('add', word), 'add'
@@ -201,9 +217,16 @@ def tui(vega, module, seeds, sizes, steps=300):
         area = rows - 5  # title, field, list header, key bar, input line
         for seed in seeds:
             rng = random.Random(seed * 7 + columns)
-            model, script, states = Todo(), [], []
-            for _ in range(steps):
-                if rng.random() < 0.3:
+            model, script, states, scroll = Todo(), [], [], 0
+            for step in range(steps):
+                roll = rng.random()
+                if roll < 0.12 and step:
+                    # A click on a line of the last frame: an item line focuses that item.
+                    line = rng.randrange(rows)
+                    script.append(f'click {line + 1} 3')
+                    if 3 <= line < 3 + area and scroll + line - 3 < len(model.tasks):
+                        model.event('point', scroll + line - 3)
+                elif roll < 0.4:
                     word = rng.choice(WORDS)
                     script.append('text ' + (word.encode().hex() or '-'))
                     model.event('add', word)
@@ -212,6 +235,10 @@ def tui(vega, module, seeds, sizes, steps=300):
                     script.append(f'key {KEYS[name]}')
                     model.event(name)
                 script.append('show')
+                n = len(model.tasks)
+                if model.at < scroll: scroll = model.at
+                if model.at >= scroll + area: scroll = model.at - area + 1
+                if scroll + area > n: scroll = max(n - area, 0)
                 states.append(([dict(t) for t in model.tasks], model.at))
             result = run(vega, 'tui', module, '--dump', f'{columns}x{rows}', stdin='\n'.join(script) + '\n')
             assert result.returncode == 0, result.stderr
@@ -382,7 +409,8 @@ def interactive(vega, module, store=None):
         return data
 
     screen = read_for(0.3)
-    for keys in (b'milk\r', 'b\u00e9ton\r'.encode(), b'\t', b'\x1b[A', b' ', b'u'):
+    # Then a click on line 5 (béton's row): a mouse report, press and release.
+    for keys in (b'milk\r', 'b\u00e9ton\r'.encode(), b'\t', b'\x1b[A', b' ', b'u', b'\x1b[<0;3;5M\x1b[<0;3;5m'):
         os.write(fd, keys)
         screen += read_for(0.2)
     os.write(fd, b'\x03')
@@ -395,11 +423,13 @@ def interactive(vega, module, store=None):
     # What the terminal ended up showing, from the bytes it was sent.
     grid = [[[' ', 0, False] for _ in range(40)] for _ in range(10)]
     replay(screen, grid)
-    final = '\n'.join(shown(grid))
-    assert 'milk' in final and 'béton' in final and '(2)' in final and 'done' in final, final
+    final = shown(grid)
+    assert 'milk' in '\n'.join(final) and '(2)' in final[2] and 'done' in final[3], final
+    assert final[4].startswith('>> béton') and final[3].startswith('|  milk'), final  # the click moved the focus
+    assert '\x1b[?1000h' in text and '\x1b[?1000l' in text, 'mouse reports on, then off'
     if store:  # what was typed is still there in the next session
         again = run(vega, 'cli', module, '--store', store, stdin='show\n').stdout.splitlines()
-        assert again == ['To do', 'left: 2 tasks', 'tasks_list (2)', '> milk [done] (muted)', '  béton'], again
+        assert again == ['To do', 'left: 2 tasks', 'tasks_list (2)', '  milk [done] (muted)', '> béton'], again
     return 1
 
 
@@ -479,6 +509,7 @@ def robustness(vega, aup, work, rounds):
                 elif roll < 0.3: script.append('show')
                 elif roll < 0.35: script.append('frame 3')
                 elif roll < 0.4: script.append(rng.choice(['type 61', 'enter', 'tab']))
+                elif roll < 0.45: script.append(f'click {rng.randrange(1, 30)} {rng.randrange(1, 90)}')
                 else: script.append('key ' + rng.choice(keys))
             text = '\n'.join(script) + '\nshow\n'
             size = rng.choice(['80x24', '12x5', '1x1', '200x3'])