Record in database when end time is "--"

We need this so that reverse sync reproduces these values correctly.

To handle this in the database, we have a composite type (dashed: boolean, value: timestamp).
Value is always valid and is equivalent to the old timestamp column,
but must be equal to start_time if dashed is true.

The only place we directly reference this column outside sheetsync is thrimshim, where we
always consider the value only.

common/common/database.py

@@ -17,6 +17,7 @@ from psycogreen.gevent import patch_psycopg
 COMPOSITE_TYPES = [
 	"video_range",
 	"video_transition",
+	"end_time",
 ]
 COLUMN_CASTS = {
 	"video_ranges": "video_range[]",

postgres/schema.sql

@@ -26,12 +26,24 @@ CREATE TYPE thumbnail_mode as ENUM (
 	'CUSTOM'
 );
 
+-- The end time for an event can be unset, "--" or a timestamp.
+-- If dashed is true, value should be the same as start time (which may be NULL if start time is unset).
+-- Otherwise value is the value (which may be NULL if end time is unset).
+-- dashed should be non-NULL.
+CREATE TYPE end_time AS (
+	dashed BOOLEAN,
+	value TIMESTAMP
+)
+
 CREATE TABLE events (
 	id TEXT PRIMARY KEY,
 
 	sheet_name TEXT NOT NULL,
 	event_start TIMESTAMP,
-	event_end TIMESTAMP,
+	event_end end_time DEFAULT ROW(false, NULL) CHECK (
+		event_end.dashed IS NOT NULL
+		AND (event_end.dashed != TRUE OR event_end.value IS NOT DISTINCT FROM event_start)
+	),
 	category TEXT NOT NULL DEFAULT '',
 	description TEXT NOT NULL DEFAULT '',
 	submitter_winner TEXT NOT NULL DEFAULT '',

sheetsync/sheetsync/sheets.py

@@ -288,7 +288,7 @@ class SheetsEventsMiddleware(SheetsMiddleware):
 		}
 		self.column_encode = {
 			"event_start": self.encode_bustime,
-			"event_end": self.encode_bustime,
+			"event_end": lambda v: ("--" if v[0] else self.encode_bustime(v[1])),
 			"poster_moment": ENCODE_CHECKMARK,
 			"image_links": lambda v: " ".join(v),
 			"tags": lambda v: ", ".join(v),
@@ -336,9 +336,14 @@ class SheetsEventsMiddleware(SheetsMiddleware):
 				+ row_dict['tags']
 			)
 
-		# As a special case, treat an end time of "--" as equal to the start time.
-		if row_dict["event_end"] == "--":
-			row_dict["event_end"] = row_dict["event_start"]
+		# As a special case, transform event_end into (dashed, value) form
+		# where value = event_start if dashed is true.
+		event_end = row_dict["event_end"]
+		row_dict["event_end"] = (
+			(True, row_dict["event_start"])
+			if event_end == "--"
+			else (False, event_end)
+		)
 
 		# Set edit link if marked for editing and start/end set.
 		# This prevents accidents / clicking the wrong row and provides
@@ -384,4 +389,4 @@ class SheetsArchiveMiddleware(SheetsEventsMiddleware):
 	}
 
 	def show_edit_url(self, row):
-		return row['event_start'] is not None and row['event_end'] is not None
+		return row['event_start'] is not None and row['event_end'][1] is not None

sheetsync/sheetsync/streamlog.py

@@ -105,7 +105,11 @@ class StreamLogEventsMiddleware(Middleware):
 		# Omitted columns act as the identity function.
 		self.column_decode = {
 			'event_start': parse_utc_only,
-			'event_end': lambda v: parse_utc_only(v["time"]) if v["type"] == "Time" else None,
+			'event_end': lambda v: (
+				parse_utc_only(v["time"]) if v["type"] == "Time"
+				else "--" if v["type"] == "NoTime"
+				else None
+			),
 			'category': lambda v: v["name"],
 			'state': lambda v: v.upper() if v else None,
 			'error': lambda v: None if v == '' else v,
@@ -161,6 +165,15 @@ class StreamLogEventsMiddleware(Middleware):
 		# Tab name is sheet name
 		output["sheet_name"] = row["tab"]["name"] if row["tab"] else "unknown"
 
+		# Transform event_end into (dashed, value) form
+		# where value = event_start if dashed is true.
+		event_end = output["event_end"]
+		output["event_end"] = (
+			(True, output["event_start"])
+			if event_end == "--"
+			else (False, event_end)
+		)
+
 		# Implicit tags
 		implicit_tags = [
 			output['category'],

thrimshim/thrimshim/main.py

@@ -180,6 +180,8 @@ def get_row(ident):
 	response['id'] = str(response['id'])	
 	if response["video_channel"] is None:
 		response["video_channel"] = app.default_channel
+	# Unwrap end time (dashed, value) to just value
+	response["event_end"] = response["event_end"][1]
 	title_header = "" if is_archive else app.title_header
 	response["title_prefix"] = title_header
 	response["title_max_length"] = MAX_TITLE_LENGTH - len(title_header)
@@ -394,6 +396,9 @@ def update_row(ident, editor=None):
 	# check whether row has been changed in the sheet since editing has begun
 	changes = ''
 	for column in sheet_columns:
+		if column == "event_end":
+			# convert (dashed, value) to value
+			old_row[column] = old_row[column][1]
 		if isinstance(old_row[column], datetime.datetime):
 			old_row[column] = old_row[column].isoformat()
 		def normalize(value):
@@ -408,6 +413,7 @@ def update_row(ident, editor=None):
 		return 'Sheet columns have changed since editing has begun. Please review changes\n' + changes, 409
 
 	if new_row['state'] == 'MODIFIED':
+		missing = []
 		# Modifying published rows is more limited, we ignore all other fields.
 		for column in set(modifiable_columns) & set(non_null_columns):
 			if new_row.get(column) is None: