feat: playlist browsing

pagination still needs refinement for some of the clients.
on another note, this is an anniversary commit, as ythdd turns 1 year
today.

ythdd_struct_parser.py

@@ -312,6 +312,34 @@ def parseRenderers(entry: dict, context: dict = {}) -> dict:
 				"descriptionHtml": description_html
 			}
 
+		case "playlistVideoRenderer":
+
+			video_id       = safeTraverse(entry, ["playlistVideoRenderer", "videoId"], default="UnknownVideoId")
+			title          = safeTraverse(entry, ["playlistVideoRenderer", "title", "runs", 0, "text"], default="Unknown video title")
+			author_ucid    = safeTraverse(entry, ["playlistVideoRenderer", "shortBylineText", "runs", 0, "navigationEndpoint", "browseEndpoint", "browseId"], default="UNKNOWNCHANNELID")
+			author_name    = safeTraverse(entry, ["playlistVideoRenderer", "shortBylineText", "runs", 0, "text"], default="Unknown author")
+			video_index    = int(safeTraverse(entry, ["playlistVideoRenderer", "index", "simpleText"], default="1")) - 1
+			length         = parseLengthFromTimeBadge(safeTraverse(entry, ["playlistVideoRenderer", "lengthText", "simpleText"], default="0:0"))
+			published_date = safeTraverse(entry, ["playlistVideoRenderer", "videoInfo", "runs", -1, "text"], default="2000-01-01")
+			published_date = published_date.removeprefix("Streamed ")
+
+			return {
+				"type": "video",
+				"title": title,
+				"videoId": video_id,
+				"author": author_name,
+				"authorId": author_ucid,
+				"authorUrl": "/channel/" + author_ucid,
+				"videoThumbnails": genThumbs(video_id),
+				"index": video_index,
+				"lengthSeconds": length,
+				"liveNow": False, # todo: check this?
+				# these do not need to be returned, but some clients try to read it
+				# so we return an approximation here:
+				"published": int(dateparser.parse(published_date).timestamp()),
+				"publishedText": published_date
+			}
+
 		case _:
 			print("received an entry of unknown type:")
 			print(entry)
@@ -372,3 +400,27 @@ def parseDescriptionSnippet(snippet: list):
 	text_html = escape(text_html).replace("\r\n", "<br>").replace("\n", "<br>")
 
 	return text, text_html
+
+def runsToText(runs: list, default: str = "") -> str:
+	# "default" will be returned when text extraction fails.
+	extracted_text = ""
+
+	for field in runs:
+		extracted_text += safeTraverse(field, ["text"], default="")
+
+	if extracted_text:
+		return extracted_text
+
+	return default
+
+def extractTextFromSimpleOrRuns(obj: dict, default: str = "") -> str:
+	# Extracts the text both from "runs" and "simpleText"
+	# with failsafe to default.
+	text = default
+	if "runs" in obj:
+		text = runsToText(obj["runs"])
+	elif "simpleText" in obj:
+		text = obj["simpleText"]
+	else:
+		print(f"error(extractTextFromSimpleOrRuns): text extraction failed for {obj}")
+	return text