insert MIT license here

facetbuilder.py

from typing import Self, Tuple, List
import io

class FacetBuilder():
	def __init__(self) -> None:
		self.buffer = io.BytesIO()
		self.facets = []
	
	def build(self) -> Tuple[str, List[dict]]:
		return self.buffer.getvalue().decode(), self.facets

	def text(self, text: str) -> Self:
		self.buffer.write(text.encode())
		return self
	
	def link(self, text: str, uri: str) -> Self:
		start_index = self.buffer.tell()
		self.buffer.write(text.encode())
		end_index = self.buffer.tell()
		self.facets.append({
			'index': {'byteStart': start_index, 'byteEnd': end_index},
			'features': [{
				'$type': 'app.bsky.richtext.facet#link',
				'uri': uri
			}]
		})
		return self
	
	def mention(self, text: str, did: str) -> Self:
		start_index = self.buffer.tell()
		self.buffer.write(text.encode())
		end_index = self.buffer.tell()
		self.facets.append({
			'index': {'byteStart': start_index, 'byteEnd': end_index},
			'features': [{
				'$type': 'app.bsky.richtext.facet#mention',
				'did': did
			}]
		})
		return self

if __name__ == "__main__":
	text, facets = FacetBuilder() \
		.text("hello, ").mention("@user", "did:plc:blah") \
		.text("! please visit my ").link("website.", "https://example.com/") \
		.build()
	
	print(text)  # -> hello, @user! please visit my website.
	print(facets)  # -> [{'index': {'byteStart': 7, 'byteEnd': 12}, 'features': [{'$type': 'app.bsky.richtext.facet#mention', 'did': 'did:plc:blah'}]}, {'index': {'byteStart': 30, 'byteEnd': 38}, 'features': [{'$type': 'app.bsky.richtext.facet#link', 'uri': 'https://example.com/'}]}]