import json
import pprint
from typing import List, Iterable
from ._transcripts import FetchedTranscript, FetchedTranscriptSnippet
class Formatter:
"""Formatter should be used as an abstract base class.
Formatter classes should inherit from this class and implement
their own .format() method which should return a string. A
transcript is represented by a List of Dictionary items.
"""
def format_transcript(self, transcript: FetchedTranscript, **kwargs) -> str:
raise NotImplementedError(
"A subclass of Formatter must implement "
"their own .format_transcript() method."
)
def format_transcripts(self, transcripts: List[FetchedTranscript], **kwargs):
raise NotImplementedError(
"A subclass of Formatter must implement "
"their own .format_transcripts() method."
)
class PrettyPrintFormatter(Formatter):
def format_transcript(self, transcript: FetchedTranscript, **kwargs) -> str:
"""Pretty prints a transcript.
:param transcript:
:return: A pretty printed string representation of the transcript.
"""
return pprint.pformat(transcript.to_raw_data(), **kwargs)
def format_transcripts(self, transcripts: List[FetchedTranscript], **kwargs) -> str:
"""Converts a list of transcripts into a JSON string.
:param transcripts:
:return: A JSON string representation of the transcript.
"""
return pprint.pformat(
[transcript.to_raw_data() for transcript in transcripts], **kwargs
)
class JSONFormatter(Formatter):
def format_transcript(self, transcript: FetchedTranscript, **kwargs) -> str:
"""Converts a transcript into a JSON string.
:param transcript:
:return: A JSON string representation of the transcript.
"""
return json.dumps(transcript.to_raw_data(), **kwargs)
def format_transcripts(self, transcripts: List[FetchedTranscript], **kwargs) -> str:
"""Converts a list of transcripts into a JSON string.
:param transcripts:
:return: A JSON string representation of the transcript.
"""
return json.dumps(
[transcript.to_raw_data() for transcript in transcripts], **kwargs
)
class TextFormatter(Formatter):
def format_transcript(self, transcript: FetchedTranscript, **kwargs) -> str:
"""Converts a transcript into plain text with no timestamps.
:param transcript:
:return: all transcript text lines separated by newline breaks.
"""
return "\n".join(line.text for line in transcript)
def format_transcripts(self, transcripts: List[FetchedTranscript], **kwargs) -> str:
"""Converts a list of transcripts into plain text with no timestamps.
:param transcripts:
:return: all transcript text lines separated by newline breaks.
"""
return "\n\n\n".join(
[self.format_transcript(transcript, **kwargs) for transcript in transcripts]
)
class _TextBasedFormatter(TextFormatter):
def _format_timestamp(self, hours: int, mins: int, secs: int, ms: int) -> str:
raise NotImplementedError(
"A subclass of _TextBasedFormatter must implement "
"their own .format_timestamp() method."
)
def _format_transcript_header(self, lines: Iterable[str]) -> str:
raise NotImplementedError(
"A subclass of _TextBasedFormatter must implement "
"their own _format_transcript_header method."
)
def _format_transcript_helper(
self, i: int, time_text: str, snippet: FetchedTranscriptSnippet
) -> str:
raise NotImplementedError(
"A subclass of _TextBasedFormatter must implement "
"their own _format_transcript_helper method."
)
def _seconds_to_timestamp(self, time: float) -> str:
"""Helper that converts `time` into a transcript cue timestamp.
:reference: https://www.w3.org/TR/webvtt1/#webvtt-timestamp
:param time: a float representing time in seconds.
:type time: float
:return: a string formatted as a cue timestamp, 'HH:MM:SS.MS'
:example:
>>> self._seconds_to_timestamp(6.93)
'00:00:06.930'
"""
time = float(time)
hours_float, remainder = divmod(time, 3600)
mins_float, secs_float = divmod(remainder, 60)
hours, mins, secs = int(hours_float), int(mins_float), int(secs_float)
ms = int(round((time - int(time)) * 1000, 2))
return self._format_timestamp(hours, mins, secs, ms)
def format_transcript(self, transcript: FetchedTranscript, **kwargs) -> str:
"""A basic implementation of WEBVTT/SRT formatting.
:param transcript:
:reference:
https://www.w3.org/TR/webvtt1/#introduction-caption
https://www.3playmedia.com/blog/create-srt-file/
"""
lines = []
for i, line in enumerate(transcript):
end = line.start + line.duration
time_text = "{} --> {}".format(
self._seconds_to_timestamp(line.start),
self._seconds_to_timestamp(
transcript[i + 1].start
if i < len(transcript) - 1 and transcript[i + 1].start < end
else end
),
)
lines.append(self._format_transcript_helper(i, time_text, line))
return self._format_transcript_header(lines)
class SRTFormatter(_TextBasedFormatter):
def _format_timestamp(self, hours: int, mins: int, secs: int, ms: int) -> str:
return "{:02d}:{:02d}:{:02d},{:03d}".format(hours, mins, secs, ms)
def _format_transcript_header(self, lines: Iterable[str]) -> str:
return "\n\n".join(lines) + "\n"
def _format_transcript_helper(
self, i: int, time_text: str, snippet: FetchedTranscriptSnippet
) -> str:
return "{}\n{}\n{}".format(i + 1, time_text, snippet.text)
class WebVTTFormatter(_TextBasedFormatter):
def _format_timestamp(self, hours: int, mins: int, secs: int, ms: int) -> str:
return "{:02d}:{:02d}:{:02d}.{:03d}".format(hours, mins, secs, ms)
def _format_transcript_header(self, lines: Iterable[str]) -> str:
return "WEBVTT\n\n" + "\n\n".join(lines) + "\n"
def _format_transcript_helper(
self, i: int, time_text: str, snippet: FetchedTranscriptSnippet
) -> str:
return "{}\n{}".format(time_text, snippet.text)
class FormatterLoader:
TYPES = {
"json": JSONFormatter,
"pretty": PrettyPrintFormatter,
"text": TextFormatter,
"webvtt": WebVTTFormatter,
"srt": SRTFormatter,
}
class UnknownFormatterType(Exception):
def __init__(self, formatter_type: str):
super().__init__(
"The format '{formatter_type}' is not supported. "
"Choose one of the following formats: {supported_formatter_types}".format(
formatter_type=formatter_type,
supported_formatter_types=", ".join(FormatterLoader.TYPES.keys()),
)
)
def load(self, formatter_type: str = "pretty") -> Formatter:
"""
Loads the Formatter for the given formatter type.
:param formatter_type:
:return: Formatter object
"""
if formatter_type not in FormatterLoader.TYPES.keys():
raise FormatterLoader.UnknownFormatterType(formatter_type)
return FormatterLoader.TYPES[formatter_type]()