#!/usr/bin/env python3
"""Decode a validated or raw TRK1 byte stream into CSV."""

import argparse
import csv
from pathlib import Path

from trikke_protocol import (
    CSV_COLUMNS,
    PACKET_FLAG_TIMESTAMP_DELTA_SATURATED,
    PACKET_TYPE_METADATA,
    Frame,
    StreamParser,
    sample_to_csv_row,
)


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("input", type=Path)
    parser.add_argument("output", type=Path)
    args = parser.parse_args()

    stream = StreamParser()
    frames: list[Frame] = []
    with args.input.open("rb") as source:
        while chunk := source.read(64 * 1024):
            frames.extend(stream.feed(chunk))

    metadata = next(
        (frame.metadata for frame in frames if frame.packet_type == PACKET_TYPE_METADATA),
        None,
    )
    if metadata is None:
        print(
            "No valid metadata frame found; "
            f"trailing_partial_bytes={stream.buffered_bytes}"
        )
        return 2

    args.output.parent.mkdir(parents=True, exist_ok=True)
    sample_count = 0
    timestamp_saturation_frame_count = 0
    with args.output.open("w", encoding="utf-8", newline="") as target:
        writer = csv.writer(target)
        writer.writerow(CSV_COLUMNS)
        for frame in frames:
            if frame.flags & PACKET_FLAG_TIMESTAMP_DELTA_SATURATED:
                timestamp_saturation_frame_count += 1
            if frame.packet_type == PACKET_TYPE_METADATA:
                if frame.metadata is not None:
                    metadata = frame.metadata
                continue
            for sample in frame.samples:
                writer.writerow(
                    sample_to_csv_row(sample, metadata, frame.loop_overrun_count)
                )
                sample_count += 1

    print(
        f"Decoded {sample_count} samples from {len(frames)} frames; "
        f"startup_crc_rejects={stream.startup_crc_errors}, "
        f"stream_crc_errors={stream.crc_errors}, header_errors={stream.header_errors}, "
        f"skipped_nonframe_bytes={stream.skipped_bytes}, "
        f"timestamp_saturation_frames={timestamp_saturation_frame_count}, "
        f"trailing_partial_bytes={stream.buffered_bytes}; saved {args.output}"
    )
    return 0


if __name__ == "__main__":
    raise SystemExit(main())