#!/usr/bin/env python3
"""Compare two runs of the identical Wii conformance DOL."""

import argparse
import csv
import sys
from pathlib import Path


METADATA = ("schema", "rounds", "observations", "ios_version", "ios_revision")
HEADER = ["seq", "test", "round", "value", "extra"]


def read_capture(path: Path):
    with path.open(newline="", encoding="utf-8") as stream:
        rows = csv.reader(stream)
        metadata = {}
        for key in METADATA:
            row = next(rows, None)
            if row is None or len(row) != 2 or row[0] != key:
                raise ValueError(f"{path}: expected metadata row {key!r}")
            metadata[key] = int(row[1])
        if next(rows, None) != HEADER:
            raise ValueError(f"{path}: invalid observation header")
        observations = []
        for line, row in enumerate(rows, start=7):
            if len(row) != 5:
                raise ValueError(f"{path}:{line}: expected 5 columns")
            seq, test, round_number, value, extra = row
            if int(seq) != len(observations):
                raise ValueError(f"{path}:{line}: sequence is not contiguous")
            observations.append((test, int(round_number), int(value), int(extra)))
        if len(observations) != metadata["observations"]:
            raise ValueError(
                f"{path}: expected {metadata['observations']} observations, "
                f"found {len(observations)}"
            )
    return metadata, observations


def compare(reference, candidate, limit=20):
    reference_meta, reference_rows = reference
    candidate_meta, candidate_rows = candidate
    for key in METADATA:
        if reference_meta[key] != candidate_meta[key]:
            print(f"Incomparable runs: {key}: Wii={reference_meta[key]}, Dolphin={candidate_meta[key]}")
            return 2

    differences = 0
    for index in range(max(len(reference_rows), len(candidate_rows))):
        expected = reference_rows[index] if index < len(reference_rows) else None
        actual = candidate_rows[index] if index < len(candidate_rows) else None
        if expected == actual:
            continue
        differences += 1
        if differences <= limit:
            print(f"#{index} Wii={expected} Dolphin={actual}")

    if differences:
        print(f"{differences} differences across {max(len(reference_rows), len(candidate_rows))} observations")
        return 1
    print(f"Identical: {len(reference_rows)} observations")
    return 0


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("wii", type=Path, help="CSV from the real Wii")
    parser.add_argument("dolphin", type=Path, help="CSV from Dolphin")
    args = parser.parse_args()
    try:
        return compare(read_capture(args.wii), read_capture(args.dolphin))
    except (OSError, ValueError) as error:
        print(error, file=sys.stderr)
        return 2


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