#!/usr/bin/env python3
"""
Runs musrfit -c on a given msr-file, extracts the maxLH (or chisq)
value from stdout, and compares it against an expected reference value.
Returns exit code 1 if the relative deviation exceeds the tolerance.

Usage:
  maxLH_check.py <musrfit> <msr-file> <expected_value> [tolerance]
"""

import subprocess
import sys
import re

def main():
    if len(sys.argv) < 4 or len(sys.argv) > 5:
        print(f"usage: {sys.argv[0]} <musrfit> <msr-file> <expected> [tolerance]")
        return 1

    musrfit  = sys.argv[1]
    msr_file = sys.argv[2]
    expected = float(sys.argv[3])
    tol      = float(sys.argv[4]) if len(sys.argv) == 5 else 1e-4

    # run musrfit -c
    result = subprocess.run([musrfit, "-c", msr_file],
                            capture_output=True, text=True)
    if result.returncode != 0:
        print(f"**ERROR** musrfit returned exit code {result.returncode}")
        print(result.stdout + result.stderr)
        return 1

    # extract maxLH or chisq from stdout
    match = re.search(r">>\s+(maxLH|chisq)\s*=\s*([0-9.eE+-]+)", result.stdout)
    if not match:
        print("**ERROR** could not extract maxLH or chisq from output:")
        print(result.stdout)
        return 1

    label = match.group(1)
    value = float(match.group(2))
    rel_dev = abs((value - expected) / expected)

    if rel_dev > tol:
        print(f"FAIL: {label} = {value}, expected = {expected}, "
              f"rel. deviation = {rel_dev:.6e} > {tol:.6e}")
        return 1

    print(f"PASS: {label} = {value}, expected = {expected}, "
          f"rel. deviation = {rel_dev:.6e} <= {tol:.6e}")
    return 0

if __name__ == "__main__":
    sys.exit(main())