#! /usr/bin/env python3
"""make_gacos_correction — tropospheric correction via GACOS (SCAFFOLD).

Python port of csh make_gacos_correction.csh (W. Tang 2018; Z. Xiangjun 2024;
H. Xu 2025). 200-line csh. Not yet implemented; complex GACOS-specific I/O
pipeline (.ztd files + .rsc metadata, per-date master/slave ZTDs).

Usage:  make_gacos_correction intf_dir GACOS_path ref_range ref_azimuth dem.grd
"""
import sys


def make_gacos_correction():
    if len(sys.argv) != 6:
        sys.exit(
            "Usage: make_gacos_correction intf_dir GACOS_path ref_range "
            "ref_azimuth dem.grd\n"
            "  PLAN Phase 5 scaffold — not yet implemented (200 csh lines).\n"
            "  GACOS files (.ztd, .rsc) must exist in GACOS_path."
        )
    raise NotImplementedError("make_gacos_correction: Phase 5 scaffold")


if __name__ == "__main__":
    make_gacos_correction()
