#!/usr/bin/env python3

# Copyright (c) 2017-2023 California Institute of Technology ("Caltech"). U.S.
# Government sponsorship acknowledged. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0


r"""Converts a cameramodel to the cahvor file format

SYNOPSIS

  $ mrcal-to-cahvor model1.cameramodel model2.cameramodel
  Wrote model1.cahvor
  Wrote model2.cahvor

File formats supported by mrcal are described at
https://mrcal.secretsauce.net/cameramodels.html#cameramodel-file-formats

This tool converts the given model(s) to the cahvor file format. No changes to
the content are made; this is purely a format converter (the
mrcal-convert-lensmodel tool fits different lens models instead). Model
filenames are given on the commandline. Output is written to the same directory,
with the same filename, but with a .cahvor extension.

If the model is omitted or given as "-", the input is read from standard input,
and the output is written to standard output

"""

import sys
import argparse
import os


def parse_args():
    parser = argparse.ArgumentParser(
        description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter
    )

    parser.add_argument(
        "--force",
        "-f",
        action="store_true",
        default=False,
        help="""By default existing files are not overwritten. Pass --force to overwrite them
                        without complaint""",
    )
    parser.add_argument(
        "--outdir",
        required=False,
        type=lambda d: d
        if os.path.isdir(d)
        else parser.error(
            "--outdir requires an existing directory as the arg, but got '{}'".format(d)
        ),
        help="""Directory to write the output models into. If omitted, we write the output
                        models to the same directory as the input models""",
    )
    parser.add_argument(
        "model", default=["-"], nargs="*", type=str, help="""Input camera model"""
    )

    return parser.parse_args()


args = parse_args()

# arg-parsing is done before the imports so that --help works without building
# stuff, so that I can generate the manpages and README

Nstdin = sum(1 for m in args.model if m == "-")
if Nstdin > 1:
    print(
        f"At most one model can be read from standard input ('-'), but I got {Nstdin}",
        file=sys.stderr,
    )
    sys.exit(1)

import mrcal

for model in args.model:
    if model == "-":
        try:
            m = mrcal.cameramodel(model)
        except KeyboardInterrupt:
            sys.exit(1)
        m.write(sys.stdout, cahvor=True)
    else:
        base, extension = os.path.splitext(model)
        if extension.lower() == ".cahvor":
            print(
                "Input file is already in the cahvor format (judging from the filename). Doing nothing",
                file=sys.stderr,
            )
            sys.exit(0)

        if args.outdir is not None:
            base = args.outdir + "/" + os.path.split(base)[1]
        filename_out = base + ".cahvor"
        if not args.force and os.path.exists(filename_out):
            print(
                f"Target model '{filename_out}' already exists. Doing nothing with this model. Pass -f to overwrite",
                file=sys.stderr,
            )
        else:
            m = mrcal.cameramodel(model)
            m.write(filename_out)
            print("Wrote " + filename_out)
