#!/usr/bin/python3
"""
Assembles the tree into a tar archive named `filename`.

Uses the buildhost's `tar` command, like: `tar -cf $FILENAME -C $TREE`

If the `compression` option is given, the archive will be compressed by passing
the `--{compression}` option to `tar`. (This option is non-standard and might
not work for anything other than GNU tar.)

Known options for `compression`: "bzip2", "xz", "lzip", "lzma", "lzop", "gzip".

Note that using `compression` does not add an extension to `filename`, so the
caller is responsible for making sure that `compression` and `filename` match.

By default POSIX ACLs, SELinux contexts and extended attributes are included,
in order to preserve the tree as closely as possible. It is possible to opt
out of any of those by supplying the corresponding option.

Buildhost commands used: `tar` and any named `compression` program.
"""


import subprocess
import sys

import osbuild.api


SCHEMA = """
"additionalProperties": false,
"required": ["filename"],
"properties": {
  "filename": {
    "description": "Filename for tar archive",
    "type": "string"
  },
  "compression": {
    "description": "Name of compression program",
    "type": "string",
    "enum": ["bzip2", "xz", "lzip", "lzma", "lzop", "gzip"]
  },
  "acls": {
      "description": "Enable support for POSIX ACLs",
      "type": "boolean",
      "default": true
  },
  "selinux": {
      "description": "Enable support for SELinux contexts",
      "type": "boolean",
      "default": true
  },
  "xattrs": {
      "description": "Enable support for extended attributes",
      "type": "boolean",
      "default": true
  }
}
"""


def main(tree, output_dir, options):
    filename = options["filename"]
    compression = options.get("compression")

    extra_args = []
    if compression is not None:
        if compression not in {"bzip2", "xz", "lzip", "lzma", "lzop", "gzip"}:
            return 1
        extra_args.append(f"--{compression}")

    # Set environment variables for the tar operation.
    tar_env = {
        # Speed up xz by allowing it to use all CPU cores for compression.
        "XZ_OPT": "--threads 0"
    }

    # SELinux context, ACLs and extended attributes
    if options.get("acls", True):
        extra_args += ["--acls"]

    if options.get("selinux", True):
        extra_args += ["--selinux"]

    if options.get("xattrs", True):
        extra_args += ["--xattrs", "--xattrs-include", "*"]

    # Set up the tar command.
    tar_cmd = [
        "tar",
        *extra_args,
        "-cf", f"{output_dir}/{filename}",
        "-C", tree,
        "."
    ]

    # Make a tarball of the tree.
    subprocess.run(
        tar_cmd,
        stdout=subprocess.DEVNULL,
        check=True,
        env=tar_env
    )

    return 0


if __name__ == '__main__':
    args = osbuild.api.arguments()
    args_input = args["inputs"]["tree"]["path"]
    args_output = args["tree"]
    r = main(args_input, args_output, args["options"])
    sys.exit(r)