Add initial script to update the database

Author: pganssle

tox.ini

@@ -0,0 +1,23 @@
+[tox]
+minversion = 3.3.0
+isolated_build = True
+skip_missing_interpreters = true
+
+[testenv:update]
+description = Update the tzdata contents
+skip_install = True
+deps =
+    requests
+    click
+commands =
+    python update.py {posargs}
+
+[testenv:build]
+description = Build a wheel and source distribution
+skip_install = True
+deps =
+    pep517
+    twine
+commands =
+    python -m pep517.build -s -b {toxinidir} -o {envtmpdir}/dist
+    twine check {envtmpdir}/dist/*

update.py

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+import logging
+import os
+import pathlib
+import shutil
+import subprocess
+import tempfile
+import typing
+
+import click
+import requests
+
+SOURCE = "https://data.iana.org/time-zones/releases"
+WORKING_DIR = pathlib.Path("tmp")
+REPO_ROOT = pathlib.Path(__file__).parent
+PKG_BASE = REPO_ROOT / "src"
+TEMPLATES_DIR = REPO_ROOT / "templates"
+
+
+def download_tzdb_tarballs(
+    version: str, base_url: str = SOURCE, working_dir: pathlib.Path = WORKING_DIR
+) -> typing.List[pathlib.Path]:
+    """Download the tzdata and tzcode tarballs."""
+    tzdata_file = f"tzdata{version}.tar.gz"
+    tzcode_file = f"tzcode{version}.tar.gz"
+
+    target_dir = working_dir / version / "download"
+    # mkdir -p target_dir
+    target_dir.mkdir(parents=True, exist_ok=True)
+
+    download_locations = []
+    for filename in [tzdata_file, tzcode_file]:
+        download_location = target_dir / filename
+        download_locations.append(download_location)
+
+        if download_location.exists():
+            logging.info("File %s already exists, skipping", download_location)
+            continue
+
+        url = f"{base_url}/{filename}"
+        logging.info("Downloading %s from %s", filename, url)
+
+        r = requests.get(url)
+        with open(download_location, "wb") as f:
+            f.write(r.content)
+
+    return download_locations
+
+
+def unpack_tzdb_tarballs(download_locations: typing.List[pathlib.Path]) -> pathlib.Path:
+    assert len(download_locations) == 2
+    assert download_locations[0].parent == download_locations[1].parent
+    base_dir = download_locations[0].parent.parent
+    target_dir = base_dir / "tzdb"
+
+    # Remove the directory and re-create it if it does not exist
+    if target_dir.exists():
+        shutil.rmtree(target_dir)
+
+    target_dir.mkdir()
+
+    for tarball in download_locations:
+        logging.info("Unpacking %s to %s", tarball, target_dir)
+        subprocess.run(
+            ["tar", "-xf", os.fspath(tarball.absolute())], cwd=target_dir, check=True,
+        )
+
+    return target_dir
+
+
+def load_zonefiles(base_dir: pathlib.Path) -> pathlib.Path:
+    target_dir = base_dir.parent / "zoneinfo"
+    if target_dir.exists():
+        shutil.rmtree(target_dir)
+
+    with tempfile.TemporaryDirectory() as td:
+        td_path = pathlib.Path(td)
+
+        # First run the makefile, which does all kinds of other random stuff
+        subprocess.run(
+            ["make", f"DESTDIR={td}", "ZFLAGS=-b slim", "install"], cwd=base_dir
+        )
+
+        # Move the zoneinfo files into the target directory
+        src_dir = td_path / "usr" / "share" / "zoneinfo"
+        shutil.move(os.fspath(src_dir), os.fspath(target_dir))
+
+    return target_dir
+
+
+def create_package(version: str, zoneinfo_dir: pathlib.Path):
+    """Creates the tzdata package"""
+    # First remove the existing package contents
+    target_dir = PKG_BASE / "tzdata"
+    if target_dir.exists():
+        shutil.rmtree(target_dir)
+
+    # Next move the zoneinfo file to the target location
+    shutil.move(os.fspath(zoneinfo_dir), target_dir)
+
+    # Generate the base __init__.py from a template
+    with open(TEMPLATES_DIR / "__init__.py.in", "r") as f_in:
+        contents = f_in.read()
+        contents = contents.replace("%%IANA_VERSION%%", version)
+
+        with open(target_dir / "__init__.py", "w") as f_out:
+            f_out.write(contents)
+
+    # Now recursively create __init__.py files in every directory we need to
+    for dirpath, _, filenames in os.walk(target_dir):
+        if "__init__.py" not in filenames:
+            init_file = pathlib.Path(dirpath) / "__init__.py"
+            init_file.touch()
+
+
+@click.command()
+@click.option(
+    "--version", "-v", default=None, help="The version of the tzdata file to download"
+)
+def main(version: str):
+    logging.basicConfig(level=logging.INFO)
+
+    download_locations = download_tzdb_tarballs(version)
+    tzdb_location = unpack_tzdb_tarballs(download_locations)
+
+    zonefile_path = load_zonefiles(tzdb_location)
+
+    create_package(version, zonefile_path)
+
+
+if __name__ == "__main__":
+    main()