hspkgnotify

#!/usr/bin/env python3
import argparse, re, sqlite3, sys
import requests

def hackage_get_pkg_version(name):
    r = requests.get("https://hackage.haskell.org/package/{name}".format(**locals()))
    r.raise_for_status()
    m = re.search(
        "/package/{name}-(?P<version>[0-9.]+)/{name}-(?P=version)\.tar\.gz"
        .format(**locals()), r.text)
    if not m:
        raise ValueError("could not find version in HTML")
    version, = m.groups()
    return version

def pkg_notify(pkg_names, data_fn):
    db = sqlite3.connect(data_fn)
    try:
        with db:
            db.executescript("""
            CREATE TABLE IF NOT EXISTS "versions"
                ("name" TEXT UNIQUE, "version" TEXT)
            """)
        for name in pkg_names:
            version = hackage_get_pkg_version(name)
            with db:
                old_versions = tuple(db.execute("""
                SELECT "version" FROM "versions" WHERE "name" = ?
                """, [name]))
            for old_version, in old_versions:
                if version != old_version:
                    sys.stderr.write(
                        "Package '{name}' has changed: "
                        "{old_version} -> {version}\n"
                        .format(**locals()))
                    sys.stderr.flush()
            with db:
                old_versions = tuple(db.execute("""
                INSERT OR REPLACE INTO "versions"
                    ("name", "version") VALUES (?, ?)
                """, [name, version]))
    finally:
        db.close()

def main():
    p = argparse.ArgumentParser()
    p.add_argument("-d", "--data-fn", required=True)
    p.add_argument("pkg_names", metavar="pkg-name", nargs="*")
    pkg_notify(**vars(p.parse_args()))
    return 0

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