#!/usr/bin/python3

import collections
import os
from pathlib import Path
import sys
import tempfile

import click
import requests
from requests.compat import urljoin
import solv

XDG_CACHE_HOME = Path(os.getenv("XDG_CACHE_HOME", os.path.expanduser("~/.cache")))
CACHEDIR = XDG_CACHE_HOME / "rust2rpm"

# Arch that is used for resolving dependencies and such
ARCH = "x86_64"
# The repo that contains crates
REPO_URL = f"https://kojipkgs.fedoraproject.org/repos/f33-build/latest/{ARCH}/"
# Just some sane chunk size
CHUNK_SIZE = 8192


def _download(fname, chksum=None, uncompress=False):
    url = urljoin(REPO_URL, fname)
    with requests.get(urljoin(REPO_URL, fname), stream=True) as r:
        tmp = tempfile.TemporaryFile()
        total = int(r.headers["Content-Length"])
        with click.progressbar(
            length=total, label=f"Downloading {url}", file=sys.stderr
        ) as pb:
            for chunk in r.iter_content(chunk_size=CHUNK_SIZE):
                pb.update(tmp.write(chunk))
    tmp.seek(0)

    if chksum is not None:
        fchksum = solv.Chksum(chksum.type)
        fchksum.add_fd(tmp.fileno())
        if chksum != fchksum:
            raise Exception(f"Checksums do not match: {fchksum} != {chksum}")

    return solv.xfopen_fd(os.path.basename(url) if uncompress else None, tmp.fileno())


@click.group()
def cli():
    pass


@cli.command()
@click.pass_context
@click.argument("source", type=click.Path(exists=True))
@click.option(
    "-a",
    "--add",
    multiple=True,
    type=click.Path(exists=True),
    help="Add local RPMs to the pool that is used in dependency resolution.",
)
@click.option(
    "-v", "--verbose", is_flag=True, help="Enable verbose mode.",
)
def get_binary_license(ctx, source, add, verbose):
    """Get the resulting license of a binary.

    Since all crates (aka `rust-*-devel`) are linked statically, the resulting
    binary license should be result of combining source license and all used
    crates.

    Combined with dynamic BuildRequires generation, the usage would look like:

        \b
        rpmbuild -br *.spec -D "_sourcedir $PWD" --without check
        fedora-helper.py get-binary-license /path/to/buildreqs.nosrc.rpm

    This command resolves dependencies and outputs final license(s).
    """
    pool = solv.Pool()
    pool.setarch(ARCH)

    repo = pool.add_repo("upstream")
    fd = _download("repodata/repomd.xml")
    chksum = solv.Chksum(solv.REPOKEY_TYPE_SHA256)
    chksum.add("1.1")
    chksum.add_fd(fd.fileno())
    cookie = chksum.raw()
    repo.add_repomdxml(fd)
    fd.close()

    # Find "primary"
    di = repo.Dataiterator_meta(
        solv.REPOSITORY_REPOMD_TYPE, "primary", solv.Dataiterator.SEARCH_STRING
    )
    di.prepend_keyname(solv.REPOSITORY_REPOMD)
    for d in di:
        dp = d.parentpos()
        filename = dp.lookup_str(solv.REPOSITORY_REPOMD_LOCATION)
        checksum = dp.lookup_checksum(solv.REPOSITORY_REPOMD_CHECKSUM)
        # FIXME: Can filename be None?

    cache_file = CACHEDIR / "upstream.solv"
    try:
        with open(cache_file, "rb") as f:
            clen = len(cookie)
            f.seek(-clen, os.SEEK_END)
            fcookie = f.read(clen)
            if fcookie != cookie:
                raise IOError("repomd.xml has changed")
            f.seek(0)
            fd = solv.xfopen_fd(None, f.fileno())
            repo.add_solv(fd)
            fd.close()
        cached = True
    except IOError:
        # Failed to load from cache
        cached = False

    if not cached:
        fd = _download(filename, chksum=checksum, uncompress=True)
        repo.add_rpmmd(fd, None)
        fd.close()

        os.makedirs(CACHEDIR, exist_ok=True)
        with tempfile.NamedTemporaryFile(prefix=".newsolv-", dir=CACHEDIR) as tmp:
            fd = solv.xfopen_fd(None, tmp.fileno())
            repo.write(fd)
            fd.flush()
            fd.write(cookie)
            fd.close()
            if repo.iscontiguous():
                repo.empty()
                repo.add_solv(tmp.name)
            try:
                os.unlink(cache_file)
            except FileNotFoundError:
                pass
            os.link(tmp.name, cache_file)

    repo_local = pool.add_repo("local")
    repo_local.priority = 99
    s = repo_local.add_rpm(source)
    for f in add:
        repo_local.add_rpm(f)

    pool.addfileprovides()
    pool.createwhatprovides()

    solver = pool.Solver()
    solver.set_flag(solv.Solver.SOLVER_FLAG_IGNORE_RECOMMENDED, True)
    problems = solver.solve(
        [pool.Job(solv.Job.SOLVER_SOLVABLE | solv.Job.SOLVER_INSTALL, s.id)]
    )
    if problems:
        click.echo("Failed to resolve dependencies:", err=True)
        for problem in problems:
            for rule in problem.findallproblemrules():
                for info in rule.allinfos():
                    click.echo(f"  - ", nl=False)
                    click.secho(info.problemstr(), fg="red")
        ctx.abort()

    licenses = collections.defaultdict(set)
    for p in solver.transaction().newsolvables():
        if (
            not (p.name.startswith("rust-") and p.name.endswith("-devel"))
            and not p == s
        ):
            continue
        licenses[p.lookup_str(solv.SOLVABLE_LICENSE)].add(p)
    # XXX: This is pure hack and we should optimize license set in much better way
    if "MIT or ASL 2.0" in licenses and "ASL 2.0 or MIT" in licenses:
        licenses["MIT or ASL 2.0"].update(licenses.pop("ASL 2.0 or MIT"))

    for license, packages in sorted(licenses.items()):
        click.echo(f"# {license}")
        if verbose:
            for package in packages:
                click.secho(f"#   * {package}", fg="white")


if __name__ == "__main__":
    cli()