import os
import subprocess
import tempfile
import hashlib
import logging
from datetime import datetime
from typing import Tuple

log = logging.getLogger(__name__)


# ----------------------------
# utility: run command
# ----------------------------
def run(cmd: str, cwd: str = "/") -> Tuple[str, int]:
    """Run ``cmd`` (a shell string) and return (stdout+stderr, returncode).

    Note: shell=True is intentional here — snapshot commands are
    operator-authored config strings (git clone, hg clone, svn checkout),
    NOT user input. The operator controls what gets run.
    """
    process = subprocess.Popen(
        cmd,
        shell=True,
        cwd=cwd,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        text=True
    )

    out = []
    for line in process.stdout:
        out.append(line)

    process.wait()
    return "".join(out), process.returncode


# ----------------------------
# git (Forgejo primary)
# ----------------------------
def snapshot_git(repo_url):
    workdir = tempfile.mkdtemp(prefix="fester-snap-git-")

    run(f"git clone --depth 1 {repo_url} {workdir}")

    return workdir


# ----------------------------
# hg adapter (snapshot only)
# ----------------------------
def snapshot_hg(repo_url):
    workdir = tempfile.mkdtemp(prefix="fester-snap-hg-")

    run(f"hg clone {repo_url} {workdir}")

    return workdir


# ----------------------------
# svn adapter (export only)
# ----------------------------
def snapshot_svn(repo_url):
    workdir = tempfile.mkdtemp(prefix="fester-snap-svn-")

    run(f"svn checkout {repo_url} {workdir}")

    return workdir


# ----------------------------
# cvs adapter (legacy dump)
# ----------------------------
def snapshot_cvs(repo_url):
    workdir = tempfile.mkdtemp(prefix="fester-snap-cvs-")

    # best-effort export only
    run(f"cvs export -d {workdir} {repo_url}")

    return workdir


# ----------------------------
# unified entry point
# ----------------------------
def create_snapshot(source):
    kind = source["type"]
    url = source["url"]

    if kind == "git":
        path = snapshot_git(url)
    elif kind == "hg":
        path = snapshot_hg(url)
    elif kind == "svn":
        path = snapshot_svn(url)
    elif kind == "cvs":
        path = snapshot_cvs(url)
    else:
        raise Exception(f"Unsupported VCS type: {kind}")

    return fingerprint(path)


# ----------------------------
# deterministic fingerprint
# ----------------------------
def fingerprint(path: str) -> dict:
    sha = hashlib.sha256()

    for root, dirs, files in os.walk(path):
        for f in sorted(files):
            fp = os.path.join(root, f)
            try:
                with open(fp, "rb") as fh:
                    sha.update(fh.read())
            except (OSError, PermissionError) as e:
                # Best-effort — log and skip unreadable files
                log.debug("could not read %s for fingerprint: %s", fp, e)

    return {
        "path": path,
        "hash": sha.hexdigest(),
        "timestamp": datetime.utcnow().isoformat() + "Z"
    }