"""Kindred Create update checker.

Queries the Gitea releases API to determine if a newer version is
available. Designed to run in the background on startup without
blocking the UI.
"""

import json
import re
import urllib.request
from datetime import datetime, timezone

import FreeCAD

_RELEASES_URL = "https://git.kindred-systems.com/api/v1/repos/kindred/create/releases"
_PREF_PATH = "User parameter:BaseApp/Preferences/Mod/KindredCreate/Update"
_TIMEOUT = 5


def _parse_version(tag):
    """Parse a version tag like 'v0.1.3' into a comparable tuple.

    Returns None if the tag doesn't match the expected pattern.
    """
    m = re.match(r"^v?(\d+)\.(\d+)\.(\d+)$", tag)
    if not m:
        return None
    return (int(m.group(1)), int(m.group(2)), int(m.group(3)))


def check_for_update(current_version):
    """Check if a newer release is available on Gitea.

    Args:
        current_version: Version string like "0.1.3".

    Returns:
        Dict with update info if a newer version exists, None otherwise.
        Dict keys: version, tag, release_url, assets, body.
    """
    current = _parse_version(current_version)
    if current is None:
        return None

    req = urllib.request.Request(
        f"{_RELEASES_URL}?limit=10",
        headers={"Accept": "application/json"},
    )
    with urllib.request.urlopen(req, timeout=_TIMEOUT) as resp:
        releases = json.loads(resp.read())

    best = None
    best_version = current

    for release in releases:
        if release.get("draft"):
            continue
        if release.get("prerelease"):
            continue

        tag = release.get("tag_name", "")
        # Skip the rolling 'latest' tag
        if tag == "latest":
            continue

        ver = _parse_version(tag)
        if ver is None:
            continue

        if ver > best_version:
            best_version = ver
            best = release

    if best is None:
        return None

    assets = []
    for asset in best.get("assets", []):
        assets.append(
            {
                "name": asset.get("name", ""),
                "url": asset.get("browser_download_url", ""),
                "size": asset.get("size", 0),
            }
        )

    return {
        "version": ".".join(str(x) for x in best_version),
        "tag": best["tag_name"],
        "release_url": best.get("html_url", ""),
        "assets": assets,
        "body": best.get("body", ""),
    }


def _should_check(param):
    """Determine whether an update check should run now.

    Args:
        param: FreeCAD parameter group for update preferences.

    Returns:
        True if a check should be performed.
    """
    if not param.GetBool("CheckEnabled", True):
        return False

    last_check = param.GetString("LastCheckTimestamp", "")
    if not last_check:
        return True

    interval_days = param.GetInt("CheckIntervalDays", 1)
    if interval_days <= 0:
        return True

    try:
        last_dt = datetime.fromisoformat(last_check)
        now = datetime.now(timezone.utc)
        elapsed = (now - last_dt).total_seconds()
        return elapsed >= interval_days * 86400
    except (ValueError, TypeError):
        return True


def _run_update_check():
    """Entry point called from the deferred startup timer."""
    param = FreeCAD.ParamGet(_PREF_PATH)

    if not _should_check(param):
        return

    try:
        from version import VERSION
    except ImportError:
        FreeCAD.Console.PrintLog(
            "Create: update check skipped — version module not available\n"
        )
        return

    try:
        result = check_for_update(VERSION)
    except Exception as e:
        FreeCAD.Console.PrintLog(f"Create: update check failed: {e}\n")
        return

    # Record that we checked
    param.SetString(
        "LastCheckTimestamp",
        datetime.now(timezone.utc).isoformat(),
    )

    if result is None:
        FreeCAD.Console.PrintLog("Create: application is up to date\n")
        return

    skipped = param.GetString("SkippedVersion", "")
    if result["version"] == skipped:
        FreeCAD.Console.PrintLog(
            f"Create: update {result['version']} available but skipped by user\n"
        )
        return

    FreeCAD.Console.PrintMessage(
        f"Kindred Create {result['version']} is available (current: {VERSION})\n"
    )