"""Поиск и выбор Java."""

import json
import os
import re
import shutil
import struct
import subprocess
import sys

CREATE_NO_WINDOW = 0x08000000 if os.name == "nt" else 0


def is64():
    return struct.calcsize("P") * 8 == 64


def _exe(name="java"):
    return name + (".exe" if os.name == "nt" else "")


def java_major(path):
    """Версия Java в виде числа (8, 11, 17, 21...), 0 если не определилась."""
    try:
        p = subprocess.run(
            [path, "-version"],
            capture_output=True, text=True, timeout=20,
            creationflags=CREATE_NO_WINDOW,
        )
        text = (p.stderr or "") + (p.stdout or "")
    except Exception:
        return 0
    m = re.search(r'version\s+"(\d+)(?:\.(\d+))?(?:_(\d+))?', text)
    if not m:
        return 0
    major = int(m.group(1))
    if major == 1:  # старый формат 1.8.0_382
        return int(m.group(2) or 0)
    return major


def _add(cands, home):
    if not home:
        return
    exe = os.path.join(home, "bin", _exe())
    if os.path.isfile(exe) and exe not in cands:
        cands.append(exe)


def find_javas():
    cands = []

    # Переменные окружения
    _add(cands, os.environ.get("JAVA_HOME"))
    for k, v in os.environ.items():
        if k.upper().startswith("JAVA_HOME") and v:
            _add(cands, v)

    # PATH
    w = shutil.which(_exe())
    if w:
        cands.append(w)

    if os.name == "nt":
        pf = [
            r"C:\Program Files\Java",
            r"C:\Program Files (x86)\Java",
            r"C:\Program Files\Eclipse Adoptium",
            r"C:\Program Files\AdoptOpenJDK",
            r"C:\Program Files\Microsoft",
            r"C:\Program Files\Amazon Corretto",
            r"C:\Program Files\Zulu",
            r"C:\Program Files\BellSoft",
            r"C:\Program Files\GraalVM",
            r"C:\Program Files\JetBrains",
        ]
        home_jdks = os.path.join(os.path.expanduser("~"), ".jdks")
        pf.append(home_jdks)
        for root in pf:
            if not os.path.isdir(root):
                continue
            try:
                for name in os.listdir(root):
                    _add(cands, os.path.join(root, name))
            except OSError:
                pass
    elif sys.platform == "darwin":
        for root in ("/Library/Java/JavaVirtualMachines",
                     os.path.expanduser("~/Library/Java/JavaVirtualMachines")):
            if not os.path.isdir(root):
                continue
            try:
                for name in os.listdir(root):
                    _add(cands, os.path.join(root, name, "Contents", "Home"))
            except OSError:
                pass
    else:
        jvm_dir = "/usr/lib/jvm"
        if os.path.isdir(jvm_dir):
            try:
                for name in os.listdir(jvm_dir):
                    _add(cands, os.path.join(jvm_dir, name))
            except OSError:
                pass

    return cands


def pick_java(required=8, preferred="", cache_path=""):
    """Выбирает Java: (путь, major, подходит_ли).

    Из подходящих (major >= required) берётся самая старая — максимальная
    совместимость со старыми версиями Minecraft.

    cache_path — файл кэша с результатами определения версии. Пока файл
    java.exe не менялся, `java -version` повторно не запускается.
    """
    if preferred and os.path.isfile(preferred):
        major = java_major(preferred)
        return preferred, major, (major == 0 or major >= required)

    cache = {}
    if cache_path:
        try:
            with open(cache_path, encoding="utf-8") as f:
                cache = json.load(f)
            if not isinstance(cache, dict):
                cache = {}
        except Exception:  # noqa: BLE001
            cache = {}

    changed = False
    cands = find_javas()
    scored = []
    for exe in cands:
        try:
            mtime = int(os.path.getmtime(exe))
        except OSError:
            continue
        ent = cache.get(exe)
        if isinstance(ent, list) and len(ent) == 2 and ent[1] == mtime:
            major = int(ent[0])  # кэш валиден: файл не менялся
        else:
            major = java_major(exe)
            cache[exe] = [major, mtime]
            changed = True
        if major > 0:
            scored.append((exe, major))

    # выбывшие установки — убрать из кэша
    alive = set(cands)
    for exe in [e for e in cache if e not in alive]:
        del cache[exe]
        changed = True

    if cache_path and changed:
        try:
            os.makedirs(os.path.dirname(cache_path), exist_ok=True)
            with open(cache_path, "w", encoding="utf-8") as f:
                json.dump(cache, f)
        except OSError:
            pass

    if not scored:
        return "", 0, False

    suitable = [s for s in scored if s[1] >= required]
    if suitable:
        suitable.sort(key=lambda s: s[1])
        exe, major = suitable[0]
        return exe, major, True
    # Ничего подходящего — берём самую новую и предупредим
    scored.sort(key=lambda s: s[1])
    exe, major = scored[-1]
    return exe, major, False