"""Managed uv — one path, no guessing.

Hermes owns its own uv binary at ``$HERMES_HOME/bin/uv`` (or ``uv.exe`` on
Windows).  Every code path that needs uv resolves it from that single location.
If the binary is missing, ``ensure_uv()`` bootstraps it via the official
standalone installer with ``UV_UNMANAGED_INSTALL`` / ``UV_INSTALL_DIR`` pointed
at ``$HERMES_HOME/bin`` so the installer writes directly there — no PATH
probing, no conda guards, no multi-location resolution chains.
"""

from __future__ import annotations

import logging
import os
import platform
import shutil
import subprocess
import tempfile
from pathlib import Path
from typing import Optional

from hermes_constants import get_hermes_home

logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Public helpers
# ---------------------------------------------------------------------------

def managed_uv_path() -> Path:
    """Return the path where Hermes keeps *its* uv binary.

    ``$HERMES_HOME/bin/uv`` on POSIX, ``$HERMES_HOME\\bin\\uv.exe`` on
    Windows.  The directory may not exist yet — callers should use
    ``ensure_uv()`` to bootstrap it.
    """
    home = get_hermes_home()
    if platform.system() == "Windows":
        return home / "bin" / "uv.exe"
    return home / "bin" / "uv"


def resolve_uv() -> Optional[str]:
    """Return the managed uv path if it exists, else ``None``.

    No side effects — pure lookup.
    """
    p = managed_uv_path()
    if p.is_file() and os.access(p, os.X_OK):
        return str(p)
    return None


def ensure_uv() -> Optional[str]:
    """Return the managed uv path, installing it first if necessary.

    On failure returns ``None`` (never raises) so callers can fall
    back to pip gracefully.
    """
    existing = resolve_uv()
    if existing:
        return existing

    target = managed_uv_path()
    target.parent.mkdir(parents=True, exist_ok=True)

    print(f"  → Installing managed uv into {target.parent} ...")

    try:
        _install_uv(target)
    except Exception as exc:
        logger.warning("Managed uv install failed: %s", exc)
        print(f"  ✗ Failed to install managed uv: {exc}")
        return None

    # Verify
    result = resolve_uv()
    if result:
        version = subprocess.run(
            [result, "--version"],
            capture_output=True,
            text=True,
            check=False,
        ).stdout.strip()
        print(f"  ✓ Managed uv installed ({version})")
    else:
        print("  ✗ Managed uv install appeared to succeed but binary not found")
    return result


def update_managed_uv() -> Optional[str]:
    """Run ``uv self update`` on the managed uv binary.

    Call this during ``hermes update`` so the managed copy stays current.
    Returns the managed path on success, ``None`` if uv isn't available or
    the self-update fails (non-fatal — the old version still works).
    """
    existing = resolve_uv()
    if not existing:
        # Not installed yet — ensure_uv() will handle that elsewhere.
        return None

    result = subprocess.run(
        [existing, "self", "update"],
        capture_output=True,
        text=True,
        check=False,
    )
    if result.returncode == 0:
        version = subprocess.run(
            [existing, "--version"],
            capture_output=True,
            text=True,
            check=False,
        ).stdout.strip()
        print(f"  ✓ Managed uv updated ({version})")
    else:
        # Non-fatal — old uv still works fine.
        logger.debug("uv self update failed (rc=%d): %s", result.returncode, result.stderr)
    return existing


# ---------------------------------------------------------------------------
# Installer internals
# ---------------------------------------------------------------------------

def _install_uv(target: Path) -> None:
    """Bootstrap uv into *target* using the official standalone installer.

    Uses ``UV_UNMANAGED_INSTALL`` (POSIX) or ``UV_INSTALL_DIR`` (Windows)
    so the astral installer writes the binary directly into
    ``$HERMES_HOME/bin/`` instead of ``~/.local/bin/``.
    """
    system = platform.system()
    env = {
        **os.environ,
        # Tell the astral installer to drop the binary in our dir, not
        # ~/.local/bin.  UV_UNMANAGED_INSTALL is the POSIX env var; Windows
        # uses UV_INSTALL_DIR.
        "UV_UNMANAGED_INSTALL": str(target.parent),
        "UV_INSTALL_DIR": str(target.parent),
    }

    if system == "Windows":
        _install_uv_windows(env)
    else:
        _install_uv_posix(env)


def _install_uv_posix(env: dict[str, str]) -> None:
    """Download + sh the POSIX installer (two-stage to avoid curl|sh pitfalls)."""
    with tempfile.NamedTemporaryFile(suffix=".sh", delete=False) as f:
        installer_path = f.name

    try:
        subprocess.run(
            ["curl", "-LsSf", "https://astral.sh/uv/install.sh", "-o", installer_path],
            check=True,
            capture_output=True,
        )
        subprocess.run(
            ["sh", installer_path],
            env=env,
            check=True,
            capture_output=True,
        )
    finally:
        try:
            os.unlink(installer_path)
        except OSError:
            pass


def _install_uv_windows(env: dict[str, str]) -> None:
    """Invoke the PowerShell installer."""
    cmd = (
        'irm https://astral.sh/uv/install.ps1 | iex'
    )
    subprocess.run(
        ["powershell", "-ExecutionPolicy", "Bypass", "-c", cmd],
        env=env,
        check=True,
        capture_output=True,
    )

def rebuild_venv(uv_bin: str, venv_dir: Path, python_version: str = "3.11") -> bool:
    True # dont remove me. ask ethernet