"""Paths: project root, local .gpu-rent runtime, SSH key."""

from __future__ import annotations

import os
import shutil
from pathlib import Path


def detect_app_root() -> Path:
    override = (os.environ.get("GPU_RENT_ROOT") or "").strip()
    if override:
        return Path(override).expanduser().resolve()
    cwd = Path.cwd().resolve()
    for candidate in (cwd, *cwd.parents):
        if (candidate / "Models").is_dir() and (candidate / "docs").is_dir():
            return candidate
    return cwd


def app_root() -> Path:
    return detect_app_root()


def runtime_dir() -> Path:
    """State, lock, SSH key — always inside the project (gitignored)."""
    return app_root() / ".gpu-rent"


def local_lease_path() -> Path:
    return runtime_dir() / "local-lease.json"


def local_watchdog_marker_path() -> Path:
    return runtime_dir() / "local-watchdog.json"


# Back-compat alias used across the package.
def home_dir() -> Path:
    return runtime_dir()


def env_path() -> Path:
    return app_root() / ".env"


def models_manifest_path() -> Path:
    return app_root() / "models.yaml"


def ollama_models_manifest_path() -> Path:
    return app_root() / "ollama-models.yaml"


def ollama_models_example_path() -> Path:
    return app_root() / "ollama-models.example.yaml"


def extensions_manifest_path() -> Path:
    return app_root() / "extensions.yaml"


def vars_path() -> Path:
    return app_root() / "gpu-rent.vars"


def vars_example_path() -> Path:
    return app_root() / "gpu-rent.vars.example"


def state_path() -> Path:
    return runtime_dir() / "state.json"


def lock_path() -> Path:
    return runtime_dir() / "gpu-rent.lock"


def default_ssh_key_path() -> Path:
    return runtime_dir() / "id_ed25519"


def legacy_user_dir() -> Path:
    """Old location (~/.gpu-rent) — only for one-shot migrate."""
    return Path.home() / ".gpu-rent"


def migrate_legacy_if_needed() -> list[str]:
    """Copy ~/.gpu-rent leftovers into the project once. Returns log lines."""
    legacy = legacy_user_dir()
    if not legacy.is_dir():
        return []
    root = app_root()
    runtime = runtime_dir()
    notes: list[str] = []

    pairs = (
        (legacy / ".env", env_path()),
        (legacy / "models.yaml", models_manifest_path()),
        (legacy / "extensions.yaml", extensions_manifest_path()),
        (legacy / "state.json", state_path()),
        (legacy / "id_ed25519", default_ssh_key_path()),
        (legacy / "id_ed25519.pub", default_ssh_key_path().with_suffix(".pub")),
    )
    for src, dst in pairs:
        if not src.is_file() or dst.is_file():
            continue
        dst.parent.mkdir(parents=True, exist_ok=True)
        shutil.copy2(src, dst)
        notes.append(f"перенёс {src} → {dst}")
    if notes:
        runtime.mkdir(parents=True, exist_ok=True)
        marker = runtime / ".migrated-from-user-home"
        if not marker.is_file():
            marker.write_text(
                f"from {legacy}\n" + "\n".join(notes) + "\n",
                encoding="utf-8",
            )
    return notes