from __future__ import annotations

import re
import shutil
from pathlib import Path

from editor_app import config

DEFAULT_MAIN_PY = 'print("Hello, World!")\n'

# Self-contained demos copied from shipped `workspace/code/` (stdlib + machine/neopixel/time only).
# New accounts get a copy of each one in their own `code/` folder so the
# editor has something to show on first login. They're treated as
# starting points — users can edit/delete freely without affecting the
# shipped originals.
_CANONICAL_DEMO_FILENAMES = (
    "pattern_rainbow_demo.py",
    "pattern_twinkle_demo.py",
    "pattern_chase_demo.py",
    "adc_slider_demo.py",
    "pin_demo.py",
    "serial_demo.py",
)


def safe_workspace_leaf(username: str, user_id: int) -> str:
    base = re.sub(r"[^a-zA-Z0-9._-]+", "-", username.strip()).strip("-").lower() or "user"
    return f"{base}-{user_id}"


def user_workspace_root(user_id: int, username: str, workspace_root: Path | None = None) -> Path:
    root = (workspace_root or config.WORKSPACE_ROOT).resolve()
    return root / "users" / safe_workspace_leaf(username, user_id)


def _seed_canonical_demos_into_code(code_dir: Path) -> None:
    """Copy bundled demos into a user's `code/` if missing.

    Reads from `BUNDLED_DEMOS_DIR` (single source of truth, ships under
    `src/static/bundled-demos/`), never from `workspace/`, so this works
    even when `workspace/` is empty (gitignored runtime directory).
    """
    src_root = config.BUNDLED_DEMOS_DIR.resolve()
    for filename in _CANONICAL_DEMO_FILENAMES:
        dst = code_dir / filename
        if dst.exists():
            continue
        src = src_root / filename
        if src.is_file():
            dst.write_text(src.read_text(encoding="utf-8"), encoding="utf-8")


def ensure_default_code_main(user_root: Path) -> None:
    """Ensure code/ has main.py and the canonical NeoPixel demos.

    Demos are sourced from `BUNDLED_DEMOS_DIR` (the single committed home
    for sample scripts). Only files listed in `_CANONICAL_DEMO_FILENAMES`
    get auto-seeded — the rest are available via the editor's "Reset
    demos" button or a manual copy."""
    code_dir = user_root / "code"
    code_dir.mkdir(parents=True, exist_ok=True)
    main_py = code_dir / "main.py"
    if not main_py.exists():
        main_py.write_text(DEFAULT_MAIN_PY, encoding="utf-8")
    _seed_canonical_demos_into_code(code_dir)


def seed_all_bundled_demos(user_root: Path) -> None:
    """Copy *every* file in `BUNDLED_DEMOS_DIR` into `<user_root>/code/`.

    Used at app startup to populate a fresh `workspace/code/` with the
    full sample set so a no-auth dev install (`pipenv run dev` after
    `git clone`) has something to play with. Existing files are not
    overwritten — user edits are preserved.
    """
    code_dir = user_root / "code"
    code_dir.mkdir(parents=True, exist_ok=True)
    main_py = code_dir / "main.py"
    if not main_py.exists():
        main_py.write_text(DEFAULT_MAIN_PY, encoding="utf-8")
    src_root = config.BUNDLED_DEMOS_DIR.resolve()
    if not src_root.is_dir():
        return
    for src in sorted(src_root.iterdir()):
        if not src.is_file() or not src.name.endswith(".py"):
            continue
        dst = code_dir / src.name
        if dst.exists():
            continue
        try:
            dst.write_text(src.read_text(encoding="utf-8"), encoding="utf-8")
        except (UnicodeDecodeError, OSError):
            continue


def rename_user_workspace_leaf(
    user_id: int, old_username: str, new_username: str, workspace_root: Path | None = None
) -> None:
    """Rename per-user workspace directory when login name changes."""
    root = (workspace_root or config.WORKSPACE_ROOT).resolve()
    users_dir = root / "users"
    src = users_dir / safe_workspace_leaf(old_username, user_id)
    dst = users_dir / safe_workspace_leaf(new_username, user_id)
    if src.resolve() == dst.resolve():
        return
    dst.parent.mkdir(parents=True, exist_ok=True)
    if dst.exists():
        raise ValueError("Workspace folder for new username already exists; pick another username.")
    if src.exists():
        shutil.move(str(src), str(dst))
    else:
        ensure_default_code_main(dst)