"""Canonical project paths (repo root, data files, config)."""

from __future__ import annotations

from pathlib import Path

PROJECT_ROOT = Path(__file__).resolve().parent.parent
DATA_DIR = PROJECT_ROOT / "data"
VOCAB_PATH = DATA_DIR / "vocab.txt"
VOCAB_BASE_PATH = DATA_DIR / "vocab_base.txt"
SKILLS_DIR = DATA_DIR / "skills"
HELP_DIR = DATA_DIR / "help"
# Runtime translation system skill (formerly data/prompt.txt).
PROMPT_PATH = SKILLS_DIR / "system.md"
LEGACY_PROMPT_PATH = DATA_DIR / "prompt.txt"
LAST_UPDATE_SHA_PATH = DATA_DIR / "last_update_sha.txt"
ENV_PATH = PROJECT_ROOT / ".env"
ICON_PATH = PROJECT_ROOT / "assets" / "icon.png"
ENGINE_ICONS_DIR = PROJECT_ROOT / "assets" / "engine_icons"
TRANSLATION_CONTEXTS_PATH = DATA_DIR / "translation_contexts.json"
# Per-game quirks skill (API overlay). Legacy flat file still migrated on load.
GAME_QUIRKS_RELATIVE = Path("skills") / "quirks.md"
LEGACY_QUIRKS_FILENAME = "translation_quirks.txt"
GAME_SKILL_RELATIVE = Path("skills") / "game.md"
LEGACY_GAME_SKILL_RELATIVE = Path("skills") / "translation.md"
# Built-in skill filenames under <game>/skills/ (not user-custom overlays).
GAME_SKILL_RESERVED_NAMES = frozenset({"quirks.md", "game.md", "translation.md"})

_ROOT_DATA_FILES = (
    "vocab.txt",
    "vocab_base.txt",
    "prompt.txt",
    "last_update_sha.txt",
)


def migrate_root_data_files() -> None:
    """Move legacy root-level data files into data/ on first run."""
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    for name in _ROOT_DATA_FILES:
        src = PROJECT_ROOT / name
        dst = DATA_DIR / name
        if src.is_file() and not dst.exists():
            src.rename(dst)


def migrate_prompt_to_skills() -> None:
    """Move legacy ``data/prompt.txt`` to ``data/skills/system.md`` when needed."""
    SKILLS_DIR.mkdir(parents=True, exist_ok=True)
    if PROMPT_PATH.is_file():
        return
    for legacy in (LEGACY_PROMPT_PATH, PROJECT_ROOT / "prompt.txt"):
        if legacy.is_file():
            legacy.rename(PROMPT_PATH)
            return


migrate_root_data_files()
migrate_prompt_to_skills()


def ensure_vocab_file() -> None:
    """Create data/vocab.txt from vocab_base.txt when missing."""
    migrate_root_data_files()
    if VOCAB_PATH.is_file():
        return
    if VOCAB_BASE_PATH.is_file():
        VOCAB_PATH.write_text(VOCAB_BASE_PATH.read_text(encoding="utf-8"), encoding="utf-8")
    else:
        VOCAB_PATH.write_text("", encoding="utf-8")