"""Cortex configuration — all paths and settings resolved here.

Priority: CLI args > environment variables > config file > defaults.

Environment variables:
    CORTEX_HOME         Base directory (default: ~/.cortex)
    CORTEX_MEMORY_DIR   Memory files directory
    CORTEX_CONFIG       Path to config.json
    CORTEX_GROWTH_LOG   Path to growth log file
    CORTEX_ROADMAP      Path to roadmap.json
"""

import json
import os
from pathlib import Path
from typing import Any, Optional


def _env(key: str, default: str | None = None) -> str | None:
    return os.environ.get(key, default)


def cortex_home() -> Path:
    """Base directory for cortex data."""
    return Path(_env("CORTEX_HOME", str(Path.home() / ".cortex")))


def memory_dir() -> Path:
    return Path(_env("CORTEX_MEMORY_DIR", str(cortex_home() / "memory")))


def growth_log() -> Path:
    return Path(_env("CORTEX_GROWTH_LOG", str(memory_dir() / "growth-log.md")))


def roadmap_file() -> Path:
    return Path(_env("CORTEX_ROADMAP", str(memory_dir() / "roadmap.json")))


def archive_dir() -> Path:
    return memory_dir() / "archive"


def logs_dir() -> Path:
    return cortex_home() / "logs"


def config_path() -> Path:
    return Path(_env("CORTEX_CONFIG", str(cortex_home() / "config.json")))


def load_config(path: Optional[Path] = None) -> dict[str, Any]:
    """Load config.json. Returns empty dict if not found."""
    p = path or config_path()
    if p.exists():
        return json.loads(p.read_text())
    return {}


# Default permanent files — overridable via config.json "permanent_files" key
DEFAULT_PERMANENT_FILES = {
    "README.md",
}


def permanent_files(config: Optional[dict] = None) -> set[str]:
    """Files that should never be archived or deleted."""
    cfg = config or load_config()
    custom = cfg.get("permanent_files", [])
    if custom:
        return set(custom)
    return DEFAULT_PERMANENT_FILES