"""Calibration session path resolution and camera folder discovery."""

from __future__ import annotations

import os
from dataclasses import dataclass
from pathlib import Path
from typing import Dict, List, Optional, Tuple

IMAGE_EXTENSIONS = (".bmp", ".png", ".jpg", ".jpeg")

# Logical camera name -> folder aliases on disk
CAMERA_FOLDER_ALIASES: Dict[str, Tuple[str, ...]] = {
    "lc": ("lc",),
    "lc-ir": ("lc-ir", "lc_ir", "LC-IR"),
    "rc": ("rc",),
    "rg": ("rg", "rgb"),
    "ir": ("ir", "IR"),
}

STEREO_PARTNERS = ("rc", "rg", "ir")


@dataclass(frozen=True)
class CameraFolder:
    logical_name: str
    path: Path
    folder_name: str


def resolve_session_root(input_path: str | Path) -> Path:
    """Return flat or nested `images/` root containing camera folders."""
    input_path = Path(input_path)
    images_dir = input_path / "images"
    if images_dir.is_dir():
        return images_dir
    return input_path


def discover_camera_folder(
    session_root: Path, logical_name: str
) -> Optional[CameraFolder]:
    aliases = CAMERA_FOLDER_ALIASES.get(logical_name)
    if not aliases:
        return None
    for folder in aliases:
        path = session_root / folder
        if path.is_dir():
            return CameraFolder(logical_name, path, folder)
    return None


def list_image_paths(camera_dir: Path) -> List[Path]:
    paths = [
        camera_dir / name
        for name in os.listdir(camera_dir)
        if name.lower().endswith(IMAGE_EXTENSIONS)
    ]
    return sorted(paths)


def json_path_for_image(image_path: Path) -> Path:
    return image_path.with_suffix(".json")


def list_cameras_present(session_root: Path) -> List[CameraFolder]:
    found = []
    for logical in CAMERA_FOLDER_ALIASES:
        cam = discover_camera_folder(session_root, logical)
        if cam is not None:
            found.append(cam)
    return found