import os
import re
from pathlib import Path

# 1. DYNAMIC ANCHOR - Works on ANY machine
HOME_DIR = Path.home()

# 2. MAIN DIRECTORIES
SOURCE_CODE_DIR = HOME_DIR / "Speckle-Scanner"
RAW_DATA_DIR    = HOME_DIR / "3D-Scans"
CALIB_DATA_DIR  = HOME_DIR / "Calib-data"
PROCESSING_DIR  = HOME_DIR / "Speckle-Scanner_Processing_data"

# 3. HELPER FUNCTIONS FOR DYNAMIC PATHING
def get_raw_dir(project, date_str, session, scan):
    """Path to original untouched data."""
    return RAW_DATA_DIR / project / date_str / session / scan

def get_calib_dir(project, date_str, calib_number):
    """Path to camera calibration data."""
    return CALIB_DATA_DIR / project / date_str / calib_number

def get_processing_step_dir(project, date_str, session, scan, step_folder_name):
    """
    Path for sequential pipeline steps (e.g., '01_raw_images', '02_rect_images').
    Automatically creates the folder if it does not exist.
    """
    path = PROCESSING_DIR / project / date_str / session / scan / step_folder_name
    path.mkdir(parents=True, exist_ok=True)
    return path


def get_session_processing_dir(project, date_str, session):
    """Path to one processing session directory."""
    path = PROCESSING_DIR / project / date_str / session
    path.mkdir(parents=True, exist_ok=True)
    return path


def get_params_link_dir(project, date_str, session):
    """Path to shared params_link folder for one session."""
    return get_session_processing_dir(project, date_str, session) / "params_link"


def list_session_dirs(project, date_str):
    """Return sorted session folder names under a project/date."""
    date_dir = PROCESSING_DIR / project / date_str
    if not date_dir.exists():
        return []
    sessions = [
        p.name for p in date_dir.iterdir()
        if p.is_dir() and "session" in p.name.lower()
    ]

    def session_sort_key(name):
        m = re.search(r'\d+', name)
        return int(m.group()) if m else 0

    return sorted(sessions, key=session_sort_key)


def list_scan_dirs(project, date_str, session):
    """Return sorted scan folder names (handles 'Scan000001' and 'scan-1' patterns)."""
    session_dir = get_session_processing_dir(project, date_str, session)
    scans = [
        p.name for p in session_dir.iterdir()
        if p.is_dir() and (p.name.startswith("Scan") or p.name.startswith("scan-"))
    ]

    def scan_sort_key(name):
        m = re.search(r'\d+', name)
        return int(m.group()) if m else 0

    return sorted(scans, key=scan_sort_key)