#!/usr/bin/env python3
"""
Script: GetImageRun_3y.py
Orchestrates Google Earth Engine exports for DHS cluster points.
"""

from __future__ import annotations

import datetime as dt
import os
from pathlib import Path
import pandas as pd
import ee

# Local package
from satellite_sampling_5k_3y_ctj import export_images

# --------------------------------------------------------------------------- #
# Configuration                                                               #
# --------------------------------------------------------------------------- #
ROOT_DIR          = os.environ.get(
    'IMAGEDECONFOUND_REPLICATION_ROOT',
    str(Path(__file__).resolve().parents[3])
)
INTERIM_DATA_DIR  = os.path.join(ROOT_DIR, 'data', 'interim')
DATA_DIR          = os.environ.get(
    'IMAGEDECONFOUND_IMAGE_DOWNLOAD_ROOT',
    os.path.join(ROOT_DIR, 'external_artifacts', 'images')
)
DHS_FILE          = os.path.join(INTERIM_DATA_DIR, 'dhs_est_iwi.csv')

SPAN_LENGTH_YRS   = 3          # each frame is a 3‑year composite
NUM_WORKERS       = 8         # concurrent EE tasks to launch

# --------------------------------------------------------------------------- #
# Helper                                                                      #
# --------------------------------------------------------------------------- #

def _already_downloaded(row: pd.Series, folder: str, min_bytes: int = 2_600_000) -> bool:
    """True iff the expected .tif exists and is larger than the safety margin."""
    tif = os.path.join(folder, f"{row['dhs_id']}.tif")
    return os.path.isfile(tif) and os.stat(tif).st_size > min_bytes

# --------------------------------------------------------------------------- #
# Main                                                                         #
# --------------------------------------------------------------------------- #

def main() -> None:
    os.chdir(ROOT_DIR)                                # keep relative paths tidy

    # ---- GEE session ------------------------------------------------------- #
    ee.Authenticate()                                 # cached after first run
    ee.Initialize(opt_url='https://earthengine-highvolume.googleapis.com')

    # ---- Load DHS clusters -------------------------------------------------- #
    df             = pd.read_csv(DHS_FILE)
    grouped        = df.groupby(['country', 'year'])

    for (country, year), survey_df in grouped:
        ts   = dt.datetime.now().strftime('%d.%b %Y %H:%M:%S')
        print(f'Downloading images for {country}-{year} … {ts}')

        out_dir = os.path.join(DATA_DIR,
                               f'dhs_tifs_5k_3yr/{country}_{year}')
        os.makedirs(out_dir, exist_ok=True)

        mask   = ~survey_df.apply(_already_downloaded, axis=1, folder=out_dir)
        to_do  = survey_df[mask]

        if to_do.empty:
            print(f'  ✓ all {len(survey_df)} tiles already present')
            continue

        export_images(to_do, out_dir,
                      span_length=SPAN_LENGTH_YRS,
                      num_workers=NUM_WORKERS)


if __name__ == '__main__':          # ***** CRUCIAL for multiprocessing *****
    main()