#!/usr/bin/env python3
import os
import sys
import mercantile
from rio_tiler.io import COGReader
from rio_tiler.utils import render

# ---------------------------------------------------------
# USO:
#   python3 make_tiles_rio_tiler.py input_rgb.tif tiles_out/
#
# Genera tile PNG Terrain-RGB senza alterare i pixel.
# Corretto per evitare buchi tra quadranti Copernicus.
# ---------------------------------------------------------

ZOOM_MIN = 5
ZOOM_MAX = 14
BUFFER = 0.001   # espansione per evitare tile mancanti ai bordi

def generate_tiles(input_tif, output_dir):
    os.makedirs(output_dir, exist_ok=True)

    with COGReader(input_tif) as cog:
        for z in range(ZOOM_MIN, ZOOM_MAX + 1):
            print(f"== Zoom {z} ==")

            # Bounds originali del TIFF
            bounds = cog.bounds

            # Espansione per evitare buchi tra quadranti
            minx = bounds[0] - BUFFER
            miny = bounds[1] - BUFFER
            maxx = bounds[2] + BUFFER
            maxy = bounds[3] + BUFFER

            # Tile da generare
            tiles = list(mercantile.tiles(minx, miny, maxx, maxy, z))

            for t in tiles:
                out_dir_zxy = os.path.join(output_dir, str(z), str(t.x))
                os.makedirs(out_dir_zxy, exist_ok=True)
                out_path = os.path.join(out_dir_zxy, f"{t.y}.png")

                # Estrazione tile
                tile, mask = cog.tile(t.x, t.y, z, resampling_method="nearest")

                # Render PNG
                img = render(tile, mask=mask, img_format="PNG")

                with open(out_path, "wb") as f:
                    f.write(img)

                print(f"Tile {z}/{t.x}/{t.y} generata")

    print("Completato.")


if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Uso: python3 make_tiles_rio_tiler.py <input_rgb.tif> <output_dir>")
        sys.exit(1)

    INPUT_TIF = sys.argv[1]
    OUTPUT_DIR = sys.argv[2]

    if not os.path.isfile(INPUT_TIF):
        print(f"Errore: file non trovato: {INPUT_TIF}")
        sys.exit(1)

    generate_tiles(INPUT_TIF, OUTPUT_DIR)