import os
import shutil
from opendm import system
from opendm.concurrency import get_max_memory
from opendm import io
from opendm import log

def convert_to_cogeo(src_path, blocksize=256, max_workers=1, compression="DEFLATE"):
    """
    Guarantee that the .tif passed as an argument is a Cloud Optimized GeoTIFF (cogeo)
    The file is destructively converted into a cogeo.
    If the file cannot be converted, the function does not change the file
    :param src_path: path to GeoTIFF
    :return: True on success
    """

    if not os.path.isfile(src_path):
        logger.warning("Cannot convert to cogeo: %s (file does not exist)" % src_path)
        return False

    log.ODM_INFO("Optimizing %s as Cloud Optimized GeoTIFF" % src_path)

    
    tmpfile = io.related_file_path(src_path, postfix='_cogeo')
    swapfile = io.related_file_path(src_path, postfix='_cogeo_swap')

    kwargs = {
        'threads': max_workers if max_workers else 'ALL_CPUS',
        'blocksize': blocksize,
        'max_memory': get_max_memory(),
        'src_path': src_path,
        'tmpfile': tmpfile,
        'compress': compression,
        'predictor': '2' if compression in ['LZW', 'DEFLATE'] else '1',
    }

    try:
        system.run("gdal_translate "
                "-of COG "
                "-co NUM_THREADS={threads} "
                "-co BLOCKSIZE={blocksize} "
                "-co COMPRESS={compress} "
                "-co PREDICTOR={predictor} "
                "-co BIGTIFF=IF_SAFER "
                "-co RESAMPLING=NEAREST "
                "--config GDAL_CACHEMAX {max_memory}% "
                "--config GDAL_NUM_THREADS {threads} "
                "\"{src_path}\" \"{tmpfile}\" ".format(**kwargs))
    except Exception as e:
        log.ODM_WARNING("Cannot create Cloud Optimized GeoTIFF: %s" % str(e))

    if os.path.isfile(tmpfile):
        shutil.move(src_path, swapfile) # Move to swap location

        try:
            shutil.move(tmpfile, src_path)
        except IOError as e:
            log.ODM_WARNING("Cannot move %s to %s: %s" % (tmpfile, src_path, str(e)))
            shutil.move(swapfile, src_path) # Attempt to restore

        if os.path.isfile(swapfile):
            os.remove(swapfile)

        return True
    else:
        return False