generate-metadata

#!/usr/bin/env python
"""Generate and clean metadata to tiles.mbtiles.

Usage:
  generate_metadata [--force] <mbtiles>
  generate_metadata [--force] <mbtiles> <west> <south> <east> <north>
  generate_metadata (-h | --help)
  generate_metadata --version

Options:
  -h --help                     Show this screen.
  --version                     Show version.
  --force                       Overwrite all metadata, not only missing

This script reads environment variable: METADATA_* for overwriting metadata values.
This script parses BBOX, MIN_ZOOM, MAX_ZOOM and CENTER_ZOOM to prepare bounds and center values.
"""
from docopt import docopt
import sqlite3
import os.path
import json
import openmaptiles
from openmaptiles.utils import Bbox
from openmaptiles.consts import *


def update_metadata(mbtiles_file, metadata, force=False):
    """
    Update metadata key value pairs inside the MBTiles file
    with the provided metadata
    """
    conn = sqlite3.connect(mbtiles_file)
    cursor = conn.cursor()

    def upsert_entry(entry_key, entry_value):
        # ID should be overwritten always!
        if not force and entry_key != 'id':
            cursor.execute("SELECT value FROM metadata WHERE name = ?", (entry_key, ))
            for entry_row in cursor:
                # Skip if the value exists
                # print(f"{entry_key}={entry_row}")
                if entry_row[0]:
                    return
        conn.execute("DELETE FROM metadata WHERE name=?", (entry_key, ))
        conn.execute("INSERT INTO metadata VALUES(?, ?)", (entry_key, entry_value, ))

    for key, value in metadata.items():
        upsert_entry(key, value)

    # Change json value in metadata
    cursor.execute("SELECT name, value FROM metadata WHERE name = 'json'")
    metadata_json = ''
    for row in cursor:
        metadata_json = row[1]
        break

    if metadata_json:
        obj = json.loads(metadata_json)
        # Remove Layer - contains connections and SQLs
        if 'Layer' in obj:
            del obj['Layer']
        # Remove unnecessary field _prefs
        if '_prefs' in obj:
            del obj['_prefs']
        # Update maxzoom in vector_layers:
        if 'vector_layers' in obj:
            # find out maxzoom from metadata
            maxzoom = 0
            cursor.execute("SELECT name, value FROM metadata WHERE name='maxzoom'")
            for row in cursor:
                try:
                    maxzoom = int(row[1])
                except:
                    maxzoom = 0
                break
            if maxzoom > 0:
                vector_layers = obj['vector_layers']
                for layer in vector_layers:
                    layer['maxzoom'] = maxzoom
        # Save json back into metadata minified
        metadata_json = json.dumps(obj, separators=(',', ':'))
        cursor.execute("REPLACE INTO metadata VALUES (?, ?)", ('json', metadata_json, ))
        conn.commit()

    conn.commit()
    conn.close()


def main(args):
    extract_file = args['<mbtiles>']
    bbox = Bbox(bbox=os.environ.get('BBOX'),
                top=args.get('<north>'),
                left=args.get('<west>'),
                bottom=args.get('<south>'),
                right=args.get('<east>'),
                center_zoom=os.environ.get('CENTER_ZOOM'))

    metadata = {
        "type": os.environ.get('METADATA_TYPE', METADATA_TYPE),
        "attribution": os.environ.get('METADATA_ATTRIBUTION', METADATA_ATTRIBUTION),
        "description": os.environ.get('METADATA_DESCRIPTION', METADATA_DESCRIPTION),
        "version": os.environ.get('METADATA_VERSION', METADATA_VERSION),
        "minzoom": os.environ.get('MIN_ZOOM', MIN_ZOOM),
        "maxzoom": os.environ.get('MAX_ZOOM', MAX_ZOOM),
        "name": os.environ.get('METADATA_NAME', METADATA_NAME),
        "id": os.environ.get('METADATA_ID', METADATA_ID),
        "bounds": bbox.bounds_str(),
        "center": bbox.center_str(),
        "basename": os.path.basename(extract_file) if extract_file else None,
        "filesize": os.path.getsize(extract_file) if extract_file else None,
    }

    print(f'Update metadata {extract_file}')
    update_metadata(extract_file, metadata, args.get('--force', False))


if __name__ == '__main__':
    main(docopt(__doc__, version=openmaptiles.__version__, options_first=True))