#!/usr/bin/env python3
"""Quick script to show unique values of a field."""
import gzip
import json
import sys

backup_file = sys.argv[1]
field_name = sys.argv[2]
limit = int(sys.argv[3]) if len(sys.argv) > 3 else 10

seen = set()
with gzip.open(backup_file, 'rt', encoding='utf-8') as f:
    for line in f:
        doc = json.loads(line)
        if doc.get('type') != 'document':
            continue
        val = doc.get('_source', {}).get(field_name)
        if val is not None and val not in seen:
            seen.add(val)
            print(f"  {val}")
        if len(seen) >= limit:
            break

print(f"\n(Showing {len(seen)} unique values)")