import json
from pathlib import Path
from datetime import datetime

def parse_timestamp(entry):
    ts = entry.get('fetched_at')
    if ts:
        try:
            return datetime.fromisoformat(ts)
        except Exception:
            return None
    return None

def merge_dict_json(local_path, merge_path, output_path=None, timestamp_field='fetched_at'):
    """
    Merge two dict-based JSON files (keyed by id), deduplicate by key.
    If duplicate, keep entry with latest timestamp_field.
    """
    output_path = output_path or local_path
    with open(local_path, encoding='utf-8') as f:
        local = json.load(f)
    with open(merge_path, encoding='utf-8') as f:
        remote = json.load(f)
    merged = {}
    all_keys = set(local.keys()) | set(remote.keys())
    for key in all_keys:
        l_entry = local.get(key)
        r_entry = remote.get(key)
        if l_entry and r_entry:
            l_ts = l_entry.get(timestamp_field)
            r_ts = r_entry.get(timestamp_field)
            if l_ts and r_ts:
                merged[key] = l_entry if l_ts > r_ts else r_entry
            else:
                merged[key] = l_entry  # fallback
        else:
            merged[key] = l_entry or r_entry
    with open(output_path, 'w', encoding='utf-8') as f:
        json.dump(merged, f, ensure_ascii=False, indent=2)
    print(f"Merged {len(merged)} unique entries to {output_path}")

if __name__ == "__main__":
    merge_dict_json(
        "data/listings.json",
        "data/to_merge/listings.json"
    )
    merge_dict_json(
        "data/wgcompany_listings.json",
        "data/to_merge/wgcompany_listings.json"
    )