def mock_get_analytics(
    metric: str = "volume", 
    group_by: str = "day", 
    sub_group_by: str = None,
    date_from: str = None, 
    date_to: str = None,
    isins: str = None,
    continents: str = None
):
    # Determine if we need to join metadata
    needs_metadata = any([
        group_by in ["name", "continent", "sector"],
        sub_group_by in ["name", "continent", "sector"],
        continents is not None
    ])
    
    # Use prefixes only if joining
    t_prefix = "t." if needs_metadata else ""
    m_prefix = "m." if needs_metadata else ""
    
    metrics_map = {
        "volume": f"sum({t_prefix}price * {t_prefix}quantity)",
        "count": f"count(*)",
        "avg_price": f"avg({t_prefix}price)"
    }
    
    groups_map = {
        "day": f"date_trunc('day', {t_prefix}timestamp)",
        "month": f"date_trunc('month', {t_prefix}timestamp)",
        "exchange": f"{t_prefix}exchange",
        "isin": f"{t_prefix}isin",
        "name": f"coalesce({m_prefix}name, {t_prefix}isin)" if needs_metadata else "isin",
        "continent": f"coalesce({m_prefix}continent, 'Unknown')" if needs_metadata else "'Unknown'",
        "sector": f"coalesce({m_prefix}sector, 'Unknown')" if needs_metadata else "'Unknown'"
    }
    
    selected_metric = metrics_map.get(metric, metrics_map["volume"])
    selected_group = groups_map.get(group_by, groups_map["day"])
    
    query = f"select {selected_group} as label"
    
    if sub_group_by and sub_group_by in groups_map:
        query += f", {groups_map[sub_group_by]} as sub_label"
        
    query += f", {selected_metric} as value from trades"
    if needs_metadata:
        query += " t left join metadata m on t.isin = m.isin"
    
    query += " where 1=1"
    
    if date_from:
        query += f" and {t_prefix}timestamp >= '{date_from}'"
    if date_to:
        query += f" and {t_prefix}timestamp <= '{date_to}'"
        
    if isins:
        isins_list = ",".join([f"'{i.strip()}'" for i in isins.split(",")])
        query += f" and {t_prefix}isin in ({isins_list})"

    if continents and needs_metadata:
        cont_list = ",".join([f"'{c.strip()}'" for c in continents.split(",")])
        query += f" and {m_prefix}continent in ({cont_list})"
        
    query += " group by label"
    if sub_group_by and sub_group_by in groups_map:
        query += ", sub_label"
    
    query += " order by label asc"
    return query

# Test cases
print("Case 1: Basic analytics (reported error case)")
print(mock_get_analytics(metric="volume", group_by="day", date_from="2025-12-26", date_to="2026-01-25", isins="DE000LS1LUS9"))

print("\nCase 2: Filtering by continent (should join)")
print(mock_get_analytics(metric="volume", group_by="day", continents="Europe"))

print("\nCase 3: Grouping by name (should join)")
print(mock_get_analytics(metric="count", group_by="name"))