"""Database connectivity and query execution.

Replaces database.js:
  - pyodbc connection pool (via DBUtils)
  - Health check (checkBackendOkay)
  - Parameterized query execution (runquery)
  - All SQL statement definitions
  - Stats query aggregations
"""

import logging

logger = logging.getLogger(__name__)

# TODO Phase 2: import pyodbc, DBUtils.PooledDB
# import pyodbc
# from DBUtils.PooledDB import PooledDB

# Module-level connection pool
_pool = None


def init(config=None):
    """Initialize the MSSQL connection pool.

    Replaces database.init() from database.js.
    Uses the same config keys: user, password, server, port, database.
    """
    global _pool
    # TODO Phase 2: create PooledDB
    raise NotImplementedError("Database not yet initialized")


def connected():
    """Check if the connection pool is alive."""
    # TODO Phase 2
    raise NotImplementedError


def check_backend_okay():
    """Health check: verify DB is reachable and has expected data.

    Replaces checkBackendOkay() from database.js.
    """
    # TODO Phase 2
    raise NotImplementedError


def run_query(query_def, params):
    """Execute a parameterized query and return rows as list of dicts.

    Replaces runquery() from database.js.

    Args:
        query_def: dict with 'statement' (str) and 'params' (dict of names)
                   or 'special' (str) for stats queries
        params: dict of parameter values

    Returns:
        list of dict rows
    """
    # TODO Phase 2
    raise NotImplementedError


def run_query_stats_members():
    """Special aggregation query for member count over time."""
    # TODO Phase 2
    raise NotImplementedError


def run_query_stats_contracts():
    """Special aggregation query for contract statistics."""
    # TODO Phase 2
    raise NotImplementedError


def run_query_stats_genders():
    """Special aggregation query for gender demographics."""
    # TODO Phase 2
    raise NotImplementedError


def run_query_stats_ages():
    """Special aggregation query for age demographics."""
    # TODO Phase 2
    raise NotImplementedError


def member_lookup(crewname):
    """Look up a single member by crewname.

    Replaces memberlookup() from database.js.
    Returns a single dict row or raises.
    """
    # TODO Phase 2
    raise NotImplementedError


# ─── SQL Statement Definitions ───────────────────────────────────────────────
# Replacing the QUERY_* constants from database.js
# Parameter placeholders use pyodbc '?' style instead of T-SQL '@name'

QUERY_CONTRACTLIST_BY_CREWNAME = {
    'statement': (
        'SELECT MgVert.* FROM Adresse, MgVert '
        'WHERE Adresse.Kurzname = ? AND MgVert.AdrNr = Adresse.AdrNr'
    ),
    'params': ['crewname'],
}

QUERY_CONTRACT_BY_CREWNAME_AND_CONTRACT = {
    'statement': (
        'SELECT MgVert.* FROM Adresse, MgVert '
        'WHERE Adresse.Kurzname = ? AND MgVert.AdrNr = Adresse.AdrNr '
        "AND (MgVert.VertragNr = ? OR MgVert.VertragNr = ' ' + ?)"
    ),
    'params': ['crewname', 'contract'],
}

QUERY_DEBITLIST_BY_CREWNAME = {
    'statement': (
        'SELECT MgSolln.* FROM Adresse, MgSolln '
        'WHERE Adresse.Kurzname = ? AND MgSolln.AdrNr = Adresse.AdrNr '
        'ORDER BY MgSolln.Jahr, MgSolln.Zeitraum'
    ),
    'params': ['crewname'],
}

QUERY_DEBIT_BY_CREWNAME_AND_GUID = {
    'statement': (
        'SELECT MgSolln.* FROM Adresse, MgSolln '
        'WHERE Adresse.Kurzname = ? AND MgSolln.AdrNr = Adresse.AdrNr '
        'AND MgSolln.GUID = ?'
    ),
    'params': ['crewname', 'guid'],
}

QUERY_MEMBERLIST = {
    'statement': (
        "SELECT AdrNr, Firma4, Nachname, Vorname, Kurzname, Kennung3, "
        "Telefon3, Kontaktwoher, Eintritt, Austritt "
        "FROM Adresse WHERE Kurzname != '' ORDER BY Nachname"
    ),
    'params': [],
}

QUERY_STATS_MEMBERS = {
    'special': 'QUERY_STATS_MEMBERS',
}

QUERY_STATS_CONTRACTS = {
    'special': 'QUERY_STATS_CONTRACTS',
}

QUERY_STATS_GENDERS = {
    'special': 'QUERY_STATS_GENDERS',
}

QUERY_STATS_AGES = {
    'special': 'QUERY_STATS_AGES',
}

QUERY_MEMBERLIST_RAW = {
    'statement': 'SELECT * FROM Adresse ORDER BY Nachname',
    'params': [],
}

QUERY_MEMBER_BY_CREWNAME = {
    'statement': 'SELECT * FROM Adresse WHERE Kurzname = ?',
    'params': ['crewname'],
}

QUERY_MEMBER_MEMO_BY_CREWNAME = {
    'statement': (
        'SELECT Memof.* FROM Adresse, Memof '
        'WHERE Adresse.Kurzname = ? AND Memof.AdrNr = Adresse.AdrNr'
    ),
    'params': ['crewname'],
}

QUERY_WITHDRAWALLIST_BY_CREWNAME = {
    'statement': (
        'SELECT MgLast.* FROM Adresse, MgLast '
        'WHERE Adresse.Kurzname = ? AND MgLast.Adr_Nummer = Adresse.AdrNr'
    ),
    'params': ['crewname'],
}

QUERY_WITHDRAWAL_BY_CREWNAME_AND_GUID = {
    'statement': (
        'SELECT MgLast.* FROM Adresse, MgLast '
        'WHERE Adresse.Kurzname = ? AND MgLast.Adr_Nummer = Adresse.AdrNr '
        'AND MgLast.GUID = ?'
    ),
    'params': ['crewname', 'guid'],
}

QUERY_PAYMENTLIST_BY_CREWNAME = {
    'statement': (
        'SELECT F5bew4.* FROM Adresse, F5bew4 '
        'WHERE Adresse.Kurzname = ? AND F5bew4.AdrNr = Adresse.AdrNr'
    ),
    'params': ['crewname'],
}