from datetime import datetime

import psycopg2
from psycopg2.extensions import connection

from domain.entities import ConsumptionPoint
from domain.exceptions import DatabaseError
from domain.value_objects import Granularity
from ports.reading_query_repository import ReadingQueryRepository


class PgReadingQueryRepository(ReadingQueryRepository):
    def __init__(self, conn: connection) -> None:
        self._conn = conn

    def get_consumption(
        self,
        dev_eui: str,
        start: datetime,
        end: datetime,
        granularity: Granularity,
    ) -> list[ConsumptionPoint]:
        date_trunc = granularity
        query = """
            SELECT
                DATE_TRUNC(%s, r.date)          AS period,
                MIN(r.pulses)                   AS pulse_start,
                MAX(r.pulses)                   AS pulse_end,
                MAX(r.pulses) - MIN(r.pulses)   AS delta_pulses
            FROM reading r
            JOIN device d ON d.device_id = r.device_id
            WHERE d.device_eui = %s
              AND r.date >= %s
              AND r.date <  %s
            GROUP BY period
            ORDER BY period ASC
        """
        try:
            with self._conn.cursor() as cur:
                cur.execute(query, (date_trunc, dev_eui, start, end))
                rows = cur.fetchall()
        except psycopg2.DatabaseError as e:
            raise DatabaseError(f"Erreur requête consumption : {e}") from e

        return [
            ConsumptionPoint(
                period=row[0],
                pulse_count_start=row[1],
                pulse_count_end=row[2],
                delta_pulses=row[3],
                delta_m3=round(row[3] * 0.010, 3),
            )
            for row in rows
        ]