from datetime import datetime
from dateutil.relativedelta import relativedelta

import psycopg2

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


_GRANULARITY_DELTA = {
    "hour": relativedelta(hours=1),
    "day": relativedelta(days=1),
    "week": relativedelta(weeks=1),
    "month": relativedelta(months=1),
}


class PgReadingQueryRepository(ReadingQueryRepository):
    def get_consumption(
        self,
        dev_eui: str,
        start: datetime,
        end: datetime,
        granularity: Granularity,
    ) -> list[ConsumptionPoint]:
        if start == end:
            end = start + _GRANULARITY_DELTA[granularity]
        adjusted_start = start - _GRANULARITY_DELTA[granularity]
        date_trunc = granularity
        query = """
            WITH periods AS (
                SELECT
                    DATE_TRUNC(%s, r.date) AS period,
                    MAX(r.pulses) AS pulse_end
                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
            )
            SELECT
                period,
                LAG(pulse_end) OVER (ORDER BY period) AS pulse_start,
                pulse_end,
                pulse_end - LAG(pulse_end) OVER (ORDER BY period) AS delta_pulses
            FROM periods
            ORDER BY period ASC
        """
        try:
            with get_conn() as conn:
                with conn.cursor() as cur:
                    cur.execute(query, (date_trunc, dev_eui, adjusted_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
            if row[1] is not None
        ]