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# to you under the Apache License, Version 2.0 (the
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#
#   http://www.apache.org/licenses/LICENSE-2.0
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from superset.db_engine_specs.base import BaseEngineSpec, LimitMethod


class Db2EngineSpec(BaseEngineSpec):
    engine = "db2"
    engine_aliases = {"ibm_db_sa"}
    engine_name = "IBM Db2"
    limit_method = LimitMethod.WRAP_SQL
    force_column_alias_quotes = True
    max_column_name_length = 30

    _time_grain_expressions = {
        None: "{col}",
        "PT1S": "CAST({col} as TIMESTAMP)" " - MICROSECOND({col}) MICROSECONDS",
        "PT1M": "CAST({col} as TIMESTAMP)"
        " - SECOND({col}) SECONDS"
        " - MICROSECOND({col}) MICROSECONDS",
        "PT1H": "CAST({col} as TIMESTAMP)"
        " - MINUTE({col}) MINUTES"
        " - SECOND({col}) SECONDS"
        " - MICROSECOND({col}) MICROSECONDS ",
        "P1D": "CAST({col} as TIMESTAMP)"
        " - HOUR({col}) HOURS"
        " - MINUTE({col}) MINUTES"
        " - SECOND({col}) SECONDS"
        " - MICROSECOND({col}) MICROSECONDS",
        "P1W": "{col} - (DAYOFWEEK({col})) DAYS",
        "P1M": "{col} - (DAY({col})-1) DAYS",
        "P3M": "{col} - (DAY({col})-1) DAYS"
        " - (MONTH({col})-1) MONTHS"
        " + ((QUARTER({col})-1) * 3) MONTHS",
        "P1Y": "{col} - (DAY({col})-1) DAYS" " - (MONTH({col})-1) MONTHS",
    }

    @classmethod
    def epoch_to_dttm(cls) -> str:
        return "(TIMESTAMP('1970-01-01', '00:00:00') + {col} SECONDS)"