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use core::fmt;
use std::fmt::Formatter;

use nom::bytes::complete::tag_no_case;
use nom::character::complete;
use nom::character::complete::{multispace0, multispace1};
use nom::combinator::map;
use nom::sequence::{terminated, tuple};
use nom::IResult;

use base::error::ParseSQLError;
use base::CommonParser;

/// parse `DROP SPATIAL REFERENCE SYSTEM
///     [IF EXISTS]
///     srid`
///
/// `srid: 32-bit unsigned integer`
#[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
pub struct DropSpatialReferenceSystemStatement {
    pub if_exists: bool,
    pub srid: u32,
}

impl DropSpatialReferenceSystemStatement {
    pub fn parse(
        i: &str,
    ) -> IResult<&str, DropSpatialReferenceSystemStatement, ParseSQLError<&str>> {
        map(
            tuple((
                terminated(tag_no_case("DROP"), multispace1),
                terminated(tag_no_case("SPATIAL"), multispace1),
                terminated(tag_no_case("REFERENCE"), multispace1),
                terminated(tag_no_case("SYSTEM"), multispace1),
                CommonParser::parse_if_exists,
                complete::u32,
                multispace0,
                CommonParser::statement_terminator,
            )),
            |x| DropSpatialReferenceSystemStatement {
                if_exists: x.4.is_some(),
                srid: x.5,
            },
        )(i)
    }
}

impl fmt::Display for DropSpatialReferenceSystemStatement {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        write!(f, "DROP SPATIAL REFERENCE SYSTEM")?;
        if self.if_exists {
            write!(f, " IF EXISTS")?;
        }
        write!(f, " {}", self.srid)?;
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use dds::drop_spatial_reference_system::DropSpatialReferenceSystemStatement;

    #[test]
    fn parse_drop_spatial_reference_system() {
        let sqls = [
            "DROP SPATIAL REFERENCE SYSTEM 4120;",
            "DROP SPATIAL REFERENCE SYSTEM IF EXISTS 4120;",
        ];
        let exp_statements = [
            DropSpatialReferenceSystemStatement {
                if_exists: false,
                srid: 4120,
            },
            DropSpatialReferenceSystemStatement {
                if_exists: true,
                srid: 4120,
            },
        ];
        for i in 0..sqls.len() {
            let res = DropSpatialReferenceSystemStatement::parse(sqls[i]);
            assert!(res.is_ok());
            assert_eq!(res.unwrap().1, exp_statements[i]);
        }
    }
}