prax-postgres 0.8.2

//! Type conversions for PostgreSQL.

use prax_query::filter::FilterValue;
use tokio_postgres::types::{IsNull, ToSql, Type};

use crate::error::{PgError, PgResult};

/// Polymorphic integer binding. `FilterValue::Int` always carries an i64
/// (the widest scalar variant), but Postgres strictly validates client
/// bindings against column types: binding an i64 to an `INT4` column
/// fails with `WrongType { postgres: Int4, rust: "i64" }`. This wrapper
/// inspects the target column type at bind time and narrows to i16 /
/// i32 / i64 with a bounds check before forwarding to tokio-postgres'
/// own impls.
#[derive(Debug)]
struct PgInt(i64);

impl ToSql for PgInt {
    fn to_sql(
        &self,
        ty: &Type,
        out: &mut bytes::BytesMut,
    ) -> Result<IsNull, Box<dyn std::error::Error + Sync + Send>> {
        match *ty {
            Type::INT2 => {
                let v: i16 = self
                    .0
                    .try_into()
                    .map_err(|_| format!("value {} overflows INT2", self.0))?;
                v.to_sql(ty, out)
            }
            Type::INT4 => {
                let v: i32 = self
                    .0
                    .try_into()
                    .map_err(|_| format!("value {} overflows INT4", self.0))?;
                v.to_sql(ty, out)
            }
            Type::INT8 => self.0.to_sql(ty, out),
            _ => Err(format!("cannot bind integer to postgres type {ty:?}").into()),
        }
    }

    fn accepts(ty: &Type) -> bool {
        matches!(*ty, Type::INT2 | Type::INT4 | Type::INT8)
    }

    tokio_postgres::types::to_sql_checked!();
}

/// Convert a FilterValue to a type that can be used as a PostgreSQL parameter.
pub fn filter_value_to_sql(value: &FilterValue) -> PgResult<Box<dyn ToSql + Sync + Send>> {
    match value {
        FilterValue::Null => Ok(Box::new(Option::<String>::None)),
        FilterValue::Bool(b) => Ok(Box::new(*b)),
        FilterValue::Int(i) => Ok(Box::new(PgInt(*i))),
        FilterValue::Float(f) => Ok(Box::new(*f)),
        FilterValue::String(s) => Ok(Box::new(s.clone())),
        FilterValue::Json(j) => Ok(Box::new(j.clone())),
        FilterValue::List(_) => {
            // Lists need special handling - they should be converted to arrays
            // For now, return an error and handle lists specially in the engine
            Err(PgError::type_conversion(
                "list values should be handled specially",
            ))
        }
    }
}

/// Convert filter values to PostgreSQL parameters.
pub fn filter_values_to_params(
    values: &[FilterValue],
) -> PgResult<Vec<Box<dyn ToSql + Sync + Send>>> {
    values.iter().map(filter_value_to_sql).collect()
}

/// PostgreSQL type mapping utilities.
pub mod pg_types {
    use super::*;

    /// Get the PostgreSQL type for a Rust type name.
    pub fn rust_type_to_pg(rust_type: &str) -> Option<Type> {
        match rust_type {
            "i16" => Some(Type::INT2),
            "i32" => Some(Type::INT4),
            "i64" => Some(Type::INT8),
            "f32" => Some(Type::FLOAT4),
            "f64" => Some(Type::FLOAT8),
            "bool" => Some(Type::BOOL),
            "String" | "&str" => Some(Type::TEXT),
            "Vec<u8>" | "&[u8]" => Some(Type::BYTEA),
            "chrono::NaiveDate" => Some(Type::DATE),
            "chrono::NaiveTime" => Some(Type::TIME),
            "chrono::NaiveDateTime" => Some(Type::TIMESTAMP),
            "chrono::DateTime<chrono::Utc>" => Some(Type::TIMESTAMPTZ),
            "uuid::Uuid" => Some(Type::UUID),
            "serde_json::Value" => Some(Type::JSONB),
            _ => None,
        }
    }

    /// Get the Rust type for a PostgreSQL type.
    pub fn pg_type_to_rust(pg_type: &Type) -> &'static str {
        match *pg_type {
            Type::BOOL => "bool",
            Type::INT2 => "i16",
            Type::INT4 => "i32",
            Type::INT8 => "i64",
            Type::FLOAT4 => "f32",
            Type::FLOAT8 => "f64",
            Type::TEXT | Type::VARCHAR | Type::CHAR | Type::NAME => "String",
            Type::BYTEA => "Vec<u8>",
            Type::DATE => "chrono::NaiveDate",
            Type::TIME => "chrono::NaiveTime",
            Type::TIMESTAMP => "chrono::NaiveDateTime",
            Type::TIMESTAMPTZ => "chrono::DateTime<chrono::Utc>",
            Type::UUID => "uuid::Uuid",
            Type::JSON | Type::JSONB => "serde_json::Value",
            _ => "unknown",
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_filter_value_to_sql() {
        let result = filter_value_to_sql(&FilterValue::Int(42));
        assert!(result.is_ok());

        let result = filter_value_to_sql(&FilterValue::String("test".to_string()));
        assert!(result.is_ok());

        let result = filter_value_to_sql(&FilterValue::Bool(true));
        assert!(result.is_ok());
    }

    #[test]
    fn test_pg_type_mapping() {
        use pg_types::*;

        assert_eq!(rust_type_to_pg("i32"), Some(Type::INT4));
        assert_eq!(rust_type_to_pg("String"), Some(Type::TEXT));
        assert_eq!(rust_type_to_pg("bool"), Some(Type::BOOL));

        assert_eq!(pg_type_to_rust(&Type::INT4), "i32");
        assert_eq!(pg_type_to_rust(&Type::TEXT), "String");
    }
}