//! Conversions between Rust and SQL types.
//!
//! To see how each SQL type maps to a Rust type, see the corresponding `types` module for each
//! database:
//!
//!  * [PostgreSQL](crate::postgres::types)
//!  * [MySQL](crate::mysql::types)
//!  * [SQLite](crate::sqlite::types)
//!  * [MSSQL](crate::mssql::types)
//!
//! Any external types that have had [`Type`] implemented for, are re-exported in this module
//! for convenience as downstream users need to use a compatible version of the external crate
//! to take advantage of the implementation.
//!
//! # Nullable
//!
//! To represent nullable SQL types, `Option<T>` is supported where `T` implements `Type`.
//! An `Option<T>` represents a potentially `NULL` value from SQL.
//!

use crate::database::Database;

#[cfg(feature = "bstr")]
#[cfg_attr(docsrs, doc(cfg(feature = "bstr")))]
pub mod bstr;

#[cfg(feature = "json")]
#[cfg_attr(docsrs, doc(cfg(feature = "json")))]
mod json;

#[cfg(feature = "uuid")]
#[cfg_attr(docsrs, doc(cfg(feature = "uuid")))]
#[doc(no_inline)]
pub use uuid::{self, Uuid};

#[cfg(feature = "chrono")]
#[cfg_attr(docsrs, doc(cfg(feature = "chrono")))]
pub mod chrono {
    #[doc(no_inline)]
    pub use chrono::{
        DateTime, FixedOffset, Local, NaiveDate, NaiveDateTime, NaiveTime, TimeZone, Utc,
    };
}

#[cfg(feature = "bit-vec")]
#[cfg_attr(docsrs, doc(cfg(feature = "bit-vec")))]
#[doc(no_inline)]
pub use bit_vec::BitVec;

#[cfg(feature = "time")]
#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
pub mod time {
    #[doc(no_inline)]
    pub use time::{Date, OffsetDateTime, PrimitiveDateTime, Time, UtcOffset};
}

#[cfg(feature = "bigdecimal")]
#[cfg_attr(docsrs, doc(cfg(feature = "bigdecimal")))]
#[doc(no_inline)]
pub use bigdecimal::BigDecimal;

#[cfg(feature = "rust_decimal")]
#[cfg_attr(docsrs, doc(cfg(feature = "rust_decimal")))]
#[doc(no_inline)]
pub use rust_decimal::Decimal;

#[cfg(feature = "ipnetwork")]
#[cfg_attr(docsrs, doc(cfg(feature = "ipnetwork")))]
pub mod ipnetwork {
    #[doc(no_inline)]
    pub use ipnetwork::{IpNetwork, Ipv4Network, Ipv6Network};
}

#[cfg(feature = "mac_address")]
#[cfg_attr(docsrs, doc(cfg(feature = "mac_address")))]
pub mod mac_address {
    #[doc(no_inline)]
    pub use mac_address::MacAddress;
}

#[cfg(feature = "json")]
pub use json::{Json, JsonRawValue, JsonValue};

/// Indicates that a SQL type is supported for a database.
///
/// ## Compile-time verification
///
/// With compile-time verification, the use of type overrides is currently required to make
/// use of any user-defined types.
///
/// ```rust,ignore
/// struct MyUser { id: UserId, name: String }
///
/// // fetch all properties from user and override the type in Rust for `id`
/// let user = query_as!(MyUser, r#"SELECT users.*, id as "id: UserId" FROM users"#)
///     .fetch_one(&pool).await?;
/// ```
///
/// ## Derivable
///
/// This trait can be derived by SQLx to support Rust-only wrapper types, enumerations, and (for
/// postgres) structured records. Additionally, an implementation of [`Encode`](crate::encode::Encode) and [`Decode`](crate::decode::Decode) is
/// generated.
///
/// ### Transparent
///
/// Rust-only domain wrappers around SQL types. The generated implementations directly delegate
/// to the implementation of the inner type.
///
/// ```rust,ignore
/// #[derive(sqlx::Type)]
/// #[sqlx(transparent)]
/// struct UserId(i64);
/// ```
///
/// ##### Note: `PgHasArrayType`
/// If you have the `postgres` feature enabled, this derive also generates a `PgHasArrayType` impl
/// so that you may use it with `Vec` and other types that decode from an array in Postgres:
///
/// ```rust,ignore
/// let user_ids: Vec<UserId> = sqlx::query_scalar("select '{ 123, 456 }'::int8[]")
///    .fetch(&mut pg_connection)
///    .await?;
/// ```
///
/// However, if you are wrapping a type that does not implement `PgHasArrayType`
/// (e.g. `Vec` itself, because we don't currently support multidimensional arrays),
/// you may receive an error:
///
/// ```rust,ignore
/// #[derive(sqlx::Type)] // ERROR: `Vec<i64>` does not implement `PgHasArrayType`
/// #[sqlx(transparent)]
/// struct UserIds(Vec<i64>);
/// ```
///
/// To remedy this, add `#[sqlx(no_pg_array)]`, which disables the generation
/// of the `PgHasArrayType` impl:
///
/// ```rust,ignore
/// #[derive(sqlx::Type)]
/// #[sqlx(transparent, no_pg_array)]
/// struct UserIds(Vec<i64>);
/// ```
///
/// ##### Attributes
///
/// * `#[sqlx(type_name = "<SQL type name>")]` on struct definition: instead of inferring the SQL
///   type name from the inner field (in the above case, `BIGINT`), explicitly set it to
///   `<SQL type name>` instead. May trigger errors or unexpected behavior if the encoding of the
///   given type is different than that of the inferred type (e.g. if you rename the above to
///   `VARCHAR`). Affects Postgres only.
/// * `#[sqlx(rename_all = "<strategy>")]` on struct definition: See [`derive docs in FromRow`](crate::from_row::FromRow#rename_all)
/// * `#[sqlx(no_pg_array)]`: do not emit a `PgHasArrayType` impl (see above).
///
/// ### Enumeration
///
/// Enumerations may be defined in Rust and can match SQL by
/// integer discriminant or variant name.
///
/// With `#[repr(_)]` the integer representation is used when converting from/to SQL and expects
/// that SQL type (e.g., `INT`). Without, the names of the variants are used instead and
/// expects a textual SQL type (e.g., `VARCHAR`, `TEXT`).
///
/// ```rust,ignore
/// #[derive(sqlx::Type)]
/// #[repr(i32)]
/// enum Color { Red = 1, Green = 2, Blue = 3 }
/// ```
///
/// ```rust,ignore
/// #[derive(sqlx::Type)]
/// #[sqlx(type_name = "color")] // only for PostgreSQL to match a type definition
/// #[sqlx(rename_all = "lowercase")]
/// enum Color { Red, Green, Blue }
/// ```
///
/// ### Records
///
/// User-defined composite types are supported through deriving a `struct`.
///
/// This is only supported for PostgreSQL.
///
/// ```rust,ignore
/// #[derive(sqlx::Type)]
/// #[sqlx(type_name = "interface_type")]
/// struct InterfaceType {
///     name: String,
///     supplier_id: i32,
///     price: f64
/// }
/// ```
///
pub trait Type<DB: Database> {
    /// Returns the canonical SQL type for this Rust type.
    ///
    /// When binding arguments, this is used to tell the database what is about to be sent; which,
    /// the database then uses to guide query plans. This can be overridden by `Encode::produces`.
    ///
    /// A map of SQL types to Rust types is populated with this and used
    /// to determine the type that is returned from the anonymous struct type from `query!`.
    fn type_info() -> DB::TypeInfo;

    /// Determines if this Rust type is compatible with the given SQL type.
    ///
    /// When decoding values from a row, this method is checked to determine if we should continue
    /// or raise a runtime type mismatch error.
    ///
    /// When binding arguments with `query!` or `query_as!`, this method is consulted to determine
    /// if the Rust type is acceptable.
    fn compatible(ty: &DB::TypeInfo) -> bool {
        *ty == Self::type_info()
    }
}

// for references, the underlying SQL type is identical
impl<T: ?Sized + Type<DB>, DB: Database> Type<DB> for &'_ T {
    fn type_info() -> DB::TypeInfo {
        <T as Type<DB>>::type_info()
    }

    fn compatible(ty: &DB::TypeInfo) -> bool {
        <T as Type<DB>>::compatible(ty)
    }
}

// for optionals, the underlying SQL type is identical
impl<T: Type<DB>, DB: Database> Type<DB> for Option<T> {
    fn type_info() -> DB::TypeInfo {
        <T as Type<DB>>::type_info()
    }

    fn compatible(ty: &DB::TypeInfo) -> bool {
        <T as Type<DB>>::compatible(ty)
    }
}
