drop/libraries/native_model/src/lib.rs

//! `native_model` is a Rust crate that acts as a thin wrapper around serialized data, adding identity and version information.
//!
//! - It aims to ensure:
//!   - **Interoperability**: Different applications can work together even if they use different data model versions.
//!   - **Data Consistency**: Ensures the data is processed as expected.
//!   - **Flexibility**: Allows the use of any serialization format. Mode details [here](https://github.com/vincent-herlemont/native_model#setup-your-serialization-format).
//!   - **Minimal Performance Overhead**: Current performance has a minimal overhead see [performance](https://github.com/vincent-herlemont/native_model#performance) section.
//! - **Suitability**:
//!   - Suitable for applications that are written in Rust, evolve independently, store data locally, and require incremental upgrades.
//!   - Not suitable for non-Rust applications, systems not controlled by the user, or when human-readable formats are needed.
//! - **Setup**:
//!   - Users must define their own serialization format and data model. Mode details [here](https://github.com/vincent-herlemont/native_model#setup-your-serialization-format).
//! - **Development Stage**:
//!   - The crate is in early development, and performance is expected to improve over time.
//!
//! See examples in the [README.md](https://github.com/vincent-herlemont/native_model) file.
//!
//! # Codecs
//!
//! `native_model` comes with several optional built-in serializer features
//! available:
//!
//! - [bincode](https://crates.io/crates/bincode/1.3.3) `1.3` ·
//! [`Annotate your type`](crate::native_model) with
//! `native_model::bincode_1_3::Bincode` to have `native_db` use this default
//! codec for serializing & deserializing. **Warning: This codec may not work
//! with all serde-derived types.**
//!
//! - [bincode](https://crates.io/crates/bincode/2.0.0-rc.3) `2.0.0-rc.3` ·
//! Enable the `bincode_2_rc` feature and use the
//! `native_model::bincode_2_rc::Bincode` attribute to have `native_db` use this
//! crate. **Warning: This codec may not work with all serde-derived types.**
//!
//! - [postcard](https://crates.io/crates/postcard/1.0.8) `1.0` ·
//! Enable the `postcard_1_0` feature and use the
//! `native_model::postcard_1_0::PostCard` attribute. **Warning: This codec may
//! not work with all serde-derived types.**
//!
//! - [rmp-serde](https://crates.io/crates/rmp-serde/1.3.0) `1.3` ·
//! Enable the `rmp_serde_1_3` feature and use the
//! `native_model::rmp_serde_1_3::RmpSerde` attribute.
//!
//! ###### Codec example:
//!
//! As example, to use `rmp-serde`:
//!
//! 1. In your project's `Cargo.toml` file, enable the `rmp_serde_1_3` feature
//! for the `native_model` dependency. Check
//! [crates.io](https://crates.io/crates/native_model) for the most recent
//! version number.
//!
//! ```toml
//! [dependencies]
//! serde = { version = "1.0", features = [ "derive" ] }
//! native_model = { version = "0.4", features = [ "rmp_serde_1_3" ] }
//! ```
//!
//! 2. Assign the `rmp_serde_1_3` codec to your type using the `with` attribute:
//!
//! ```rust
//! #[derive(Clone, Default, serde::Deserialize, serde::Serialize)]
//! #[native_model(id = 1, version = 1, with = native_model::rmp_serde_1_3::RmpSerde)]
//! struct MyStruct {
//!     my_string: String,
//!     // etc.
//! }
//! ```
//!
//! ###### Additional reading
//!
//! You may also want to check out
//! [David Koloski](https://github.com/djkoloski)'s
//! [Rust serialization benchmarks](https://github.com/djkoloski/rust_serialization_benchmark)
//! for help selecting the codec (i.e. `bincode_1_3`, `rmp_serde_1_3`, etc.)
//! that's best for your project.

#[cfg(any(
    feature = "serde",
    feature = "bincode_1_3",
    feature = "bincode_2_rc",
    feature = "postcard_1_0",
    feature = "rmp_serde_1_3",
    doc
))]
mod codec;

#[cfg(any(
    feature = "serde",
    feature = "bincode_1_3",
    feature = "bincode_2_rc",
    feature = "postcard_1_0",
    feature = "rmp_serde_1_3",
    doc
))]
pub use codec::*;
mod header;
pub mod wrapper;

// Macro to generate a [`native_model`] implementation for a struct.
pub use native_model_macro::*;

use wrapper::*;

use thiserror::Error;

pub type Result<T> = std::result::Result<T, Error>;

#[derive(Error, Debug)]
pub enum Error {
    #[error("Invalid header")]
    InvalidHeader,
    #[error("Failed to decode native model")]
    DecodeError,
    #[error(transparent)]
    DecodeBodyError(#[from] DecodeBodyError),
    #[error(transparent)]
    EncodeBodyError(#[from] EncodeBodyError),
    #[error(transparent)]
    UpgradeError(#[from] UpgradeError),
    #[error("Upgrade from {} to {} is not supported", from, to)]
    UpgradeNotSupported { from: u32, to: u32 },
    #[error(transparent)]
    DowngradeError(#[from] DowngradeError),
    #[error("Downgrade from {} to {} is not supported", from, to)]
    DowngradeNotSupported { from: u32, to: u32 },
    #[error("Wrong type id expected: {}, actual: {}", expected, actual)]
    WrongTypeId { expected: u32, actual: u32 },
}

pub type DecodeResult<T> = std::result::Result<T, DecodeBodyError>;

#[derive(Error, Debug)]
#[error("Decode body error: {msg}")]
pub enum DecodeBodyError {
    #[error("Mismatched model id")]
    MismatchedModelId,
    #[error("Decode error: {msg}")]
    DecodeError {
        msg: String,
        #[source]
        source: anyhow::Error,
    },
}

pub type EncodeResult<T> = std::result::Result<T, EncodeBodyError>;

#[derive(Error, Debug)]
#[error("Encode body error: {msg}")]
pub struct EncodeBodyError {
    pub msg: String,
    #[source]
    pub source: anyhow::Error,
}

#[derive(Error, Debug)]
#[error("Upgrade error: {msg}")]
pub struct UpgradeError {
    pub msg: String,
    #[source]
    pub source: anyhow::Error,
}

#[derive(Error, Debug)]
#[error("Downgrade error: {msg}")]
pub struct DowngradeError {
    pub msg: String,
    #[source]
    pub source: anyhow::Error,
}

/// Allows to encode a [`native_model`] into a [`Vec<u8>`].
///
/// See examples:
///    - [README.md](https://github.com/vincent-herlemont/native_model) file.
///    - other [examples](https://github.com/vincent-herlemont/native_model/tree/master/tests/example)
///
/// # Errors
///
/// The errors returned from this function depend on the [`Encode`] trait
/// implementor (the serializer), i.e. `bincode_2_rc`.
pub fn encode<T: crate::Model>(model: &T) -> Result<Vec<u8>> {
    T::native_model_encode(model)
}

/// Allows to encode a [`native_model`] into a [`Vec<u8>`] with a specific version.
/// See examples:
///    - [README.md](https://github.com/vincent-herlemont/native_model) file.
///    - other [examples](https://github.com/vincent-herlemont/native_model/tree/master/tests/example)
pub fn encode_downgrade<T: crate::Model>(model: T, version: u32) -> Result<Vec<u8>> {
    T::native_model_encode_downgrade(model, version)
}

/// Allows to decode a [`native_model`] from a [`Vec<u8>`] and returns the version ([`u32`]).
/// See examples:
///    - [README.md](https://github.com/vincent-herlemont/native_model) file.
///    - other [examples](https://github.com/vincent-herlemont/native_model/tree/master/tests/example)
///
/// # Errors
///
/// The errors returned from this function depend on the [`Decode`] trait
/// implementor (the deserializer), i.e. `bincode_2_rc`.
pub fn decode<T: crate::Model>(data: Vec<u8>) -> Result<(T, u32)> {
    T::native_model_decode(data)
}

pub trait Model: Sized {
    fn native_model_id() -> u32;
    fn native_model_id_str() -> &'static str;
    fn native_model_version() -> u32;
    fn native_model_version_str() -> &'static str;

    // --------------- Decode ---------------
    fn native_model_decode_body(data: Vec<u8>, id: u32) -> DecodeResult<Self>;

    fn native_model_decode_upgrade_body(data: Vec<u8>, id: u32, version: u32) -> Result<Self>;

    fn native_model_decode(data: Vec<u8>) -> Result<(Self, u32)> {
        let native_model = crate::Wrapper::deserialize(&data[..]).unwrap();
        let source_id = native_model.get_id();
        let source_version = native_model.get_version();
        let result = Self::native_model_decode_upgrade_body(
            native_model.value().to_vec(),
            source_id,
            source_version,
        )?;
        Ok((result, source_version))
    }

    // --------------- Encode ---------------

    fn native_model_encode_body(&self) -> EncodeResult<Vec<u8>>;

    fn native_model_encode_downgrade_body(self, version: u32) -> Result<Vec<u8>>;

    fn native_model_encode(&self) -> Result<Vec<u8>> {
        let mut data = self.native_model_encode_body()?;
        let data = crate::native_model_encode(
            &mut data,
            Self::native_model_id(),
            Self::native_model_version(),
        );
        Ok(data)
    }

    fn native_model_encode_downgrade(self, version: u32) -> Result<Vec<u8>> {
        let mut data = self.native_model_encode_downgrade_body(version)?;
        let data = crate::native_model_encode(&mut data, Self::native_model_id(), version);
        Ok(data)
    }
}