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use std::fmt::{Debug, Display};
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use std::ops::Deref;
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pub use bonsaidb_macros::Api;
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use serde::{Deserialize, Serialize};
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use crate::schema::{Authority, Name, Qualified, QualifiedName};
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/// An API request type. This trait is used by BonsaiDb's server to allow a
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/// client to send a request of this type, and the server can respond with a
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/// `Result<`[`Api::Response`]`,`[`Api::Error`]`>`.
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///
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/// # Deriving this trait
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///
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/// This trait can be derived. The only required attribute is `name`:
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///
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/// - `name = "api-name"` or `name = "api-name", authority = "api-authority"`:
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///   Configures the Api's fully qualified name. This name must be unique across
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///   all other Apis installed. When creating an Api that is meant to be reused,
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///   ensure that a unique authority is used to prevent name collisions.
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/// - `response = ResponseType`: Configures the [`Api::Response`] associated
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///   type. This is the type that the handler will return upon success. If not
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///   specified, `()` is used.
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/// - `error = ErrorType`: Configures the [`Api::Error`] associated type. This
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///   is the type that the handler will return upon error. If not specified,
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///   [`Infallible`] is used.
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///
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/// ```rust
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/// use bonsaidb_core::api::Api;
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/// use serde::{Deserialize, Serialize};
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///
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/// #[derive(Api, Debug, Serialize, Deserialize)]
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/// #[api(name = "list-records", response = Vec<Record>)]
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/// # #[api(core = bonsaidb_core)]
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/// struct ListRecords {
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///     starting_id: u64,
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/// }
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///
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/// #[derive(Debug, Serialize, Deserialize, Clone)]
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/// struct Record {
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///     title: String,
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/// }
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/// ```
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pub trait Api: Serialize + for<'de> Deserialize<'de> + Send + Sync + Debug + 'static {
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    /// The type that represents an API response. This type will be sent to clients from the server.
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    type Response: Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync + Debug;
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    /// The error type that this  can return.
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    type Error: ApiError;
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    /// Returns the unique name of this api.
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    fn name() -> ApiName;
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}
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/// An Error type that can be used in within an [`Api`] definition.
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///
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/// The reason `std::convert::Infallible` can't be used is because `Api`
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/// errors must be able to be serialized across a network connection. While a
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/// value will never be present when this is Infallible, the associated type
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/// still must be declared as Serializable.
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#[derive(thiserror::Error, Debug, Clone, Serialize, Deserialize)]
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#[error("an unreachable error")]
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pub enum Infallible {}
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/// An error that can be used within a [`Api`] definition.
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pub trait ApiError:
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    std::fmt::Display + Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync + Debug
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{
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}
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impl<T> ApiError for T where
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    T: std::fmt::Display + Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync + Debug
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{
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}
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/// The result of executing a custom API call.
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pub type ApiResult<Api> = Result<<Api as self::Api>::Response, <Api as self::Api>::Error>;
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/// The qualified name of an [`Api`](crate::api::Api).
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#[derive(Hash, PartialEq, Eq, Deserialize, Serialize, Debug, Clone, Ord, PartialOrd)]
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#[serde(transparent)]
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pub struct ApiName(QualifiedName);
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impl Qualified for ApiName {
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    fn new<A: Into<Authority>, N: Into<Name>>(authority: A, name: N) -> Self {
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        Self(QualifiedName::new(authority, name))
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    }
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}
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impl Display for ApiName {
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    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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        Display::fmt(&self.0, f)
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    }
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}
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impl Deref for ApiName {
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    type Target = QualifiedName;
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    fn deref(&self) -> &Self::Target {
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        &self.0
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    }
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}