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use super::StatusCode;
use crate::SharedString;
use serde::Serialize;
use std::borrow::Cow;

/// Trait for response code.
/// See [Problem Details for HTTP APIs](https://tools.ietf.org/html/rfc7807).
pub trait ResponseCode {
    /// A type for the error code.
    type ErrorCode: Serialize;

    /// A type for the business code.
    type BusinessCode: Serialize;

    /// 200 Ok.
    const OK: Self;
    /// 400 Bad Request.
    const BAD_REQUEST: Self;
    /// 500 Internal Server Error.
    const INTERNAL_SERVER_ERROR: Self;

    /// Status code.
    fn status_code(&self) -> u16;

    /// Returns `true` if the response is successful.
    fn is_success(&self) -> bool;

    /// Error code.
    #[inline]
    fn error_code(&self) -> Option<Self::ErrorCode> {
        None
    }

    /// Business code.
    #[inline]
    fn business_code(&self) -> Option<Self::BusinessCode> {
        None
    }

    /// A URI reference that identifies the problem type.
    /// For successful response, it should be `None`.
    fn type_uri(&self) -> Option<SharedString> {
        None
    }

    /// A short, human-readable summary of the problem type.
    /// For successful response, it should be `None`.
    fn title(&self) -> Option<SharedString> {
        None
    }

    /// A context-specific descriptive message. If the response is not successful,
    /// it should be a human-readable explanation specific to this occurrence of the problem.
    fn message(&self) -> Option<SharedString> {
        None
    }
}

impl ResponseCode for StatusCode {
    type ErrorCode = SharedString;
    type BusinessCode = u16;

    const OK: Self = StatusCode::OK;
    const BAD_REQUEST: Self = StatusCode::BAD_REQUEST;
    const INTERNAL_SERVER_ERROR: Self = StatusCode::INTERNAL_SERVER_ERROR;

    #[inline]
    fn status_code(&self) -> u16 {
        self.as_u16()
    }

    #[inline]
    fn is_success(&self) -> bool {
        self.is_success()
    }

    #[inline]
    fn type_uri(&self) -> Option<SharedString> {
        None
    }

    #[inline]
    fn title(&self) -> Option<SharedString> {
        if self.is_success() {
            None
        } else {
            self.canonical_reason().map(Cow::Borrowed)
        }
    }

    #[inline]
    fn message(&self) -> Option<SharedString> {
        if self.is_success() {
            self.canonical_reason().map(Cow::Borrowed)
        } else {
            None
        }
    }
}