src/domain/error.rs

use axum::{
    http::StatusCode,
    response::{IntoResponse, Response},
    Json,
};
use thiserror::Error;

/// Production-grade error codes for API clients
/// Follows Google API error code conventions
#[derive(Error, Debug)]
pub enum AppError {
    #[error("Database error: {0}")]
    Database(#[from] sqlx::Error),

    #[error("Authentication failed: {0}")]
    Auth(String),

    #[error("Authorization failed: {0}")]
    Forbidden(String),

    #[error("Invalid request: {0}")]
    BadRequest(String),

    #[error("Resource not found: {0}")]
    NotFound(String),

    #[error("Internal server error: {0}")]
    Internal(String),

    #[error("Validation error: {0}")]
    Validation(String),

    #[error("Too many requests")]
    RateLimited,

    #[error("Request timeout")]
    Timeout,

    #[error("Conflict: {0}")]
    Conflict(String),

    #[error("Unprocessable entity: {0}")]
    UnprocessableEntity(String),
}

#[derive(serde::Serialize)]
pub struct ErrorResponse {
    pub success: bool,
    pub error: ErrorDetails,
}

#[derive(serde::Serialize)]
pub struct ErrorDetails {
    pub code: String,
    pub message: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub details: Option<String>,
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        let (status, error_code, message, details) = match self {
            AppError::Database(ref e) => {
                tracing::error!("Database error: {:?}", e);
                (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    "INTERNAL_ERROR",
                    "Database operation failed".to_string(),
                    Some(format!("{:?}", e)),
                )
            }
            AppError::Auth(msg) => {
                tracing::warn!("Auth failure: {}", msg);
                (StatusCode::UNAUTHORIZED, "UNAUTHENTICATED", msg, None)
            }
            AppError::Forbidden(msg) => {
                tracing::warn!("Authorization failure: {}", msg);
                (StatusCode::FORBIDDEN, "PERMISSION_DENIED", msg, None)
            }
            AppError::BadRequest(msg) => {
                tracing::debug!("Bad request: {}", msg);
                (StatusCode::BAD_REQUEST, "INVALID_ARGUMENT", msg, None)
            }
            AppError::NotFound(msg) => {
                tracing::debug!("Resource not found: {}", msg);
                (StatusCode::NOT_FOUND, "NOT_FOUND", msg, None)
            }
            AppError::Internal(msg) => {
                tracing::error!("Internal error: {}", msg);
                (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    "INTERNAL_ERROR",
                    "An unexpected error occurred".to_string(),
                    Some(msg),
                )
            }
            AppError::Validation(msg) => {
                tracing::debug!("Validation error: {}", msg);
                (StatusCode::BAD_REQUEST, "INVALID_ARGUMENT", msg, None)
            }
            AppError::RateLimited => {
                tracing::warn!("Rate limit exceeded");
                (
                    StatusCode::TOO_MANY_REQUESTS,
                    "RESOURCE_EXHAUSTED",
                    "Too many requests. Please try again later.".to_string(),
                    None,
                )
            }
            AppError::Timeout => {
                tracing::warn!("Request timeout");
                (
                    StatusCode::REQUEST_TIMEOUT,
                    "DEADLINE_EXCEEDED",
                    "Request processing timeout. Please try again.".to_string(),
                    None,
                )
            }
            AppError::Conflict(msg) => {
                tracing::warn!("Conflict: {}", msg);
                (StatusCode::CONFLICT, "ALREADY_EXISTS", msg, None)
            }
            AppError::UnprocessableEntity(msg) => {
                tracing::warn!("Unprocessable entity: {}", msg);
                (
                    StatusCode::UNPROCESSABLE_ENTITY,
                    "FAILED_PRECONDITION",
                    msg,
                    None,
                )
            }
        };

        let body = Json(ErrorResponse {
            success: false,
            error: ErrorDetails {
                code: error_code.to_string(),
                message,
                details: if cfg!(debug_assertions) {
                    details
                } else {
                    None
                },
            },
        });

        (status, body).into_response()
    }
}

pub type AppResult<T> = Result<T, AppError>;