use axum::http::StatusCode;
use axum::response::{IntoResponse, Response};
use axum::Json;
use serde_json::json;

/// Every handler returns `Result<_, AppError>`; errors become
/// `{"error": "..."}` with a sensible status code.
#[derive(Debug)]
pub struct AppError {
    pub status: StatusCode,
    pub message: String,
}

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

impl AppError {
    pub fn new(status: StatusCode, message: impl Into<String>) -> Self {
        Self { status, message: message.into() }
    }
    pub fn bad_request(m: impl Into<String>) -> Self {
        Self::new(StatusCode::BAD_REQUEST, m)
    }
    pub fn unauthorized(m: impl Into<String>) -> Self {
        Self::new(StatusCode::UNAUTHORIZED, m)
    }
    pub fn forbidden(m: impl Into<String>) -> Self {
        Self::new(StatusCode::FORBIDDEN, m)
    }
    pub fn not_found(m: impl Into<String>) -> Self {
        Self::new(StatusCode::NOT_FOUND, m)
    }
    pub fn conflict(m: impl Into<String>) -> Self {
        Self::new(StatusCode::CONFLICT, m)
    }
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        if self.status.is_server_error() {
            tracing::error!("{}", self.message);
        }
        (self.status, Json(json!({ "error": self.message }))).into_response()
    }
}

impl From<anyhow::Error> for AppError {
    fn from(e: anyhow::Error) -> Self {
        Self::new(StatusCode::BAD_GATEWAY, format!("{e:#}"))
    }
}

impl From<sqlx::Error> for AppError {
    fn from(e: sqlx::Error) -> Self {
        Self::new(StatusCode::INTERNAL_SERVER_ERROR, format!("database error: {e}"))
    }
}

impl From<std::io::Error> for AppError {
    fn from(e: std::io::Error) -> Self {
        Self::new(StatusCode::INTERNAL_SERVER_ERROR, format!("io error: {e}"))
    }
}

impl From<serde_json::Error> for AppError {
    fn from(e: serde_json::Error) -> Self {
        Self::bad_request(format!("invalid JSON: {e}"))
    }
}

impl From<axum::extract::multipart::MultipartError> for AppError {
    fn from(e: axum::extract::multipart::MultipartError) -> Self {
        Self::bad_request(format!("upload failed: {e}"))
    }
}