use axum::http::StatusCode;
use axum::response::{IntoResponse, Response};
use export::data::{AppResponseData, NoData};
use thiserror::Error;

use cache::redis::RedisError;
use storage::StorageError;

pub type UserResult<T> = Result<T, UserError>;

#[derive(Debug, Error)]
pub enum UserError {
    #[error("bad request: {0}")]
    BadRequest(String),
    #[error("unauthorized: {0}")]
    Unauthorized(String),
    #[error("forbidden: {0}")]
    Forbidden(String),
    #[error("not found: {0}")]
    NotFound(String),
    #[error("conflict: {0}")]
    Conflict(String),
    #[error("rate limited: {0}")]
    RateLimited(String),
    #[error("internal error: {0}")]
    Internal(String),

    #[error("database error: {0}")]
    Sqlx(#[from] db::conn::SqlxError),
    #[error("redis error: {0}")]
    Redis(#[from] RedisError),
    #[error("storage error: {0}")]
    Storage(#[from] StorageError),
    #[error("uuid: {0}")]
    Uuid(#[from] uuid::Error),
}

impl From<axum::extract::rejection::JsonRejection> for UserError {
    fn from(re: axum::extract::rejection::JsonRejection) -> Self {
        UserError::BadRequest(re.body_text())
    }
}

impl From<axum::extract::rejection::PathRejection> for UserError {
    fn from(re: axum::extract::rejection::PathRejection) -> Self {
        UserError::BadRequest(re.body_text())
    }
}

impl From<axum::extract::rejection::QueryRejection> for UserError {
    fn from(re: axum::extract::rejection::QueryRejection) -> Self {
        UserError::BadRequest(re.body_text())
    }
}

impl UserError {
    fn status(&self) -> StatusCode {
        match self {
            UserError::BadRequest(_) => StatusCode::BAD_REQUEST,
            UserError::Forbidden(_) => StatusCode::FORBIDDEN,
            UserError::Conflict(_) => StatusCode::CONFLICT,
            UserError::Unauthorized(_) => StatusCode::UNAUTHORIZED,
            UserError::NotFound(_) => StatusCode::NOT_FOUND,
            UserError::RateLimited(_) => StatusCode::TOO_MANY_REQUESTS,
            UserError::Internal(_)
            | UserError::Sqlx(_)
            | UserError::Redis(_)
            | UserError::Storage(_)
            | UserError::Uuid(_) => StatusCode::INTERNAL_SERVER_ERROR,
        }
    }

    fn is_user_facing(&self) -> bool {
        matches!(
            self,
            UserError::BadRequest(_)
                | UserError::Unauthorized(_)
                | UserError::Forbidden(_)
                | UserError::NotFound(_)
                | UserError::Conflict(_)
                | UserError::RateLimited(_)
        )
    }

    /// Low-cardinality label for metrics emission.
    /// Bounded vocabulary; never derives from the error message body.
    pub fn error_kind(&self) -> &'static str {
        match self {
            UserError::BadRequest(_) => "bad_request",
            UserError::Unauthorized(_) => "unauthorized",
            UserError::Forbidden(_) => "forbidden",
            UserError::NotFound(_) => "not_found",
            UserError::Conflict(_) => "conflict",
            UserError::RateLimited(_) => "rate_limited",
            UserError::Internal(_) => "internal_other",
            UserError::Sqlx(_) => "internal_db",
            UserError::Redis(_) => "internal_redis",
            UserError::Storage(_) => "internal_storage",
            UserError::Uuid(_) => "internal_uuid",
        }
    }
}

impl IntoResponse for UserError {
    fn into_response(self) -> Response {
        let status = self.status();
        let msg = if self.is_user_facing() {
            self.to_string()
        } else {
            tracing::error!(error = %self, "user internal error");
            "internal error".to_string()
        };
        AppResponseData::<NoData>::err_plain(status.as_u16() as i32, msg).into_response()
    }
}