use axum::http::StatusCode;
use axum::response::{IntoResponse, Response};
use serde::Serialize;

/// Unified API error type
#[derive(Debug, thiserror::Error)]
pub enum ApiError {
    #[error("Not found: {0}")]
    NotFound(String),

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

    #[error("Unauthorized")]
    Unauthorized,

    #[error("Forbidden")]
    Forbidden,

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

    #[error("License invalid or expired")]
    LicenseInvalid,

    #[error("Module not enabled: {0}")]
    ModuleNotEnabled(String),

    #[error("Rate limited")]
    RateLimited,

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

    #[error(transparent)]
    Database(#[from] sqlx::Error),

    #[error(transparent)]
    Anyhow(#[from] anyhow::Error),
}

#[derive(Serialize)]
struct ErrorResponse {
    error: String,
    message: String,
}

impl IntoResponse for ApiError {
    fn into_response(self) -> Response {
        let (status, error_type, message) = match &self {
            ApiError::NotFound(msg) => (StatusCode::NOT_FOUND, "not_found", msg.clone()),
            ApiError::BadRequest(msg) => (StatusCode::BAD_REQUEST, "bad_request", msg.clone()),
            ApiError::Unauthorized => {
                (StatusCode::UNAUTHORIZED, "unauthorized", "Unauthorized".to_string())
            }
            ApiError::Forbidden => {
                (StatusCode::FORBIDDEN, "forbidden", "Forbidden".to_string())
            }
            ApiError::Conflict(msg) => (StatusCode::CONFLICT, "conflict", msg.clone()),
            ApiError::LicenseInvalid => (
                StatusCode::PAYMENT_REQUIRED,
                "license_invalid",
                "License invalid or expired".to_string(),
            ),
            ApiError::ModuleNotEnabled(module) => (
                StatusCode::PAYMENT_REQUIRED,
                "module_not_enabled",
                format!("Module not enabled: {module}"),
            ),
            ApiError::RateLimited => (
                StatusCode::TOO_MANY_REQUESTS,
                "rate_limited",
                "Too many requests".to_string(),
            ),
            ApiError::Internal(msg) => {
                tracing::error!("Internal error: {msg}");
                (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    "internal_error",
                    "Internal server error".to_string(),
                )
            }
            ApiError::Database(e) => {
                tracing::error!("Database error: {e}");
                (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    "internal_error",
                    "Internal server error".to_string(),
                )
            }
            ApiError::Anyhow(e) => {
                tracing::error!("Unexpected error: {e}");
                (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    "internal_error",
                    "Internal server error".to_string(),
                )
            }
        };

        let body = ErrorResponse {
            error: error_type.to_string(),
            message,
        };

        (status, axum::Json(body)).into_response()
    }
}

/// Result alias for API handlers
pub type ApiResult<T> = Result<T, ApiError>;