//! Error types and transformations

use crate::headers::vapid::VapidError;
use crate::routers::RouterError;
use actix_web::{
    dev::ServiceResponse,
    error::{JsonPayloadError, PayloadError, ResponseError},
    http::header::{CacheControl, CacheDirective},
    http::StatusCode,
    middleware::ErrorHandlerResponse,
    HttpResponse, Result,
};
// Sentry uses the backtrace crate, not std::backtrace.
use actix_http::header;
use backtrace::Backtrace;
use serde::ser::SerializeMap;
use serde::{Serialize, Serializer};
use std::error::Error;
use std::fmt::{self, Display};
use thiserror::Error;
use validator::{ValidationErrors, ValidationErrorsKind};

use autopush_common::{db::error::DbError, errors::ReportableError};

/// Common `Result` type.
pub type ApiResult<T> = Result<T, ApiError>;

/// A link for more info on the returned error
const ERROR_URL: &str = "http://autopush.readthedocs.io/en/latest/http.html#error-codes";
const RETRY_AFTER_PERIOD: &str = "120"; // retry after 2 minutes;

/// The main error type.
#[derive(Debug)]
pub struct ApiError {
    pub kind: ApiErrorKind,
    pub backtrace: Backtrace,
    pub extras: Option<Vec<(String, String)>>,
}

impl ApiError {
    /// Render a 404 response
    // wrapper during the move. this should switch to autopush-common's impl.
    pub fn render_404<B>(res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
        //TODO: remove unwrap here.
        Ok(autopush_common::errors::render_404(res).unwrap())
    }
}

/// The possible errors this application could encounter
#[derive(Debug, Error)]
pub enum ApiErrorKind {
    #[error(transparent)]
    Io(#[from] std::io::Error),

    #[error(transparent)]
    Metrics(#[from] cadence::MetricError),

    #[error(transparent)]
    Validation(#[from] validator::ValidationErrors),

    #[error(transparent)]
    PayloadError(actix_web::Error),

    #[error(transparent)]
    VapidError(#[from] VapidError),

    #[error(transparent)]
    Router(#[from] RouterError),

    #[error(transparent)]
    Jwt(#[from] jsonwebtoken::errors::Error),

    #[error("Error while validating token")]
    TokenHashValidation(#[source] openssl::error::ErrorStack),

    #[error("Error while creating secret")]
    RegistrationSecretHash(#[source] openssl::error::ErrorStack),

    #[error("Error while creating endpoint URL: {0}")]
    EndpointUrl(#[source] autopush_common::errors::ApcError),

    #[error("Database error: {0}")]
    Database(#[from] DbError),

    #[error("Conditional database operation failed: {0}")]
    Conditional(String),

    #[error("Invalid token")]
    InvalidToken,

    #[error("UAID not found")]
    NoUser,

    #[error("No such subscription")]
    NoSubscription,

    /// A specific issue with the encryption headers
    #[error("{0}")]
    InvalidEncryption(String),

    /// Used if the API version given is not v1 or v2
    #[error("Invalid API version")]
    InvalidApiVersion,

    #[error("Missing TTL value")]
    NoTTL,

    #[error("Invalid router type")]
    InvalidRouterType,

    #[error("Invalid router token")]
    InvalidRouterToken,

    #[error("Invalid message ID")]
    InvalidMessageId,

    #[error("Invalid Authentication")]
    InvalidAuthentication,

    #[error("Invalid Local Auth {0}")]
    InvalidLocalAuth(String),

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

    #[error("ERROR:Success")]
    LogCheck,
}

impl ApiErrorKind {
    /// Get the associated HTTP status code
    pub fn status(&self) -> StatusCode {
        match self {
            ApiErrorKind::PayloadError(e) => e.as_response_error().status_code(),
            ApiErrorKind::Router(e) => e.status(),

            ApiErrorKind::Validation(_)
            | ApiErrorKind::InvalidEncryption(_)
            | ApiErrorKind::NoTTL
            | ApiErrorKind::InvalidRouterType
            | ApiErrorKind::InvalidRouterToken
            | ApiErrorKind::InvalidMessageId => StatusCode::BAD_REQUEST,

            ApiErrorKind::VapidError(_)
            | ApiErrorKind::Jwt(_)
            | ApiErrorKind::TokenHashValidation(_)
            | ApiErrorKind::InvalidAuthentication
            | ApiErrorKind::InvalidLocalAuth(_) => StatusCode::UNAUTHORIZED,

            ApiErrorKind::InvalidToken | ApiErrorKind::InvalidApiVersion => StatusCode::NOT_FOUND,

            ApiErrorKind::NoUser | ApiErrorKind::NoSubscription => StatusCode::GONE,

            ApiErrorKind::LogCheck => StatusCode::IM_A_TEAPOT,

            ApiErrorKind::Conditional(_) => StatusCode::SERVICE_UNAVAILABLE,

            ApiErrorKind::Database(e) => e.status(),

            ApiErrorKind::General(_)
            | ApiErrorKind::Io(_)
            | ApiErrorKind::Metrics(_)
            | ApiErrorKind::EndpointUrl(_)
            | ApiErrorKind::RegistrationSecretHash(_) => StatusCode::INTERNAL_SERVER_ERROR,
        }
    }

    /// Specify the label to use for metrics reporting.
    pub fn metric_label(&self) -> Option<&'static str> {
        Some(match self {
            ApiErrorKind::PayloadError(_) => "payload_error",
            ApiErrorKind::Router(e) => return e.metric_label(),

            ApiErrorKind::Validation(_) => "validation",
            ApiErrorKind::InvalidEncryption(_) => "invalid_encryption",
            ApiErrorKind::NoTTL => "no_ttl",
            ApiErrorKind::InvalidRouterType => "invalid_router_type",
            ApiErrorKind::InvalidRouterToken => "invalid_router_token",
            ApiErrorKind::InvalidMessageId => "invalid_message_id",

            ApiErrorKind::VapidError(_) => "vapid_error",
            ApiErrorKind::Jwt(_) => "jwt",
            ApiErrorKind::TokenHashValidation(_) => "token_hash_validation",
            ApiErrorKind::InvalidAuthentication => "invalid_authentication",
            ApiErrorKind::InvalidLocalAuth(_) => "invalid_local_auth",

            ApiErrorKind::InvalidToken => "invalid_token",
            ApiErrorKind::InvalidApiVersion => "invalid_api_version",

            ApiErrorKind::NoUser => "no_user",
            ApiErrorKind::NoSubscription => "no_subscription",

            ApiErrorKind::LogCheck => "log_check",

            ApiErrorKind::General(_) => "general",
            ApiErrorKind::Io(_) => "io",
            ApiErrorKind::Metrics(_) => "metrics",
            ApiErrorKind::Database(e) => return e.metric_label(),
            ApiErrorKind::Conditional(_) => "conditional",
            ApiErrorKind::EndpointUrl(e) => return e.metric_label(),
            ApiErrorKind::RegistrationSecretHash(_) => "registration_secret_hash",
        })
    }

    /// Don't report all errors to sentry
    pub fn is_sentry_event(&self) -> bool {
        match self {
            // ignore selected validation errors.
            ApiErrorKind::Router(e) => e.is_sentry_event(),
            ApiErrorKind::Database(e) => e.is_sentry_event(),
            // Ignore common webpush errors
            ApiErrorKind::NoTTL | ApiErrorKind::InvalidEncryption(_) |
            // Ignore common VAPID erros
            ApiErrorKind::VapidError(_)
                | ApiErrorKind::Jwt(_)
                | ApiErrorKind::TokenHashValidation(_)
                | ApiErrorKind::InvalidAuthentication
                | ApiErrorKind::InvalidLocalAuth(_) |
            // Ignore missing or invalid user errors
            ApiErrorKind::NoUser | ApiErrorKind::NoSubscription |
            // Ignore oversized payload.
            ApiErrorKind::PayloadError(_) |
            ApiErrorKind::Validation(_) |
            ApiErrorKind::Conditional(_) => false,
            _ => true,
        }
    }

    /// Get the associated error number
    pub fn errno(&self) -> Option<usize> {
        match self {
            ApiErrorKind::Router(e) => e.errno(),

            ApiErrorKind::Validation(e) => errno_from_validation_errors(e),

            ApiErrorKind::InvalidToken | ApiErrorKind::InvalidApiVersion => Some(102),

            ApiErrorKind::NoUser => Some(103),

            ApiErrorKind::PayloadError(error)
                if matches!(error.as_error(), Some(PayloadError::Overflow))
                    || matches!(error.as_error(), Some(JsonPayloadError::Overflow { .. })) =>
            {
                Some(104)
            }

            ApiErrorKind::NoSubscription => Some(106),

            ApiErrorKind::InvalidRouterType => Some(108),

            ApiErrorKind::VapidError(_)
            | ApiErrorKind::TokenHashValidation(_)
            | ApiErrorKind::Jwt(_)
            | ApiErrorKind::InvalidAuthentication
            | ApiErrorKind::InvalidLocalAuth(_) => Some(109),

            ApiErrorKind::InvalidEncryption(_) => Some(110),

            ApiErrorKind::NoTTL => Some(111),

            ApiErrorKind::LogCheck => Some(999),

            ApiErrorKind::General(_)
            | ApiErrorKind::Io(_)
            | ApiErrorKind::Metrics(_)
            | ApiErrorKind::Database(_)
            | ApiErrorKind::Conditional(_)
            | ApiErrorKind::PayloadError(_)
            | ApiErrorKind::InvalidRouterToken
            | ApiErrorKind::RegistrationSecretHash(_)
            | ApiErrorKind::EndpointUrl(_)
            | ApiErrorKind::InvalidMessageId => None,
        }
    }
}

impl Display for ApiError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.kind.fmt(f)
    }
}

impl Error for ApiError {
    fn source(&self) -> Option<&(dyn Error + 'static)> {
        self.kind.source()
    }
}

// Forward From impls to ApiError from ApiErrorKind. Because From is reflexive,
// this impl also takes care of From<ApiErrorKind>.
impl<T> From<T> for ApiError
where
    ApiErrorKind: From<T>,
{
    fn from(item: T) -> Self {
        ApiError {
            kind: ApiErrorKind::from(item),
            backtrace: Backtrace::new(),
            extras: None,
        }
    }
}

impl ResponseError for ApiError {
    fn status_code(&self) -> StatusCode {
        self.kind.status()
    }

    fn error_response(&self) -> HttpResponse {
        let mut builder = HttpResponse::build(self.kind.status());

        match self.status_code() {
            StatusCode::GONE => {
                builder.insert_header(CacheControl(vec![CacheDirective::MaxAge(86400)]));
            }
            StatusCode::SERVICE_UNAVAILABLE => {
                builder.insert_header((header::RETRY_AFTER, RETRY_AFTER_PERIOD));
            }
            _ => {}
        }

        builder.json(self)
    }
}

impl Serialize for ApiError {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        let status = self.kind.status();
        let mut map = serializer.serialize_map(Some(5))?;

        map.serialize_entry("code", &status.as_u16())?;
        map.serialize_entry("errno", &self.kind.errno())?;
        map.serialize_entry("error", &status.canonical_reason())?;
        map.serialize_entry("message", &self.kind.to_string())?;
        map.serialize_entry("more_info", ERROR_URL)?;
        map.end()
    }
}

impl ReportableError for ApiError {
    fn reportable_source(&self) -> Option<&(dyn ReportableError + 'static)> {
        match &self.kind {
            ApiErrorKind::EndpointUrl(e) => Some(e),
            ApiErrorKind::Database(e) => Some(e),
            _ => None,
        }
    }

    fn backtrace(&self) -> Option<&Backtrace> {
        Some(&self.backtrace)
    }

    fn is_sentry_event(&self) -> bool {
        self.kind.is_sentry_event()
    }

    fn metric_label(&self) -> Option<&'static str> {
        self.kind.metric_label()
    }

    fn extras(&self) -> Vec<(&str, String)> {
        let mut extras: Vec<(&str, String)> = match &self.extras {
            Some(extras) => extras.iter().map(|e| (e.0.as_str(), e.1.clone())).collect(),
            None => Default::default(),
        };

        match &self.kind {
            ApiErrorKind::Router(e) => extras.extend(e.extras()),
            ApiErrorKind::LogCheck => extras.extend(vec![("coffee", "Unsupported".to_owned())]),
            _ => {}
        };
        extras
    }
}

/// Get the error number from validation errors. If multiple errors are present,
/// the first one with a valid error code is used.
fn errno_from_validation_errors(e: &ValidationErrors) -> Option<usize> {
    // Build an iterator over the error numbers, then get the first one
    e.errors()
        .values()
        .flat_map(|error| match error {
            ValidationErrorsKind::Struct(inner_errors) => {
                Box::new(errno_from_validation_errors(inner_errors).into_iter())
                    as Box<dyn Iterator<Item = usize>>
            }
            ValidationErrorsKind::List(indexed_errors) => Box::new(
                indexed_errors
                    .values()
                    .filter_map(|errors| errno_from_validation_errors(errors)),
            )
                as Box<dyn Iterator<Item = usize>>,
            ValidationErrorsKind::Field(errors) => {
                Box::new(errors.iter().filter_map(|error| error.code.parse().ok()))
                    as Box<dyn Iterator<Item = usize>>
            }
        })
        .next()
}

#[cfg(test)]
mod tests {
    use autopush_common::{db::error::DbError, sentry::event_from_error};

    use crate::routers::RouterError;

    use super::{ApiError, ApiErrorKind};
    use crate::error::ReportableError;

    #[test]
    fn sentry_event_with_extras() {
        let dbe = DbError::Integrity("foo".to_owned(), Some("bar".to_owned()));
        let e: ApiError = ApiErrorKind::Database(dbe).into();
        let event = event_from_error(&e);
        assert_eq!(event.exception.len(), 2);
        assert_eq!(event.exception[0].ty, "Integrity");
        assert_eq!(event.exception[1].ty, "ApiError");
        assert_eq!(event.extra.get("row"), Some(&"bar".into()));
    }

    /// Ensure that Pool error metric labels are specified and that they return a 503 status code.
    #[cfg(feature = "bigtable")]
    #[test]
    fn test_label_for_metrics() {
        // specifically test for a timeout on pool entry creation.
        let e: ApiError = ApiErrorKind::Database(DbError::BTError(
            autopush_common::db::bigtable::BigTableError::PoolTimeout(
                deadpool::managed::TimeoutType::Create,
            ),
        ))
        .into();

        // Remember, `autoendpoint` is prefixed to this metric label.
        assert_eq!(
            e.kind.metric_label(),
            Some("storage.bigtable.error.pool_timeout")
        );

        // "Retry-After" is applied on any 503 response (See ApiError::error_response)
        assert_eq!(e.kind.status(), actix_http::StatusCode::SERVICE_UNAVAILABLE)
    }

    /// Ensure that extras set on a given error are included in the ApiError.extras() call.
    #[tokio::test]
    async fn pass_extras() {
        let e = RouterError::NotFound;
        let mut ae = ApiError::from(e);
        ae.extras = Some([("foo".to_owned(), "bar".to_owned())].to_vec());

        let aex: Vec<(&str, String)> = ae.extras();
        assert!(aex.contains(&("foo", "bar".to_owned())));

        let e = ApiErrorKind::LogCheck;
        let mut ae = ApiError::from(e);
        ae.extras = Some([("foo".to_owned(), "bar".to_owned())].to_vec());

        let aex: Vec<(&str, String)> = ae.extras();
        assert!(aex.contains(&("foo", "bar".to_owned())));
        assert!(aex.contains(&("coffee", "Unsupported".to_owned())));
    }
}