//! All errors which Medea can return to Control API user.
//!
//! # Error codes ranges
//! - `1000` ... `1999` Client errors
//! - `2000` ... `2999` Server errors

use std::string::ToString;

use derive_more::Display;
use medea_control_api_proto::grpc::api as proto;

use crate::{
    api::control::{
        callback::url::CallbackUrlParseError,
        grpc::server::GrpcControlApiError,
        refs::{
            fid::ParseFidError, local_uri::LocalUriParseError,
            src_uri::SrcParseError,
        },
        TryFromElementError, TryFromProtobufError,
    },
    signalling::{
        elements::{member::MemberError, MembersLoadError},
        participants::ParticipantServiceErr,
        room::RoomError,
        room_service::RoomServiceError,
    },
};

/// Medea's Control API error response.
pub struct ErrorResponse {
    /// [`ErrorCode`] which will be returned with code and message.
    error_code: ErrorCode,

    /// Element ID where some error happened. May be empty.
    element_id: Option<String>,

    /// All [`ErrorCode`]s have [`Display`] implementation. And this
    /// implementation will be used if this field is [`None`]. But
    /// sometimes we want to add some error explanation. Then we set this
    /// field to [`Some`] and this text will be added to
    /// [`Display`] implementation's text.
    ///
    /// By default this field should be [`None`].
    ///
    /// For providing error explanation use [`ErrorResponse::with_explanation`]
    /// method.
    ///
    /// [`Display`]: std::fmt::Display
    explanation: Option<String>,
}

impl ErrorResponse {
    /// New [`ErrorResponse`] with [`ErrorCode`] and element ID.
    pub fn new<T: ToString>(error_code: ErrorCode, element_id: &T) -> Self {
        Self {
            error_code,
            element_id: Some(element_id.to_string()),
            explanation: None,
        }
    }

    /// New [`ErrorResponse`] only with [`ErrorCode`].
    #[inline]
    #[must_use]
    pub fn without_id(error_code: ErrorCode) -> Self {
        Self {
            error_code,
            element_id: None,
            explanation: None,
        }
    }

    /// [`ErrorResponse`] for all unexpected errors.
    ///
    /// Provide unexpected `Error` to this function.
    /// This error will be printed with [`Display`] implementation
    /// of provided `Error` as error explanation.
    ///
    /// [`Display`]: std::fmt::Display
    pub fn unexpected<B: ToString>(unknown_error: &B) -> Self {
        Self {
            error_code: ErrorCode::UnexpectedError,
            explanation: Some(unknown_error.to_string()),
            element_id: None,
        }
    }

    /// [`ErrorResponse`] with some additional info.
    ///
    /// With this method you can add additional text to error message of
    /// [`ErrorCode`].
    #[inline]
    #[must_use]
    pub fn with_explanation(
        error_code: ErrorCode,
        explanation: String,
        id: Option<String>,
    ) -> Self {
        Self {
            error_code,
            explanation: Some(explanation),
            element_id: id,
        }
    }
}

impl From<ErrorResponse> for proto::Error {
    fn from(resp: ErrorResponse) -> Self {
        let text = if let Some(additional_text) = &resp.explanation {
            format!("{} {}", resp.error_code.to_string(), additional_text)
        } else {
            resp.error_code.to_string()
        };
        Self {
            doc: String::new(),
            text,
            element: resp.element_id.unwrap_or_default(),
            code: resp.error_code as u32,
        }
    }
}

/// [Medea]'s [Control API] errors.
///
/// [Medea]: https://github.com/instrumentisto/medea
/// [Control API]: https://tinyurl.com/yxsqplq7
#[derive(Debug, Display)]
pub enum ErrorCode {
    /// Unimplemented API call.
    ///
    /// This code should be with additional text which explains what
    /// exactly unimplemented (you can do it with
    /// [`ErrorResponse::with_explanation`] function).
    ///
    /// Code: __1000__.
    #[display(fmt = "Unimplemented API call.")]
    UnimplementedCall = 1000,

    /// Request doesn't contain any elements.
    ///
    /// Code: __1001__.
    #[display(fmt = "Request doesn't contain any elements")]
    NoElement = 1001,

    /// Provided fid can't point to provided element.
    ///
    /// Code: __1002__.
    #[display(fmt = "Provided fid can't point to provided element")]
    ElementIdMismatch = 1002,

    /// Room not found.
    ///
    /// Code: __1003__.
    #[display(fmt = "Room not found.")]
    RoomNotFound = 1003,

    /// Member not found.
    ///
    /// Code: __1004__.
    #[display(fmt = "Member not found.")]
    MemberNotFound = 1004,

    /// Endpoint not found.
    ///
    /// Code: __1005__.
    #[display(fmt = "Endpoint not found.")]
    EndpointNotFound = 1005,

    /// Medea expects `Room` element in pipeline but received not him.
    ///
    /// Code: __1006__.
    #[display(fmt = "Expecting Room element but it's not.")]
    NotRoomInSpec = 1006,

    /// Medea expects `Member` element in pipeline but received not him.
    ///
    /// Code: __1007__.
    #[display(fmt = "Expected Member element but it's not.")]
    NotMemberInSpec = 1007,

    /// Invalid source URI in [`WebRtcPlayEndpoint`].
    ///
    /// Code: __1008__.
    ///
    /// [`WebRtcPlayEndpoint`]:
    /// crate::signalling::elements::endpoints::webrtc::WebRtcPlayEndpoint
    #[display(fmt = "Invalid source URI in 'WebRtcPlayEndpoint'.")]
    InvalidSrcUri = 1008,

    /// Provided not source URI in [`WebRtcPlayEndpoint`].
    ///
    /// Code: __1009__.
    ///
    /// [`WebRtcPlayEndpoint`]:
    /// crate::signalling::elements::endpoints::webrtc::WebRtcPlayEndpoint
    #[display(fmt = "Provided not source URI in 'WebRtcPlayEndpoint'.")]
    NotSourceUri = 1009,

    /// Element's URI don't have `local://` prefix.
    ///
    /// Code: __1010__.
    #[display(fmt = "Element's URI don't have 'local://' prefix.")]
    ElementIdIsNotLocal = 1010,

    /// Provided element's FID/URI with too many paths.
    ///
    /// Code: __1011__.
    #[display(fmt = "You provided element's FID/URI with too many paths.")]
    ElementIdIsTooLong = 1011,

    /// Missing some fields in source URI of WebRtcPublishEndpoint.
    ///
    /// Code: __1012__.
    #[display(
        fmt = "Missing some fields in source URI of WebRtcPublishEndpoint."
    )]
    MissingFieldsInSrcUri = 1012,

    /// Empty element ID.
    ///
    /// Code: __1013__.
    #[display(fmt = "Provided empty element ID.")]
    EmptyElementId = 1013,

    /// Provided empty elements FIDs list.
    ///
    /// Code: __1014__.
    #[display(fmt = "Provided empty elements FIDs list.")]
    EmptyElementsList = 1014,

    /// Provided not the same Room IDs in elements IDs. Probably you try use
    /// `Delete` method for elements with different Room IDs
    ///
    /// Code: __1015__.
    ///
    /// [`RoomId`]: crate::api::control::room::Id
    #[display(fmt = "Provided not the same Room IDs in elements IDs. \
                     Probably you try use 'Delete' method for elements with \
                     different Room IDs")]
    ProvidedNotSameRoomIds = 1015,

    /// Room with provided fid already exists.
    ///
    /// Code: __1016__.
    #[display(fmt = "Room with provided FID already exists.")]
    RoomAlreadyExists = 1016,

    /// Member with provided FID already exists.
    ///
    /// Code: __1017__.
    #[display(fmt = "Member with provided FID already exists.")]
    MemberAlreadyExists = 1017,

    /// Endpoint with provided FID already exists.
    ///
    /// Code: __1018__.
    #[display(fmt = "Endpoint with provided FID already exists.")]
    EndpointAlreadyExists = 1018,

    /// Missing path in some reference to the Medea element.
    ///
    /// Code: __1019__.
    #[display(fmt = "Missing path in some reference to the Medea element.")]
    MissingPath = 1019,

    /// Missing host in callback URL.
    ///
    /// Code: __1020__.
    #[display(fmt = "Missing host in callback URL.")]
    MissingHostInCallbackUrl = 1020,

    /// Unsupported callback URL protocol.
    ///
    /// Code: __1021__.
    #[display(fmt = "Unsupported callback URL protocol.")]
    UnsupportedCallbackUrlProtocol = 1021,

    /// Invalid callback URL.
    ///
    /// Code: __1022__.
    #[display(fmt = "Invalid callback URL.")]
    InvalidCallbackUrl = 1022,

    /// Encountered negative duration.
    ///
    /// Code: __1023__.
    #[display(fmt = "Encountered negative duration")]
    NegativeDuration = 1023,

    /// Unexpected server error.
    ///
    /// Use this [`ErrorCode`] only with [`ErrorResponse::unexpected`]
    /// function. In error text with this code should be error message
    /// which explain what exactly goes wrong
    /// ([`ErrorResponse::unexpected`] do this).
    ///
    /// Code: __2000__.
    #[display(fmt = "Unexpected error happened.")]
    UnexpectedError = 2000,
}

impl From<ParticipantServiceErr> for ErrorResponse {
    fn from(err: ParticipantServiceErr) -> Self {
        use ParticipantServiceErr::{
            EndpointNotFound, MemberError, ParticipantNotFound,
        };

        match err {
            EndpointNotFound(id) => Self::new(ErrorCode::EndpointNotFound, &id),
            ParticipantNotFound(id) => {
                Self::new(ErrorCode::MemberNotFound, &id)
            }
            MemberError(_) => Self::unexpected(&err),
        }
    }
}

impl From<TryFromProtobufError> for ErrorResponse {
    fn from(err: TryFromProtobufError) -> Self {
        use TryFromProtobufError as E;

        match err {
            E::SrcUriError(e) => e.into(),
            E::CallbackUrlParseErr(e) => e.into(),
            E::NotMemberElementInRoomElement(id) => Self::with_explanation(
                ErrorCode::UnimplementedCall,
                String::from(
                    "Not Member elements in Room element currently is \
                     unimplemented.",
                ),
                Some(id),
            ),
            E::UnimplementedEndpoint(id) => Self::with_explanation(
                ErrorCode::UnimplementedCall,
                String::from("Endpoint is not implemented."),
                Some(id),
            ),
            E::ExpectedOtherElement(element, id) => Self::with_explanation(
                ErrorCode::ElementIdMismatch,
                format!(
                    "Provided fid can not point to element of type [{}]",
                    element
                ),
                Some(id),
            ),
            E::EmptyElement(id) => Self::with_explanation(
                ErrorCode::NoElement,
                String::from("No element was provided"),
                Some(id),
            ),
            E::NegativeDuration(id, field) => Self::with_explanation(
                ErrorCode::NegativeDuration,
                format!(
                    "Element [id = {}] contains negative duration field `{}`",
                    id, field
                ),
                Some(id),
            ),
        }
    }
}

impl From<LocalUriParseError> for ErrorResponse {
    fn from(err: LocalUriParseError) -> Self {
        use LocalUriParseError as E;

        match err {
            E::NotLocal(text) => {
                Self::new(ErrorCode::ElementIdIsNotLocal, &text)
            }
            E::TooManyPaths(text) => {
                Self::new(ErrorCode::ElementIdIsTooLong, &text)
            }
            E::Empty => Self::without_id(ErrorCode::EmptyElementId),
            E::MissingPaths(text) => {
                Self::new(ErrorCode::MissingFieldsInSrcUri, &text)
            }
            E::UrlParseErr(id, _) => Self::new(ErrorCode::InvalidSrcUri, &id),
        }
    }
}

impl From<CallbackUrlParseError> for ErrorResponse {
    fn from(err: CallbackUrlParseError) -> Self {
        use CallbackUrlParseError::{
            MissingHost, UnsupportedScheme, UrlParseErr,
        };

        match err {
            MissingHost => {
                Self::without_id(ErrorCode::MissingHostInCallbackUrl)
            }
            UnsupportedScheme => {
                Self::without_id(ErrorCode::UnsupportedCallbackUrlProtocol)
            }
            UrlParseErr(_) => Self::without_id(ErrorCode::InvalidCallbackUrl),
        }
    }
}

impl From<ParseFidError> for ErrorResponse {
    fn from(err: ParseFidError) -> Self {
        use ParseFidError::{Empty, MissingPath, TooManyPaths};

        match err {
            TooManyPaths(text) => {
                Self::new(ErrorCode::ElementIdIsTooLong, &text)
            }
            Empty => Self::without_id(ErrorCode::EmptyElementId),
            MissingPath(text) => Self::new(ErrorCode::MissingPath, &text),
        }
    }
}

impl From<RoomError> for ErrorResponse {
    fn from(err: RoomError) -> Self {
        use RoomError as E;

        match err {
            E::MemberError(e) => e.into(),
            E::MembersLoadError(e) => e.into(),
            E::ParticipantServiceErr(e) => e.into(),
            E::MemberAlreadyExists(id) => {
                Self::new(ErrorCode::MemberAlreadyExists, &id)
            }
            E::EndpointAlreadyExists(id) => {
                Self::new(ErrorCode::EndpointAlreadyExists, &id)
            }
            E::TryFromElement(id) => Self::new(ErrorCode::NotMemberInSpec, &id),
            E::WrongRoomId(_, _)
            | E::PeerNotFound(_)
            | E::CallbackClientError(_)
            | E::NoTurnCredentials(_)
            | E::PeerError(_)
            | E::BadRoomSpec(_)
            | E::PeerTrafficWatcherMailbox(_)
            | E::AuthorizationError
            | E::TurnServiceErr(_) => Self::unexpected(&err),
        }
    }
}

impl From<MembersLoadError> for ErrorResponse {
    fn from(err: MembersLoadError) -> Self {
        use MembersLoadError::{
            EndpointNotFound, MemberNotFound, TryFromError,
        };
        use TryFromElementError::{NotMember, NotRoom};

        match err {
            TryFromError(e, id) => match e {
                NotMember => Self::new(ErrorCode::NotMemberInSpec, &id),
                NotRoom => Self::new(ErrorCode::NotRoomInSpec, &id),
            },
            MemberNotFound(id) => Self::new(ErrorCode::MemberNotFound, &id),
            EndpointNotFound(id) => Self::new(ErrorCode::EndpointNotFound, &id),
        }
    }
}

impl From<MemberError> for ErrorResponse {
    fn from(err: MemberError) -> Self {
        match err {
            MemberError::EndpointNotFound(id) => {
                Self::new(ErrorCode::EndpointNotFound, &id)
            }
        }
    }
}

impl From<SrcParseError> for ErrorResponse {
    fn from(err: SrcParseError) -> Self {
        use SrcParseError::{LocalUriParseError, NotSrcUri};

        match err {
            NotSrcUri(text) => Self::new(ErrorCode::NotSourceUri, &text),
            LocalUriParseError(err) => err.into(),
        }
    }
}

impl From<RoomServiceError> for ErrorResponse {
    fn from(err: RoomServiceError) -> Self {
        use RoomServiceError as E;

        match err {
            E::RoomNotFound(id) => Self::new(ErrorCode::RoomNotFound, &id),
            E::RoomAlreadyExists(id) => {
                Self::new(ErrorCode::RoomAlreadyExists, &id)
            }
            E::RoomError(e) => e.into(),
            E::EmptyUrisList => Self::without_id(ErrorCode::EmptyElementsList),
            E::NotSameRoomIds(id1, id2) => Self::with_explanation(
                ErrorCode::ProvidedNotSameRoomIds,
                format!(
                    "All FID's must have equal room_id. Provided Id's are \
                     different: [{}] != [{}]",
                    id1, id2
                ),
                None,
            ),
            E::RoomMailboxErr(_)
            | E::FailedToLoadStaticSpecs(_)
            | E::TryFromElement(_) => Self::unexpected(&err),
        }
    }
}

impl From<GrpcControlApiError> for ErrorResponse {
    fn from(err: GrpcControlApiError) -> Self {
        use GrpcControlApiError as E;

        match err {
            E::Fid(e) => e.into(),
            E::TryFromProtobuf(e) => e.into(),
            E::RoomServiceError(e) => e.into(),
            E::RoomServiceMailboxError(_) => Self::unexpected(&err),
        }
    }
}