/// Event kinds for the BEX async callback system.
///
/// Each kind corresponds to a specific result type from the plugin API.
/// The C++ backend uses these to dispatch events to the appropriate UI handler.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum BexEventKind {
    InstallResult,
    UninstallResult,
    HomeResult,
    CategoryResult,
    SearchResult,
    InfoResult,
    ServersResult,
    StreamResult,
    SubtitleSearchResult,
    SubtitleDownloadResult,
    ArticleResult,
    Log,
    Progress,
    Error,
    Cancelled,
}

impl BexEventKind {
    /// Convert to the integer tag used in the C ABI callback.
    /// Must stay in sync with the C++ side enum.
    pub fn to_tag(self) -> u8 {
        match self {
            Self::InstallResult => 0,
            Self::UninstallResult => 1,
            Self::HomeResult => 2,
            Self::CategoryResult => 3,
            Self::SearchResult => 4,
            Self::InfoResult => 5,
            Self::ServersResult => 6,
            Self::StreamResult => 7,
            Self::SubtitleSearchResult => 8,
            Self::SubtitleDownloadResult => 9,
            Self::ArticleResult => 10,
            Self::Log => 11,
            Self::Progress => 12,
            Self::Error => 13,
            Self::Cancelled => 14,
        }
    }
}

/// Payload format indicator.
///
/// Tells the C++ consumer how to interpret the payload bytes.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum BexPayloadFormat {
    /// No payload (e.g., for Log/Progress events that carry data in fields).
    None,
    /// FlatBuffer binary — zero-copy deserialization on C++ side.
    FlatBuffer,
    /// JSON string — used for debug/CLI mode.
    JsonDebug,
    /// Opaque binary blob.
    Binary,
}

/// Internal event representation.
///
/// Produced by the runtime for each completed request. The C++ backend
/// drains these via `bex_drain_events()` and dispatches them to the UI.
#[derive(Debug, Clone)]
pub struct BexEvent {
    /// Monotonically increasing request ID (matches the ID returned by submit_*)
    pub request_id: u64,
    /// Monotonically increasing sequence number for ordering
    pub seq: u64,
    /// What kind of result this event carries
    pub kind: BexEventKind,
    /// Whether the operation succeeded
    pub ok: bool,
    /// Which plugin produced this event
    pub plugin_id: String,
    /// How to interpret the payload bytes
    pub payload_format: BexPayloadFormat,
    /// The actual result payload (FlatBuffer, JSON, or binary)
    pub payload: Vec<u8>,
    /// Machine-readable error code (empty if ok)
    pub error_code: String,
    /// Human-readable error message (empty if ok)
    pub error_message: String,
}

impl BexEvent {
    /// Create a success event with a FlatBuffer payload.
    pub fn success(
        request_id: u64,
        seq: u64,
        kind: BexEventKind,
        plugin_id: String,
        payload: Vec<u8>,
    ) -> Self {
        Self {
            request_id,
            seq,
            kind,
            ok: true,
            plugin_id,
            payload_format: BexPayloadFormat::FlatBuffer,
            payload,
            error_code: String::new(),
            error_message: String::new(),
        }
    }

    /// Create a success event with a JSON payload (for debug/CLI).
    pub fn success_json(
        request_id: u64,
        seq: u64,
        kind: BexEventKind,
        plugin_id: String,
        json: String,
    ) -> Self {
        Self {
            request_id,
            seq,
            kind,
            ok: true,
            plugin_id,
            payload_format: BexPayloadFormat::JsonDebug,
            payload: json.into_bytes(),
            error_code: String::new(),
            error_message: String::new(),
        }
    }

    /// Create an error event.
    pub fn error(
        request_id: u64,
        seq: u64,
        kind: BexEventKind,
        plugin_id: String,
        error_code: &str,
        error_message: &str,
    ) -> Self {
        Self {
            request_id,
            seq,
            kind,
            ok: false,
            plugin_id,
            payload_format: BexPayloadFormat::None,
            payload: Vec::new(),
            error_code: error_code.to_string(),
            error_message: error_message.to_string(),
        }
    }

    /// Create a cancellation event.
    pub fn cancelled(request_id: u64, seq: u64, plugin_id: String) -> Self {
        Self {
            request_id,
            seq,
            kind: BexEventKind::Cancelled,
            ok: false,
            plugin_id,
            payload_format: BexPayloadFormat::None,
            payload: Vec::new(),
            error_code: "CANCELLED".to_string(),
            error_message: "Request was cancelled".to_string(),
        }
    }
}