//! Mission Control error types
//!
//! Provides structured errors for IPC commands, enabling the frontend
//! to handle errors programmatically rather than parsing strings.

use serde::Serialize;
use specta::Type;

/// Structured error type for Tauri IPC commands.
///
/// This replaces string-based errors (`Result<T, String>`) with typed errors
/// that the frontend can handle programmatically.
#[derive(Debug, Clone, Serialize, Type)]
pub struct McError {
    /// Machine-readable error code (e.g., "LORE_UNAVAILABLE", "BRIDGE_LOCKED")
    pub code: McErrorCode,
    /// Human-readable error message
    pub message: String,
    /// Whether this error is recoverable (user can retry)
    pub recoverable: bool,
}

/// Error codes for frontend handling
#[derive(Debug, Clone, Serialize, PartialEq, Eq, Type)]
#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
pub enum McErrorCode {
    // Lore errors
    LoreUnavailable,
    LoreUnhealthy,
    LoreFetchFailed,

    // Bridge errors
    BridgeLocked,
    BridgeMapCorrupted,
    BridgeSyncFailed,

    // Beads errors
    BeadsUnavailable,
    BeadsCreateFailed,
    BeadsCloseFailed,

    // Bv errors
    BvUnavailable,
    BvTriageFailed,

    // General errors
    IoError,
    InternalError,
    InvalidInput,
}

impl McError {
    /// Create a new error with the given code and message
    pub fn new(code: McErrorCode, message: impl Into<String>) -> Self {
        let recoverable = matches!(
            code,
            McErrorCode::LoreUnavailable
                | McErrorCode::BeadsUnavailable
                | McErrorCode::BvUnavailable
                | McErrorCode::BridgeLocked
                | McErrorCode::IoError
        );

        Self {
            code,
            message: message.into(),
            recoverable,
        }
    }

    /// Create a lore unavailable error
    pub fn lore_unavailable() -> Self {
        Self::new(
            McErrorCode::LoreUnavailable,
            "lore CLI not found -- is it installed?",
        )
    }

    /// Create a lore unhealthy error
    pub fn lore_unhealthy() -> Self {
        Self::new(
            McErrorCode::LoreUnhealthy,
            "lore health check failed -- run 'lore index --full'",
        )
    }

    /// Create a bridge locked error
    pub fn bridge_locked() -> Self {
        Self::new(
            McErrorCode::BridgeLocked,
            "Another Mission Control instance is running",
        )
    }

    /// Create an internal error with context
    pub fn internal(context: impl Into<String>) -> Self {
        Self::new(McErrorCode::InternalError, context)
    }

    /// Create a beads unavailable error
    pub fn beads_unavailable() -> Self {
        Self::new(
            McErrorCode::BeadsUnavailable,
            "br CLI not found -- is beads installed?",
        )
    }

    /// Create an IO error with context
    pub fn io_error(context: impl Into<String>) -> Self {
        Self::new(McErrorCode::IoError, context)
    }

    /// Create a bv unavailable error
    pub fn bv_unavailable() -> Self {
        Self::new(
            McErrorCode::BvUnavailable,
            "bv CLI not found -- is beads installed?",
        )
    }

    /// Create an invalid input error
    pub fn invalid_input(message: impl Into<String>) -> Self {
        Self {
            code: McErrorCode::InvalidInput,
            message: message.into(),
            recoverable: false,
        }
    }
}

impl std::fmt::Display for McError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.message)
    }
}

impl std::error::Error for McError {}

// Conversion from bridge errors
impl From<crate::data::bridge::BridgeError> for McError {
    fn from(err: crate::data::bridge::BridgeError) -> Self {
        use crate::data::bridge::BridgeError;

        match err {
            BridgeError::InstanceLocked => Self::bridge_locked(),
            BridgeError::Lore(e) => Self::new(
                McErrorCode::LoreFetchFailed,
                format!("Lore error: {}", e),
            ),
            BridgeError::Beads(e) => Self::new(
                McErrorCode::BeadsCreateFailed,
                format!("Beads error: {}", e),
            ),
            BridgeError::Io(e) => Self::new(McErrorCode::IoError, format!("IO error: {}", e)),
            BridgeError::Json(e) => Self::new(
                McErrorCode::BridgeMapCorrupted,
                format!("Map file corrupted: {}", e),
            ),
        }
    }
}

// Conversion from lore errors
impl From<crate::data::lore::LoreError> for McError {
    fn from(err: crate::data::lore::LoreError) -> Self {
        use crate::data::lore::LoreError;

        match err {
            LoreError::ExecutionFailed(_) => Self::lore_unavailable(),
            LoreError::CommandFailed(msg) => Self::new(
                McErrorCode::LoreFetchFailed,
                format!("lore command failed: {}", msg),
            ),
            LoreError::ParseFailed(msg) => Self::new(
                McErrorCode::LoreFetchFailed,
                format!("Failed to parse lore response: {}", msg),
            ),
        }
    }
}

// Conversion from beads errors
impl From<crate::data::beads::BeadsError> for McError {
    fn from(err: crate::data::beads::BeadsError) -> Self {
        use crate::data::beads::BeadsError;

        match err {
            BeadsError::ExecutionFailed(_) => Self::beads_unavailable(),
            BeadsError::CommandFailed(msg) => Self::new(
                McErrorCode::BeadsCreateFailed,
                format!("br command failed: {}", msg),
            ),
            BeadsError::ParseFailed(msg) => Self::new(
                McErrorCode::BeadsCreateFailed,
                format!("Failed to parse br response: {}", msg),
            ),
        }
    }
}

// Conversion from bv errors
impl From<crate::data::bv::BvError> for McError {
    fn from(err: crate::data::bv::BvError) -> Self {
        use crate::data::bv::BvError;

        match err {
            BvError::ExecutionFailed(_) => Self::bv_unavailable(),
            BvError::CommandFailed(msg) => Self::new(
                McErrorCode::BvTriageFailed,
                format!("bv command failed: {}", msg),
            ),
            BvError::ParseFailed(msg) => Self::new(
                McErrorCode::BvTriageFailed,
                format!("Failed to parse bv response: {}", msg),
            ),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_error_serialization() {
        let err = McError::lore_unavailable();
        let json = serde_json::to_string(&err).unwrap();

        assert!(json.contains("LORE_UNAVAILABLE"));
        assert!(json.contains("recoverable"));
    }

    #[test]
    fn test_recoverable_errors() {
        assert!(McError::lore_unavailable().recoverable);
        assert!(McError::bridge_locked().recoverable);
        assert!(!McError::internal("test").recoverable);
    }

    #[test]
    fn test_error_codes_are_screaming_snake_case() {
        let err = McError::new(McErrorCode::BridgeMapCorrupted, "test");
        let json = serde_json::to_string(&err).unwrap();

        assert!(json.contains("BRIDGE_MAP_CORRUPTED"));
    }

    #[test]
    fn test_beads_unavailable_is_recoverable() {
        assert!(McError::beads_unavailable().recoverable);
    }

    #[test]
    fn test_beads_error_conversion() {
        use crate::data::beads::BeadsError;

        // ExecutionFailed -> BeadsUnavailable (recoverable)
        let err: McError = BeadsError::ExecutionFailed("not found".to_string()).into();
        assert_eq!(err.code, McErrorCode::BeadsUnavailable);
        assert!(err.recoverable);

        // CommandFailed -> BeadsCreateFailed (not recoverable)
        let err: McError = BeadsError::CommandFailed("failed".to_string()).into();
        assert_eq!(err.code, McErrorCode::BeadsCreateFailed);
        assert!(!err.recoverable);

        // ParseFailed -> BeadsCreateFailed (not recoverable)
        let err: McError = BeadsError::ParseFailed("bad json".to_string()).into();
        assert_eq!(err.code, McErrorCode::BeadsCreateFailed);
        assert!(!err.recoverable);
    }

    #[test]
    fn test_lore_error_conversion() {
        use crate::data::lore::LoreError;

        // ExecutionFailed -> LoreUnavailable (recoverable)
        let err: McError = LoreError::ExecutionFailed("not found".to_string()).into();
        assert_eq!(err.code, McErrorCode::LoreUnavailable);
        assert!(err.recoverable);

        // CommandFailed -> LoreFetchFailed (not recoverable)
        let err: McError = LoreError::CommandFailed("failed".to_string()).into();
        assert_eq!(err.code, McErrorCode::LoreFetchFailed);
        assert!(!err.recoverable);
    }

    #[test]
    fn test_bridge_error_conversion() {
        use crate::data::bridge::BridgeError;

        // InstanceLocked -> BridgeLocked (recoverable)
        let err: McError = BridgeError::InstanceLocked.into();
        assert_eq!(err.code, McErrorCode::BridgeLocked);
        assert!(err.recoverable);

        // Io -> IoError (recoverable)
        let err: McError = BridgeError::Io(std::io::Error::new(
            std::io::ErrorKind::NotFound,
            "file not found",
        ))
        .into();
        assert_eq!(err.code, McErrorCode::IoError);
        assert!(err.recoverable);

        // Json -> BridgeMapCorrupted (not recoverable)
        let json_err = serde_json::from_str::<()>("invalid").unwrap_err();
        let err: McError = BridgeError::Json(json_err).into();
        assert_eq!(err.code, McErrorCode::BridgeMapCorrupted);
        assert!(!err.recoverable);
    }

    #[test]
    fn test_bv_error_conversion() {
        use crate::data::bv::BvError;

        // ExecutionFailed -> BvUnavailable (recoverable)
        let err: McError = BvError::ExecutionFailed("not found".to_string()).into();
        assert_eq!(err.code, McErrorCode::BvUnavailable);
        assert!(err.recoverable);

        // CommandFailed -> BvTriageFailed (not recoverable)
        let err: McError = BvError::CommandFailed("failed".to_string()).into();
        assert_eq!(err.code, McErrorCode::BvTriageFailed);
        assert!(!err.recoverable);

        // ParseFailed -> BvTriageFailed (not recoverable)
        let err: McError = BvError::ParseFailed("bad json".to_string()).into();
        assert_eq!(err.code, McErrorCode::BvTriageFailed);
        assert!(!err.recoverable);
    }
}