// erp-diary 错误类型

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

use erp_core::error::AppError;

#[derive(Debug, thiserror::Error)]
pub enum DiaryError {
    #[error("日记未找到: {0}")]
    NotFound(String),

    #[error("版本冲突: 本地版本 {local}, 服务端版本 {server}")]
    VersionConflict { local: i32, server: i32 },

    #[error("班级码无效")]
    InvalidClassCode,

    #[error("班级码已过期")]
    ClassCodeExpired,

    #[error("班级码尝试次数过多，请 {lockout_minutes} 分钟后重试")]
    ClassCodeLocked { lockout_minutes: u32 },

    #[error("无权限执行此操作")]
    Forbidden,

    #[error("内容安全检查未通过")]
    ContentSafetyViolation,

    #[error("同步失败: {0}")]
    SyncFailed(String),

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

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

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

/// DiaryError -> AppError 转换
///
/// Handler 层统一返回 AppError，Service 层统一返回 DiaryError。
/// 这个 impl 让 Handler 中的 `?` 操作符自动完成转换。
impl From<DiaryError> for AppError {
    fn from(err: DiaryError) -> Self {
        match err {
            DiaryError::NotFound(msg) => AppError::NotFound(msg),
            DiaryError::VersionConflict { .. } => AppError::VersionMismatch,
            DiaryError::InvalidClassCode | DiaryError::ClassCodeExpired => {
                AppError::Validation(err.to_string())
            }
            DiaryError::ClassCodeLocked { .. } => AppError::TooManyRequests,
            DiaryError::Forbidden => AppError::Forbidden("权限不足".to_string()),
            DiaryError::ContentSafetyViolation => AppError::Validation(err.to_string()),
            DiaryError::SyncFailed(_) => AppError::Internal(err.to_string()),
            DiaryError::BadRequest(msg) => AppError::Validation(msg),
            DiaryError::Internal(_) => AppError::Internal(err.to_string()),
            DiaryError::Validation(msg) => AppError::Validation(msg),
        }
    }
}

/// Diary 模块 Result 类型别名
pub type DiaryResult<T> = Result<T, DiaryError>;

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

impl IntoResponse for DiaryError {
    fn into_response(self) -> Response {
        let (status, message) = match &self {
            DiaryError::NotFound(_) => (StatusCode::NOT_FOUND, self.to_string()),
            DiaryError::VersionConflict { .. } => (StatusCode::CONFLICT, self.to_string()),
            DiaryError::InvalidClassCode | DiaryError::ClassCodeExpired => {
                (StatusCode::BAD_REQUEST, self.to_string())
            }
            DiaryError::ClassCodeLocked { .. } => (StatusCode::TOO_MANY_REQUESTS, self.to_string()),
            DiaryError::Forbidden => (StatusCode::FORBIDDEN, self.to_string()),
            DiaryError::ContentSafetyViolation => (StatusCode::BAD_REQUEST, self.to_string()),
            DiaryError::SyncFailed(_) => (StatusCode::INTERNAL_SERVER_ERROR, self.to_string()),
            DiaryError::BadRequest(_) => (StatusCode::BAD_REQUEST, self.to_string()),
            DiaryError::Internal(_) => (StatusCode::INTERNAL_SERVER_ERROR, self.to_string()),
            DiaryError::Validation(_) => (StatusCode::BAD_REQUEST, self.to_string()),
        };

        let body = ErrorBody {
            error: format!("diary.{}", status.as_u16()),
            message,
        };

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

impl From<sea_orm::DbErr> for DiaryError {
    fn from(err: sea_orm::DbErr) -> Self {
        DiaryError::Internal(err.to_string())
    }
}

/// 支持 db.transaction() 闭包的错误转换
impl From<sea_orm::TransactionError<DiaryError>> for DiaryError {
    fn from(err: sea_orm::TransactionError<DiaryError>) -> Self {
        match err {
            sea_orm::TransactionError::Connection(db_err) => {
                DiaryError::Internal(db_err.to_string())
            }
            sea_orm::TransactionError::Transaction(inner) => inner,
        }
    }
}

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

    #[test]
    fn diary_error_not_found_maps_to_app_not_found() {
        let app: AppError = DiaryError::NotFound("journal-123".to_string()).into();
        match app {
            AppError::NotFound(msg) => assert_eq!(msg, "journal-123"),
            other => panic!("Expected NotFound, got {:?}", other),
        }
    }

    #[test]
    fn diary_error_version_conflict_maps_to_version_mismatch() {
        let app: AppError = DiaryError::VersionConflict {
            local: 1,
            server: 2,
        }
        .into();
        match app {
            AppError::VersionMismatch => {}
            other => panic!("Expected VersionMismatch, got {:?}", other),
        }
    }

    #[test]
    fn diary_error_forbidden_maps_to_app_forbidden() {
        let app: AppError = DiaryError::Forbidden.into();
        match app {
            AppError::Forbidden(_) => {}
            other => panic!("Expected Forbidden, got {:?}", other),
        }
    }

    #[test]
    fn diary_error_internal_maps_to_app_internal() {
        let app: AppError = DiaryError::Internal("db error".to_string()).into();
        match app {
            AppError::Internal(_) => {}
            other => panic!("Expected Internal, got {:?}", other),
        }
    }

    #[test]
    fn diary_error_validation_maps_to_app_validation() {
        let app: AppError = DiaryError::Validation("标题不能为空".to_string()).into();
        match app {
            AppError::Validation(msg) => assert_eq!(msg, "标题不能为空"),
            other => panic!("Expected Validation, got {:?}", other),
        }
    }

    #[test]
    fn diary_error_bad_request_maps_to_app_validation() {
        let app: AppError = DiaryError::BadRequest("参数错误".to_string()).into();
        match app {
            AppError::Validation(msg) => assert_eq!(msg, "参数错误"),
            other => panic!("Expected Validation, got {:?}", other),
        }
    }

    #[test]
    fn diary_error_class_code_locked_maps_to_too_many_requests() {
        let app: AppError = DiaryError::ClassCodeLocked {
            lockout_minutes: 30,
        }
        .into();
        match app {
            AppError::TooManyRequests => {}
            other => panic!("Expected TooManyRequests, got {:?}", other),
        }
    }

    #[test]
    fn db_err_maps_to_diary_internal() {
        let err = sea_orm::DbErr::Custom("connection failed".to_string());
        let diary_err: DiaryError = err.into();
        match diary_err {
            DiaryError::Internal(msg) => assert!(msg.contains("connection failed")),
            other => panic!("Expected Internal, got {:?}", other),
        }
    }
}