//! ObjectService gRPC implementation

use crate::metadata::MetadataStore;
use bytes::Bytes;
use lightningstor_api::proto::{
    AbortMultipartUploadRequest, CompleteMultipartUploadRequest, CompleteMultipartUploadResponse,
    CopyObjectRequest, CopyObjectResponse, CreateMultipartUploadRequest,
    CreateMultipartUploadResponse, DeleteObjectRequest, DeleteObjectResponse, GetObjectRequest,
    GetObjectResponse, HeadObjectRequest, HeadObjectResponse, ListMultipartUploadsRequest,
    ListMultipartUploadsResponse, ListObjectVersionsRequest, ListObjectVersionsResponse,
    ListObjectsRequest, ListObjectsResponse, ListPartsRequest, ListPartsResponse,
    ObjectInfo, ObjectMetadata as ProtoObjectMetadata, PutObjectRequest, PutObjectResponse,
    UploadPartRequest, UploadPartResponse,
};
use lightningstor_api::ObjectService;
use lightningstor_storage::StorageBackend;
use lightningstor_types::{
    BucketId, ETag, Object, ObjectKey, ObjectMetadata, ObjectVersion, Result as LightningStorResult,
};
use prost_types;
use std::str::FromStr;
use md5::{Digest, Md5};
use std::sync::Arc;
use tokio_stream::wrappers::ReceiverStream;
use tonic::{Request, Response, Status, Streaming};

/// ObjectService implementation
pub struct ObjectServiceImpl {
    /// Storage backend for object data
    storage: Arc<dyn StorageBackend>,
    /// Metadata store for object metadata
    metadata: Arc<MetadataStore>,
}

impl ObjectServiceImpl {
    /// Create a new ObjectService
    pub async fn new(
        storage: Arc<dyn StorageBackend>,
        metadata: Arc<MetadataStore>,
    ) -> LightningStorResult<Self> {
        Ok(Self { storage, metadata })
    }
    
    /// Convert LightningStor Error to gRPC Status
    fn to_status(err: lightningstor_types::Error) -> Status {
        Status::internal(err.to_string())
    }
    
    /// Convert Object to ObjectInfo proto
    fn object_to_proto(&self, obj: &Object) -> ObjectInfo {
        ObjectInfo {
            key: obj.key.as_str().to_string(),
            etag: obj.etag.as_str().to_string(),
            size: obj.size,
            last_modified: Some(prost_types::Timestamp {
                seconds: obj.last_modified.timestamp(),
                nanos: obj.last_modified.timestamp_subsec_nanos() as i32,
            }),
            storage_class: obj.storage_class.clone(),
            version_id: obj.version.as_str().to_string(),
            is_latest: obj.is_latest,
            metadata: Some(ProtoObjectMetadata {
                content_type: obj.metadata.content_type.clone().unwrap_or_default(),
                content_encoding: obj.metadata.content_encoding.clone().unwrap_or_default(),
                content_disposition: obj.metadata.content_disposition.clone().unwrap_or_default(),
                content_language: obj.metadata.content_language.clone().unwrap_or_default(),
                cache_control: obj.metadata.cache_control.clone().unwrap_or_default(),
                user_metadata: obj.metadata.user_metadata.clone(),
            }),
        }
    }
    
    /// Calculate MD5 hash of data
    fn calculate_md5(data: &[u8]) -> ETag {
        let mut hasher = Md5::new();
        hasher.update(data);
        let hash = hasher.finalize();
        let hash_array: [u8; 16] = hash.into();
        ETag::from_md5(&hash_array)
    }
}


#[tonic::async_trait]
impl ObjectService for ObjectServiceImpl {
    type GetObjectStream =
        std::pin::Pin<Box<dyn tokio_stream::Stream<Item = Result<GetObjectResponse, Status>> + Send>>;

    async fn put_object(
        &self,
        request: Request<PutObjectRequest>,
    ) -> Result<Response<PutObjectResponse>, Status> {
        let req = request.into_inner();
        tracing::info!(
            bucket = %req.bucket,
            key = %req.key,
            size = req.body.len(),
            "PutObject request"
        );
        
        // Load bucket
        // TODO: Extract org_id and project_id from request metadata/context
        // For now, assume they're in the bucket name or use default
        let org_id = "default"; // TODO: Get from request context
        let project_id = "default"; // TODO: Get from request context
        
        let bucket = self.metadata
            .load_bucket(org_id, project_id, &req.bucket)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Bucket {} not found", req.bucket)))?;
        
        let bucket_id = BucketId::from_str(&bucket.id.to_string())
            .map_err(|_| Status::internal("Invalid bucket ID"))?;
        
        // Validate object key
        let object_key = ObjectKey::new(&req.key)
            .map_err(|e| Status::invalid_argument(format!("Invalid object key: {}", e)))?;
        
        // Calculate ETag
        let etag = Self::calculate_md5(&req.body);
        
        // Create object metadata
        let metadata = if let Some(proto_meta) = req.metadata {
            ObjectMetadata {
                content_type: if proto_meta.content_type.is_empty() { None } else { Some(proto_meta.content_type) },
                content_encoding: if proto_meta.content_encoding.is_empty() { None } else { Some(proto_meta.content_encoding) },
                content_disposition: if proto_meta.content_disposition.is_empty() { None } else { Some(proto_meta.content_disposition) },
                content_language: if proto_meta.content_language.is_empty() { None } else { Some(proto_meta.content_language) },
                cache_control: if proto_meta.cache_control.is_empty() { None } else { Some(proto_meta.cache_control) },
                user_metadata: proto_meta.user_metadata,
            }
        } else {
            ObjectMetadata::default()
        };
        
        // Create object
        let mut object = Object::new(
            bucket.id.to_string(),
            object_key.clone(),
            etag.clone(),
            req.body.len() as u64,
            metadata.content_type.clone(),
        );
        object.metadata = metadata;
        
        // Handle versioning
        if bucket.versioning == lightningstor_types::Versioning::Enabled {
            object.version = ObjectVersion::new();
        }
        
        // Save object data to storage backend
        self.storage
            .put_object(&object.id, Bytes::from(req.body))
            .await
            .map_err(|e| Status::internal(format!("Failed to store object: {}", e)))?;
        
        // Save object metadata
        self.metadata
            .save_object(&object)
            .await
            .map_err(Self::to_status)?;
        
        tracing::info!(
            bucket = %req.bucket,
            key = %req.key,
            object_id = %object.id,
            etag = %etag.as_str(),
            "Object stored successfully"
        );
        
        Ok(Response::new(PutObjectResponse {
            etag: etag.as_str().to_string(),
            version_id: object.version.as_str().to_string(),
        }))
    }

    async fn get_object(
        &self,
        request: Request<GetObjectRequest>,
    ) -> Result<Response<Self::GetObjectStream>, Status> {
        let req = request.into_inner();
        tracing::info!(
            bucket = %req.bucket,
            key = %req.key,
            "GetObject request"
        );
        
        // Load bucket
        let org_id = "default"; // TODO: Get from request context
        let project_id = "default"; // TODO: Get from request context
        
        let bucket = self.metadata
            .load_bucket(org_id, project_id, &req.bucket)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Bucket {} not found", req.bucket)))?;
        
        let bucket_id = BucketId::from_str(&bucket.id.to_string())
            .map_err(|_| Status::internal("Invalid bucket ID"))?;
        
        // Load object metadata
        let version_id = if req.version_id.is_empty() {
            None
        } else {
            Some(req.version_id.as_str())
        };
        
        let object = self.metadata
            .load_object(&bucket_id, &req.key, version_id)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Object {} not found", req.key)))?;
        
        // Check if delete marker
        if object.is_delete_marker {
            return Err(Status::not_found("Object is a delete marker"));
        }
        
        // Get object data from storage backend
        let data = self.storage
            .get_object(&object.id)
            .await
            .map_err(|e| Status::internal(format!("Failed to retrieve object: {}", e)))?;
        
        // Handle range request
        let (start, end) = if req.range_start >= 0 && req.range_end >= 0 {
            let start = req.range_start as usize;
            let end = if req.range_end >= req.range_start {
                (req.range_end as usize).min(data.len())
            } else {
                data.len()
            };
            (start.min(data.len()), end)
        } else {
            (0, data.len())
        };
        
        let chunk_size = 1024 * 1024; // 1MB chunks
        let (tx, rx) = tokio::sync::mpsc::channel(16);
        
        // Send metadata first
        let object_info = self.object_to_proto(&object);
        let _ = tx.send(Ok(GetObjectResponse {
            content: Some(lightningstor_api::proto::get_object_response::Content::Metadata(object_info)),
        })).await;

        // Clone data slice for async move block
        let data_slice = data[start..end].to_vec();
        tokio::spawn(async move {
            for chunk in data_slice.chunks(chunk_size) {
                if tx.send(Ok(GetObjectResponse {
                    content: Some(lightningstor_api::proto::get_object_response::Content::BodyChunk(chunk.to_vec())),
                })).await.is_err() {
                    break;
                }
            }
        });
        
        Ok(Response::new(Box::pin(ReceiverStream::new(rx))))
    }

    async fn delete_object(
        &self,
        request: Request<DeleteObjectRequest>,
    ) -> Result<Response<DeleteObjectResponse>, Status> {
        let req = request.into_inner();
        tracing::info!(
            bucket = %req.bucket,
            key = %req.key,
            "DeleteObject request"
        );

        let org_id = "default";
        let project_id = "default";

        // Load bucket
        let bucket = self.metadata
            .load_bucket(org_id, project_id, &req.bucket)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Bucket {} not found", req.bucket)))?;

        let bucket_id = BucketId::from_str(&bucket.id.to_string())
            .map_err(|_| Status::internal("Invalid bucket ID"))?;

        // Parse version ID
        let version_id = if req.version_id.is_empty() {
            None
        } else {
            Some(req.version_id.as_str())
        };

        // Load object to get its storage ID
        let object = self.metadata
            .load_object(&bucket_id, &req.key, version_id)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Object {} not found", req.key)))?;

        // Delete from storage backend
        self.storage
            .delete_object(&object.id)
            .await
            .map_err(|e| Status::internal(format!("Failed to delete object data: {}", e)))?;

        // Delete from metadata store
        self.metadata
            .delete_object(&bucket_id, &req.key, version_id)
            .await
            .map_err(Self::to_status)?;

        tracing::info!(
            bucket = %req.bucket,
            key = %req.key,
            "Object deleted successfully"
        );

        Ok(Response::new(DeleteObjectResponse {
            version_id: object.version.as_str().to_string(),
            delete_marker: object.is_delete_marker,
        }))
    }

    async fn head_object(
        &self,
        request: Request<HeadObjectRequest>,
    ) -> Result<Response<HeadObjectResponse>, Status> {
        let req = request.into_inner();
        tracing::info!(
            bucket = %req.bucket,
            key = %req.key,
            "HeadObject request"
        );

        let org_id = "default";
        let project_id = "default";

        // Load bucket
        let bucket = self.metadata
            .load_bucket(org_id, project_id, &req.bucket)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Bucket {} not found", req.bucket)))?;

        let bucket_id = BucketId::from_str(&bucket.id.to_string())
            .map_err(|_| Status::internal("Invalid bucket ID"))?;

        // Parse version ID
        let version_id = if req.version_id.is_empty() {
            None
        } else {
            Some(req.version_id.as_str())
        };

        // Load object metadata
        let object = self.metadata
            .load_object(&bucket_id, &req.key, version_id)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Object {} not found", req.key)))?;

        // Check if delete marker
        if object.is_delete_marker {
            return Err(Status::not_found("Object is a delete marker"));
        }

        Ok(Response::new(HeadObjectResponse {
            object: Some(self.object_to_proto(&object)),
        }))
    }

    async fn copy_object(
        &self,
        _request: Request<CopyObjectRequest>,
    ) -> Result<Response<CopyObjectResponse>, Status> {
        Err(Status::unimplemented("CopyObject not yet implemented"))
    }

    async fn list_objects(
        &self,
        request: Request<ListObjectsRequest>,
    ) -> Result<Response<ListObjectsResponse>, Status> {
        let req = request.into_inner();
        tracing::info!(
            bucket = %req.bucket,
            prefix = %req.prefix,
            max_keys = req.max_keys,
            "ListObjects request"
        );

        let org_id = "default";
        let project_id = "default";

        // Load bucket
        let bucket = self.metadata
            .load_bucket(org_id, project_id, &req.bucket)
            .await
            .map_err(Self::to_status)?
            .ok_or_else(|| Status::not_found(format!("Bucket {} not found", req.bucket)))?;

        let bucket_id = BucketId::from_str(&bucket.id.to_string())
            .map_err(|_| Status::internal("Invalid bucket ID"))?;

        // Default max_keys to 1000 if not specified
        let max_keys = if req.max_keys > 0 { req.max_keys } else { 1000 };

        // List objects from metadata store
        let objects = self.metadata
            .list_objects(&bucket_id, &req.prefix, max_keys)
            .await
            .map_err(Self::to_status)?;

        // Convert to proto objects
        let object_infos: Vec<ObjectInfo> = objects
            .iter()
            .filter(|obj| !obj.is_delete_marker)
            .map(|obj| self.object_to_proto(obj))
            .collect();

        let is_truncated = object_infos.len() >= max_keys as usize;
        let next_continuation_token = if is_truncated {
            object_infos.last().map(|obj| obj.key.clone())
        } else {
            None
        };

        Ok(Response::new(ListObjectsResponse {
            objects: object_infos,
            common_prefixes: vec![], // TODO: Implement prefix grouping
            is_truncated,
            next_continuation_token: next_continuation_token.unwrap_or_default(),
            key_count: objects.len() as u32,
        }))
    }

    async fn list_object_versions(
        &self,
        _request: Request<ListObjectVersionsRequest>,
    ) -> Result<Response<ListObjectVersionsResponse>, Status> {
        Err(Status::unimplemented(
            "ListObjectVersions not yet implemented",
        ))
    }

    async fn create_multipart_upload(
        &self,
        _request: Request<CreateMultipartUploadRequest>,
    ) -> Result<Response<CreateMultipartUploadResponse>, Status> {
        Err(Status::unimplemented(
            "CreateMultipartUpload not yet implemented",
        ))
    }

    async fn upload_part(
        &self,
        _request: Request<Streaming<UploadPartRequest>>,
    ) -> Result<Response<UploadPartResponse>, Status> {
        Err(Status::unimplemented("UploadPart not yet implemented"))
    }

    async fn complete_multipart_upload(
        &self,
        _request: Request<CompleteMultipartUploadRequest>,
    ) -> Result<Response<CompleteMultipartUploadResponse>, Status> {
        Err(Status::unimplemented(
            "CompleteMultipartUpload not yet implemented",
        ))
    }

    async fn abort_multipart_upload(
        &self,
        _request: Request<AbortMultipartUploadRequest>,
    ) -> Result<Response<()>, Status> {
        Err(Status::unimplemented(
            "AbortMultipartUpload not yet implemented",
        ))
    }

    async fn list_parts(
        &self,
        _request: Request<ListPartsRequest>,
    ) -> Result<Response<ListPartsResponse>, Status> {
        Err(Status::unimplemented("ListParts not yet implemented"))
    }

    async fn list_multipart_uploads(
        &self,
        _request: Request<ListMultipartUploadsRequest>,
    ) -> Result<Response<ListMultipartUploadsResponse>, Status> {
        Err(Status::unimplemented(
            "ListMultipartUploads not yet implemented",
        ))
    }
}