//! Async operations for graph database using wasm-bindgen-futures

use crate::types::{GraphError, QueryResult};
use js_sys::Promise;
use wasm_bindgen::prelude::*;
use wasm_bindgen_futures::JsFuture;
use web_sys::console;

/// Async query executor for streaming results
#[wasm_bindgen]
pub struct AsyncQueryExecutor {
    batch_size: usize,
}

#[wasm_bindgen]
impl AsyncQueryExecutor {
    /// Create a new async query executor
    #[wasm_bindgen(constructor)]
    pub fn new(batch_size: Option<usize>) -> Self {
        Self {
            batch_size: batch_size.unwrap_or(100),
        }
    }

    /// Execute query asynchronously with streaming results
    /// This is useful for large result sets
    #[wasm_bindgen(js_name = executeStreaming)]
    pub async fn execute_streaming(&self, _query: String) -> Result<JsValue, JsValue> {
        // This would integrate with the actual GraphDB
        // For now, return a placeholder
        console::log_1(&"Async streaming query execution".into());

        // In a real implementation, this would:
        // 1. Parse the query
        // 2. Execute it in batches
        // 3. Stream results back using async generators or callbacks

        Ok(JsValue::NULL)
    }

    /// Execute query in a Web Worker for background processing
    #[wasm_bindgen(js_name = executeInWorker)]
    pub fn execute_in_worker(&self, _query: String) -> Promise {
        // This would send the query to a Web Worker
        // and return results via postMessage

        Promise::resolve(&JsValue::NULL)
    }

    /// Get batch size
    #[wasm_bindgen(getter, js_name = batchSize)]
    pub fn batch_size(&self) -> usize {
        self.batch_size
    }

    /// Set batch size
    #[wasm_bindgen(setter, js_name = batchSize)]
    pub fn set_batch_size(&mut self, size: usize) {
        self.batch_size = size;
    }
}

/// Async transaction handler
#[wasm_bindgen]
pub struct AsyncTransaction {
    operations: Vec<String>,
    committed: bool,
}

#[wasm_bindgen]
impl AsyncTransaction {
    /// Create a new transaction
    #[wasm_bindgen(constructor)]
    pub fn new() -> Self {
        Self {
            operations: Vec::new(),
            committed: false,
        }
    }

    /// Add operation to transaction
    #[wasm_bindgen(js_name = addOperation)]
    pub fn add_operation(&mut self, operation: String) {
        if !self.committed {
            self.operations.push(operation);
        }
    }

    /// Commit transaction asynchronously
    #[wasm_bindgen]
    pub async fn commit(&mut self) -> Result<JsValue, JsValue> {
        if self.committed {
            return Err(JsValue::from_str("Transaction already committed"));
        }

        console::log_1(&format!("Committing {} operations", self.operations.len()).into());

        // In a real implementation, this would:
        // 1. Execute all operations atomically
        // 2. Handle rollback on failure
        // 3. Return results

        self.committed = true;
        Ok(JsValue::TRUE)
    }

    /// Rollback transaction
    #[wasm_bindgen]
    pub fn rollback(&mut self) {
        if !self.committed {
            self.operations.clear();
            console::log_1(&"Transaction rolled back".into());
        }
    }

    /// Get operation count
    #[wasm_bindgen(getter, js_name = operationCount)]
    pub fn operation_count(&self) -> usize {
        self.operations.len()
    }

    /// Check if committed
    #[wasm_bindgen(getter, js_name = isCommitted)]
    pub fn is_committed(&self) -> bool {
        self.committed
    }
}

impl Default for AsyncTransaction {
    fn default() -> Self {
        Self::new()
    }
}

/// Batch operation executor for improved performance
#[wasm_bindgen]
pub struct BatchOperations {
    max_batch_size: usize,
}

#[wasm_bindgen]
impl BatchOperations {
    /// Create a new batch operations handler
    #[wasm_bindgen(constructor)]
    pub fn new(max_batch_size: Option<usize>) -> Self {
        Self {
            max_batch_size: max_batch_size.unwrap_or(1000),
        }
    }

    /// Execute multiple Cypher statements in batch
    #[wasm_bindgen(js_name = executeBatch)]
    pub async fn execute_batch(&self, statements: Vec<String>) -> Result<JsValue, JsValue> {
        if statements.len() > self.max_batch_size {
            return Err(JsValue::from_str(&format!(
                "Batch size {} exceeds maximum {}",
                statements.len(),
                self.max_batch_size
            )));
        }

        console::log_1(&format!("Executing batch of {} statements", statements.len()).into());

        // In a real implementation, this would:
        // 1. Optimize execution order
        // 2. Execute in parallel where possible
        // 3. Collect and return all results

        Ok(JsValue::NULL)
    }

    /// Get max batch size
    #[wasm_bindgen(getter, js_name = maxBatchSize)]
    pub fn max_batch_size(&self) -> usize {
        self.max_batch_size
    }
}

/// Stream handler for large result sets
#[wasm_bindgen]
pub struct ResultStream {
    chunk_size: usize,
    current_offset: usize,
}

#[wasm_bindgen]
impl ResultStream {
    /// Create a new result stream
    #[wasm_bindgen(constructor)]
    pub fn new(chunk_size: Option<usize>) -> Self {
        Self {
            chunk_size: chunk_size.unwrap_or(50),
            current_offset: 0,
        }
    }

    /// Get next chunk of results
    #[wasm_bindgen(js_name = nextChunk)]
    pub async fn next_chunk(&mut self) -> Result<JsValue, JsValue> {
        // This would fetch the next chunk from the result set
        console::log_1(&format!("Fetching chunk at offset {}", self.current_offset).into());

        self.current_offset += self.chunk_size;

        Ok(JsValue::NULL)
    }

    /// Reset stream to beginning
    #[wasm_bindgen]
    pub fn reset(&mut self) {
        self.current_offset = 0;
    }

    /// Get current offset
    #[wasm_bindgen(getter)]
    pub fn offset(&self) -> usize {
        self.current_offset
    }

    /// Get chunk size
    #[wasm_bindgen(getter, js_name = chunkSize)]
    pub fn chunk_size(&self) -> usize {
        self.chunk_size
    }
}
