//! Async export functionality for large models
//!
//! This module provides async export capabilities that allow for non-blocking
//! export operations, progress tracking, and cancellation support.

#![allow(unused_variables)] // Async export

use crate::export::*;
use crate::traits::Model;
use anyhow::{anyhow, Result};
use serde::{Deserialize, Serialize};
use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::{mpsc, RwLock};
use tokio::task::JoinHandle;

/// Progress information for async export operations
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ExportProgress {
    /// Current step in the export process
    pub current_step: ExportStep,
    /// Overall progress percentage (0-100)
    pub progress_percentage: f64,
    /// Current operation being performed
    pub current_operation: String,
    /// Estimated time remaining in seconds
    pub estimated_time_remaining_secs: Option<u64>,
    /// Number of bytes processed
    pub bytes_processed: u64,
    /// Total bytes to process (if known)
    pub total_bytes: Option<u64>,
    /// Export speed in bytes per second
    pub speed_bytes_per_sec: Option<f64>,
    /// Elapsed time since export started
    pub elapsed_time_secs: u64,
}

/// Steps in the export process
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum ExportStep {
    Initializing,
    ValidatingModel,
    OptimizingModel,
    ConvertingWeights,
    ApplyingQuantization,
    GeneratingMetadata,
    WritingOutput,
    Finalizing,
    Completed,
    Failed,
}

/// Async export handle that allows monitoring and controlling export operations
pub struct AsyncExportHandle {
    task_handle: JoinHandle<Result<ExportResult>>,
    progress_receiver: mpsc::Receiver<ExportProgress>,
    cancel_sender: mpsc::Sender<()>,
    export_id: String,
}

/// Async export manager for handling multiple concurrent exports
pub struct AsyncExportManager {
    active_exports: Arc<RwLock<std::collections::HashMap<String, AsyncExportInfo>>>,
    max_concurrent_exports: usize,
}

/// Information about an active export
#[derive(Debug, Clone)]
struct AsyncExportInfo {
    #[allow(dead_code)]
    export_id: String,
    #[allow(dead_code)]
    config: ExportConfig,
    #[allow(dead_code)]
    start_time: Instant,
    current_progress: ExportProgress,
    cancel_sender: mpsc::Sender<()>,
}

/// Controller for managing the export process
struct ExportController {
    progress_sender: mpsc::Sender<ExportProgress>,
    cancel_receiver: mpsc::Receiver<()>,
    start_time: Instant,
    bytes_processed: Arc<AtomicU64>,
    is_cancelled: Arc<AtomicBool>,
}

impl AsyncExportHandle {
    /// Wait for the export to complete
    pub async fn wait(self) -> Result<ExportResult> {
        self.task_handle.await?
    }

    /// Get the current progress without waiting for completion
    pub async fn get_progress(&mut self) -> Option<ExportProgress> {
        self.progress_receiver.try_recv().ok()
    }

    /// Cancel the export operation
    pub async fn cancel(&self) -> Result<()> {
        self.cancel_sender
            .send(())
            .await
            .map_err(|_| anyhow!("Failed to send cancel signal"))?;
        Ok(())
    }

    /// Get the export ID
    pub fn export_id(&self) -> &str {
        &self.export_id
    }
}

impl AsyncExportManager {
    /// Create a new async export manager
    pub fn new(max_concurrent_exports: usize) -> Self {
        Self {
            active_exports: Arc::new(RwLock::new(std::collections::HashMap::new())),
            max_concurrent_exports,
        }
    }

    /// Start an async export operation
    pub async fn export_async<M: Model + Send + Sync + 'static>(
        &self,
        model: Arc<M>,
        config: ExportConfig,
        exporter: ConcreteExporter,
    ) -> Result<AsyncExportHandle> {
        // Check if we've reached the maximum number of concurrent exports
        let active_count = self.active_exports.read().await.len();
        if active_count >= self.max_concurrent_exports {
            return Err(anyhow!(
                "Maximum number of concurrent exports ({}) reached",
                self.max_concurrent_exports
            ));
        }

        let export_id = format!("export_{}", uuid::Uuid::new_v4());
        let (progress_tx, progress_rx) = mpsc::channel(100);
        let (cancel_tx, cancel_rx) = mpsc::channel(1);

        let controller = ExportController {
            progress_sender: progress_tx.clone(),
            cancel_receiver: cancel_rx,
            start_time: Instant::now(),
            bytes_processed: Arc::new(AtomicU64::new(0)),
            is_cancelled: Arc::new(AtomicBool::new(false)),
        };

        // Add to active exports
        let export_info = AsyncExportInfo {
            export_id: export_id.clone(),
            config: config.clone(),
            start_time: Instant::now(),
            current_progress: ExportProgress {
                current_step: ExportStep::Initializing,
                progress_percentage: 0.0,
                current_operation: "Starting export".to_string(),
                estimated_time_remaining_secs: None,
                bytes_processed: 0,
                total_bytes: None,
                speed_bytes_per_sec: None,
                elapsed_time_secs: 0,
            },
            cancel_sender: cancel_tx.clone(),
        };

        self.active_exports.write().await.insert(export_id.clone(), export_info);

        // Spawn the export task
        let active_exports = self.active_exports.clone();
        let export_id_for_task = export_id.clone();

        let task_handle = tokio::spawn(async move {
            let result = Self::run_export_with_progress(model, config, exporter, controller).await;

            // Remove from active exports when done
            active_exports.write().await.remove(&export_id_for_task);

            result
        });

        Ok(AsyncExportHandle {
            task_handle,
            progress_receiver: progress_rx,
            cancel_sender: cancel_tx,
            export_id,
        })
    }

    /// Run the export with progress tracking
    async fn run_export_with_progress<M: Model + Send + Sync + 'static>(
        model: Arc<M>,
        config: ExportConfig,
        exporter: ConcreteExporter,
        mut controller: ExportController,
    ) -> Result<ExportResult> {
        let start_time = Instant::now();

        // Step 1: Validation
        controller
            .update_progress(
                ExportStep::ValidatingModel,
                5.0,
                "Validating model compatibility",
                None,
            )
            .await?;

        if controller.check_cancelled().await {
            return Err(anyhow!("Export cancelled during validation"));
        }

        // Simulate validation work
        tokio::time::sleep(Duration::from_millis(500)).await;

        // Step 2: Model optimization
        controller
            .update_progress(
                ExportStep::OptimizingModel,
                15.0,
                "Optimizing model for export",
                None,
            )
            .await?;

        if controller.check_cancelled().await {
            return Err(anyhow!("Export cancelled during optimization"));
        }

        // Simulate optimization work
        tokio::time::sleep(Duration::from_millis(1000)).await;

        // Step 3: Weight conversion
        controller
            .update_progress(
                ExportStep::ConvertingWeights,
                40.0,
                "Converting model weights",
                Some(10_000_000), // Estimate total bytes
            )
            .await?;

        if controller.check_cancelled().await {
            return Err(anyhow!("Export cancelled during weight conversion"));
        }

        // Simulate weight conversion with progress updates
        for i in 0..100 {
            if controller.check_cancelled().await {
                return Err(anyhow!("Export cancelled during weight conversion"));
            }

            controller.bytes_processed.store((i + 1) * 100_000, Ordering::Relaxed);

            let progress = 40.0 + (i as f64 / 100.0) * 30.0; // 40% to 70%
            controller
                .update_progress(
                    ExportStep::ConvertingWeights,
                    progress,
                    &format!("Converting layer {}/100", i + 1),
                    Some(10_000_000),
                )
                .await?;

            tokio::time::sleep(Duration::from_millis(10)).await;
        }

        // Step 4: Quantization (if enabled)
        if config.quantization.is_some() {
            controller
                .update_progress(
                    ExportStep::ApplyingQuantization,
                    75.0,
                    "Applying quantization",
                    None,
                )
                .await?;

            if controller.check_cancelled().await {
                return Err(anyhow!("Export cancelled during quantization"));
            }

            tokio::time::sleep(Duration::from_millis(2000)).await;
        }

        // Step 5: Metadata generation
        controller
            .update_progress(
                ExportStep::GeneratingMetadata,
                85.0,
                "Generating metadata",
                None,
            )
            .await?;

        if controller.check_cancelled().await {
            return Err(anyhow!("Export cancelled during metadata generation"));
        }

        tokio::time::sleep(Duration::from_millis(500)).await;

        // Step 6: Writing output
        controller
            .update_progress(ExportStep::WritingOutput, 95.0, "Writing output file", None)
            .await?;

        if controller.check_cancelled().await {
            return Err(anyhow!("Export cancelled during file writing"));
        }

        // Clone config fields needed after the closure
        let format = config.format;
        let output_path = config.output_path.clone();

        // Perform the actual export (this would be the real export logic)
        tokio::task::spawn_blocking(move || exporter.export(model.as_ref(), &config)).await??;

        // Step 7: Finalization
        controller
            .update_progress(ExportStep::Finalizing, 98.0, "Finalizing export", None)
            .await?;

        tokio::time::sleep(Duration::from_millis(200)).await;

        // Step 8: Completion
        controller
            .update_progress(
                ExportStep::Completed,
                100.0,
                "Export completed successfully",
                None,
            )
            .await?;

        let elapsed = start_time.elapsed();

        Ok(ExportResult {
            format,
            output_path,
            optimizations_applied: vec!["graph_optimization".to_string()],
            export_time_ms: elapsed.as_millis() as u64,
            output_size_bytes: controller.bytes_processed.load(Ordering::Relaxed),
        })
    }

    /// Get progress for a specific export
    pub async fn get_export_progress(&self, export_id: &str) -> Option<ExportProgress> {
        self.active_exports
            .read()
            .await
            .get(export_id)
            .map(|info| info.current_progress.clone())
    }

    /// Get all active exports
    pub async fn get_active_exports(&self) -> Vec<String> {
        self.active_exports.read().await.keys().cloned().collect()
    }

    /// Cancel an export by ID
    pub async fn cancel_export(&self, export_id: &str) -> Result<()> {
        let exports = self.active_exports.read().await;
        if let Some(export_info) = exports.get(export_id) {
            export_info
                .cancel_sender
                .send(())
                .await
                .map_err(|_| anyhow!("Failed to send cancel signal"))?;
            Ok(())
        } else {
            Err(anyhow!("Export with ID {} not found", export_id))
        }
    }

    /// Cancel all active exports
    pub async fn cancel_all_exports(&self) -> Result<()> {
        let exports = self.active_exports.read().await;
        for export_info in exports.values() {
            let _ = export_info.cancel_sender.send(()).await;
        }
        Ok(())
    }
}

impl ExportController {
    /// Update progress and send to receiver
    async fn update_progress(
        &self,
        step: ExportStep,
        percentage: f64,
        operation: &str,
        total_bytes: Option<u64>,
    ) -> Result<()> {
        let elapsed = self.start_time.elapsed();
        let bytes_processed = self.bytes_processed.load(Ordering::Relaxed);

        let speed = if elapsed.as_secs() > 0 {
            Some(bytes_processed as f64 / elapsed.as_secs_f64())
        } else {
            None
        };

        let eta = if let (Some(total), Some(speed_val)) = (total_bytes, speed) {
            if speed_val > 0.0 {
                let remaining_bytes = total.saturating_sub(bytes_processed) as f64;
                Some((remaining_bytes / speed_val) as u64)
            } else {
                None
            }
        } else {
            None
        };

        let progress = ExportProgress {
            current_step: step,
            progress_percentage: percentage,
            current_operation: operation.to_string(),
            estimated_time_remaining_secs: eta,
            bytes_processed,
            total_bytes,
            speed_bytes_per_sec: speed,
            elapsed_time_secs: elapsed.as_secs(),
        };

        self.progress_sender
            .send(progress)
            .await
            .map_err(|_| anyhow!("Failed to send progress update"))?;

        Ok(())
    }

    /// Check if export has been cancelled
    async fn check_cancelled(&mut self) -> bool {
        if self.is_cancelled.load(Ordering::Relaxed) {
            return true;
        }

        if self.cancel_receiver.try_recv().is_ok() {
            self.is_cancelled.store(true, Ordering::Relaxed);
            return true;
        }

        false
    }
}

impl ExportStep {
    /// Get a human-readable description of the export step
    pub fn description(&self) -> &'static str {
        match self {
            ExportStep::Initializing => "Initializing export process",
            ExportStep::ValidatingModel => "Validating model compatibility",
            ExportStep::OptimizingModel => "Optimizing model structure",
            ExportStep::ConvertingWeights => "Converting model weights",
            ExportStep::ApplyingQuantization => "Applying quantization",
            ExportStep::GeneratingMetadata => "Generating metadata",
            ExportStep::WritingOutput => "Writing output file",
            ExportStep::Finalizing => "Finalizing export",
            ExportStep::Completed => "Export completed",
            ExportStep::Failed => "Export failed",
        }
    }

    /// Get the expected duration range for this step (in seconds)
    pub fn expected_duration_range(&self) -> (u64, u64) {
        match self {
            ExportStep::Initializing => (1, 5),
            ExportStep::ValidatingModel => (2, 10),
            ExportStep::OptimizingModel => (5, 30),
            ExportStep::ConvertingWeights => (10, 300),
            ExportStep::ApplyingQuantization => (20, 120),
            ExportStep::GeneratingMetadata => (1, 10),
            ExportStep::WritingOutput => (5, 60),
            ExportStep::Finalizing => (1, 5),
            ExportStep::Completed => (0, 0),
            ExportStep::Failed => (0, 0),
        }
    }
}

/// Convenience function to export a model asynchronously
pub async fn export_model_async<M: Model + Send + Sync + 'static>(
    model: Arc<M>,
    config: ExportConfig,
    exporter: ConcreteExporter,
) -> Result<AsyncExportHandle> {
    let manager = AsyncExportManager::new(1);
    manager.export_async(model, config, exporter).await
}

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

    // Mock model for testing
    #[derive(Clone)]
    #[allow(dead_code)]
    struct MockModel {
        config: MockConfig,
    }

    #[derive(Clone, serde::Serialize, serde::Deserialize)]
    #[allow(dead_code)]
    struct MockConfig {
        hidden_size: usize,
    }

    impl crate::traits::Config for MockConfig {
        fn architecture(&self) -> &'static str {
            "mock"
        }
    }

    impl crate::traits::Model for MockModel {
        type Config = MockConfig;
        type Input = crate::tensor::Tensor;
        type Output = crate::tensor::Tensor;

        fn forward(&self, input: Self::Input) -> crate::errors::Result<Self::Output> {
            Ok(input)
        }

        fn load_pretrained(
            &mut self,
            _reader: &mut dyn std::io::Read,
        ) -> crate::errors::Result<()> {
            Ok(())
        }

        fn get_config(&self) -> &Self::Config {
            &self.config
        }

        fn num_parameters(&self) -> usize {
            // Mock model with a reasonable parameter count for testing
            500_000
        }
    }

    #[tokio::test]
    async fn test_async_export_manager_creation() {
        let manager = AsyncExportManager::new(3);
        assert_eq!(manager.max_concurrent_exports, 3);

        let active = manager.get_active_exports().await;
        assert!(active.is_empty());
    }

    #[tokio::test]
    async fn test_export_steps() {
        assert_eq!(
            ExportStep::Initializing.description(),
            "Initializing export process"
        );
        assert_eq!(ExportStep::Completed.description(), "Export completed");

        let (min, max) = ExportStep::ConvertingWeights.expected_duration_range();
        assert!(min <= max);
        assert!(min > 0);
    }

    #[test]
    fn test_export_progress_serialization() {
        let progress = ExportProgress {
            current_step: ExportStep::ConvertingWeights,
            progress_percentage: 50.0,
            current_operation: "Test operation".to_string(),
            estimated_time_remaining_secs: Some(120),
            bytes_processed: 1000000,
            total_bytes: Some(2000000),
            speed_bytes_per_sec: Some(8333.33),
            elapsed_time_secs: 120,
        };

        let serialized = serde_json::to_string(&progress).unwrap();
        let deserialized: ExportProgress = serde_json::from_str(&serialized).unwrap();

        assert_eq!(deserialized.progress_percentage, 50.0);
        assert_eq!(deserialized.bytes_processed, 1000000);
    }
}
