use crate::Job;
use log::{debug, error, info};
use rhai::{Engine, packages::Package};
use std::collections::HashMap;
use std::sync::Arc;
use std::time::Duration;
use tokio::sync::{mpsc, Mutex};
use tokio::task::JoinHandle;

use crate::runner_trait::Runner;

/// Represents a running job with its handle and metadata
struct RunningJob {
    job_id: String,
    handle: JoinHandle<Result<String, Box<dyn std::error::Error + Send + Sync>>>,
    started_at: std::time::Instant,
}

/// Builder for AsyncRunner
#[derive(Default)]
pub struct AsyncRunnerBuilder {
    runner_id: Option<String>,
    db_path: Option<String>,
    redis_url: Option<String>,
    default_timeout: Option<Duration>,
    engine: Option<Arc<dyn Fn() -> Engine + Send + Sync>>,
}

impl AsyncRunnerBuilder {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn runner_id<S: Into<String>>(mut self, runner_id: S) -> Self {
        self.runner_id = Some(runner_id.into());
        self
    }

    pub fn db_path<S: Into<String>>(mut self, db_path: S) -> Self {
        self.db_path = Some(db_path.into());
        self
    }

    pub fn redis_url<S: Into<String>>(mut self, redis_url: S) -> Self {
        self.redis_url = Some(redis_url.into());
        self
    }

    pub fn default_timeout(mut self, timeout: Duration) -> Self {
        self.default_timeout = Some(timeout);
        self
    }

    pub fn engine_factory<F>(mut self, factory: F) -> Self 
    where 
        F: Fn() -> Engine + Send + Sync + 'static,
    {
        self.engine = Some(Arc::new(factory));
        self
    }

    pub fn build(self) -> Result<AsyncRunner, String> {
        Ok(AsyncRunner {
            runner_id: self.runner_id.ok_or("runner_id is required")?,
            db_path: self.db_path.ok_or("db_path is required")?,
            redis_url: self.redis_url.ok_or("redis_url is required")?,
            default_timeout: self.default_timeout.unwrap_or(Duration::from_secs(300)),
            engine_factory: self.engine.ok_or("engine factory is required")?,
            running_jobs: Arc::new(Mutex::new(HashMap::new())),
        })
    }
}

/// Asynchronous runner that processes jobs concurrently
pub struct AsyncRunner {
    pub runner_id: String,
    pub db_path: String,
    pub redis_url: String,
    pub default_timeout: Duration,
    pub engine_factory: Arc<dyn Fn() -> Engine + Send + Sync>,
    running_jobs: Arc<Mutex<HashMap<String, RunningJob>>>,
}

impl AsyncRunner {
    /// Create a new AsyncRunnerBuilder
    pub fn builder() -> AsyncRunnerBuilder {
        AsyncRunnerBuilder::new()
    }

    /// Add a running job to the tracking map
    async fn add_running_job(&self, job_id: String, handle: JoinHandle<Result<String, Box<dyn std::error::Error + Send + Sync>>>) {
        let running_job = RunningJob {
            job_id: job_id.clone(),
            handle,
            started_at: std::time::Instant::now(),
        };
        
        let mut jobs = self.running_jobs.lock().await;
        jobs.insert(job_id.clone(), running_job);
        debug!("Async Runner: Added running job '{}'. Total running: {}", 
               job_id, jobs.len());
    }

    /// Remove a completed job from the tracking map
    async fn remove_running_job(&self, job_id: &str) {
        let mut jobs = self.running_jobs.lock().await;
        if let Some(job) = jobs.remove(job_id) {
            let duration = job.started_at.elapsed();
            debug!("Async Runner: Removed completed job '{}' after {:?}. Remaining: {}", 
                   job_id, duration, jobs.len());
        }
    }

    /// Get the count of currently running jobs
    pub async fn running_job_count(&self) -> usize {
        let jobs = self.running_jobs.lock().await;
        jobs.len()
    }

    /// Cleanup any finished jobs from the running jobs map
    async fn cleanup_finished_jobs(&self) {
        let mut jobs = self.running_jobs.lock().await;
        let mut to_remove = Vec::new();
        
        for (job_id, running_job) in jobs.iter() {
            if running_job.handle.is_finished() {
                to_remove.push(job_id.clone());
            }
        }
        
        for job_id in to_remove {
            if let Some(job) = jobs.remove(&job_id) {
                let duration = job.started_at.elapsed();
                debug!("Async Runner: Cleaned up finished job '{}' after {:?}", 
                       job_id, duration);
            }
        }
    }

}


impl Runner for AsyncRunner {
    fn process_job(&self, job: Job) -> Result<String, Box<dyn std::error::Error + Send + Sync>> {
        let job_id = job.id.clone();
        let runner_id = &self.runner_id;

        // Determine timeout (use job-specific timeout if available, otherwise default)
        let job_timeout = if job.timeout > 0 {
            Duration::from_secs(job.timeout)
        } else {
            self.default_timeout
        };

        info!("Async Runner '{}', Job {}: Spawning job execution task with timeout {:?}", 
              runner_id, job_id, job_timeout);

        // Clone necessary data for the spawned task
        let job_id_clone = job_id.clone();
        let runner_id_clone = runner_id.clone();
        let runner_id_debug = runner_id.clone();
        let job_id_debug = job_id.clone();
        let _redis_url_clone = self.redis_url.clone();
        let running_jobs_clone = Arc::clone(&self.running_jobs);
        let engine_factory = Arc::clone(&self.engine_factory);
        let db_path_clone = self.db_path.clone();

        // Spawn the job execution task
        let job_handle = tokio::spawn(async move {
            // Create a new engine instance (cheap with factory pattern)
            let mut engine = engine_factory();
            let mut db_config = rhai::Map::new();
            db_config.insert("DB_PATH".into(), db_path_clone.into());
            db_config.insert("CALLER_ID".into(), job.caller_id.clone().into());
            db_config.insert("CONTEXT_ID".into(), job.context_id.clone().into());
            engine.set_default_tag(rhai::Dynamic::from(db_config));
            
            // Execute the Rhai script
            let result = match engine.eval::<rhai::Dynamic>(&job.payload) {
                Ok(result) => {
                    let result_str = if result.is::<String>() {
                        result.into_string().unwrap()
                    } else {
                        result.to_string()
                    };
                    info!("Async Runner '{}', Job {}: Script executed successfully. Result: {}", 
                          runner_id_clone, job_id_clone, result_str);
                    Ok(result_str)
                }
                Err(e) => {
                    let error_msg = format!("Script execution error: {}", e);
                    error!("Async Runner '{}', Job {}: {}", runner_id_clone, job_id_clone, error_msg);
                    Err(Box::new(e) as Box<dyn std::error::Error + Send + Sync>)
                }
            };
            
            // Remove this job from the running jobs map when it completes
            let mut jobs = running_jobs_clone.lock().await;
            if let Some(running_job) = jobs.remove(&job_id_clone) {
                let duration = running_job.started_at.elapsed();
                debug!("Async Runner '{}': Removed completed job '{}' after {:?}", 
                       runner_id_debug, job_id_debug, duration);
            }
            
            result
        });

        // Add the job to the running jobs map
        let running_job = RunningJob {
            job_id: job_id.clone(),
            handle: job_handle,
            started_at: std::time::Instant::now(),
        };
        
        let running_jobs_clone = Arc::clone(&self.running_jobs);
        let job_id_for_map = job_id.clone();
        tokio::spawn(async move {
            let mut jobs = running_jobs_clone.lock().await;
            jobs.insert(job_id_for_map, running_job);
            debug!("Async Runner: Added running job '{}'. Total running: {}", 
                   job_id, jobs.len());
        });

        // For async runners, we return immediately with a placeholder
        // The actual result will be handled by the spawned task
        Ok("Job spawned for async processing".to_string())
    }

    fn runner_type(&self) -> &'static str {
        "Async"
    }
    
    fn runner_id(&self) -> &str {
        &self.runner_id
    }
    
    fn redis_url(&self) -> &str {
        &self.redis_url
    }
}

/// Convenience function to spawn an asynchronous runner using the trait interface
/// 
/// This function provides a clean interface for the new async runner implementation
/// with timeout support.
pub fn spawn_async_runner<F>(
    runner_id: String,
    db_path: String,
    redis_url: String,
    shutdown_rx: mpsc::Receiver<()>,
    default_timeout: std::time::Duration,
    engine_factory: F,
) -> JoinHandle<Result<(), Box<dyn std::error::Error + Send + Sync>>> 
where
    F: Fn() -> Engine + Send + Sync + 'static, 
{
    use std::sync::Arc;
    
    let runner = Arc::new(
        AsyncRunner::builder()
            .runner_id(runner_id)
            .db_path(db_path)
            .redis_url(redis_url)
            .default_timeout(default_timeout)
            .engine_factory(engine_factory)
            .build()
            .expect("Failed to build AsyncRunner")
    );
    crate::runner_trait::spawn_runner(runner, shutdown_rx)
}