use crate::error::Result;
use crate::state::{AppState, ServiceOperationalStatus};
use common_contracts::messages::FetchCompanyDataCommand;
use futures_util::StreamExt;
use tracing::{error, info, warn};

use std::sync::Arc;
use tokio::sync::mpsc;
use chrono::Utc;
use std::time::Duration;

const SUBJECT_NAME: &str = "data_fetch_commands";

pub async fn run(state: AppState) -> Result<()> {
    info!("Starting NATS message consumer...");

    loop {
        let status = state.status.read().await.clone();
        if let ServiceOperationalStatus::Degraded { reason } = status {
            warn!(
                "Service is in degraded state (reason: {}). Pausing message consumption for 30s.",
                reason
            );
            tokio::time::sleep(Duration::from_secs(30)).await;
            continue;
        }

        info!("Service is Active. Connecting to NATS...");
        match async_nats::connect(&state.config.nats_addr).await {
            Ok(client) => {
                info!("Successfully connected to NATS.");
                if let Err(e) = subscribe_and_process(state.clone(), client).await {
                    error!("NATS subscription error: {}. Reconnecting in 10s...", e);
                }
            }
            Err(e) => {
                error!("Failed to connect to NATS: {}. Retrying in 10s...", e);
            }
        }
        tokio::time::sleep(Duration::from_secs(10)).await;
    }
}

async fn subscribe_and_process(
    state: AppState,
    client: async_nats::Client,
) -> Result<()> {
    let mut subscriber = client.subscribe(SUBJECT_NAME.to_string()).await?;
    info!(
        "Consumer started, waiting for messages on subject '{}'",
        SUBJECT_NAME
    );

    while let Some(message) = subscriber.next().await {
        let current_status = state.status.read().await.clone();
        if matches!(current_status, ServiceOperationalStatus::Degraded {..}) {
            warn!("Service became degraded. Disconnecting from NATS and pausing consumption.");
            subscriber.unsubscribe().await?;
            return Ok(());
        }

        info!("Received NATS message.");
        let state_for_closure = Arc::new(state.clone());

        tokio::spawn(async move {
            if let Err(e) = serde_json::from_slice::<FetchCompanyDataCommand>(&message.payload) {
                error!("Failed to deserialize message: {}", e);
                warn!("Received non-json message: {:?}", message.payload);
                return;
            }

            let command = match serde_json::from_slice::<FetchCompanyDataCommand>(&message.payload) {
                Ok(c) => c,
                Err(e) => {
                    error!("Failed to deserialize message: {}", e);
                    return;
                }
            };
            info!("Received data fetch command for symbol: {}", command.symbol);

            // Tushare is for the Chinese market ("CN")
            if command.market.to_uppercase() != "CN" {
                info!(
                    "Skipping command for symbol '{}' as its market ('{}') is not 'CN'.",
                    command.symbol, command.market
                );
                return;
            }

            let (tx, rx) = mpsc::channel(1);
            let task_id = command.request_id;
            // Initialize deterministic progress entry
            state_for_closure.tasks.insert(task_id, common_contracts::observability::TaskProgress {
                request_id: task_id,
                task_name: format!("tushare:{}", command.symbol),
                status: "Received".to_string(),
                progress_percent: 0,
                details: "Command received".to_string(),
                started_at: Utc::now(),
            });

            // Spawn the workflow in a separate task
            let workflow_state = state_for_closure.clone();
            tokio::spawn(async move {
                let workflow_state_for_error = workflow_state.clone();
                let result = crate::worker::run_tushare_workflow(workflow_state, command, tx).await;
                if let Err(e) = result {
                    error!(
                        "Error executing Tushare workflow for task {}: {:?}",
                        task_id, e
                    );
                    // Update task to failed status
                    if let Some(mut task) = workflow_state_for_error.tasks.get_mut(&task_id) {
                        task.status = "Failed".to_string();
                        task.details = format!("Workflow failed: {}", e);
                    }
                }
            });

            // Spawn a separate task to clean up the task entry after completion or timeout
            let cleanup_state = state_for_closure.clone();
            tokio::spawn(async move {
                let mut rx = rx;
                match rx.recv().await {
                    Some(_) => {
                        info!("Task {} completed successfully, removing from map.", task_id);
                        cleanup_state.tasks.remove(&task_id);
                    }
                    None => {
                        warn!(
                            "Task {} completion signal not received, removing after timeout.",
                            task_id
                        );
                        cleanup_state.tasks.remove(&task_id);
                    }
                }
            });
        });
    }
    Ok(())
}