use std::sync::Arc;

use super::analytic_unit::types::{AnalyticUnitConfig, PatternConfig, PatchConfig};
use super::types::{self, DetectionRunnerConfig, LearningTrain};
use super::{
    analytic_client::AnalyticClient,
    analytic_unit::pattern_analytic_unit::{self, LearningResults, PatternAnalyticUnit},
    types::{AnalyticServiceMessage, DetectionTask, LearningStatus, RequestType, ResponseType},
};

use crate::services::analytic_service::analytic_unit::resolve;
use crate::services::{
    metric_service::MetricService,
    segments_service::{self, Segment, SegmentType, SegmentsService, ID_LENGTH},
};
use crate::utils::{self};

use crate::services::analytic_service::analytic_unit::types::{AnalyticUnit, LearningResult};

use anyhow;

use serde_json::Value;
use tokio::sync::{mpsc, oneshot, RwLock};

use chrono::Utc;



// TODO: now it's basically single analytic unit, service will operate on many AU
pub struct AnalyticService {
    metric_service: MetricService,
    segments_service: SegmentsService,

    analytic_unit: Option<Arc<RwLock<Box<dyn AnalyticUnit + Send + Sync>>>>,
    analytic_unit_config: AnalyticUnitConfig,
    analytic_unit_learning_status: LearningStatus,

    tx: mpsc::Sender<AnalyticServiceMessage>,
    rx: mpsc::Receiver<AnalyticServiceMessage>,

    endpoint: Option<String>,

    // handlers
    learning_handler: Option<tokio::task::JoinHandle<()>>,

    // awaiters
    learning_waiters: Vec<DetectionTask>,

    // runner
    runner_handler: Option<tokio::task::JoinHandle<()>>,
}

impl AnalyticService {
    pub fn new(
        metric_service: MetricService,
        segments_service: segments_service::SegmentsService,
        endpoint: Option<String>,
    ) -> AnalyticService {
        let (tx, rx) = mpsc::channel::<AnalyticServiceMessage>(32);

        AnalyticService {
            metric_service,
            segments_service,

            // TODO: get it from persistance
            analytic_unit: None,
            analytic_unit_config: AnalyticUnitConfig::Pattern(PatternConfig {
                correlation_score: 0.95,
                model_score: 0.95,
            }),

            analytic_unit_learning_status: LearningStatus::Initialization,
            tx,
            rx,

            endpoint,

            // handlers
            learning_handler: None,

            // awaiters
            learning_waiters: Vec::new(),

            runner_handler: None,
        }
    }

    pub fn get_client(&self) -> AnalyticClient {
        AnalyticClient::new(self.tx.clone())
    }

    fn run_detection_task(&self, task: DetectionTask) {
        // TODO: save handler of the task
        tokio::spawn({
            let ms = self.metric_service.clone();
            let au = self.analytic_unit.as_ref().unwrap().clone();
            async move {
                AnalyticService::get_detections(task.sender, au, ms, task.from, task.to).await;
            }
        });
    }

    // fn run_detection_runner(&mut self, task: DetectionRunnerConfig) {
    //     if self.runner_handler.is_some() {
    //         self.runner_handler.as_mut().unwrap().abort();
    //     }
    //     // TODO: save handler of the task
    //     self.runner_handler = Some(tokio::spawn({
    //         let au = self.analytic_unit.unwrap();
    //         let ms = self.metric_service.clone();
    //         async move {
    //             // TODO: implement
    //         }
    //     }));
    // }

    fn consume_request(&mut self, req: types::RequestType) -> () {
        match req {
            RequestType::RunLearning => {
                if self.learning_handler.is_some() {
                    self.learning_handler.as_ref().unwrap().abort();
                    self.learning_handler = None;
                }
                self.learning_handler = Some(tokio::spawn({
                    self.analytic_unit_learning_status = LearningStatus::Starting;
                    let tx = self.tx.clone();
                    let ms = self.metric_service.clone();
                    let ss = self.segments_service.clone();
                    let cfg = self.analytic_unit_config.clone();
                    async move {
                        AnalyticService::run_learning(tx, cfg, ms, ss).await;
                    }
                }));
            }
            RequestType::RunDetection(task) => {
                if self.analytic_unit_learning_status == LearningStatus::Initialization {
                    match task
                        .sender
                        .send(Err(anyhow::format_err!("Analytics in initialization")))
                    {
                        Ok(_) => {}
                        Err(e) => {
                            println!("failed to send error about initialization");
                            println!("{:?}", e);
                        }
                    }
                    return;
                }
                if self.analytic_unit_learning_status == LearningStatus::Ready {
                    self.run_detection_task(task);
                } else {
                    self.learning_waiters.push(task);
                }
            }
            RequestType::GetStatus(tx) => {
                tx.send(self.analytic_unit_learning_status.clone()).unwrap();
            }
            // RequestType::GetLearningTrain(tx) => {
            //     if self.analytic_unit_learning_results.is_none() {
            //         tx.send(LearningTrain::default()).unwrap();
            //     } else {
            //         tx.send(
            //             self.analytic_unit_learning_results
            //                 .as_ref()
            //                 .unwrap()
            //                 .learning_train
            //                 .clone(),
            //         )
            //         .unwrap();
            //     }
            // }
            RequestType::GetConfig(tx) => {
                tx.send(self.analytic_unit_config.clone()).unwrap();
            },
            RequestType::PatchConfig(patch_obj, tx) => {
                // TODO: path config
                // TODO: run learning if config type changed
                self.patch_config(patch_obj);
                tx.send(()).unwrap();
            }
        };
    }

    fn consume_response(&mut self, res: types::ResponseType) {
        match res {
            // TODO: handle when learning panic
            ResponseType::LearningStarted => {
                self.analytic_unit_learning_status = LearningStatus::Learning
            }
            ResponseType::LearningFinished(results) => {
                self.learning_handler = None;
                self.analytic_unit = Some(Arc::new(tokio::sync::RwLock::new(results)));
                self.analytic_unit_learning_status = LearningStatus::Ready;

                // TODO: run tasks from self.learning_waiter
                while self.learning_waiters.len() > 0 {
                    let task = self.learning_waiters.pop().unwrap();
                    self.run_detection_task(task);
                }

                // TODO: fix this
                // if self.endpoint.is_some() {
                //     self.run_detection_runner(DetectionRunnerConfig {
                //         endpoint: self.endpoint.as_ref().unwrap().clone(),
                //         from: Utc::now().timestamp() as u64,
                //     });
                // }
            }
            ResponseType::LearningFinishedEmpty => {
                // TODO: drop all learning_waiters with empty results
                self.analytic_unit = None;
                self.analytic_unit_learning_status = LearningStatus::Initialization;
            }
            ResponseType::LearningDatasourceError => {
                // TODO: drop all learning_waiters with error
                self.analytic_unit = None;
                self.analytic_unit_learning_status = LearningStatus::Error;
            }
        }
    }

    fn patch_config(&mut self, mut patch: PatchConfig) {
        // let r = patch.take();
        println!("{:?}", patch);
    }

    pub async fn serve(&mut self) {
        // TODO: remove this hack
        self.consume_request(RequestType::RunLearning);

        while let Some(message) = self.rx.recv().await {
            match message {
                AnalyticServiceMessage::Request(req) => self.consume_request(req),
                AnalyticServiceMessage::Response(res) => self.consume_response(res),
            }
        }
    }

    async fn run_learning(
        tx: mpsc::Sender<AnalyticServiceMessage>,
        aucfg: AnalyticUnitConfig,
        ms: MetricService,
        ss: SegmentsService,
    ) {
        let mut au = resolve(aucfg);

        match tx
            .send(AnalyticServiceMessage::Response(
                ResponseType::LearningStarted,
            ))
            .await
        {
            Ok(_) => {}
            Err(_e) => println!("Fail to send learning started notification"),
        }

        // TODO: maybe to spawn_blocking here
        let lr = match au.learn(ms, ss).await {
            LearningResult::Finished => ResponseType::LearningFinished(au),
            LearningResult::DatasourceError => ResponseType::LearningDatasourceError,
            LearningResult::FinishedEmpty => ResponseType::LearningFinishedEmpty,
        };

        match tx.send(AnalyticServiceMessage::Response(lr)).await {
            Ok(_) => {}
            Err(_e) => println!("Fail to send learning results"),
        }
    }

    async fn get_detections(
        tx: oneshot::Sender<anyhow::Result<Vec<Segment>>>,
        analytic_unit: Arc<RwLock<Box<dyn AnalyticUnit + Send + Sync>>>,
        ms: MetricService,
        from: u64,
        to: u64,
    ) {
        let result = analytic_unit
            .read()
            .await
            .detect(ms, from, to)
            .await
            .unwrap();

        let result_segments: Vec<Segment> = result
            .iter()
            .map(|(p, q)| Segment {
                from: *p,
                to: *q,
                id: Some(utils::get_random_str(ID_LENGTH)),
                segment_type: SegmentType::Detection,
            })
            .collect();

        match tx.send(Ok(result_segments)) {
            Ok(_) => {}
            Err(_e) => {
                println!("failed to send results");
            }
        }
        return;
    }
}