use crate::{
    bcmr::{parsedbcmr::parse_all_bcmr_identities, utilurl::get_url},
    db::{
        bcmr::{delete_entries_for_well_known, insert_well_known_bcmr},
        DBPool,
    },
};
use anyhow::Result;
use log::{info, warn};
use serde_json::Value;
use std::{
    sync::{atomic::AtomicBool, Arc},
    thread::{self, JoinHandle},
    time::{Duration, Instant},
};

// List of 'trust me bro' sources of truth
const WELL_KNOWN: [(&str, &str); 1] = [(
    "otr",
    "https://otr.cash/.well-known/bitcoin-cash-metadata-registry.json",
)];

pub struct WellKnownDownloader {
    db: DBPool,
    keep_running: Arc<AtomicBool>,
    download_thread: Option<JoinHandle<()>>,
}

const LOOP_SLEEP_TIME: Duration = Duration::from_secs(2);
const UPDATE_INTERVAL: Duration = Duration::from_secs(3600 * 24); // once per day
const DOWNLOAD_TIMEOUT: Duration = Duration::from_secs(120);
const MAX_BCMR_SIZE: usize = 1024 * 1024 * 500; // 500 MB

impl WellKnownDownloader {
    pub fn new(db: DBPool) -> Self {
        Self {
            db,
            keep_running: Arc::new(AtomicBool::new(true)),
            download_thread: None,
        }
    }

    pub fn start(&mut self) -> Result<()> {
        let db_cpy = self.db.clone();
        let keep_running_cpy = self.keep_running.clone();
        self.download_thread = Some(
            thread::Builder::new()
                .name("wellknown downloader".to_string())
                .spawn(move || {
                    let mut last_update: Option<Instant> = None;
                    loop {
                    thread::sleep(LOOP_SLEEP_TIME);
                    if !keep_running_cpy.load(std::sync::atomic::Ordering::Relaxed) {
                        info!("Exiting bcmr well known thread");
                        return;
                    }

                    if let Some(last_time) = last_update {
                        if Instant::now().duration_since(last_time) < UPDATE_INTERVAL {
                            continue;
                        }
                    }
                    last_update = Some(Instant::now());



                    for (source, url) in WELL_KNOWN {
                        info!("bcmr: Fetching well known '{}' token list", source);

                        let json_str: String = match get_url(url, DOWNLOAD_TIMEOUT, MAX_BCMR_SIZE) {
                            Ok((json_str, _)) => json_str,
                            Err(e) => {
                                info!("bcmr: Failed to download well known url {}: {}", url, e);
                                continue;
                            }
                        };

                        let json: Value = match serde_json::from_str(&json_str) {
                            Ok(j) => j,
                            Err(e) => {
                                info!("bcmr: Failed to parse well known url {}: {}", url, e);
                                continue;
                            }
                        };

                        let bcmr_entries = match parse_all_bcmr_identities(&json, true, source) {
                            Ok(entries) => entries,
                            Err(e) => {
                                info!("bcmr: Failed to parse bcmr from well known url {}: {}", url, e);
                                continue;
                            }
                        };

                        let mut tx = match db_cpy.get() {
                            Ok(conn) => conn,
                            Err(e) => {
                                warn!("bcmr: Failed to get DB connection: {}", e);
                                continue;
                            }
                        };
                        let tx = match tx.transaction() {
                            Ok(tx) => tx,
                            Err(e) => {
                                warn!("bcmr: Failed to initiate DB transaction: {}", e);
                                continue;
                            }
                        };

                        if let Err(e) = delete_entries_for_well_known(&tx, source) {
                            warn!("bcmr: Failed to delete entries for well known source {}: {}", source, e);
                        }
                        for bcmr in bcmr_entries {
                            if let Err(e) = insert_well_known_bcmr(&tx, source, &bcmr) {
                                warn!("bcmr: Failed to insert an entry from well known source {}: {}", source, e);
                            }
                        }

                        if let Err(e) = tx.commit() {
                            warn!("bcmr: Failed to update DB entries for {}: {}", source, e);
                        }

                    }

                }})
                .expect("failed to start bcmr wellknown thread"),
        );

        Ok(())
    }
}

impl Drop for WellKnownDownloader {
    fn drop(&mut self) {
        self.keep_running
            .store(false, std::sync::atomic::Ordering::SeqCst);
        if let Some(thread) = self.download_thread.take() {
            // Wake the thread in case it is sleeping
            thread.thread().unpark();

            match thread.join() {
                Ok(_) => info!("bcmr well knownthread done"),
                Err(e) => warn!("Failed to join bcmr wellknown thread: {:?}", e),
            }
        }
    }
}