mod collector;

use std::fs::File;
use std::io::Write;
use std::time::{Duration, Instant};

use anyhow::Context;
use aquatic_common::IndexMap;
use aquatic_udp_protocol::{PeerClient, PeerId};
use compact_str::CompactString;
use crossbeam_channel::Receiver;
use num_format::{Locale, ToFormattedString};
use serde::Serialize;
use time::format_description::well_known::Rfc2822;
use time::OffsetDateTime;
use tinytemplate::TinyTemplate;

use collector::{CollectedStatistics, StatisticsCollector};

use crate::common::*;
use crate::config::Config;

const TEMPLATE_KEY: &str = "statistics";
const TEMPLATE_CONTENTS: &str = include_str!("../../../templates/statistics.html");
const STYLESHEET_CONTENTS: &str = concat!(
    "<style>",
    include_str!("../../../templates/statistics.css"),
    "</style>"
);

#[derive(Debug, Serialize)]
struct TemplateData {
    stylesheet: String,
    ipv4_active: bool,
    ipv6_active: bool,
    extended_active: bool,
    ipv4: CollectedStatistics,
    ipv6: CollectedStatistics,
    last_updated: String,
    peer_update_interval: String,
    peer_clients: Vec<(String, String)>,
}

pub fn run_statistics_worker(
    config: Config,
    shared_state: State,
    statistics_receiver: Receiver<StatisticsMessage>,
) -> anyhow::Result<()> {
    let process_peer_client_data = {
        let mut collect = config.statistics.write_html_to_file;

        #[cfg(feature = "prometheus")]
        {
            collect |= config.statistics.run_prometheus_endpoint;
        }

        collect & config.statistics.peer_clients
    };

    let opt_tt = if config.statistics.write_html_to_file {
        let mut tt = TinyTemplate::new();

        tt.add_template(TEMPLATE_KEY, TEMPLATE_CONTENTS)
            .context("parse statistics html template")?;

        Some(tt)
    } else {
        None
    };

    let mut ipv4_collector = StatisticsCollector::new(
        shared_state.statistics_ipv4,
        #[cfg(feature = "prometheus")]
        "4".into(),
    );
    let mut ipv6_collector = StatisticsCollector::new(
        shared_state.statistics_ipv6,
        #[cfg(feature = "prometheus")]
        "6".into(),
    );

    // Store a count to enable not removing peers from the count completely
    // just because they were removed from one torrent
    let mut peers: IndexMap<PeerId, (usize, PeerClient, CompactString)> = IndexMap::default();

    loop {
        let start_time = Instant::now();

        for message in statistics_receiver.try_iter() {
            match message {
                StatisticsMessage::Ipv4PeerHistogram(h) => ipv4_collector.add_histogram(&config, h),
                StatisticsMessage::Ipv6PeerHistogram(h) => ipv6_collector.add_histogram(&config, h),
                StatisticsMessage::PeerAdded(peer_id) => {
                    if process_peer_client_data {
                        peers
                            .entry(peer_id)
                            .or_insert_with(|| (0, peer_id.client(), peer_id.first_8_bytes_hex()))
                            .0 += 1;
                    }
                }
                StatisticsMessage::PeerRemoved(peer_id) => {
                    if process_peer_client_data {
                        if let Some((count, _, _)) = peers.get_mut(&peer_id) {
                            *count -= 1;

                            if *count == 0 {
                                peers.remove(&peer_id);
                            }
                        }
                    }
                }
            }
        }

        let statistics_ipv4 = ipv4_collector.collect_from_shared(
            #[cfg(feature = "prometheus")]
            &config,
        );
        let statistics_ipv6 = ipv6_collector.collect_from_shared(
            #[cfg(feature = "prometheus")]
            &config,
        );

        let peer_clients = if process_peer_client_data {
            let mut clients: IndexMap<PeerClient, usize> = IndexMap::default();

            #[cfg(feature = "prometheus")]
            let mut prefixes: IndexMap<CompactString, usize> = IndexMap::default();

            // Only count peer_ids once, even if they are in multiple torrents
            for (_, peer_client, prefix) in peers.values() {
                *clients.entry(peer_client.to_owned()).or_insert(0) += 1;

                #[cfg(feature = "prometheus")]
                if config.statistics.run_prometheus_endpoint
                    && config.statistics.prometheus_peer_id_prefixes
                {
                    *prefixes.entry(prefix.to_owned()).or_insert(0) += 1;
                }
            }

            clients.sort_unstable_by(|_, a, _, b| b.cmp(a));

            #[cfg(feature = "prometheus")]
            if config.statistics.run_prometheus_endpoint
                && config.statistics.prometheus_peer_id_prefixes
            {
                for (prefix, count) in prefixes {
                    ::metrics::gauge!(
                        "aquatic_peer_id_prefixes",
                        "prefix_hex" => prefix.to_string(),
                    )
                    .set(count as f64);
                }
            }

            let mut client_vec = Vec::with_capacity(clients.len());

            for (client, count) in clients {
                if config.statistics.write_html_to_file {
                    client_vec.push((client.to_string(), count.to_formatted_string(&Locale::en)));
                }

                #[cfg(feature = "prometheus")]
                if config.statistics.run_prometheus_endpoint {
                    ::metrics::gauge!(
                        "aquatic_peer_clients",
                        "client" => client.to_string(),
                    )
                    .set(count as f64);
                }
            }

            client_vec
        } else {
            Vec::new()
        };

        if config.statistics.print_to_stdout {
            println!("General:");
            println!(
                "  access list entries: {}",
                shared_state.access_list.load().len()
            );

            if config.network.ipv4_active() {
                println!("IPv4:");
                print_to_stdout(&config, &statistics_ipv4);
            }
            if config.network.ipv6_active() {
                println!("IPv6:");
                print_to_stdout(&config, &statistics_ipv6);
            }

            println!();
        }

        if let Some(tt) = opt_tt.as_ref() {
            let template_data = TemplateData {
                stylesheet: STYLESHEET_CONTENTS.to_string(),
                ipv4_active: config.network.ipv4_active(),
                ipv6_active: config.network.ipv6_active(),
                extended_active: config.statistics.torrent_peer_histograms,
                ipv4: statistics_ipv4,
                ipv6: statistics_ipv6,
                last_updated: OffsetDateTime::now_utc()
                    .format(&Rfc2822)
                    .unwrap_or("(formatting error)".into()),
                peer_update_interval: format!("{}", config.cleaning.torrent_cleaning_interval),
                peer_clients,
            };

            if let Err(err) = save_html_to_file(&config, tt, &template_data) {
                ::log::error!("Couldn't save statistics to file: {:#}", err)
            }
        }

        peers.shrink_to_fit();

        if let Some(time_remaining) =
            Duration::from_secs(config.statistics.interval).checked_sub(start_time.elapsed())
        {
            ::std::thread::sleep(time_remaining);
        } else {
            ::log::warn!(
                "statistics interval not long enough to process all data, output may be misleading"
            );
        }
    }
}

fn print_to_stdout(config: &Config, statistics: &CollectedStatistics) {
    println!(
        "  bandwidth: {:>7} Mbit/s in, {:7} Mbit/s out",
        statistics.rx_mbits, statistics.tx_mbits,
    );
    println!("  requests/second: {:>10}", statistics.requests_per_second);
    println!("  responses/second");
    println!(
        "    total:         {:>10}",
        statistics.responses_per_second_total
    );
    println!(
        "    connect:       {:>10}",
        statistics.responses_per_second_connect
    );
    println!(
        "    announce:      {:>10}",
        statistics.responses_per_second_announce
    );
    println!(
        "    scrape:        {:>10}",
        statistics.responses_per_second_scrape
    );
    println!(
        "    error:         {:>10}",
        statistics.responses_per_second_error
    );
    println!("  torrents:        {:>10}", statistics.num_torrents);
    println!(
        "  peers:           {:>10} (updated every {}s)",
        statistics.num_peers, config.cleaning.torrent_cleaning_interval
    );

    if config.statistics.torrent_peer_histograms {
        println!(
            "  peers per torrent (updated every {}s)",
            config.cleaning.torrent_cleaning_interval
        );
        println!("    min            {:>10}", statistics.peer_histogram.min);
        println!("    p10            {:>10}", statistics.peer_histogram.p10);
        println!("    p20            {:>10}", statistics.peer_histogram.p20);
        println!("    p30            {:>10}", statistics.peer_histogram.p30);
        println!("    p40            {:>10}", statistics.peer_histogram.p40);
        println!("    p50            {:>10}", statistics.peer_histogram.p50);
        println!("    p60            {:>10}", statistics.peer_histogram.p60);
        println!("    p70            {:>10}", statistics.peer_histogram.p70);
        println!("    p80            {:>10}", statistics.peer_histogram.p80);
        println!("    p90            {:>10}", statistics.peer_histogram.p90);
        println!("    p95            {:>10}", statistics.peer_histogram.p95);
        println!("    p99            {:>10}", statistics.peer_histogram.p99);
        println!("    p99.9          {:>10}", statistics.peer_histogram.p999);
        println!("    max            {:>10}", statistics.peer_histogram.max);
    }
}

fn save_html_to_file(
    config: &Config,
    tt: &TinyTemplate,
    template_data: &TemplateData,
) -> anyhow::Result<()> {
    let mut file = File::create(&config.statistics.html_file_path).with_context(|| {
        format!(
            "File path: {}",
            &config.statistics.html_file_path.to_string_lossy()
        )
    })?;

    write!(file, "{}", tt.render(TEMPLATE_KEY, template_data)?)?;

    Ok(())
}