use crate::caddy::CaddyController;
use async_std::io::{BufReader, BufWriter, WriteExt};
use async_std::net::TcpStream;
use async_std::stream::StreamExt;
use async_std::sync::RwLock;
use async_std::task::JoinHandle;
use async_std::{fs, task};
use camino::{Utf8Path, Utf8PathBuf};
use color_eyre::Result;
use color_eyre::eyre::{WrapErr, eyre};
use log::{debug, info};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::Arc;
use std::time::Duration;

#[derive(Serialize, Deserialize)]
pub struct SiteState {
    active_version: Option<SiteStateVersion>,
    current_version: Option<SiteStateVersion>,
}

impl SiteState {
    async fn read_from_site_directory(site_directory_path: &Utf8Path) -> Result<Self> {
        let string = fs::read_to_string(site_directory_path.join("site.toml").into_std_path_buf()).await?;
        Ok(toml::from_str::<SiteState>(&string)?)
    }

    async fn write_to_site_directory(&self, site_directory_path: &Utf8Path) -> Result<()> {
        fs::create_dir_all(site_directory_path.as_std_path()).await?;
        let mut file = fs::File::create(site_directory_path.join("site.toml").into_std_path_buf()).await?;
        file.write_all(toml::to_string(&self).unwrap().as_bytes()).await?;
        Ok(())
    }

    fn get_current_version_if_outdated(&self) -> Option<&SiteStateVersion> {
        if let Some(current_version) = &self.current_version {
            if let Some(active_version) = &self.active_version {
                if current_version.id != active_version.id {
                    return Some(current_version);
                }
            } else {
                return Some(current_version);
            }
        }

        None
    }
}

#[derive(Serialize, Deserialize, Clone)]
pub struct SiteStateVersion {
    id: String,
    download_url: String,
}

pub struct Site {
    pub domain: String,
    pub path: Utf8PathBuf,
    pub state: RwLock<SiteState>,
}

type Sites = RwLock<HashMap<String, Arc<Site>>>;

pub struct SitesWorker {
    sites: Arc<Sites>,
    sites_directory_path: Utf8PathBuf,
    download_tasks_sender: async_std::channel::Sender<String>,
}

impl SitesWorker {
    pub async fn set_current_version(&self, domain: String, id: String, download_url: String) -> Result<()> {
        let mut sites = self.sites.write().await;
        let site = sites.entry(domain.clone()).or_insert_with(|| {
            Arc::new(Site {
                domain: domain.clone(),
                path: self.sites_directory_path.join(&domain),
                state: RwLock::new(SiteState {
                    current_version: None,
                    active_version: None,
                }),
            })
        });

        let mut state = site.state.write().await;
        state.current_version = Some(SiteStateVersion { id, download_url });
        state.write_to_site_directory(&site.path).await?;
        self.download_tasks_sender.send(domain).await?;

        Ok(())
    }
}

pub async fn load_sites(sites_directory_path: &Utf8Path) -> Result<Sites> {
    let mut sites: HashMap<String, Arc<Site>> = HashMap::new();

    if fs::metadata(sites_directory_path.as_std_path()).await.map(|m| m.is_dir()).unwrap_or(false) {
        let mut dir = fs::read_dir(sites_directory_path.as_std_path()).await?;
        loop {
            if let Some(entry) = dir.next().await {
                let entry = entry?;
                if entry.file_type().await?.is_dir() {
                    let path = Utf8PathBuf::from_path_buf(entry.path().into()).unwrap();
                    let domain = path.file_name().unwrap().to_string();
                    let state = SiteState::read_from_site_directory(&path).await?;

                    sites.insert(
                        domain.clone(),
                        Arc::new(Site {
                            path,
                            domain,
                            state: RwLock::new(state),
                        }),
                    );
                }
            } else {
                break;
            }
        }
    } else {
        fs::create_dir_all(sites_directory_path.as_std_path())
            .await
            .wrap_err("Failed to create the sites directory (and its parents)")?;
    }

    Ok(RwLock::new(sites))
}

async fn handle_download(ureq_agent: Arc<ureq::Agent>, sites: &Sites, caddy_controller: &mut CaddyController, domain: String) -> Result<()> {
    let site = {
        let sites = sites.read().await;
        match sites.get(&domain) {
            None => {
                debug!("Skipping download for {domain} because it is no longer managed.");
                return Ok(());
            }
            Some(a) => Arc::clone(a),
        }
    };

    let mut state = site.state.write().await;
    let current_version = match state.get_current_version_if_outdated() {
        None => {
            debug!("Skipping download for {domain} because it is not outdated.");
            return Ok(());
        }
        Some(v) => v,
    };

    info!("Starting download for {domain} ({}).", current_version.id);

    // Download
    let archive_file_path = site.path.join(format!("{}.zip", current_version.id));

    let response = task::spawn_blocking({
        let url = current_version.download_url.clone();
        move || ureq_agent.get(url).call()
    })
    .await?;
    
    let status = response.status();
    if !status.is_success() {
        return Err(eyre!("Download request failed with status code {status}"));
    }

    let archive_file = task::spawn_blocking({
        let archive_file_path = archive_file_path.to_owned().into_std_path_buf();

        move || -> std::io::Result<std::fs::File> {
            let mut writer = std::io::BufWriter::new(
                std::fs::OpenOptions::new()
                    .truncate(true)
                    .create(true)
                    .write(true)
                    .read(true)
                    .open(archive_file_path)?,
            );

            std::io::copy(&mut response.into_body().into_reader(), &mut writer)?;

            Ok(writer.into_inner()?)
        }
    })
    .await?;

    let extraction_directory_path = site.path.join(&current_version.id);
    let _ = fs::remove_dir_all(extraction_directory_path.as_std_path()).await;
    fs::create_dir_all(extraction_directory_path.as_std_path()).await?;

    debug!("Finished download for {domain} ({}), now unpacking…", current_version.id);

    // Unpack to temp dir
    task::spawn_blocking({
        let extraction_directory_path = extraction_directory_path.clone();

        move || -> Result<()> {
            let mut archive = zip::ZipArchive::new(std::io::BufReader::new(archive_file))?;
            archive.extract(&extraction_directory_path)?;
            Ok(())
        }
    })
    .await?;

    // Update and write state
    let current_version = current_version.clone();
    let old_active_version = state.active_version.replace(current_version);
    state.write_to_site_directory(&site.path).await?;

    // Update Caddy configuration
    info!("Download for {domain} successful, now updating proxy configuration…");
    caddy_controller.upsert_site_configuration(&domain, &extraction_directory_path).await?;

    // Cleanup
    fs::remove_file(archive_file_path.as_std_path()).await?;
    if let Some(old_active_version) = old_active_version {
        let _ = fs::remove_dir_all(site.path.join(old_active_version.id).into_std_path_buf()).await;
    }

    info!("Cleanup finished for {domain}");

    Ok(())
}

async fn sites_worker(
    mut download_tasks_receiver: async_std::channel::Receiver<String>,
    sites: Arc<Sites>,
    mut caddy_controller: CaddyController,
) -> Result<!> {
    let ureq_agent = Arc::new(ureq::Agent::new_with_config(
        ureq::Agent::config_builder()
            .timeout_resolve(Some(Duration::from_secs(10)))
            .timeout_connect(Some(Duration::from_secs(30)))
            .timeout_global(Some(Duration::from_mins(15)))
            .build(),
    ));

    loop {
        let domain = download_tasks_receiver.recv().await.unwrap();
        handle_download(Arc::clone(&ureq_agent), &sites, &mut caddy_controller, domain).await?;
    }
}

pub async fn start_sites_worker(sites_directory_path: Utf8PathBuf, mut caddy_controller: CaddyController) -> Result<(SitesWorker, JoinHandle<Result<!>>)> {
    let (download_tasks_sender, download_tasks_receiver) = async_std::channel::unbounded();

    info!("Discovering managed sites…");
    let sites = Arc::new(load_sites(&sites_directory_path).await?);
    let mut total_count = 0;
    let mut outdated_count = 0;

    for (_, site) in sites.read().await.iter() {
        let state = site.state.read().await;

        if let Some(current_version) = &state.current_version {
            let mut is_outdated = true;
            total_count += 1;

            if let Some(active_version) = &state.active_version {
                is_outdated = current_version.id != active_version.id;

                caddy_controller
                    .upsert_site_configuration(&site.domain, &site.path.join(&active_version.id))
                    .await?;
            }

            if is_outdated {
                outdated_count += 1;
                download_tasks_sender.send(site.domain.clone()).await?;
            }
        }
    }

    info!("Discovered {total_count} site(s), {outdated_count} outdated.");

    let join_handle = task::spawn(sites_worker(download_tasks_receiver, Arc::clone(&sites), caddy_controller));

    Ok((
        SitesWorker {
            sites,
            sites_directory_path,
            download_tasks_sender,
        },
        join_handle,
    ))
}