use std::{sync::Arc, time::Duration};

use anyhow::bail;
use gpapi::{auth::SamlAuthData, gp_params::GpParams, utils::redact::redact_uri};
use log::{info, warn};
use tauri::{
  webview::{PageLoadEvent, PageLoadPayload},
  AppHandle, WebviewUrl, WebviewWindow, WindowEvent,
};
use tokio::{sync::oneshot, time};

use crate::auth_prelogin;

use super::auth_messenger::{AuthError, AuthEvent, AuthMessenger};

pub trait PlatformWebviewExt {
  fn ignore_tls_errors(&self) -> anyhow::Result<()>;

  fn load_url(&self, url: &str) -> anyhow::Result<()>;

  fn load_html(&self, html: &str) -> anyhow::Result<()>;

  fn get_html(&self, callback: Box<dyn Fn(anyhow::Result<String>) + 'static>);

  fn load_auth_request(&self, auth_request: &str) -> anyhow::Result<()> {
    if auth_request.starts_with("http") {
      info!("Loading auth request as URL: {}", redact_uri(auth_request));
      self.load_url(auth_request)
    } else {
      info!("Loading auth request as HTML...");
      self.load_html(auth_request)
    }
  }
}

#[cfg(not(target_os = "macos"))]
pub trait GetHeader {
  fn get_header(&self, key: &str) -> Option<String>;
}

pub struct WebviewAuthenticator<'a> {
  server: &'a str,
  gp_params: &'a GpParams,
  auth_request: Option<&'a str>,
  clean: bool,

  is_retrying: tokio::sync::RwLock<bool>,
}

impl<'a> WebviewAuthenticator<'a> {
  pub fn new(server: &'a str, gp_params: &'a GpParams) -> Self {
    Self {
      server,
      gp_params,
      auth_request: None,
      clean: false,
      is_retrying: Default::default(),
    }
  }

  pub fn with_auth_request(mut self, auth_request: &'a str) -> Self {
    self.auth_request = Some(auth_request);
    self
  }

  pub fn with_clean(mut self, clean: bool) -> Self {
    self.clean = clean;
    self
  }

  pub async fn authenticate(&self, app_handle: &AppHandle) -> anyhow::Result<SamlAuthData> {
    let auth_messenger = Arc::new(AuthMessenger::new());
    let auth_messenger_clone = Arc::clone(&auth_messenger);

    let on_page_load = move |auth_window: WebviewWindow, event: PageLoadPayload<'_>| {
      let auth_messenger_clone = Arc::clone(&auth_messenger_clone);
      let redacted_url = redact_uri(event.url().as_str());

      match event.event() {
        PageLoadEvent::Started => {
          info!("Started loading page: {}", redacted_url);
          auth_messenger_clone.cancel_raise_window();
        }
        PageLoadEvent::Finished => {
          info!("Finished loading page: {}", redacted_url);
        }
      }

      // Read auth data from the page no matter whether it's finished loading or not
      // Because we found that the finished event may not be triggered in some cases (e.g., on macOS)
      let _ = auth_window.with_webview(move |wv| {
        wv.get_html(Box::new(move |html| match html {
          Ok(html) => auth_messenger_clone.read_from_html(&html),
          Err(err) => warn!("Failed to get html: {}", err),
        }));
      });
    };

    let title_bar_height = if cfg!(target_os = "macos") { 28.0 } else { 0.0 };

    let auth_window = WebviewWindow::builder(app_handle, "auth_window", WebviewUrl::default())
      .on_page_load(on_page_load)
      .title("GlobalProtect Login")
      .inner_size(900.0, 650.0 + title_bar_height)
      .focused(true)
      .visible(false)
      .center()
      .build()?;

    self
      .setup_auth_window(&auth_window, Arc::clone(&auth_messenger))
      .await?;

    loop {
      match auth_messenger.subscribe().await? {
        AuthEvent::Close => bail!("Authentication cancelled"),
        AuthEvent::RaiseWindow => self.raise_window(&auth_window),
        #[cfg(not(target_os = "macos"))]
        AuthEvent::Error(AuthError::TlsError) => bail!(gpapi::error::PortalError::TlsError),
        AuthEvent::Error(AuthError::NotFound(location)) => {
          info!(
            "No auth data found in {:?}, it may not be the /SAML20/SP/ACS endpoint",
            location
          );
          self.handle_not_found(&auth_window, &auth_messenger);
        }
        AuthEvent::Error(AuthError::Invalid(err, location)) => {
          warn!("Got invalid auth data in {:?}: {}", location, err);
          self.retry_auth(&auth_window).await;
        }
        AuthEvent::Data(auth_data, location) => {
          info!("Got auth data from {:?}", location);

          auth_window.close()?;
          return Ok(auth_data);
        }
      }
    }
  }

  async fn setup_auth_window(
    &self,
    auth_window: &WebviewWindow,
    auth_messenger: Arc<AuthMessenger>,
  ) -> anyhow::Result<()> {
    info!("Setting up auth window...");

    if self.clean {
      info!("Clearing all browsing data...");
      auth_window.clear_all_browsing_data()?;
    }

    // Handle window close event
    let auth_messenger_clone = Arc::clone(&auth_messenger);
    auth_window.on_window_event(move |event| {
      if let WindowEvent::CloseRequested { .. } = event {
        auth_messenger_clone.send_auth_event(AuthEvent::Close);
      }
    });

    // Show the window after 10 seconds, so that the user can see the window if the auth process is stuck
    let auth_messenger_clone = Arc::clone(&auth_messenger);
    tokio::spawn(async move {
      time::sleep(Duration::from_secs(10)).await;
      auth_messenger_clone.send_auth_event(AuthEvent::RaiseWindow);
    });

    let auth_request = match self.auth_request {
      Some(auth_request) => auth_request.to_string(),
      None => auth_prelogin(&self.server, &self.gp_params).await?,
    };

    let (tx, rx) = oneshot::channel::<anyhow::Result<()>>();
    let ignore_tls_errors = self.gp_params.ignore_tls_errors();

    // Set up webview
    auth_window.with_webview(move |wv| {
      #[cfg(not(target_os = "macos"))]
      {
        use super::platform_impl::PlatformWebviewOnResponse;
        wv.on_response(Box::new(move |response| match response {
          Ok(response) => auth_messenger.read_from_response(&response),
          Err(err) => auth_messenger.send_auth_error(err),
        }));
      }

      let result = || -> anyhow::Result<()> {
        if ignore_tls_errors {
          wv.ignore_tls_errors()?;
        }

        wv.load_auth_request(&auth_request)
      }();

      if let Err(result) = tx.send(result) {
        warn!("Failed to send setup auth window result: {:?}", result);
      }
    })?;

    rx.await??;
    info!("Auth window setup completed");

    Ok(())
  }

  fn handle_not_found(&self, auth_window: &WebviewWindow, auth_messenger: &Arc<AuthMessenger>) {
    let visible = auth_window.is_visible().unwrap_or(false);
    if visible {
      return;
    }

    auth_messenger.schedule_raise_window(2);
  }

  async fn retry_auth(&self, auth_window: &WebviewWindow) {
    let mut is_retrying = self.is_retrying.write().await;
    if *is_retrying {
      info!("Already retrying authentication, skipping...");
      return;
    }

    *is_retrying = true;
    drop(is_retrying);

    if let Err(err) = self.retry_auth_impl(auth_window).await {
      warn!("Failed to retry authentication: {}", err);
    }

    *self.is_retrying.write().await = false;
  }

  async fn retry_auth_impl(&self, auth_window: &WebviewWindow) -> anyhow::Result<()> {
    info!("Retrying authentication...");

    auth_window.eval( r#"
      var loading = document.createElement("div");
      loading.innerHTML = '<div style="position: absolute; width: 100%; text-align: center; font-size: 20px; font-weight: bold; top: 50%; left: 50%; transform: translate(-50%, -50%);">Got invalid token, retrying...</div>';
      loading.style = "position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(255, 255, 255, 0.85); z-index: 99999;";
      document.body.appendChild(loading);
    "#)?;

    let auth_request = auth_prelogin(&self.server, &self.gp_params).await?;
    let (tx, rx) = oneshot::channel::<anyhow::Result<()>>();
    auth_window.with_webview(move |wv| {
      let result = wv.load_auth_request(&auth_request);
      if let Err(result) = tx.send(result) {
        warn!("Failed to send retry auth result: {:?}", result);
      }
    })?;

    rx.await??;

    Ok(())
  }

  fn raise_window(&self, auth_window: &WebviewWindow) {
    let visible = auth_window.is_visible().unwrap_or(false);
    if visible {
      return;
    }

    info!("Raising auth window...");

    #[cfg(target_os = "macos")]
    let result = auth_window.show();

    #[cfg(not(target_os = "macos"))]
    let result = {
      use gpapi::utils::window::WindowExt;
      auth_window.raise()
    };

    if let Err(err) = result {
      warn!("Failed to raise window: {}", err);
    }
  }
}