// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.

use std::cell::RefCell;
use std::marker::PhantomData;
use std::rc::Rc;
use std::sync::Arc;

use crate::DatabaseHandler;
use anyhow::Context;
use async_trait::async_trait;
use deno_core::error::type_error;
use deno_core::error::AnyError;
use deno_core::OpState;
use deno_fetch::create_http_client;
use deno_fetch::CreateHttpClientOptions;
use deno_tls::rustls::RootCertStore;
use deno_tls::Proxy;
use deno_tls::RootCertStoreProvider;
use denokv_remote::MetadataEndpoint;
use denokv_remote::Remote;
use url::Url;

#[derive(Clone)]
pub struct HttpOptions {
  pub user_agent: String,
  pub root_cert_store_provider: Option<Arc<dyn RootCertStoreProvider>>,
  pub proxy: Option<Proxy>,
  pub unsafely_ignore_certificate_errors: Option<Vec<String>>,
  pub client_cert_chain_and_key: Option<(String, String)>,
}

impl HttpOptions {
  pub fn root_cert_store(&self) -> Result<Option<RootCertStore>, AnyError> {
    Ok(match &self.root_cert_store_provider {
      Some(provider) => Some(provider.get_or_try_init()?.clone()),
      None => None,
    })
  }
}

pub trait RemoteDbHandlerPermissions {
  fn check_env(&mut self, var: &str) -> Result<(), AnyError>;
  fn check_net_url(
    &mut self,
    url: &Url,
    api_name: &str,
  ) -> Result<(), AnyError>;
}

pub struct RemoteDbHandler<P: RemoteDbHandlerPermissions + 'static> {
  http_options: HttpOptions,
  _p: std::marker::PhantomData<P>,
}

impl<P: RemoteDbHandlerPermissions> RemoteDbHandler<P> {
  pub fn new(http_options: HttpOptions) -> Self {
    Self {
      http_options,
      _p: PhantomData,
    }
  }
}

pub struct PermissionChecker<P: RemoteDbHandlerPermissions> {
  state: Rc<RefCell<OpState>>,
  _permissions: PhantomData<P>,
}

impl<P: RemoteDbHandlerPermissions> Clone for PermissionChecker<P> {
  fn clone(&self) -> Self {
    Self {
      state: self.state.clone(),
      _permissions: PhantomData,
    }
  }
}

impl<P: RemoteDbHandlerPermissions + 'static> denokv_remote::RemotePermissions
  for PermissionChecker<P>
{
  fn check_net_url(&self, url: &Url) -> Result<(), anyhow::Error> {
    let mut state = self.state.borrow_mut();
    let permissions = state.borrow_mut::<P>();
    permissions.check_net_url(url, "Deno.openKv")
  }
}

#[async_trait(?Send)]
impl<P: RemoteDbHandlerPermissions + 'static> DatabaseHandler
  for RemoteDbHandler<P>
{
  type DB = Remote<PermissionChecker<P>>;

  async fn open(
    &self,
    state: Rc<RefCell<OpState>>,
    path: Option<String>,
  ) -> Result<Self::DB, AnyError> {
    const ENV_VAR_NAME: &str = "DENO_KV_ACCESS_TOKEN";

    let Some(url) = path else {
      return Err(type_error("Missing database url"));
    };

    let Ok(parsed_url) = Url::parse(&url) else {
      return Err(type_error(format!("Invalid database url: {}", url)));
    };

    {
      let mut state = state.borrow_mut();
      let permissions = state.borrow_mut::<P>();
      permissions.check_env(ENV_VAR_NAME)?;
      permissions.check_net_url(&parsed_url, "Deno.openKv")?;
    }

    let access_token = std::env::var(ENV_VAR_NAME)
      .map_err(anyhow::Error::from)
      .with_context(|| {
        "Missing DENO_KV_ACCESS_TOKEN environment variable. Please set it to your access token from https://dash.deno.com/account."
      })?;

    let metadata_endpoint = MetadataEndpoint {
      url: parsed_url.clone(),
      access_token: access_token.clone(),
    };

    let options = &self.http_options;
    let client = create_http_client(
      &options.user_agent,
      CreateHttpClientOptions {
        root_cert_store: options.root_cert_store()?,
        ca_certs: vec![],
        proxy: options.proxy.clone(),
        unsafely_ignore_certificate_errors: options
          .unsafely_ignore_certificate_errors
          .clone(),
        client_cert_chain_and_key: options.client_cert_chain_and_key.clone(),
        pool_max_idle_per_host: None,
        pool_idle_timeout: None,
        http1: false,
        http2: true,
      },
    )?;

    let permissions = PermissionChecker {
      state: state.clone(),
      _permissions: PhantomData,
    };

    let remote = Remote::new(client, permissions, metadata_endpoint);

    Ok(remote)
  }
}