// Copyright 2026 The NativeLink Authors. All rights reserved.

//

// Licensed under the Functional Source License, Version 1.1, Apache 2.0 Future License (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//    See LICENSE file for details

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

use core::time::Duration;

use std::sync::Arc;

use aws_config::default_provider::credentials::DefaultCredentialsChain;

use aws_config::provider_config::ProviderConfig;

use aws_config::{AppName, BehaviorVersion};

use aws_sdk_s3::Client;

use aws_sdk_s3::config::{Credentials, Region};

use nativelink_config::stores::{ExperimentalAwsSpec, ExperimentalR2Spec};

use nativelink_error::Error;

use nativelink_util::instant_wrapper::InstantWrapper;

use crate::common_s3_utils::TlsClient;

use crate::s3_store::S3Store;

/// R2-shaped config adapter over [`S3Store`]. Builds an S3 SDK client

/// pointed at R2 (custom endpoint, region `auto`, optional explicit

/// credentials) and hands it to `S3Store::new_with_client_and_jitter`.

#[derive(Debug, Clone, Copy)]

pub struct R2Store;

impl R2Store {

    #[allow(clippy::new_ret_no_self)] // Because usually everyone returns themselves

    pub async fn new<I, NowFn>(

        spec: &ExperimentalR2Spec,

        now_fn: NowFn,

    ) -> Result<Arc<S3Store<NowFn>>, Error>

    where

        I: InstantWrapper,

        NowFn: Fn() -> I + Send + Sync + Unpin + 'static,

    {

        let aws_spec = Self::build_aws_spec(spec);

        let jitter_fn = spec.common.retry.make_jitter_fn();

        let http_client = TlsClient::new(&spec.common.clone());

        let endpoint = Self::derive_endpoint(spec);

        let mut config_loader = aws_config::defaults(BehaviorVersion::latest())

            .app_name(AppName::new("nativelink").expect("valid app name"))

            .timeout_config(

                aws_config::timeout::TimeoutConfig::builder()

                    .connect_timeout(Duration::from_secs(15))

                    .build(),

            )

            .region(Region::new("auto"))

            .endpoint_url(&endpoint)

            .http_client(http_client.clone());

        config_loader = if let Some(key_id) = &spec.access_key_id

            && let Some(secret) = &spec.secret_access_key

        {

            config_loader.credentials_provider(Credentials::new(

                key_id,

                secret,

                None,

                None,

                "r2-explicit",

            ))

        } else {

            let default_chain = DefaultCredentialsChain::builder()

                .configure(

                    ProviderConfig::without_region()

                        .with_region(Some(Region::new("auto")))

                        .with_http_client(http_client),

                )

                .build()

                .await;

            config_loader.credentials_provider(default_chain)

        };

        let config = config_loader.load().await;

        let s3_client = Client::new(&config);

        S3Store::new_with_client_and_jitter(&aws_spec, s3_client, jitter_fn, now_fn)

    }

    pub fn derive_endpoint(spec: &ExperimentalR2Spec) -> String {

        format!("https://{}.r2.cloudflarestorage.com", spec.account_id)

    }

    pub fn build_aws_spec(spec: &ExperimentalR2Spec) -> ExperimentalAwsSpec {

        ExperimentalAwsSpec {

            region: "auto".to_string(),

            bucket: spec.bucket.clone(),

            common: spec.common.clone(),

        }

    }

}