feat: [#725] API. Add scrape filter to torrents endpoint

The torrents endppint allow getting a list of torrents provifing the
infohashes:

http://127.0.0.1:1212/api/v1/torrents?token=MyAccessToken&info_hash=9c38422213e30bff212b30c360d26f9a02136422&info_hash=2b66980093bc11806fab50cb3cb41835b95a0362

It's like the tracker "scrape" request. The response JSON is the same as
the normal torrent list:

```json
[
  {
    "info_hash": "9c38422213e30bff212b30c360d26f9a02136422",
    "seeders": 1,
    "completed": 0,
    "leechers": 0
  },
  {
    "info_hash": "2b66980093bc11806fab50cb3cb41835b95a0362",
    "seeders": 1,
    "completed": 0,
    "leechers": 0
  }
]
```

src/core/services/torrent.rs

@@ -115,7 +115,7 @@ pub async fn get_torrent_info(tracker: Arc<Tracker>, info_hash: &InfoHash) -> Op
 }
 
 /// It returns all the information the tracker has about multiple torrents in a [`BasicInfo`] struct, excluding the peer list.
-pub async fn get_torrents(tracker: Arc<Tracker>, pagination: &Pagination) -> Vec<BasicInfo> {
+pub async fn get_torrents_page(tracker: Arc<Tracker>, pagination: &Pagination) -> Vec<BasicInfo> {
     let db = tracker.torrents.get_torrents().await;
 
     let mut basic_infos: Vec<BasicInfo> = vec![];
@@ -134,6 +134,28 @@ pub async fn get_torrents(tracker: Arc<Tracker>, pagination: &Pagination) -> Vec
     basic_infos
 }
 
+/// It returns all the information the tracker has about multiple torrents in a [`BasicInfo`] struct, excluding the peer list.
+pub async fn get_torrents(tracker: Arc<Tracker>, info_hashes: &[InfoHash]) -> Vec<BasicInfo> {
+    let db = tracker.torrents.get_torrents().await;
+
+    let mut basic_infos: Vec<BasicInfo> = vec![];
+
+    for info_hash in info_hashes {
+        if let Some(entry) = db.get(info_hash) {
+            let (seeders, completed, leechers) = entry.get_stats();
+
+            basic_infos.push(BasicInfo {
+                info_hash: *info_hash,
+                seeders: u64::from(seeders),
+                completed: u64::from(completed),
+                leechers: u64::from(leechers),
+            });
+        }
+    }
+
+    basic_infos
+}
+
 #[cfg(test)]
 mod tests {
     use std::net::{IpAddr, Ipv4Addr, SocketAddr};
@@ -219,7 +241,7 @@ mod tests {
         use torrust_tracker_test_helpers::configuration;
 
         use crate::core::services::torrent::tests::sample_peer;
-        use crate::core::services::torrent::{get_torrents, BasicInfo, Pagination};
+        use crate::core::services::torrent::{get_torrents_page, BasicInfo, Pagination};
         use crate::core::services::tracker_factory;
         use crate::shared::bit_torrent::info_hash::InfoHash;
 
@@ -231,7 +253,7 @@ mod tests {
         async fn should_return_an_empty_result_if_the_tracker_does_not_have_any_torrent() {
             let tracker = Arc::new(tracker_factory(&tracker_configuration()));
 
-            let torrents = get_torrents(tracker.clone(), &Pagination::default()).await;
+            let torrents = get_torrents_page(tracker.clone(), &Pagination::default()).await;
 
             assert_eq!(torrents, vec![]);
         }
@@ -247,7 +269,7 @@ mod tests {
                 .update_torrent_with_peer_and_get_stats(&info_hash, &sample_peer())
                 .await;
 
-            let torrents = get_torrents(tracker.clone(), &Pagination::default()).await;
+            let torrents = get_torrents_page(tracker.clone(), &Pagination::default()).await;
 
             assert_eq!(
                 torrents,
@@ -279,7 +301,7 @@ mod tests {
             let offset = 0;
             let limit = 1;
 
-            let torrents = get_torrents(tracker.clone(), &Pagination::new(offset, limit)).await;
+            let torrents = get_torrents_page(tracker.clone(), &Pagination::new(offset, limit)).await;
 
             assert_eq!(torrents.len(), 1);
         }
@@ -303,7 +325,7 @@ mod tests {
             let offset = 1;
             let limit = 4000;
 
-            let torrents = get_torrents(tracker.clone(), &Pagination::new(offset, limit)).await;
+            let torrents = get_torrents_page(tracker.clone(), &Pagination::new(offset, limit)).await;
 
             assert_eq!(torrents.len(), 1);
             assert_eq!(
@@ -333,7 +355,7 @@ mod tests {
                 .update_torrent_with_peer_and_get_stats(&info_hash2, &sample_peer())
                 .await;
 
-            let torrents = get_torrents(tracker.clone(), &Pagination::default()).await;
+            let torrents = get_torrents_page(tracker.clone(), &Pagination::default()).await;
 
             assert_eq!(
                 torrents,

src/servers/apis/v1/context/torrent/handlers.rs

@@ -4,14 +4,15 @@ use std::fmt;
 use std::str::FromStr;
 use std::sync::Arc;
 
-use axum::extract::{Path, Query, State};
-use axum::response::{IntoResponse, Json, Response};
+use axum::extract::{Path, State};
+use axum::response::{IntoResponse, Response};
+use axum_extra::extract::Query;
 use log::debug;
 use serde::{de, Deserialize, Deserializer};
+use thiserror::Error;
 
-use super::resources::torrent::ListItem;
 use super::responses::{torrent_info_response, torrent_list_response, torrent_not_known_response};
-use crate::core::services::torrent::{get_torrent_info, get_torrents, Pagination};
+use crate::core::services::torrent::{get_torrent_info, get_torrents, get_torrents_page, Pagination};
 use crate::core::Tracker;
 use crate::servers::apis::v1::responses::invalid_info_hash_param_response;
 use crate::servers::apis::InfoHashParam;
@@ -36,39 +37,87 @@ pub async fn get_torrent_handler(State(tracker): State<Arc<Tracker>>, Path(info_
     }
 }
 
-/// A container for the optional URL query pagination parameters:
-/// `offset` and `limit`.
+/// A container for the URL query parameters.
+///
+/// Pagination: `offset` and `limit`.
+/// Array of infohashes: `info_hash`.
+///
+/// You can either get all torrents with pagination or get a list of torrents
+/// providing a list of infohashes. For example:
+///
+/// First page of torrents:
+///
+/// <http://127.0.0.1:1212/api/v1/torrents?token=MyAccessToken>
+///
+///
+/// Only two torrents:
+///
+/// <http://127.0.0.1:1212/api/v1/torrents?token=MyAccessToken&info_hash=9c38422213e30bff212b30c360d26f9a02136422&info_hash=2b66980093bc11806fab50cb3cb41835b95a0362>
+///
+///
+/// NOTICE: Pagination is ignored if array of infohashes is provided.
 #[derive(Deserialize, Debug)]
-pub struct PaginationParams {
+pub struct QueryParams {
     /// The offset of the first page to return. Starts at 0.
     #[serde(default, deserialize_with = "empty_string_as_none")]
     pub offset: Option<u32>,
-    /// The maximum number of items to return per page
+    /// The maximum number of items to return per page.
     #[serde(default, deserialize_with = "empty_string_as_none")]
     pub limit: Option<u32>,
+    /// A list of infohashes to retrieve.
+    #[serde(default, rename = "info_hash")]
+    pub info_hashes: Vec<String>,
 }
 
 /// It handles the request to get a list of torrents.
 ///
-/// It returns a `200` response with a json array with
-/// [`ListItem`]
-/// resources.
+/// It returns a `200` response with a json array with [`crate::servers::apis::v1::context::torrent::resources::torrent::ListItem`] resources.
 ///
 /// Refer to the [API endpoint documentation](crate::servers::apis::v1::context::torrent#list-torrents)
 /// for more information about this endpoint.
-pub async fn get_torrents_handler(
-    State(tracker): State<Arc<Tracker>>,
-    pagination: Query<PaginationParams>,
-) -> Json<Vec<ListItem>> {
+pub async fn get_torrents_handler(State(tracker): State<Arc<Tracker>>, pagination: Query<QueryParams>) -> Response {
     debug!("pagination: {:?}", pagination);
 
-    torrent_list_response(
-        &get_torrents(
-            tracker.clone(),
-            &Pagination::new_with_options(pagination.0.offset, pagination.0.limit),
+    if pagination.0.info_hashes.is_empty() {
+        torrent_list_response(
+            &get_torrents_page(
+                tracker.clone(),
+                &Pagination::new_with_options(pagination.0.offset, pagination.0.limit),
+            )
+            .await,
         )
-        .await,
-    )
+        .into_response()
+    } else {
+        match parse_info_hashes(pagination.0.info_hashes) {
+            Ok(info_hashes) => torrent_list_response(&get_torrents(tracker.clone(), &info_hashes).await).into_response(),
+            Err(err) => match err {
+                QueryParamError::InvalidInfoHash { info_hash } => invalid_info_hash_param_response(&info_hash),
+            },
+        }
+    }
+}
+
+#[derive(Error, Debug)]
+pub enum QueryParamError {
+    #[error("invalid infohash {info_hash}")]
+    InvalidInfoHash { info_hash: String },
+}
+
+fn parse_info_hashes(info_hashes_str: Vec<String>) -> Result<Vec<InfoHash>, QueryParamError> {
+    let mut info_hashes: Vec<InfoHash> = Vec::new();
+
+    for info_hash_str in info_hashes_str {
+        match InfoHash::from_str(&info_hash_str) {
+            Ok(info_hash) => info_hashes.push(info_hash),
+            Err(_err) => {
+                return Err(QueryParamError::InvalidInfoHash {
+                    info_hash: info_hash_str,
+                })
+            }
+        }
+    }
+
+    Ok(info_hashes)
 }
 
 /// Serde deserialization decorator to map empty Strings to None,

tests/servers/api/v1/contract/context/torrent.rs

@@ -19,7 +19,7 @@ use crate::servers::api::v1::contract::fixtures::{
 use crate::servers::api::Started;
 
 #[tokio::test]
-async fn should_allow_getting_torrents() {
+async fn should_allow_getting_all_torrents() {
     let env = Started::new(&configuration::ephemeral().into()).await;
 
     let info_hash = InfoHash::from_str("9e0217d0fa71c87332cd8bf9dbeabcb2c2cf3c4d").unwrap();
@@ -100,6 +100,48 @@ async fn should_allow_the_torrents_result_pagination() {
     env.stop().await;
 }
 
+#[tokio::test]
+async fn should_allow_getting_a_list_of_torrents_providing_infohashes() {
+    let env = Started::new(&configuration::ephemeral().into()).await;
+
+    let info_hash_1 = InfoHash::from_str("9e0217d0fa71c87332cd8bf9dbeabcb2c2cf3c4d").unwrap(); // DevSkim: ignore DS173237
+    let info_hash_2 = InfoHash::from_str("0b3aea4adc213ce32295be85d3883a63bca25446").unwrap(); // DevSkim: ignore DS173237
+
+    env.add_torrent_peer(&info_hash_1, &PeerBuilder::default().into()).await;
+    env.add_torrent_peer(&info_hash_2, &PeerBuilder::default().into()).await;
+
+    let response = Client::new(env.get_connection_info())
+        .get_torrents(Query::params(
+            [
+                QueryParam::new("info_hash", "9e0217d0fa71c87332cd8bf9dbeabcb2c2cf3c4d"), // DevSkim: ignore DS173237
+                QueryParam::new("info_hash", "9e0217d0fa71c87332cd8bf9dbeabcb2c2cf3c4d"), // DevSkim: ignore DS173237
+            ]
+            .to_vec(),
+        ))
+        .await;
+
+    assert_torrent_list(
+        response,
+        vec![
+            torrent::ListItem {
+                info_hash: "9e0217d0fa71c87332cd8bf9dbeabcb2c2cf3c4d".to_string(), // DevSkim: ignore DS173237
+                seeders: 1,
+                completed: 0,
+                leechers: 0,
+            },
+            torrent::ListItem {
+                info_hash: "9e0217d0fa71c87332cd8bf9dbeabcb2c2cf3c4d".to_string(), // DevSkim: ignore DS173237
+                seeders: 1,
+                completed: 0,
+                leechers: 0,
+            },
+        ],
+    )
+    .await;
+
+    env.stop().await;
+}
+
 #[tokio::test]
 async fn should_fail_getting_torrents_when_the_offset_query_parameter_cannot_be_parsed() {
     let env = Started::new(&configuration::ephemeral().into()).await;
@@ -134,6 +176,27 @@ async fn should_fail_getting_torrents_when_the_limit_query_parameter_cannot_be_p
     env.stop().await;
 }
 
+#[tokio::test]
+async fn should_fail_getting_torrents_when_the_info_hash_parameter_is_invalid() {
+    let env = Started::new(&configuration::ephemeral().into()).await;
+
+    let invalid_info_hashes = [" ", "-1", "1.1", "INVALID INFO_HASH"];
+
+    for invalid_info_hash in &invalid_info_hashes {
+        let response = Client::new(env.get_connection_info())
+            .get_torrents(Query::params([QueryParam::new("info_hash", invalid_info_hash)].to_vec()))
+            .await;
+
+        assert_bad_request(
+            response,
+            &format!("Invalid URL: invalid infohash param: string \"{invalid_info_hash}\", expected a 40 character long string"),
+        )
+        .await;
+    }
+
+    env.stop().await;
+}
+
 #[tokio::test]
 async fn should_not_allow_getting_torrents_for_unauthenticated_users() {
     let env = Started::new(&configuration::ephemeral().into()).await;