[FEATURE] Pagination logic implemented.

Author: Rafael24595

src/infrastructure/controller.rs

@@ -1,10 +1,10 @@
-use axum::{body::Body, extract::Path, http::{Response, StatusCode}, response::IntoResponse, routing::{get, post}, Json, Router};
+use axum::{body::Body, extract::{Path, Query}, http::{Response, StatusCode}, response::IntoResponse, routing::{get, post}, Json, Router};
 
 use rust_db_manager_core::commons::configuration::configuration::Configuration;
 
 use crate::{commons::exception::api_exception::ApiException, domain::builder_db_service::BuilderDBService};
 
-use super::dto::db_service::{dto_db_service::DTODBService, dto_db_service_lite::DTODBServiceLite};
+use super::{dto::{db_service::{dto_db_service::DTODBService, dto_db_service_lite::DTODBServiceLite, dto_paginated_collection::DTOPaginatedCollection}, dto_query_pagination::DTOQueryPagination}, pagination::Pagination};
 
 pub struct Controller{
 }
@@ -18,10 +18,11 @@ impl Controller {
             .route("/:service/status", get(Controller::status))
     }
 
-    async fn services() -> (StatusCode, Json<Vec<DTODBServiceLite>>) {
+    async fn services(Query(params): Query<DTOQueryPagination>) -> (StatusCode, Json<DTOPaginatedCollection<DTODBServiceLite>>) {
         let services = Configuration::find_services();
         let dto = DTODBServiceLite::from_vec(services);
-        (StatusCode::ACCEPTED, Json(dto))
+        let result = Pagination::paginate(params, dto);
+        (StatusCode::ACCEPTED, Json(result))
     }
 
     async fn insert_service(Json(dto): Json<DTODBService>) -> Result<(StatusCode, String), impl IntoResponse> {

src/infrastructure/dto/db_service/dto_paginated_collection.rs

@@ -0,0 +1,17 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Serialize, Deserialize)]
+pub struct DTOPaginatedCollection<T> {
+    pub total: usize,
+    pub previous: usize,
+    pub next: usize,
+    pub services: Vec<T>,
+}
+
+impl <T> DTOPaginatedCollection<T> {
+    
+    pub fn new(total: usize, previous: usize, next: usize, services: Vec<T>) -> DTOPaginatedCollection<T> {
+        DTOPaginatedCollection {total, previous, next, services}
+    }
+
+}

src/infrastructure/dto/dto_query_pagination.rs

@@ -0,0 +1,7 @@
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize)]
+pub struct DTOQueryPagination {
+    pub offset: usize,
+    pub limit: usize,
+}

src/infrastructure/pagination.rs

@@ -0,0 +1,55 @@
+use super::dto::{db_service::dto_paginated_collection::DTOPaginatedCollection, dto_query_pagination::DTOQueryPagination};
+
+pub struct Pagination {}
+
+impl Pagination {
+
+    pub fn paginate<T: Clone>(params: DTOQueryPagination, collection: Vec<T>) -> DTOPaginatedCollection<T> {
+        let size = collection.len();
+        let offset = params.offset;
+        let limit = params.limit;
+
+        if offset >= size {
+            let previous = Pagination::calculate_previous(size, offset, limit);
+            return DTOPaginatedCollection::new(size, previous, size, Vec::new());
+        }
+
+        if size == 0 || limit == 0 {
+            return DTOPaginatedCollection::new(size, offset, offset, Vec::new());
+        }
+
+        let mut limit_fixed = limit;
+        if offset + limit >= size {
+            limit_fixed = size - offset;
+        }
+
+        let cursor = offset + limit_fixed;
+
+        let next = Pagination::calculate_next(size, cursor, limit);
+        let previous = Pagination::calculate_previous(size, cursor, limit);
+
+        let slice = collection[offset..=cursor-1].to_vec();
+
+        return DTOPaginatedCollection::new(size, previous, next, slice);
+    }
+
+    fn calculate_next(size: usize, cursor: usize, limit: usize) -> usize {
+        let next = cursor + limit;
+        if next >= size {
+            return size;
+        }
+        return next;
+    }
+
+    fn calculate_previous(size: usize, cursor: usize, limit: usize) -> usize {
+        if cursor.checked_sub(limit).is_none() {
+            return 0;
+        }
+        let previous = cursor - limit;
+        if previous > size {
+            return Pagination::calculate_previous(size, size, limit);
+        }
+        return previous;
+    }
+
+}

src/lib.rs

@@ -12,9 +12,12 @@ pub mod infrastructure {
         pub mod db_service {
             pub mod dto_db_connection_data;
             pub mod dto_db_service;
+            pub mod dto_paginated_collection;
             pub mod dto_db_service_lite;
         }
+        pub mod dto_query_pagination;
     }
     pub mod controller;
+    pub mod pagination;
     pub mod utils;
 }