feat: implement media listing with sorting and filtering options

libertas_infra/src/query_builder.rs

@@ -0,0 +1,80 @@
+use libertas_core::{error::{CoreError, CoreResult}, schema::{ListMediaOptions, SortOrder}};
+use sqlx::QueryBuilder as SqlxQueryBuilder;
+
+pub trait QueryBuilder<T> {
+    fn apply_options_to_query<'a>(
+        &self,
+        query: SqlxQueryBuilder<'a, sqlx::Postgres>,
+        options: &'a T,
+    ) -> CoreResult<SqlxQueryBuilder<'a, sqlx::Postgres>>;
+}
+
+pub struct MediaQueryBuilder {
+    allowed_sort_columns: Vec<String>,
+}
+
+impl MediaQueryBuilder {
+    pub fn new(allowed_sort_columns: Vec<String>) -> Self {
+        Self {
+            allowed_sort_columns,
+        }
+    }
+
+    fn validate_sort_column<'a>(&self, column: &'a str) -> CoreResult<&'a str> {
+        if self.allowed_sort_columns.contains(&column.to_string()) {
+            Ok(column)
+        } else {
+            Err(CoreError::Validation(format!(
+                "Sorting by '{}' is not supported",
+                column
+            )))
+        }
+    }
+}
+
+impl QueryBuilder<ListMediaOptions> for MediaQueryBuilder {
+    fn apply_options_to_query<'a>(
+        &self,
+        mut query: SqlxQueryBuilder<'a, sqlx::Postgres>,
+        options: &'a ListMediaOptions,
+    ) -> CoreResult<SqlxQueryBuilder<'a, sqlx::Postgres>> {
+        if let Some(filter) = &options.filter {
+            // In the future, you would add logic here:
+            // if let Some(mime) = &filter.mime_type {
+            //     query.push(" AND mime_type = ");
+            //     query.push_bind(mime);
+            // }
+        }
+
+        if let Some(sort) = &options.sort {
+            let column = self.validate_sort_column(&sort.sort_by)?;
+            
+            let direction = match sort.sort_order {
+                SortOrder::Asc => "ASC",
+                SortOrder::Desc => "DESC",
+            };
+
+            let nulls_order = if direction == "ASC" {
+                "NULLS LAST"
+            } else {
+                "NULLS FIRST"
+            };
+
+            let order_by_clause = format!("ORDER BY {} {} {}", column, direction, nulls_order);
+            query.push(order_by_clause);
+        
+        } else {
+            query.push("ORDER BY date_taken DESC NULLS FIRST");
+        }
+
+        // --- 3. Apply Pagination (Future-Proofing Stub) ---
+        // if let Some(pagination) = &options.pagination {
+        //     query.push(" LIMIT ");
+        //     query.push_bind(pagination.limit);
+        //     query.push(" OFFSET ");
+        //     query.push_bind(pagination.offset);
+        // }
+
+        Ok(query)
+    }
+}