DistroqueryAPI: getRepositoryPackages: added pagination from query string support

src/DistroqueryAPI.cpp

@@ -104,11 +104,26 @@ json DistroqueryAPI::getPackageSourceDetailsById(configTag* ct, long id) {
     return j;
 }
 
-json DistroqueryAPI::getRepositoryPackages(string repository) {
+json DistroqueryAPI::getRepositoryPackages(string repository, int per_page, int page) {
     json j;
     string sql;
     sqlite3_stmt *stmt;
 
+    j["query"] = {};
+    j["query"]["repository"] = repository;
+    j["query"]["per_page"] = per_page;
+    j["query"]["page"] = page;
+
+    if (per_page < 1) {
+        j["error"] = "'per_page' query var must be >= 1";
+        return j;
+    }
+
+    if (page < 1) {
+        j["error"] = "'page' query var must be >= 1";
+        return j;
+    }
+
     struct configTag* ct = findRepositoryByTag(repository.c_str());
     if (ct == NULL) {
         j["error"] = "repository with tag '" + repository + "' does not exist";
@@ -121,16 +136,29 @@ json DistroqueryAPI::getRepositoryPackages(string repository) {
         return j;
     }
 
-    sql = "SELECT * FROM sources ORDER BY name COLLATE NOCASE ASC";
+    sql = "SELECT COUNT(*) OVER() AS total_count,* FROM sources ORDER BY name COLLATE NOCASE ASC"
+            " LIMIT " + to_string(per_page) +
+            " OFFSET " + to_string(per_page * (page -1));
     if (sqlite3_prepare_v2(db, sql.c_str(), sql.length(), &stmt, NULL) == SQLITE_OK) {
-        j = json::array();
+        json packages = json::array();
+        long count = 0;
         while (sqlite3_step(stmt) == SQLITE_ROW) {
+            count++;
+            // Set total packages count
+            if (j["query"].find("total") == j["query"].end()) {
+                long total_count = sqlite3_column_int(stmt,sqlite3_find_column_id(stmt, NULL, "total_count"));
+                j["query"]["total"] = total_count;
+                j["query"]["pages"] = total_count / per_page + 1;
+                j["query"]["from"] = per_page * (page - 1) + 1;
+            }
             json package;
             package["name"] = reinterpret_cast<const char*>(sqlite3_column_text(stmt,sqlite3_find_column_id(stmt, NULL, "name")));
             package["summary"] = reinterpret_cast<const char*>(sqlite3_column_text(stmt,sqlite3_find_column_id(stmt, NULL, "summary")));
-            j.push_back(package);
+            packages.push_back(package);
         }
         sqlite3_finalize(stmt);
+        j["query"]["to"] = per_page * (page - 1) + count;
+        j["packages"] = packages;
     } else {
         j["error"] = "error preparing query '" + sql + "'";
         return j;
@@ -300,7 +328,7 @@ json DistroqueryAPI::getPackageDetails(string repository, string package, string
         }
 
         // Provides
-        sql = "SELECT * FROM provides,provided WHERE provides.id_package=" + to_string(id) + 
+        sql = "SELECT * FROM provides,provided WHERE provides.id_package=" + to_string(id) +
             " AND provided.id=provides.id_provided ORDER BY provided.name";
         j["provides"] = json::array();
         if (sqlite3_prepare_v2(db, sql.c_str(), sql.length(), &stmt2, NULL) == SQLITE_OK) {
@@ -375,15 +403,31 @@ void DistroqueryAPI::getApiResponse(string path_info) {
     cout << "Content-Type: application/json;charset=utf-8\n\n" << endl;
 
     string path, query_string;
-    std::vector<std::string> path_split;
+    vector<string> path_split;
+    map<string,string> query_vars;
 
-    std::vector<std::string> v = split(path_info, "?");
+    vector<string> v = split(path_info, "?");
 
     if (v.size() > 0) {
         path = v[0];
         path_split = split(path, "/");
     }
-    if (v.size() > 1) query_string = v[1];
+
+    if (v.size() > 1) {
+        query_string = v[1];
+        vector<string> query_split = split(query_string, "&");
+
+        for (auto q:query_split) {
+            vector<string> arg_split = split(q, "=");
+            if (arg_split.size() == 1) {
+                query_vars[arg_split[0]] = "";
+            } else if (arg_split.size() == 2) {
+                query_vars[arg_split[0]] = arg_split[1];
+            } else {
+                cerr << "Error parsing query_string entry '" << q << "'" << endl;
+            }
+        }
+    }
 
     if (path_split.size() > 0 ) {
         if (path_split[0] == "repositories") {
@@ -395,7 +439,24 @@ void DistroqueryAPI::getApiResponse(string path_info) {
             // API service: repository
             if (path_split.size() != 2)
                 sendErrorResponse("expected exactly 2 arguments for " + path_split[0]);
-            auto packages = getRepositoryPackages(path_split[1]);
+            // Pagination
+            unsigned int per_page = 100;
+            unsigned int page = 1;
+            if (query_vars.find("per_page") != query_vars.end()) {
+                try {
+                    per_page = atoi(query_vars["per_page"].c_str());
+                } catch (exception const & e) {
+                    cerr << "Error converting '" << query_vars["per_page"] << " to int: " << e.what() << endl;
+                }
+            }
+            if (query_vars.find("page") != query_vars.end()) {
+                try {
+                    page = atoi(query_vars["page"].c_str());
+                } catch (exception const & e) {
+                    cerr << "Error converting '" << query_vars["page"] << " to int: " << e.what() << endl;
+                }
+            }
+            auto packages = getRepositoryPackages(path_split[1], per_page, page);
             cout << packages.dump();
         } else if (path_split[0] == "package") {
             // API service: package

src/DistroqueryAPI.hpp

@@ -41,7 +41,7 @@ class DistroqueryAPI {
         configTag *config;
         json configToJsonRepositories();
         void sendErrorResponse(string message);
-        json getRepositoryPackages(string repository);
+        json getRepositoryPackages(string repository, int per_page, int page);
         json getPackageSourceDetailsById(configTag* ct, long id);
         json getPackageSourceDetails(string repository, string package);
         json getBuiltPackagesFromSourceID(configTag* ct, long id);