feat: expand platform management, admin controls, and learning workflows

backend/src/controllers/problem_controller.cc

@@ -5,6 +5,7 @@
 #include "csp/services/problem_service.h"
 #include "csp/services/problem_solution_runner.h"
 #include "csp/services/problem_workspace_service.h"
+#include "csp/services/solution_access_service.h"
 #include "http_auth.h"
 
 #include <algorithm>
@@ -192,7 +193,7 @@ void ProblemController::saveDraft(
 }
 
 void ProblemController::listSolutions(
-    const drogon::HttpRequestPtr& /*req*/,
+    const drogon::HttpRequestPtr& req,
     std::function<void(const drogon::HttpResponsePtr&)>&& cb,
     int64_t problem_id) {
   try {
@@ -203,28 +204,72 @@ void ProblemController::listSolutions(
     }
 
     const auto rows = svc.ListSolutions(problem_id);
+    const bool has_solutions = !rows.empty();
     const auto latest_job = svc.GetLatestSolutionJob(problem_id);
+    const std::string mode = req->getParameter("mode");
+    const bool need_full = mode == "full";
 
     Json::Value arr(Json::arrayValue);
-    for (const auto& item : rows) {
-      Json::Value j;
-      j["id"] = Json::Int64(item.id);
-      j["problem_id"] = Json::Int64(item.problem_id);
-      j["variant"] = item.variant;
-      j["title"] = item.title;
-      j["idea_md"] = item.idea_md;
-      j["explanation_md"] = item.explanation_md;
-      j["code_cpp"] = item.code_cpp;
-      j["complexity"] = item.complexity;
-      j["tags_json"] = item.tags_json;
-      j["source"] = item.source;
-      j["created_at"] = Json::Int64(item.created_at);
-      j["updated_at"] = Json::Int64(item.updated_at);
-      arr.append(j);
+    Json::Value access(Json::objectValue);
+    access["required"] = true;
+    access["daily_free_quota"] = 1;
+    access["cost_after_free"] = 2;
+
+    if (need_full && has_solutions) {
+      std::string auth_error;
+      const auto user_id = GetAuthedUserId(req, auth_error);
+      if (!user_id.has_value()) {
+        cb(JsonError(drogon::k401Unauthorized, auth_error));
+        return;
+      }
+
+      services::SolutionAccessService access_svc(csp::AppState::Instance().db());
+      const auto charge = access_svc.ConsumeSolutionView(*user_id, problem_id);
+      if (!charge.granted) {
+        cb(JsonError(drogon::k402PaymentRequired,
+                     "rating 不足：首次免费后每次查看答案需 2 分"));
+        return;
+      }
+
+      access["mode"] = "full";
+      access["charged"] = charge.charged;
+      access["daily_free"] = charge.daily_free;
+      access["cost"] = charge.cost;
+      access["day_key"] = charge.day_key;
+      access["daily_used_count"] = charge.daily_used_count;
+      access["rating_before"] = charge.rating_before;
+      access["rating_after"] = charge.rating_after;
+      access["viewed_at"] = Json::Int64(charge.viewed_at);
+
+      for (const auto& item : rows) {
+        Json::Value j;
+        j["id"] = Json::Int64(item.id);
+        j["problem_id"] = Json::Int64(item.problem_id);
+        j["variant"] = item.variant;
+        j["title"] = item.title;
+        j["idea_md"] = item.idea_md;
+        j["explanation_md"] = item.explanation_md;
+        j["code_cpp"] = item.code_cpp;
+        j["complexity"] = item.complexity;
+        j["tags_json"] = item.tags_json;
+        j["source"] = item.source;
+        j["created_at"] = Json::Int64(item.created_at);
+        j["updated_at"] = Json::Int64(item.updated_at);
+        arr.append(j);
+      }
+    } else {
+      access["mode"] = "preview";
+      access["charged"] = false;
+      access["daily_free"] = false;
+      access["cost"] = 0;
+      access["daily_used_count"] = 0;
     }
 
     Json::Value payload;
     payload["items"] = arr;
+    payload["has_solutions"] = has_solutions;
+    payload["answer_status"] = has_solutions ? "已有" : "待生成";
+    payload["access"] = access;
     payload["runner_running"] =
         services::ProblemSolutionRunner::Instance().IsRunning(problem_id);
     if (latest_job.has_value()) {
@@ -280,16 +325,20 @@ void ProblemController::generateSolutions(
     }
 
     const int64_t job_id = svc.CreateSolutionJob(problem_id, *user_id, max_solutions);
-    const bool started = services::ProblemSolutionRunner::Instance().TriggerAsync(
+    auto& runner = services::ProblemSolutionRunner::Instance();
+    const bool queued = runner.TriggerAsync(
         problem_id, job_id, max_solutions);
-    if (!started) {
-      cb(JsonError(drogon::k409Conflict, "solution generation is already running"));
+    if (!queued) {
+      cb(JsonError(drogon::k500InternalServerError,
+                   "solution generation queue is unavailable"));
       return;
     }
 
     Json::Value payload;
+    payload["queued"] = true;
     payload["started"] = true;
     payload["job_id"] = Json::Int64(job_id);
+    payload["pending_jobs"] = Json::UInt64(runner.PendingCount());
     cb(JsonOk(payload));
   } catch (const std::exception& e) {
     cb(JsonError(drogon::k500InternalServerError, e.what()));