bitcoin-cli helpdetail to show full help for all RPCs

Prints to stdout a concatenation of full help text as if you had run
help on every RPC. This allows you to search help text when you
can't remember the name of an RPC.

doc/release-notes-29163.md

@@ -0,0 +1,9 @@
+Tools and Utilities
+---
+
+A new argument, `helpdetail` has been added to `bitcoin-cli` that
+displays the full help text for all RPC methods on standard output.
+Typical usage:
+```
+bitcoin-cli helpdetail | less
+```

src/rpc/server.cpp

@@ -101,8 +101,15 @@ std::string CRPCTable::help(const std::string& strCommand, const JSONRPCRequest&
     {
         const CRPCCommand *pcmd = command.second;
         std::string strMethod = pcmd->name;
-        if ((strCommand != "" || pcmd->category == "hidden") && strMethod != strCommand)
-            continue;
+
+        const bool specific_command{strCommand != "" && strCommand != "helpdetail"};
+        const bool match{strMethod == strCommand};
+        const bool hidden{pcmd->category == "hidden"};
+        const bool detail{strCommand != ""};
+
+        if (specific_command && !match) continue;
+        if (!specific_command && hidden) continue;
+
         jreq.strMethod = strMethod;
         try
         {
@@ -114,8 +121,14 @@ std::string CRPCTable::help(const std::string& strCommand, const JSONRPCRequest&
         {
             // Help text is returned in an exception
             std::string strHelp = std::string(e.what());
-            if (strCommand == "")
-            {
+            if (detail && !specific_command) {
+                // Full help for all commands, preface each with its category.
+                strRet += "== " + Capitalize(pcmd->category) + " ==\n";
+            }
+            if (!detail) {
+                // Print only the one-line summary for each RPC, which is
+                // the first line of its full help text, and also the
+                // category when entering a new category.
                 if (strHelp.find('\n') != std::string::npos)
                     strHelp = strHelp.substr(0, strHelp.find('\n'));
 
@@ -164,6 +177,60 @@ static RPCHelpMan help()
     };
 }
 
+std::string CRPCTable::helpdetail(const JSONRPCRequest& helpreq) const
+{
+    std::string strRet;
+    std::set<intptr_t> setDone;
+    std::vector<std::pair<std::string, const CRPCCommand*> > vCommands;
+    vCommands.reserve(mapCommands.size());
+
+    for (const auto& entry : mapCommands)
+        vCommands.emplace_back(entry.second.front()->category + entry.first, entry.second.front());
+    sort(vCommands.begin(), vCommands.end());
+
+    JSONRPCRequest jreq = helpreq;
+    jreq.mode = JSONRPCRequest::GET_HELP;
+    jreq.params = UniValue();
+
+    for (const std::pair<std::string, const CRPCCommand*>& command : vCommands)
+    {
+        const CRPCCommand *pcmd = command.second;
+        jreq.strMethod = pcmd->name;
+        try
+        {
+            UniValue unused_result;
+            if (setDone.insert(pcmd->unique_id).second || true)
+                pcmd->actor(jreq, unused_result, /*last_handler=*/true);
+        }
+        catch (const std::exception& e)
+        {
+            // Help text is returned in an exception
+            strRet += "== " + Capitalize(pcmd->category) + " ==\n";
+            strRet += std::string(e.what()) + '\n';
+        }
+    }
+    if (strRet.size() > 0) strRet = strRet.substr(0, strRet.size()-1);
+    return strRet;
+}
+
+static RPCHelpMan helpdetail()
+{
+    return RPCHelpMan{"helpdetail",
+                "\nList full help for all commands\n",
+                {},
+                {
+                    RPCResult{RPCResult::Type::STR, "", "The full help text"},
+                    RPCResult{RPCResult::Type::ANY, "", ""},
+                },
+                RPCExamples{""},
+        [&](const RPCHelpMan& self, const JSONRPCRequest& jsonRequest) -> UniValue
+{
+    return tableRPC.help("helpdetail", jsonRequest);
+    return tableRPC.helpdetail(jsonRequest);
+},
+    };
+}
+
 static RPCHelpMan stop()
 {
     static const std::string RESULT{PACKAGE_NAME " stopping"};
@@ -258,6 +325,7 @@ static const CRPCCommand vRPCCommands[]{
     /* Overall control/query calls */
     {"control", &getrpcinfo},
     {"control", &help},
+    {"control", &helpdetail},
     {"control", &stop},
     {"control", &uptime},
 };

src/rpc/server.h

@@ -138,6 +138,7 @@ class CRPCTable
 public:
     CRPCTable();
     std::string help(const std::string& name, const JSONRPCRequest& helpreq) const;
+    std::string helpdetail(const JSONRPCRequest& helpreq) const;
 
     /**
      * Execute a method.