Add Instance::get_post_formats().

include/instance.hpp

@@ -24,6 +24,7 @@
 #include <string>
 #include <string_view>
 #include <utility>
+#include <vector>
 
 namespace mastodonpp
 {
@@ -32,6 +33,7 @@ using std::uint64_t;
 using std::string;
 using std::string_view;
 using std::move;
+using std::vector;
 
 /*!
  *  @brief  Holds the access data of an instance.
@@ -151,12 +153,26 @@ public:
     [[nodiscard]]
     answer_type get_nodeinfo();
 
+    /*!
+     *  @brief  Returns the allowed mime types for statuses.
+     *
+     *  Extracts `metadata.postFormats` from NodeInfo. If none can be found,
+     *  returns `{"text/plain"}`.
+     *
+     *  After the first call, the value is saved internally. Subsequent calls
+     *  return the saved value.
+     *
+     *  @since  0.3.0
+     */
+    vector<string> get_post_formats();
+
 private:
     const string _hostname;
     const string _baseuri;
     string _access_token;
     uint64_t _max_chars;
     string _proxy;
+    vector<string> _post_formats;
 };
 
 } // namespace mastodonpp

src/instance.cpp

@@ -20,7 +20,6 @@
 
 #include <algorithm>
 #include <exception>
-#include <vector>
 
 namespace mastodonpp
 {
@@ -28,7 +27,6 @@ namespace mastodonpp
 using std::sort;
 using std::stoull;
 using std::exception;
-using std::vector;
 
 Instance::Instance(const string_view hostname, const string_view access_token)
     : _hostname{hostname}
@@ -108,4 +106,45 @@ answer_type Instance::get_nodeinfo()
     return make_request(http_method::GET, hrefs.back(), {});
 }
 
+vector<string> Instance::get_post_formats()
+{
+    constexpr auto default_value{"text/plain"};
+
+    if (!_post_formats.empty())
+    {
+        return _post_formats;
+    }
+
+    debuglog << "Querying " << _hostname << " for postFormats…\n";
+    const auto answer{get_nodeinfo()};
+    if (!answer)
+    {
+        debuglog << "Couldn't get NodeInfo.\n";
+        _post_formats = {default_value};
+        return _post_formats;
+    }
+
+    constexpr string_view searchstring{R"("postFormats":[)"};
+    auto pos{answer.body.find(searchstring)};
+    if (pos == string::npos)
+    {
+        debuglog << "Couldn't find metadata.postFormats.\n";
+        _post_formats = {default_value};
+        return _post_formats;
+    }
+    pos += searchstring.size();
+    auto endpos{answer.body.find("],", pos)};
+    string formats{answer.body.substr(pos, endpos - pos)};
+    debuglog << "Extracted postFormats: " << formats << '\n';
+
+    while ((pos = formats.find('"', 1)) != string::npos)
+    {
+        _post_formats.push_back(formats.substr(1, pos - 1));
+        formats.erase(0, pos + 2); // 2 is the length of: ",
+        debuglog << "Found postFormat: " << _post_formats.back() << '\n';
+    }
+
+    return _post_formats;
+}
+
 } // namespace mastodonpp