[WIP] RSS support.

src/generators/CMakeLists.txt

@@ -1,6 +1,6 @@
 include(GNUInstallDirs)
 
-add_executable(gen_html html.cpp)
+add_executable(gen_html "html.cpp")
 
 target_link_libraries(gen_html
   PRIVATE fediblock)
@@ -8,3 +8,12 @@ target_link_libraries(gen_html
 install(TARGETS gen_html
   RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
   RENAME ${PROJECT_NAME}-gen_html)
+
+add_executable(gen_rss "rss.cpp")
+
+target_link_libraries(gen_rss
+  PRIVATE fediblock)
+
+install(TARGETS gen_rss
+  RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+  RENAME ${PROJECT_NAME}-gen_rss)

src/generators/rss.cpp

@@ -0,0 +1,120 @@
+/*  This file is part of FediBlock-backend.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "rss.hpp"
+#include "time.hpp"
+
+#include <chrono>
+#include <cstdint>
+#include <cstdlib>
+#include <iostream>
+#include <ostream>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace FediBlock::rss
+{
+
+using std::getenv;
+using std::ostream;
+using std::string;
+using std::string_view;
+using std::uint8_t;
+using std::chrono::system_clock;
+
+void write_line(ostream &out, const uint8_t spaces, const string_view rsstag,
+                const string_view value)
+{
+    string endtag;
+    // If there is a space in the rsstag, use only the part up until the space
+    // for the ending rsstag.
+    const size_t pos = rsstag.find(' ');
+    if (pos == string_view::npos)
+    {
+        endtag = rsstag;
+    }
+    else
+    {
+        endtag = rsstag.substr(0, pos);
+    }
+
+    out << string(spaces, ' ');
+    out << '<' << rsstag << '>' << value << "</" << endtag << ">\n";
+}
+
+void write_rss(ostream &out, const vector<entry_type> &entries,
+               const vector<string> &tags)
+{
+    string selfurl;
+    char *env{getenv("HTTPS")};
+    if (env == nullptr || string(env) != "on")
+    {
+        selfurl = "http://";
+    }
+    else
+    {
+        selfurl = "https://";
+    }
+    env = getenv("SERVER_NAME");
+    if (env != nullptr)
+    {
+        selfurl += env;
+    }
+    env = getenv("REQUEST_URI");
+    if (env != nullptr)
+    {
+        selfurl += env;
+    }
+
+    constexpr string_view blocklist_url{
+        "https://fediblock-test.tastytea.de/blocklist/"};
+    constexpr string_view rss_time_format{"%a, %d %b %Y %T %z"};
+
+    out << R"(<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+)";
+    out << R"(    <atom:link href=")" + selfurl
+        << R"(" rel="self" type="application/rss+xml"/>)" << '\n';
+    write_line(out, 4, "title", "FediBlock: newest entries");
+    write_line(out, 4, "link", blocklist_url);
+    write_line(out, 4, "description", "FediBlock: Newest entries.");
+    write_line(out,
+               4,
+               "lastBuildDate",
+               time::to_string(system_clock::now(), rss_time_format));
+
+    // TODO: <item>s.
+
+    out << "  </channel>\n</rss>\n";
+}
+
+} // namespace FediBlock::rss
+
+using std::cout;
+using std::string_view;
+using std::vector;
+
+using namespace FediBlock::rss;
+
+int main(int argc, char *argv[])
+{
+    const vector<string_view> args(argv, argv + argc);
+
+    write_rss(cout, {}, {});
+
+    return 0;
+}

src/generators/rss.hpp

@@ -0,0 +1,64 @@
+/*  This file is part of FediBlock-backend.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef FEDIBLOCK_BACKEND_RSS_HPP
+#define FEDIBLOCK_BACKEND_RSS_HPP
+
+#include "types.hpp"
+
+#include <cstdint>
+#include <ostream>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace FediBlock::rss
+{
+
+using std::ostream;
+using std::string;
+using std::string_view;
+using std::uint8_t;
+using std::vector;
+
+/*!
+ *  @brief  Write a line of RSS.
+ *
+ *  @param  out    The ostream to use for output.
+ *  @param  spaces Preceding spaces.
+ *  @param  rsstag RSS tag.
+ *  @param  value  Content of the tag.
+ *
+ *  @since  0.2.0
+ */
+void write_line(ostream &out, uint8_t spaces, string_view rsstag,
+                string_view value);
+
+/*!
+ *  @brief  Convert entries to RSS.
+ *
+ *  @param  out     The ostream to use for output.
+ *  @param  entries The entries to write.
+ *  @param  tags    Only write entries with these tags (logical or).
+ *
+ *  @since  0.2.0
+ */
+void write_rss(ostream &out, const vector<entry_type> &entries,
+               const vector<string> &tags);
+
+} // namespace FediBlock::rss
+
+#endif // FEDIBLOCK_BACKEND_RSS_HPP