...

asibfm700_config.h

@@ -132,7 +132,51 @@ public:
 
                 fst.close();
 
-                ec = base_t::fromCharRange(buffer);
+                // remove possible header (see "save" method)
+                size_t nskip = 5;
+                auto lines = std::views::split(buffer, DEFAULT_RECORD_DELIMITER);
+                if (std::ranges::distance(lines.begin(), lines.end()) >= 5) {
+                    bool head_exists = true;
+                    std::vector<std::string_view> tl;
+                    for (auto const& l : lines) {  // lines must start with COMMENT_SEQ
+                        tl.emplace_back(mcc::utils::trimSpaces(l));
+                        if (tl.back().size() >= COMMENT_SEQ.size()) {
+                            auto found = std::ranges::search(tl.back(), COMMENT_SEQ);
+                            if (tl.back().begin() != found.begin()) {
+                                head_exists = false;
+                                break;
+                            }
+                        } else {
+                            head_exists = false;
+                            break;
+                        }
+                    }
+                    if (head_exists) {
+                        // the first and last lines must contain only a comment sequence and possible spaces
+                        if (tl[0].size() != COMMENT_SEQ.size() || tl[3].size() != COMMENT_SEQ.size()) {
+                            head_exists = false;
+                        } else {
+                            if (tl[1] != "# ASTROSIB FM-700 MOUNT CONFIGURATION") {
+                                head_exists = false;
+                            } else {
+                                std::regex rx{
+                                    "# \\(created at "
+                                    "20[0-9][0-9]-[0-9][0-9]-[0-9][0-9]T[0-9][0-9]:[0-9][0-9]:[0-9][0-9]\\.[0-9] "
+                                    "UTC\\)"};
+
+                                if (!std::regex_match(std::string{tl[2]}, rx)) {
+                                    head_exists = false;
+                                }
+                            }
+                        }
+                    }
+
+                    if (!head_exists) {  // delete the first N lines
+                        nskip = 0;
+                    }
+                }
+
+                ec = base_t::fromCharRange(buffer, nskip);
                 if (!ec) {
                     // remove possible spaces in filenames
 
@@ -206,6 +250,7 @@ public:
             ec = std::make_error_code(std::errc::io_error);
         } else {
             try {
+                fst << generateHeader();
                 fst << buff;
             } catch (std::ios_base::failure const& ex) {
                 ec = ex.code();
@@ -229,6 +274,30 @@ public:
 
 private:
     std::filesystem::path _lastConfigPath{};
+
+    static std::string generateHeader()
+    {
+        std::string s{
+            "#\n"
+            "# ASTROSIB FM-700 MOUNT CONFIGURATION\n"
+            "#\n"};
+
+        std::format_to(
+            std::back_inserter(s), "# (created at {:%FT%T} UTC)\n#\n",
+            std::chrono::round<std::chrono::duration<int64_t, std::ratio<1, 10>>>(std::chrono::system_clock::now()));
+
+        return s;
+    }
+
+    // regex for buffer started with standard header
+    inline static const std::regex headerRx{
+        "^[ \\n]*"
+        "# *\\n"
+        "# *ASTROSIB FM-700 MOUNT CONFIGURATION *\\n"
+        "# *\\n"
+        "# *\\(created at 20[0-9][0-9]-[0-9][0-9]-[0-9][0-9]T[0-9][0-9]:[0-9][0-9]:[0-9][0-9]\\.[0-9] UTC\\) *\\n"
+        "# *\\n"
+        "[\\s\\S]*"};
 };
 
 }  // namespace asibfm700