From 94e7f534cf6c70e9122bbce6578f6a8768248bf5 Mon Sep 17 00:00:00 2001
From: Jürgen Knödlseder <jurgen.knodlseder@irap.omp.eu>
Date: Wed, 28 Oct 2015 11:54:15 +0100
Subject: [PATCH] Display help file if --help option is given (#572).

---
 src/support/ctool.cpp | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 src/support/ctool.hpp |  4 ++++
 2 files changed, 51 insertions(+), 0 deletions(-)

diff --git a/src/support/ctool.cpp b/src/support/ctool.cpp
index a254a0a..a053309 100644
--- a/src/support/ctool.cpp
+++ b/src/support/ctool.cpp
@@ -49,6 +49,7 @@
 /* __ Method name definitions ____________________________________________ */
 #define G_GET_MEAN_POINTING        "ctool::get_mean_pointing(GObservations&)"
 #define G_CREATE_EBOUNDS                            "ctool::create_ebounds()"
+#define G_PROVIDE_HELP                                "ctool::provide_help()"
 
 /* __ Debug definitions __________________________________________________ */
 
@@ -109,6 +110,12 @@ ctool::ctool(const std::string& name, const std::string& version,
              int argc, char *argv[]) : 
        GApplication(name, version, argc, argv)
 {
+    // Catch --help option before doing anything else
+    if (need_help()) {
+        provide_help();
+        exit(0);
+    }
+    
     // Initialise members
     init_members();
 
@@ -978,3 +985,43 @@ size_t ctool::get_current_rss(void)
     // Return resident set size
     return rss;
 }
+
+
+/***********************************************************************//**
+ * @brief Dumps help text in the console
+ ***************************************************************************/
+void ctool::provide_help(void) const
+{
+    // Allocate line buffer
+    const int n = 1000; 
+    char  line[n];
+
+    // Build help file name
+    std::string helpfile = name()+".txt";
+
+    // Get ctools environment variable
+    char* ptr = std::getenv("CTOOLS");
+    if (ptr == NULL) {
+        std::string msg = "CTOOLS environment variable not set, cannot "
+                          "display help file. Please define CTOOLS "
+                          "environment variable.";
+        throw GException::invalid_value(G_PROVIDE_HELP, msg);
+    }
+
+    // If help file exists then display it, otherwise notify that no
+    // help is available
+    std::string fname = std::string(ptr) + "/share/help/" + helpfile;
+    FILE* fptr = fopen(fname.c_str(), "r");
+    if (fptr != NULL) {
+        while (fgets(line, n, fptr) != NULL) {
+            std::cout << std::string(line);
+        }
+        fclose(fptr);
+    }
+    else {
+        std::cout << "No help available for "+name()+"." << std::endl;
+    }
+
+    // Return
+    return;
+}
diff --git a/src/support/ctool.hpp b/src/support/ctool.hpp
index 43cb3e0..13672d5 100644
--- a/src/support/ctool.hpp
+++ b/src/support/ctool.hpp
@@ -89,6 +89,10 @@ protected:
     GSkyDir         get_mean_pointing(const GObservations& obs);
     size_t          get_current_rss(void);
 
+protected:
+    // Protected methods
+    void           provide_help(void) const;
+    
     // Protected members
     bool           m_read_ahead; //!< Read ahead parameters
     bool           m_use_xml;    //!< Use XML file instead of FITS file for observations
--
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