From abc77b992c54d0b05169c624c35cebf25da97a68 Mon Sep 17 00:00:00 2001
From: Matthew Masarik <86749872+MatthewMasarik-NOAA@users.noreply.github.com>
Date: Thu, 1 Aug 2024 14:46:01 -0700
Subject: [PATCH] Enable doxygen documentation in the cmake build system
 (#1281)

---
 CMakeLists.txt                 | 12 ++++++++++--
 docs/CMakeLists.txt            |  1 +
 docs/Doxyfile.in               |  6 +++---
 docs/cmake/EnableDoxygen.cmake | 27 +++++++++++++++++++++++++++
 4 files changed, 41 insertions(+), 5 deletions(-)
 create mode 100644 docs/CMakeLists.txt
 create mode 100644 docs/cmake/EnableDoxygen.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b485488b3..5070e3aa5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,7 +13,7 @@ project(
 
 get_directory_property(hasParent PARENT_DIRECTORY)
 if(hasParent)
-  # Unset flags that come from Parent (ie UFS or other coupled build) 
+  # Unset flags that come from Parent (ie UFS or other coupled build)
   # for potential (-r8/-r4) conflict
   set(CMAKE_Fortran_FLAGS "")
   set(CMAKE_C_FLAGS "")
@@ -22,8 +22,9 @@ endif()
 
 set(MULTI_ESMF OFF CACHE BOOL "Build ww3_multi_esmf library")
 set(NETCDF ON CACHE BOOL "Build NetCDF programs (requires NetCDF)")
-set(ENDIAN "BIG" CACHE STRING "Endianness of unformatted output files. Valid values are 'BIG', 'LITTLE', 'NATIVE'.") 
+set(ENDIAN "BIG" CACHE STRING "Endianness of unformatted output files. Valid values are 'BIG', 'LITTLE', 'NATIVE'.")
 set(EXCLUDE_FIND "" CACHE STRING "Don't try and search for these libraries (assumd to be handled by the compiler/wrapper)")
+set(ENABLE_DOCS OFF CACHE BOOL "Enable building of doxygen generated documentation")
 
 # make sure all "exclude_find" entries are lower case
 list(TRANSFORM EXCLUDE_FIND TOLOWER)
@@ -59,6 +60,13 @@ endif()
 
 add_subdirectory(model)
 
+# Turn on doxygen documentation
+if (ENABLE_DOCS)
+  list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/docs/cmake")
+  include(EnableDoxygen)
+  add_subdirectory(docs)
+endif()
+
 # Turn on unit testing.
 #include(CTest)
 #if(BUILD_TESTING)
diff --git a/docs/CMakeLists.txt b/docs/CMakeLists.txt
new file mode 100644
index 000000000..7aa89edeb
--- /dev/null
+++ b/docs/CMakeLists.txt
@@ -0,0 +1 @@
+EnableDoxygen(docs)
diff --git a/docs/Doxyfile.in b/docs/Doxyfile.in
index 23349c8da..93a26c5a2 100644
--- a/docs/Doxyfile.in
+++ b/docs/Doxyfile.in
@@ -58,7 +58,7 @@ PROJECT_LOGO           =
 # entered, it will be relative to the location where doxygen was started. If
 # left blank the current directory will be used.
 
-OUTPUT_DIRECTORY       = docs
+OUTPUT_DIRECTORY       = @doc_output@
 
 # If the CREATE_SUBDIRS tag is set to YES then doxygen will create 4096 sub-
 # directories (in 2 levels) under the output directory of each output format and
@@ -829,7 +829,7 @@ WARN_LOGFILE           =
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = model/src
+INPUT                  = @src_input@
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
@@ -2285,7 +2285,7 @@ CLASS_DIAGRAMS         = NO
 # DIA_PATH tag allows you to specify the directory where the dia binary resides.
 # If left empty dia is assumed to be found in the default search path.
 
-DIA_PATH               = 
+DIA_PATH               =
 
 # If set to YES the inheritance and collaboration graphs will hide inheritance
 # and usage relations if the target is undocumented or is not a class.
diff --git a/docs/cmake/EnableDoxygen.cmake b/docs/cmake/EnableDoxygen.cmake
new file mode 100644
index 000000000..20af91e59
--- /dev/null
+++ b/docs/cmake/EnableDoxygen.cmake
@@ -0,0 +1,27 @@
+# Doxygen documentation- Matt Masarik 24-Jul-2024.
+function(EnableDoxygen outdir)
+  find_package(Doxygen REQUIRED)
+    if (NOT DOXYGEN_FOUND)
+      add_custom_target(enable_docs
+          COMMAND false
+          COMMENT "Doxygen not found")
+      return()
+    endif()
+
+    set(src_input "${CMAKE_SOURCE_DIR}/model/src")
+    set(doc_output "${CMAKE_BINARY_DIR}/${outdir}")
+    file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/${outdir}/html)
+    CONFIGURE_FILE(${CMAKE_SOURCE_DIR}/docs/Doxyfile.in
+        ${CMAKE_BINARY_DIR}/${outdir}/Doxyfile @ONLY)
+    set(DOXYGEN_GENERATE_HTML YES)
+    set(DOXYGEN_QUIET YES)
+    add_custom_target(enable_docs
+        COMMAND
+          ${DOXYGEN_EXECUTABLE} ${CMAKE_BINARY_DIR}/${outdir}/Doxyfile
+        WORKING_DIRECTORY
+          ${CMAKE_BINARY_DIR}/${outdir}
+        COMMENT
+          "Generate Doxygen HTML documentation")
+    message("-- Doxygen HTML index page: "
+        ${CMAKE_BINARY_DIR}/${outdir}/html/index.html)
+endfunction()