add_library(library-headers INTERFACE)

# libfdk-aac headers
find_path(FDK_AAC_INCLUDES NAMES fdk-aac/aacdecoder_lib.h)
if(FDK_AAC_INCLUDES STREQUAL "FDK_AAC_INCLUDES-NOTFOUND")
    message(STATUS "fdk_aac headers not found, using bundled headers.")
    target_include_directories(library-headers INTERFACE ./fdk-aac/include)
else()
    message(STATUS "Using headers from system fdk_aac")
    target_include_directories(library-headers SYSTEM INTERFACE ${FDK_AAC_INCLUDES})
endif()

# FFmpeg headers
find_path(AVUTIL_INCLUDES NAMES libavutil/avutil.h)
find_path(AVCODEC_INCLUDES NAMES libavcodec/avcodec.h)
find_path(AVFORMAT_INCLUDES NAMES libavformat/avformat.h)
find_path(AVFILTER_INCLUDES NAMES libavfilter/avfilter.h)
find_path(SWRESAMPLE_INCLUDES NAMES libswresample/swresample.h)
# Make sure all the headers are found and from the same place, so we don't
# have missing or mismatched components.
if(AVUTIL_INCLUDES STREQUAL "AVUTIL_INCLUDES-NOTFOUND"
    OR NOT AVCODEC_INCLUDES STREQUAL AVUTIL_INCLUDES
    OR NOT AVFORMAT_INCLUDES STREQUAL AVUTIL_INCLUDES
    OR NOT AVFILTER_INCLUDES STREQUAL AVUTIL_INCLUDES
    OR NOT SWRESAMPLE_INCLUDES STREQUAL AVUTIL_INCLUDES)
    message(STATUS "Complete FFmpeg headers not found, using bundled headers.")
    target_include_directories(library-headers INTERFACE ./ffmpeg/include)
else()
    message(STATUS "Using headers from system FFmpeg")
    target_include_directories(library-headers SYSTEM INTERFACE ${AVUTIL_INCLUDES})
endif()