#[===================================================================[
   Configure sanitizers based on environment variables.

   This module reads the following environment variables:
   - SANITIZERS: The sanitizers to enable. Possible values:
     - "address"
     - "address,undefinedbehavior"
     - "thread"
     - "thread,undefinedbehavior"
     - "undefinedbehavior"

   The compiler type and platform are detected in CompilationEnv.cmake.
   The sanitizer compile options are applied to the 'common' interface library
   which is linked to all targets in the project.

   Internal flag variables set by this module:

   - SANITIZER_TYPES: List of sanitizer types to enable (e.g., "address",
     "thread", "undefined"). And two more flags for undefined behavior sanitizer (e.g., "float-divide-by-zero", "unsigned-integer-overflow").
     This list is joined with commas and passed to -fsanitize=<list>.

   - SANITIZERS_COMPILE_FLAGS: Compiler flags for sanitizer instrumentation.
     Includes:
     * -fno-omit-frame-pointer: Preserves frame pointers for stack traces
     * -O1: Minimum optimization for reasonable performance
     * -fsanitize=<types>: Enables sanitizer instrumentation
     * -fsanitize-ignorelist=<path>: (Clang only) Compile-time ignorelist
     * -mcmodel=large/medium: (GCC only) Code model for large binaries
     * -Wno-stringop-overflow: (GCC only) Suppresses false positive warnings
     * -Wno-tsan: (For GCC TSAN combination only) Suppresses atomic_thread_fence warnings

   - SANITIZERS_LINK_FLAGS: Linker flags for sanitizer runtime libraries.
     Includes:
     * -fsanitize=<types>: Links sanitizer runtime libraries
     * -mcmodel=large/medium: (GCC only) Matches compile-time code model

   - SANITIZERS_RELOCATION_FLAGS: (GCC only) Code model flags for linking.
     Used to handle large instrumented binaries on x86_64:
     * -mcmodel=large: For AddressSanitizer (prevents relocation errors)
     * -mcmodel=medium: For ThreadSanitizer (large model is incompatible)
#]===================================================================]

include(CompilationEnv)

# Read environment variable
set(SANITIZERS "")
if (DEFINED ENV{SANITIZERS})
    set(SANITIZERS "$ENV{SANITIZERS}")
endif ()

# Set SANITIZERS_ENABLED flag for use in other modules
if (SANITIZERS MATCHES "address|thread|undefinedbehavior")
    set(SANITIZERS_ENABLED TRUE)
else ()
    set(SANITIZERS_ENABLED FALSE)
    return()
endif ()

# Sanitizers are not supported on Windows/MSVC
if (is_msvc)
    message(FATAL_ERROR "Sanitizers are not supported on Windows/MSVC. "
                        "Please unset the SANITIZERS environment variable.")
endif ()

message(STATUS "Configuring sanitizers: ${SANITIZERS}")

# Parse SANITIZERS value to determine which sanitizers to enable
set(enable_asan FALSE)
set(enable_tsan FALSE)
set(enable_ubsan FALSE)

# Normalize SANITIZERS into a list
set(san_list "${SANITIZERS}")
string(REPLACE "," ";" san_list "${san_list}")
separate_arguments(san_list)

foreach (san IN LISTS san_list)
    if (san STREQUAL "address")
        set(enable_asan TRUE)
    elseif (san STREQUAL "thread")
        set(enable_tsan TRUE)
    elseif (san STREQUAL "undefinedbehavior")
        set(enable_ubsan TRUE)
    else ()
        message(FATAL_ERROR "Unsupported sanitizer type: ${san}"
                            "Supported: address, thread, undefinedbehavior and their combinations.")
    endif ()
endforeach ()

# Validate sanitizer compatibility
if (enable_asan AND enable_tsan)
    message(FATAL_ERROR "AddressSanitizer and ThreadSanitizer are incompatible and cannot be enabled simultaneously. "
                        "Use 'address' or 'thread', optionally with 'undefinedbehavior'.")
endif ()

# Frame pointer is required for meaningful stack traces. Sanitizers recommend minimum of -O1 for reasonable performance
set(SANITIZERS_COMPILE_FLAGS "-fno-omit-frame-pointer" "-O1")

# Build the sanitizer flags list
set(SANITIZER_TYPES)

if (enable_asan)
    list(APPEND SANITIZER_TYPES "address")
elseif (enable_tsan)
    list(APPEND SANITIZER_TYPES "thread")
endif ()

if (enable_ubsan)
    # UB sanitizer flags
    list(APPEND SANITIZER_TYPES "undefined" "float-divide-by-zero")
    if (is_clang)
        # Clang supports additional UB checks. More info here
        # https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
        list(APPEND SANITIZER_TYPES "unsigned-integer-overflow")
    endif ()
endif ()

# Configure code model for GCC on amd64 Use large code model for ASAN to avoid relocation errors Use medium code model
# for TSAN (large is not compatible with TSAN)
set(SANITIZERS_RELOCATION_FLAGS)

# Compiler-specific configuration
if (is_gcc)
    # Disable mold, gold and lld linkers for GCC with sanitizers Use default linker (bfd/ld) which is more lenient with
    # mixed code models This is needed since the size of instrumented binary exceeds the limits set by mold, lld and
    # gold linkers
    set(use_mold OFF CACHE BOOL "Use mold linker" FORCE)
    set(use_gold OFF CACHE BOOL "Use gold linker" FORCE)
    set(use_lld OFF CACHE BOOL "Use lld linker" FORCE)
    message(STATUS "  Disabled mold, gold, and lld linkers for GCC with sanitizers")

    # Suppress false positive warnings in GCC with stringop-overflow
    list(APPEND SANITIZERS_COMPILE_FLAGS "-Wno-stringop-overflow")

    if (is_amd64 AND enable_asan)
        message(STATUS "  Using large code model (-mcmodel=large)")
        list(APPEND SANITIZERS_COMPILE_FLAGS "-mcmodel=large")
        list(APPEND SANITIZERS_RELOCATION_FLAGS "-mcmodel=large")
    elseif (enable_tsan)
        # GCC doesn't support atomic_thread_fence with tsan. Suppress warnings.
        list(APPEND SANITIZERS_COMPILE_FLAGS "-Wno-tsan")
        message(STATUS "  Using medium code model (-mcmodel=medium)")
        list(APPEND SANITIZERS_COMPILE_FLAGS "-mcmodel=medium")
        list(APPEND SANITIZERS_RELOCATION_FLAGS "-mcmodel=medium")
    endif ()

    # Join sanitizer flags with commas for -fsanitize option
    list(JOIN SANITIZER_TYPES "," SANITIZER_TYPES_STR)

    # Add sanitizer to compile and link flags
    list(APPEND SANITIZERS_COMPILE_FLAGS "-fsanitize=${SANITIZER_TYPES_STR}")
    set(SANITIZERS_LINK_FLAGS "${SANITIZERS_RELOCATION_FLAGS}" "-fsanitize=${SANITIZER_TYPES_STR}")

elseif (is_clang)
    # Add ignorelist for Clang (GCC doesn't support this) Use CMAKE_SOURCE_DIR to get the path to the ignorelist
    set(IGNORELIST_PATH "${CMAKE_SOURCE_DIR}/sanitizers/suppressions/sanitizer-ignorelist.txt")
    if (NOT EXISTS "${IGNORELIST_PATH}")
        message(FATAL_ERROR "Sanitizer ignorelist not found: ${IGNORELIST_PATH}")
    endif ()

    list(APPEND SANITIZERS_COMPILE_FLAGS "-fsanitize-ignorelist=${IGNORELIST_PATH}")
    message(STATUS "  Using sanitizer ignorelist: ${IGNORELIST_PATH}")

    # Join sanitizer flags with commas for -fsanitize option
    list(JOIN SANITIZER_TYPES "," SANITIZER_TYPES_STR)

    # Add sanitizer to compile and link flags
    list(APPEND SANITIZERS_COMPILE_FLAGS "-fsanitize=${SANITIZER_TYPES_STR}")
    set(SANITIZERS_LINK_FLAGS "-fsanitize=${SANITIZER_TYPES_STR}")
endif ()

message(STATUS "  Compile flags: ${SANITIZERS_COMPILE_FLAGS}")
message(STATUS "  Link flags: ${SANITIZERS_LINK_FLAGS}")

# Apply the sanitizer flags to the 'common' interface library This is the same library used by XrplCompiler.cmake
target_compile_options(common INTERFACE $<$<COMPILE_LANGUAGE:CXX>:${SANITIZERS_COMPILE_FLAGS}>
                                        $<$<COMPILE_LANGUAGE:C>:${SANITIZERS_COMPILE_FLAGS}>)

# Apply linker flags
target_link_options(common INTERFACE ${SANITIZERS_LINK_FLAGS})

# Define SANITIZERS macro for BuildInfo.cpp
set(sanitizers_list)
if (enable_asan)
    list(APPEND sanitizers_list "ASAN")
endif ()
if (enable_tsan)
    list(APPEND sanitizers_list "TSAN")
endif ()
if (enable_ubsan)
    list(APPEND sanitizers_list "UBSAN")
endif ()

if (sanitizers_list)
    list(JOIN sanitizers_list "." sanitizers_str)
    target_compile_definitions(common INTERFACE SANITIZERS=${sanitizers_str})
endif ()