cmake_minimum_required(VERSION 3.10)
# 1.0.0 replaced the consumer-sized __AKERR_ERROR_NAMES array with private
# storage. 2.0.0 makes the library thread safe, which is a second ABI break in
# the same places: __akerr_last_ignored became thread-local storage, and
# ENSURE_ERROR_READY no longer takes the pool reference that akerr_next_error()
# now takes for it. Consumer code compiled against a 1.x header would
# double-count every reference. Hence the major bump and the SOVERSION, so a
# stale installed libakerror.so cannot be silently paired with new headers.
# 2.0.1 fixes the unhandled-error exit code, which reported success for any
# status whose low byte was zero. It adds akerr_exit() but breaks nothing: the
# soname is unchanged and no existing entry point changed shape.
project(akerror VERSION 2.0.1 LANGUAGES C)

include(GNUInstallDirs)
include(CMakePackageConfigHelpers)
include(CTest)

set(AKERR_USE_STDLIB 1 CACHE BOOL "Use the C standard library")
set(AKERR_COVERAGE 0 CACHE BOOL "Instrument the build with gcov coverage counters")
set(AKERR_SANITIZE "" CACHE STRING
    "Sanitizers to build the library and tests with, e.g. thread or address,undefined")

# Threading backend for the library's global state (the error pool and the
# status registry). "auto" takes POSIX threads when they exist and fails the
# configure when they do not: a build that silently fell back to no locking
# would produce a library that reports itself thread safe and is not. Say
# -DAKERR_THREADS=none to mean it on purpose.
set(AKERR_THREADS "auto" CACHE STRING "Threading backend: auto, pthread, or none")
set_property(CACHE AKERR_THREADS PROPERTY STRINGS auto pthread none)

if(AKERR_THREADS STREQUAL "auto" OR AKERR_THREADS STREQUAL "pthread")
    set(THREADS_PREFER_PTHREAD_FLAG ON)
    find_package(Threads)
    if(CMAKE_USE_PTHREADS_INIT)
        set(AKERR_THREAD_SAFE 1)
    elseif(AKERR_THREADS STREQUAL "pthread")
        message(FATAL_ERROR
            "-DAKERR_THREADS=pthread was requested but no POSIX thread library "
            "was found.")
    else()
        message(FATAL_ERROR
            "No POSIX thread library was found. libakerror serializes its "
            "global state with a recursive pthread mutex; without one it "
            "cannot be thread safe. Configure with -DAKERR_THREADS=none to "
            "build a deliberately single-threaded library instead.")
    endif()
elseif(AKERR_THREADS STREQUAL "none")
    set(AKERR_THREAD_SAFE 0)
else()
    message(FATAL_ERROR
        "AKERR_THREADS must be auto, pthread or none, not '${AKERR_THREADS}'")
endif()

# Size of the private status-name hash table. Must be a power of two; usable
# capacity is 75% of it (src/error.c asserts both). The host's errno list
# consumes part of that at akerr_init() time, so the remainder is what all
# consumer libraries in the process share. These are applied PRIVATE on purpose:
# the table lives entirely in src/error.c, so raising them never changes
# anything a consumer can see. That is what makes them safe to tune, unlike the
# AKERR_MAX_ERR_VALUE they replaced.
set(AKERR_STATUS_NAME_SLOTS 4096 CACHE STRING
    "Slots in the status-name table (power of two; 75% usable)")
set(AKERR_MAX_RESERVED_STATUS_RANGES 64 CACHE STRING
    "Maximum number of status ranges that may be reserved")
set(akerror_install_cmakedir "${CMAKE_INSTALL_LIBDIR}/cmake/akerror")

# Coverage instrumentation. Applied per target (not globally) so it never leaks
# into the exported/installed target interface. Only the library is
# instrumented: the tests are the thing doing the covering, and the public
# header's macros cannot be measured this way at all -- GCC attributes an
# expanded macro to its call site, so header logic shows up as test-file lines.
# Coverage of those macros is what mutation testing (--target
# include/akerror.tmpl.h) is for.
if(AKERR_COVERAGE)
    if(NOT CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
        message(FATAL_ERROR
            "AKERR_COVERAGE requires GCC or Clang, not ${CMAKE_C_COMPILER_ID}")
    endif()
    # -O0 keeps line counts attributable; no inlining or code motion.
    set(AKERR_COVERAGE_FLAGS --coverage -O0 -g)
    if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
        # Record absolute source paths so gcov resolves sources built from the
        # generated directory (GCC 8+; harmless to check).
        include(CheckCCompilerFlag)
        check_c_compiler_flag(-fprofile-abs-path AKERR_HAVE_PROFILE_ABS_PATH)
        if(AKERR_HAVE_PROFILE_ABS_PATH)
            list(APPEND AKERR_COVERAGE_FLAGS -fprofile-abs-path)
        endif()
    endif()
endif()

# Add coverage compile/link flags to one target, if coverage is enabled.
function(akerr_instrument_for_coverage _target)
    if(AKERR_COVERAGE)
        target_compile_options(${_target} PRIVATE ${AKERR_COVERAGE_FLAGS})
        set_property(TARGET ${_target} APPEND_STRING
                     PROPERTY LINK_FLAGS " --coverage")
    endif()
endfunction()

# Sanitizers. Unlike coverage these go on the tests as well as the library:
# ThreadSanitizer only sees a race if every thread that touches the memory was
# compiled with it, and the threads live in the test programs.
#   cmake -S . -B build/tsan -DAKERR_SANITIZE=thread
if(AKERR_SANITIZE AND NOT CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
    message(FATAL_ERROR
        "AKERR_SANITIZE requires GCC or Clang, not ${CMAKE_C_COMPILER_ID}")
endif()

function(akerr_instrument_for_sanitizers _target)
    if(AKERR_SANITIZE)
        target_compile_options(${_target} PRIVATE
                               -fsanitize=${AKERR_SANITIZE}
                               -fno-omit-frame-pointer -g -O1)
        set_property(TARGET ${_target} APPEND_STRING
                     PROPERTY LINK_FLAGS " -fsanitize=${AKERR_SANITIZE}")
    endif()
endfunction()

set(SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/scripts/generrno.sh)
set(INFILE ${CMAKE_CURRENT_SOURCE_DIR}/include/akerror.tmpl.h)

set(GENERATED_DIR ${CMAKE_CURRENT_BINARY_DIR}/generated)

set(GENERATED_ERRNO_C ${GENERATED_DIR}/src/errno.c)
set(GENERATED_AKERROR_H ${GENERATED_DIR}/include/akerror.h)

# The threading decision is stamped into the generated header, so the header has
# to be regenerated when it changes. Makefile generators compare timestamps
# rather than command lines, so carry the value through a file: configure_file
# rewrites it only when the content differs, which is exactly the trigger we
# want and no trigger at all on an unchanged reconfigure.
set(GENERATED_THREAD_STAMP ${CMAKE_CURRENT_BINARY_DIR}/akerr_thread_safe.stamp)
configure_file(cmake/thread_safe.stamp.in ${GENERATED_THREAD_STAMP} @ONLY)

add_custom_command(
  OUTPUT ${GENERATED_ERRNO_C} ${GENERATED_AKERROR_H}
  COMMAND ${CMAKE_COMMAND} -E make_directory ${GENERATED_DIR}
  COMMAND /usr/bin/env bash
          ${SCRIPT}
          ${CMAKE_CURRENT_SOURCE_DIR}
          ${GENERATED_DIR}
          ${AKERR_THREAD_SAFE}
  DEPENDS ${SCRIPT} ${INFILE} ${GENERATED_THREAD_STAMP}
  VERBATIM
)

add_library(akerror SHARED
  src/error.c
  ${GENERATED_ERRNO_C}
)

target_include_directories(akerror PUBLIC
  $<BUILD_INTERFACE:${GENERATED_DIR}/include>
  $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
)

find_package(PkgConfig REQUIRED)
add_library(akerror::akerror ALIAS akerror)

# The threading backend is PRIVATE: src/lock.h is not installed, so which
# primitive the library locks with is invisible to a consumer. What a consumer
# does see -- whether the library locks at all -- travels in the generated
# header instead, where it cannot disagree with this build.
if(AKERR_THREAD_SAFE)
    set(AKERR_THREADS_DEFINE AKERR_THREADS_PTHREAD=1)
else()
    set(AKERR_THREADS_DEFINE AKERR_THREADS_NONE=1)
endif()

target_compile_definitions(akerror
    PUBLIC AKERR_USE_STDLIB=${AKERR_USE_STDLIB}
    PRIVATE AKERR_STATUS_NAME_SLOTS=${AKERR_STATUS_NAME_SLOTS}
    PRIVATE AKERR_MAX_RESERVED_STATUS_RANGES=${AKERR_MAX_RESERVED_STATUS_RANGES}
    PRIVATE ${AKERR_THREADS_DEFINE}
)

if(AKERR_THREAD_SAFE)
    target_link_libraries(akerror PRIVATE Threads::Threads)
endif()

set_target_properties(akerror PROPERTIES
    VERSION ${PROJECT_VERSION}
    SOVERSION ${PROJECT_VERSION_MAJOR}
)

akerr_instrument_for_coverage(akerror)
akerr_instrument_for_sanitizers(akerror)

# Each test is one source file in tests/ built into test_<name> and registered
# as CTest <name>. Tests expected to abort (unhandled error / contract
# violation) go in AKERR_WILL_FAIL_TESTS; all others must exit 0.
set(AKERR_TESTS
    err_catch
    err_cleanup
    err_trace
    err_improper_closure
    err_success
    err_pool_refcount
    err_handle_default
    err_handle_group
    err_handle_dispatch
    err_pass
    err_ignore
    err_swallow
    err_errno
    err_break_variants
    err_custom_handler
    err_error_names
    err_release_clears
    err_pool_exhaust
    err_maxval
    err_name_ownership
    err_registry_init_order
    err_status_exception
    err_copy_string
    err_library_status_fatal
    err_refcount_double_fail
    err_stacktrace_bounds
    err_name_bounds
    err_format_string
    err_unhandled_null
    err_exit_status
    err_release_null
    err_release_refcount
)

# These drive the library from many threads at once. They are worth running on
# their own -- they assert exclusive ownership of pool slots and of reserved
# ranges, which is checkable without a sanitizer -- but the run that proves the
# absence of a race is the one under -DAKERR_SANITIZE=thread.
if(AKERR_THREAD_SAFE)
    list(APPEND AKERR_TESTS
        err_threads_init
        err_threads_pool
        err_threads_registry
        err_threads_handoff
    )
endif()

set(AKERR_WILL_FAIL_TESTS
    err_trace
    err_improper_closure
    err_library_status_fatal
)

foreach(_test IN LISTS AKERR_TESTS)
    add_executable(test_${_test} tests/${_test}.c)
    target_include_directories(test_${_test} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/tests)
    target_link_libraries(test_${_test} PRIVATE akerror)
    if(AKERR_THREAD_SAFE)
        target_link_libraries(test_${_test} PRIVATE Threads::Threads)
    endif()
    akerr_instrument_for_sanitizers(test_${_test})
    add_test(NAME ${_test} COMMAND test_${_test})
    # A sanitizer report is a test failure. Without halt_on_error the runtime
    # prints and continues, which leaves a race to be noticed in the log by
    # somebody reading it -- and under a race storm the reporting itself is slow
    # enough to look like a hang.
    if(AKERR_SANITIZE)
        set_tests_properties(${_test} PROPERTIES ENVIRONMENT
            "TSAN_OPTIONS=halt_on_error=1;ASAN_OPTIONS=halt_on_error=1;UBSAN_OPTIONS=halt_on_error=1:print_stacktrace=1")
    endif()
endforeach()

set_tests_properties(
    ${AKERR_WILL_FAIL_TESTS}
    PROPERTIES WILL_FAIL TRUE
)

# Coverage and mutation testing are meta-checks on the test suite itself, and
# both rebuild and re-run the whole suite, so they are manual targets rather
# than CTest tests.
find_package(Python3 COMPONENTS Interpreter)
if(Python3_FOUND)
    # Code coverage: which library lines/branches the CTest suite reaches.
    #   cmake --build build --target coverage
    # The script configures and drives its own instrumented build tree (under
    # ${CMAKE_BINARY_DIR}/coverage) so this build's binaries and its coverage
    # counters can never be stale or half-instrumented. Reports via gcov.
    add_custom_target(coverage
        COMMAND ${Python3_EXECUTABLE}
                ${CMAKE_CURRENT_SOURCE_DIR}/scripts/coverage.py
                --source-root ${CMAKE_CURRENT_SOURCE_DIR}
                --build-dir ${CMAKE_CURRENT_BINARY_DIR}/coverage
                --cmake ${CMAKE_COMMAND}
                --ctest ${CMAKE_CTEST_COMMAND}
        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
        USES_TERMINAL
        COMMENT "Running the test suite instrumented for coverage"
    )

    # Mutation testing: break the library in small ways and confirm the test
    # suite notices.
    #   cmake --build build --target mutation
    # When embedded in another project, use a namespaced target to avoid
    # collisions with mutation targets provided by sibling dependencies.
    if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
        set(AKERR_MUTATION_TARGET mutation)
    else()
        set(AKERR_MUTATION_TARGET akerror_mutation)
    endif()
    add_custom_target(${AKERR_MUTATION_TARGET}
        COMMAND ${Python3_EXECUTABLE}
                ${CMAKE_CURRENT_SOURCE_DIR}/scripts/mutation_test.py
                --source-root ${CMAKE_CURRENT_SOURCE_DIR}
        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
        USES_TERMINAL
        COMMENT "Running mutation tests (breaks the library, expects tests to fail)"
    )
endif()

set(main_lib_dest "lib/my_library-${MY_LIBRARY_VERSION}")
install(TARGETS akerror
  EXPORT akerrorTargets
  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
  INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
)

install(FILES ${GENERATED_AKERROR_H} DESTINATION "include/")
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/akerror.pc DESTINATION "lib/pkgconfig/")

install(EXPORT akerrorTargets
    FILE akerrorTargets.cmake
    NAMESPACE akerror::
    DESTINATION ${akerror_install_cmakedir}
)

configure_package_config_file(
    cmake/akerror.cmake.in
    "${CMAKE_CURRENT_BINARY_DIR}/akerrorConfig.cmake"
    INSTALL_DESTINATION ${akerror_install_cmakedir}
)

install(FILES
    "${CMAKE_CURRENT_BINARY_DIR}/akerrorConfig.cmake"
    DESTINATION ${akerror_install_cmakedir}
)

# pkgconfig
set(prefix      ${CMAKE_INSTALL_PREFIX})
set(exec_prefix "\${prefix}")
set(libdir      "\${exec_prefix}/lib")
set(includedir  "\${prefix}/include")
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/akerror.pc.in ${CMAKE_CURRENT_BINARY_DIR}/akerror.pc @ONLY)