cmake_minimum_required(VERSION 3.10)
project(musl C ASM)

set(S "${CMAKE_SOURCE_DIR}")
set(GEN "${CMAKE_BINARY_DIR}/obj")

if(NOT DEFINED MUSL_ARCH)
    set(MUSL_ARCH "x86_64")
endif()
if(NOT DEFINED MUSL_SYSLIBDIR)
    set(MUSL_SYSLIBDIR "${CMAKE_INSTALL_PREFIX}/lib")
endif()
if(MUSL_ARCH STREQUAL "x86_64")
    set(MUSL_LDSO "ld-musl-x86_64.so.1")
elseif(MUSL_ARCH STREQUAL "aarch64")
    set(MUSL_LDSO "ld-musl-aarch64.so.1")
elseif(MUSL_ARCH STREQUAL "i386")
    set(MUSL_LDSO "ld-musl-i386.so.1")
else()
    set(MUSL_LDSO "ld-musl-${MUSL_ARCH}.so.1")
endif()

# ── Generated headers ────────────────────────────────────────────────────
file(MAKE_DIRECTORY "${GEN}/include/bits")
file(MAKE_DIRECTORY "${GEN}/src/internal")

execute_process(
    COMMAND sed -f "${S}/tools/mkalltypes.sed"
            "${S}/arch/${MUSL_ARCH}/bits/alltypes.h.in"
            "${S}/include/alltypes.h.in"
    OUTPUT_FILE "${GEN}/include/bits/alltypes.h"
    RESULT_VARIABLE alltypes_res
)
if(NOT alltypes_res EQUAL 0)
    message(FATAL_ERROR "musl: failed to generate bits/alltypes.h")
endif()

file(READ  "${S}/arch/${MUSL_ARCH}/bits/syscall.h.in" _syscall_in)
file(WRITE "${GEN}/include/bits/syscall.h" "${_syscall_in}")
execute_process(
    COMMAND sed -n -e "s/__NR_/SYS_/p"
            "${S}/arch/${MUSL_ARCH}/bits/syscall.h.in"
    OUTPUT_VARIABLE _syscall_aliases
)
file(APPEND "${GEN}/include/bits/syscall.h" "${_syscall_aliases}")

execute_process(
    COMMAND sh "${S}/tools/version.sh"
    WORKING_DIRECTORY "${S}"
    OUTPUT_VARIABLE MUSL_VERSION
    OUTPUT_STRIP_TRAILING_WHITESPACE
)
if(MUSL_VERSION STREQUAL "")
    set(MUSL_VERSION "unknown")
endif()
file(WRITE "${GEN}/src/internal/version.h" "#define VERSION \"${MUSL_VERSION}\"\n")

# ── Include search path ──────────────────────────────────────────────────
set(MUSL_INCLUDES
    "${GEN}/include"
    "${S}/arch/${MUSL_ARCH}"
    "${S}/arch/generic"
    "${GEN}/src/internal"
    "${S}/src/include"
    "${S}/src/internal"
    "${S}/include"
)

# ── Compile flags ─────────────────────────────────────────────────────────
set(MUSL_CFLAGS
    -std=c99 -nostdinc -ffreestanding -fexcess-precision=standard
    -frounding-math -fno-stack-protector -fno-strict-aliasing
    -fPIC -D_XOPEN_SOURCE=700 -Os -pipe
    -Wno-implicit-function-declaration -Wno-parentheses
)

# ── Source selection with per-arch overrides ──────────────────────────────
file(GLOB_RECURSE ALL_REL RELATIVE "${S}/src" "${S}/src/*.c" "${S}/src/*.s")

# Discover valid arch names from the arch/ directory
file(GLOB _arch_dirs "${S}/arch/*")
set(MUSL_ALL_ARCHS "")
foreach(_ad ${_arch_dirs})
    get_filename_component(_aname "${_ad}" NAME)
    list(APPEND MUSL_ALL_ARCHS "${_aname}")
endforeach()

# First pass: find which generic files are overridden by our target arch
set(ARCH_KEYS "")
foreach(rel ${ALL_REL})
    string(REPLACE "/" ";" parts "${rel}")
    list(LENGTH parts n)
    if(n EQUAL 3)
        list(GET parts 0 sub)
        list(GET parts 1 mid)
        list(GET parts 2 fname)
        list(FIND MUSL_ALL_ARCHS "${mid}" _is_arch)
        if(_is_arch GREATER -1 AND mid STREQUAL "${MUSL_ARCH}")
            get_filename_component(base "${fname}" NAME_WE)
            list(APPEND ARCH_KEYS "${sub}|${base}")
        endif()
    endif()
endforeach()

# Second pass: build the source list
set(MUSL_SRCS "")
foreach(rel ${ALL_REL})
    string(REPLACE "/" ";" parts "${rel}")
    list(LENGTH parts n)
    if(n EQUAL 2)
        list(GET parts 0 sub)
        list(GET parts 1 fname)
        get_filename_component(base "${fname}" NAME_WE)
        list(FIND ARCH_KEYS "${sub}|${base}" found)
        if(found EQUAL -1)
            list(APPEND MUSL_SRCS "${S}/src/${rel}")
        endif()
    elseif(n EQUAL 3)
        list(GET parts 0 sub)
        list(GET parts 1 mid)
        list(FIND MUSL_ALL_ARCHS "${mid}" _is_arch)
        if(_is_arch GREATER -1)
            if(mid STREQUAL "${MUSL_ARCH}")
                list(APPEND MUSL_SRCS "${S}/src/${rel}")
            endif()
        else()
            # Non-arch subdir: include, but skip oldmalloc (musl defaults to mallocng)
            if(NOT (sub STREQUAL "malloc" AND mid STREQUAL "oldmalloc"))
                list(APPEND MUSL_SRCS "${S}/src/${rel}")
            endif()
        endif()
    endif()
endforeach()

# Dynamic-linker sources
file(GLOB LDSO_SRCS "${S}/ldso/*.c" "${S}/ldso/*.s"
                    "${S}/ldso/${MUSL_ARCH}/*.c" "${S}/ldso/${MUSL_ARCH}/*.s")

# ── Shared libc ──────────────────────────────────────────────────────────
add_library(c SHARED ${MUSL_SRCS} ${LDSO_SRCS})
target_include_directories(c PRIVATE ${MUSL_INCLUDES})
target_compile_options(c PRIVATE ${MUSL_CFLAGS})
target_compile_definitions(c PRIVATE _XOPEN_SOURCE=700)
set_target_properties(c PROPERTIES OUTPUT_NAME c PREFIX "lib" SUFFIX ".so")
target_link_options(c PRIVATE
    -nostdlib -shared -Wl,-e,_dlstart
    -Wl,-Bsymbolic-functions -Wl,--exclude-libs=ALL
)

# ── Static libc.a ────────────────────────────────────────────────────────
add_library(c-static STATIC ${MUSL_SRCS})
target_include_directories(c-static PRIVATE ${MUSL_INCLUDES})
target_compile_options(c-static PRIVATE ${MUSL_CFLAGS})
target_compile_definitions(c-static PRIVATE _XOPEN_SOURCE=700)
set_target_properties(c-static PROPERTIES OUTPUT_NAME c)

# ── crt objects ───────────────────────────────────────────────────────────
set(_inc_flags "")
foreach(d ${MUSL_INCLUDES})
    list(APPEND _inc_flags "-I${d}")
endforeach()

set(CRT_OBJS "")
function(musl_crt out src)
    set(extra ${ARGN})
    add_custom_command(
        OUTPUT  "${CMAKE_BINARY_DIR}/${out}"
        COMMAND ${CMAKE_C_COMPILER} ${MUSL_CFLAGS} ${_inc_flags} -DCRT ${extra}
                -c "${src}" -o "${CMAKE_BINARY_DIR}/${out}"
        DEPENDS "${src}"
        COMMENT "musl crt: ${out}"
        VERBATIM
    )
    set(CRT_OBJS ${CRT_OBJS} "${CMAKE_BINARY_DIR}/${out}" PARENT_SCOPE)
endfunction()

musl_crt(crt1.o  "${S}/crt/crt1.c")
musl_crt(Scrt1.o "${S}/crt/Scrt1.c")
musl_crt(rcrt1.o "${S}/crt/rcrt1.c")
musl_crt(crti.o  "${S}/crt/${MUSL_ARCH}/crti.s")
musl_crt(crtn.o  "${S}/crt/${MUSL_ARCH}/crtn.s")
add_custom_target(crt ALL DEPENDS ${CRT_OBJS})

# ── Install ───────────────────────────────────────────────────────────────
install(TARGETS c c-static LIBRARY DESTINATION lib ARCHIVE DESTINATION lib RUNTIME DESTINATION lib)
install(FILES ${CRT_OBJS} DESTINATION lib)

install(DIRECTORY "${S}/include/" DESTINATION include FILES_MATCHING PATTERN "*.h")
install(DIRECTORY "${S}/arch/generic/bits/" DESTINATION include/bits FILES_MATCHING PATTERN "*.h")
install(DIRECTORY "${S}/arch/${MUSL_ARCH}/bits/" DESTINATION include/bits FILES_MATCHING PATTERN "*.h")
install(FILES "${GEN}/include/bits/alltypes.h" "${GEN}/include/bits/syscall.h" DESTINATION include/bits)