load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
load("@rules_cc//cc:cc_library.bzl", "cc_library")
load("@rules_cc_autoconf//autoconf:autoconf.bzl", "autoconf")
load("@rules_cc_autoconf//autoconf:autoconf_hdr.bzl", "autoconf_hdr")
load("@rules_cc_autoconf//autoconf:checks.bzl", "checks", "macros")
load("@rules_cc_autoconf//autoconf:package_info.bzl", "package_info")

# AC_INIT([the fast lexical analyser generator],[2.6.4],
#         [flex-help@lists.sourceforge.net],[flex])
package_info(
    name = "package",
    package_name = "the fast lexical analyser generator",
    aliases = {
        "PACKAGE": "PACKAGE_TARNAME",
        "VERSION": "PACKAGE_VERSION",
    },
    module_bazel = "//:MODULE.bazel",
    package_bugreport = "flex-help@lists.sourceforge.net",
    package_tarname = "flex",
)

string_flag(
    name = "m4_path",
    build_setting_default = "/bin/false",
    values = [
        "m4",
        "/bin/false",
    ],
    visibility = ["//visibility:public"],
)

config_setting(
    name = "bazel_m4_path",
    flag_values = {":m4_path": "/bin/false"},
)

autoconf(
    name = "autoconf",
    checks = [
        # AC_PROG_CC
        checks.AC_PROG_CC(),
        # AC_PROG_CXX
        checks.AC_PROG_CXX(),
        # AM_PROG_CC_C_O
        checks.AC_PROG_CC_C_O(),
    ] +
    # AC_CHECK_HEADERS - required (configure.ac:117)
    macros.AC_CHECK_HEADERS([
        "regex.h",
        "strings.h",
        "sys/stat.h",
        "sys/wait.h",
        "unistd.h",
    ]) +
    # AC_CHECK_HEADERS - optional (configure.ac:120)
    macros.AC_CHECK_HEADERS([
        "inttypes.h",
        "libintl.h",
        "limits.h",
        "locale.h",
        "malloc.h",
        "netinet/in.h",
    ]) +
    # Implicit from AC_HEADER_STDC, AC_HEADER_STDBOOL, AC_FUNC_ALLOCA,
    # AC_FUNC_FORK, AC_CHECK_LIB(pthread, ...)
    macros.AC_CHECK_HEADERS([
        "alloca.h",
        "dlfcn.h",
        "memory.h",
        "stdbool.h",
        "stdint.h",
        "stdlib.h",
        "string.h",
        "sys/types.h",
        "vfork.h",
        "pthread.h",
    ]) +
    # AC_CHECK_FUNCS - required (configure.ac:156-163)
    macros.AC_CHECK_FUNCS([
        "dup2",
        "memset",
        "regcomp",
        "strcasecmp",
        "strchr",
        "strdup",
        "strtol",
    ]) +
    # AC_CHECK_FUNCS - optional (configure.ac:166-170)
    # NOTE: reallocarray is intentionally omitted. Its glibc declaration
    # requires _GNU_SOURCE, but AC_CHECK_FUNCS detects the linker symbol.
    # Without the declaration, GCC treats the return as int, truncating
    # the pointer on 64-bit and causing a segfault.
    macros.AC_CHECK_FUNCS([
        "pow",
        "setlocale",
    ]) +
    # AC_FUNC_ALLOCA (configure.ac:145)
    macros.AC_CHECK_FUNCS([
        "alloca",
    ]) +
    # AC_FUNC_FORK (configure.ac:146)
    macros.AC_CHECK_FUNCS([
        "fork",
        "vfork",
    ]) + [
        # AC_CHECK_LIB(m, log10) (configure.ac:135)
        checks.AC_CHECK_LIB("m", "log10"),

        # AC_HEADER_STDBOOL (configure.ac:139) - _Bool type check
        checks.AC_CHECK_TYPE(
            "_Bool",
            define = "HAVE__BOOL",
            includes = ["#include <stdbool.h>"],
        ),

        # STDC_HEADERS (always 1 on modern systems)
        checks.AC_DEFINE("STDC_HEADERS", 1),

        # YYTEXT_POINTER (AM_PROG_LEX sets this; flex uses char *yytext)
        checks.AC_DEFINE("YYTEXT_POINTER", 1),

        # LT_OBJDIR (libtool)
        checks.AC_DEFINE("LT_OBJDIR", "\".libs/\""),

        # AC_FUNC_MALLOC (configure.ac:149)
        # On all modern systems (glibc, macOS, Windows), malloc(0) returns
        # non-NULL. Set to 1 unconditionally; for exotic targets where this
        # is not the case, override with lib/malloc.c.
        checks.AC_DEFINE("HAVE_MALLOC", 1),

        # AC_FUNC_REALLOC (configure.ac:152)
        checks.AC_DEFINE("HAVE_REALLOC", 1),

        # AC_FUNC_FORK derived defines (configure.ac:146)
        checks.AC_DEFINE(
            "HAVE_WORKING_FORK",
            condition = "ac_cv_func_fork",
            if_false = None,
            if_true = 1,
        ),
        checks.AC_DEFINE(
            "HAVE_WORKING_VFORK",
            condition = "ac_cv_func_vfork",
            if_false = None,
            if_true = 1,
        ),

        # AC_FUNC_FORK: On systems without vfork, config.h.in's "#undef vfork"
        # stays as "/* #undef vfork */" and HAVE_WORKING_VFORK is unset.
        # All modern systems (Linux, macOS) have working vfork.
    ] + select({
        ":bazel_m4_path": [
            # Prevent any host installed m4 from being run.
            checks.AC_DEFINE_UNQUOTED("M4", "\"/bin/false\""),
        ],
        "//conditions:default": [
            # Allow users to have a canonical flex binary that would look for host m4.
            checks.AC_DEFINE_UNQUOTED("M4", "\"m4\""),
        ],
    }),
    deps = [":package"],
)

# AC_CONFIG_HEADER([src/config.h])
autoconf_hdr(
    name = "gen_config_h",
    out = "src/config.h",
    template = "src/config.h.in",
    deps = [":autoconf"],
)

cc_library(
    name = "config",
    hdrs = [":gen_config_h"],
    strip_include_prefix = "src",
    visibility = ["//:__subpackages__"],
)

FLEX_SRCS = [
    "src/buf.c",
    "src/ccl.c",
    "src/dfa.c",
    "src/ecs.c",
    "src/filter.c",
    "src/gen.c",
    "src/main.c",
    "src/misc.c",
    "src/nfa.c",
    "src/options.c",
    "src/regex.c",
    "src/scanflags.c",
    "src/scanopt.c",
    "src/skel.c",
    "src/sym.c",
    "src/tables.c",
    "src/tables_shared.c",
    "src/tblcmp.c",
    "src/yylex.c",
    # Pre-generated from parse.y (bison) and scan.l (flex bootstrap)
    "src/parse.c",
    "src/scan.c",
]

FLEX_HDRS = [
    "src/flexdef.h",
    "src/flexint.h",
    "src/gettext.h",
    "src/options.h",
    "src/parse.h",
    "src/scanopt.h",
    "src/tables.h",
    "src/tables_shared.h",
    "src/version.h",
]

filegroup(
    name = "flex_runfiles",
    srcs = [
        "@m4",
    ],
)

label_flag(
    name = "m4",
    build_setting_default = "@m4//:m4",
    visibility = ["//visibility:public"],
)

cc_binary(
    name = "flex",
    srcs = FLEX_SRCS + FLEX_HDRS,
    copts = ["-DHAVE_CONFIG_H"],
    data = [
        ":flex_runfiles",
    ],
    linkopts = select({
        "@platforms//os:windows": [],
        "//conditions:default": ["-lm"],
    }),
    visibility = ["//visibility:public"],
    deps = [":config"],
)

cc_library(
    name = "libfl",
    srcs = [
        "src/libmain.c",
        "src/libyywrap.c",
    ],
    visibility = ["//visibility:public"],
)

cc_library(
    name = "headers",
    hdrs = ["src/FlexLexer.h"],
    strip_include_prefix = "src",
    visibility = ["//visibility:public"],
)