/*
 * mkproj - dumb project generator.
 *
 * generates boilerplate for make, cmake, meson or premake5 so i don't
 * have to keep writing build files for small dumb projects.
 *
 * Author:  hachem <im@hachem.wtf>
 * Version: 0.1.0
 */

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

#define mkproj_program "mkproj"
#define mkproj_version "0.1.0"
#define mkproj_tagline "dumb project generator"

enum Language
{
    language_c,
    language_cpp,
    language_objc,
    language_count
};

enum Build_System
{
    build_make,
    build_cmake,
    build_meson,
    build_premake,
    build_system_count
};

struct Language_Info
{
    const char* key;
    const char* name;
    const char* compiler;
    const char* extension;
    const char* const* standards;
    size_t standard_count;
    const char* default_standard;
};

struct Build_Info
{
    const char* key;
    const char* name;
    const char* default_bin;
    const char* default_bin_int;
};

struct Config
{
    const char* name;
    enum Language language;
    const char* standard;
    enum Build_System build;
    const char* bin_dir;
    const char* bin_int_dir;
    int use_git;
    int use_intermediate;
    int use_clangd_ignore;
};

static const char* const c_standards[] =
{
    "c89", 
    "c99", 
    "c11", 
    "c17", 
    "c23", 
    "c2y"
};

static const char* const cpp_standards[] =
{
    "c++98", 
    "c++03", 
    "c++11", 
    "c++14", 
    "c++17", 
    "c++20", 
    "c++23", 
    "c++26"
};

static const struct Language_Info languages[language_count] =
{
    [language_c] =
    {
        .key = "c",
        .name = "C",
        .compiler = "clang",
        .extension = "c",
        .standards = c_standards,
        .standard_count = sizeof c_standards / sizeof c_standards[0],
        .default_standard = "c17",
    },
    [language_cpp] =
    {
        .key = "cpp",
        .name = "C++",
        .compiler = "clang++",
        .extension = "cpp",
        .standards = cpp_standards,
        .standard_count = sizeof cpp_standards / sizeof cpp_standards[0],
        .default_standard = "c++23",
    },
    [language_objc] =
    {
        .key = "objc",
        .name = "Objective-C",
        .compiler = "clang",
        .extension = "m",
        .standards = c_standards,
        .standard_count = sizeof c_standards / sizeof c_standards[0],
        .default_standard = "c17",
    },
};

static const struct Build_Info build_systems[build_system_count] =
{
    [build_make] =
    {
        .key = "make", .name = "Make",
        .default_bin = "bin", .default_bin_int = "bin-int",
    },
    [build_cmake] =
    {
        .key = "cmake", .name = "CMake",
        .default_bin = "build", .default_bin_int = "build",
    },
    [build_meson] =
    {
        .key = "meson", .name = "Meson",
        .default_bin = "builddir", .default_bin_int = "builddir",
    },
    [build_premake] =
    {
        .key = "premake", .name = "premake5",
        .default_bin = "bin", .default_bin_int = "bin-int",
    },
};

static void print_version(void)
{
    (void) printf("%s %s\n", mkproj_program, mkproj_version);
}

static void print_usage(FILE* stream)
{
    (void) fprintf(
        stream,
        "%s %s - %s\n"
        "\n"
        "generates boilerplate for make, cmake, meson or premake5 so i don't\n"
        "have to keep writing build files for small dumb projects.\n"
        "\n"
        "usage: %s [-l lang] [-s std] [-b system] [--no-git] [--intermediate]\n"
        "              [--bin dir] [--bin-int dir] [--no-clangd] <name>\n"
        "       %s [-v | -h]\n"
        "\n"
        "options:\n"
        "  -l, --lang LANG     language: c, cpp, objc (default c)\n"
        "  -s, --std STD       language standard (default per language)\n"
        "  -b, --build SYSTEM  build system: make, cmake, meson, premake (default make)\n"
        "      --no-git        don't initialize a git repository\n"
        "      --intermediate  use a separate intermediate object directory\n"
        "      --bin DIR       build directory (default per build system)\n"
        "      --bin-int DIR   separate object dir for make/premake; implies --intermediate\n"
        "      --no-clangd     don't ignore clangd files in .gitignore\n"
        "  -v, --version       print version and bail\n"
        "  -h, --help          print this and bail\n"
        "\n"
        "by hachem <im@hachem.wtf>\n",
        mkproj_program, mkproj_version, mkproj_tagline,
        mkproj_program, mkproj_program);
}

static int find_language(const char* key, enum Language* out)
{
    for (enum Language language = 0; language < language_count; language++)
        if (strcmp(languages[language].key, key) == 0)
        {
            *out = language;
            return 1;
        }

    return 0;
}

static int find_build_system(const char* key, enum Build_System* out)
{
    for (enum Build_System build = 0; build < build_system_count; build++)
        if (strcmp(build_systems[build].key, key) == 0)
        {
            *out = build;
            return 1;
        }

    return 0;
}

static int valid_standard(enum Language language, const char* standard)
{
    const struct Language_Info* info = &languages[language];

    for (size_t i = 0; i < info->standard_count; i++)
        if (strcmp(info->standards[i], standard) == 0)
            return 1;

    return 0;
}

static void error(const char* message, const char* detail)
{
    if (detail != NULL)
        (void) fprintf(stderr, "%s: error: %s: %s\n", mkproj_program, message, detail);
    else
        (void) fprintf(stderr, "%s: error: %s\n", mkproj_program, message);
}

/*
 * parse argv into config. returns 0 on success, a negative value when the
 * program should exit successfully (help/version), or a positive value on a
 * usage error.
 */
static int parse_args(int argc, char** argv, struct Config* config)
{
    const char* lang_arg = NULL;
    const char* std_arg = NULL;
    const char* build_arg = NULL;
    const char* bin_arg = NULL;
    const char* bin_int_arg = NULL;
    const char* name = NULL;

    for (int i = 1; i < argc; i++)
    {
        const char* arg = argv[i];

        if (strcmp(arg, "-h") == 0 || strcmp(arg, "--help") == 0)
        {
            print_usage(stdout);
            return -1;
        }

        if (strcmp(arg, "-v") == 0 || strcmp(arg, "--version") == 0)
        {
            print_version();
            return -1;
        }

        if (strcmp(arg, "--no-git") == 0)
        {
            config->use_git = 0;
            continue;
        }

        if (strcmp(arg, "--intermediate") == 0)
        {
            config->use_intermediate = 1;
            continue;
        }

        if (strcmp(arg, "--no-clangd") == 0)
        {
            config->use_clangd_ignore = 0;
            continue;
        }

        if (strcmp(arg, "--bin") == 0)
        {
            if (++i >= argc)
            {
                error("missing argument for", arg);
                return 1;
            }

            bin_arg = argv[i];
            continue;
        }

        if (strcmp(arg, "--bin-int") == 0)
        {
            if (++i >= argc)
            {
                error("missing argument for", arg);
                return 1;
            }

            bin_int_arg = argv[i];
            config->use_intermediate = 1;
            continue;
        }

        if (strcmp(arg, "-l") == 0 || strcmp(arg, "--lang") == 0)
        {
            if (++i >= argc)
            {
                error("missing argument for", arg);
                return 1;
            }

            lang_arg = argv[i];
            continue;
        }

        if (strcmp(arg, "-s") == 0 || strcmp(arg, "--std") == 0)
        {
            if (++i >= argc)
            {
                error("missing argument for", arg);
                return 1;
            }

            std_arg = argv[i];
            continue;
        }

        if (strcmp(arg, "-b") == 0 || strcmp(arg, "--build") == 0)
        {
            if (++i >= argc)
            {
                error("missing argument for", arg);
                return 1;
            }

            build_arg = argv[i];
            continue;
        }

        if (arg[0] == '-' && arg[1] != '\0')
        {
            error("unknown option", arg);
            return 1;
        }

        if (name != NULL)
        {
            error("unexpected extra argument", arg);
            return 1;
        }

        name = arg;
    }

    if (name == NULL)
    {
        error("missing project name", NULL);
        return 1;
    }

    config->name = name;

    if (lang_arg != NULL && !find_language(lang_arg, &config->language))
    {
        error("unknown language", lang_arg);
        return 1;
    }

    if (build_arg != NULL && !find_build_system(build_arg, &config->build))
    {
        error("unknown build system", build_arg);
        return 1;
    }

    if (std_arg != NULL)
    {
        if (!valid_standard(config->language, std_arg))
        {
            error("invalid standard for language", std_arg);
            return 1;
        }

        config->standard = std_arg;
    }
    else
    {
        config->standard = languages[config->language].default_standard;
    }

    if (config->use_intermediate
        && config->build != build_make
        && config->build != build_premake)
    {
        error("--intermediate/--bin-int only apply to make and premake", build_systems[config->build].key);
        return 1;
    }

    config->bin_dir = bin_arg != NULL ? bin_arg : build_systems[config->build].default_bin;
    config->bin_int_dir = bin_int_arg != NULL ? bin_int_arg : build_systems[config->build].default_bin_int;

    return 0;
}

/* run argv to completion. returns the exit code, 127 if it could not be
 * executed, or -1 on a fork/wait failure. */
static int run(char* const argv[], int quiet)
{
    pid_t pid = fork();

    if (pid < 0)
        return -1;

    if (pid == 0)
    {
        if (quiet)
        {
            int devnull = open("/dev/null", O_WRONLY);

            if (devnull >= 0)
            {
                (void) dup2(devnull, STDOUT_FILENO);
                (void) dup2(devnull, STDERR_FILENO);
                (void) close(devnull);
            }
        }

        (void) execvp(argv[0], argv);
        _exit(127);
    }

    int status = 0;

    if (waitpid(pid, &status, 0) < 0)
        return -1;

    if (WIFEXITED(status))
        return WEXITSTATUS(status);

    return -1;
}

static int git_init(const char* root)
{
    char* const argv[] = { "git", "-C", (char*) root, "init", NULL };

    return run(argv, 1);
}

static const char* main_source(const struct Config* config)
{
    if (config->language == language_objc)
        return
            "#import <Foundation/Foundation.h>\n"
            "\n"
            "int main(void)\n"
            "{\n"
            "    @autoreleasepool {\n"
            "        (void) NSLog(@\"type shi\");\n"
            "    }\n"
            "}\n";

    if (config->language == language_cpp)
    {
        const char* std = config->standard;

        if (strcmp(std, "c++23") == 0 || strcmp(std, "c++26") == 0)
            return
                "#include <print>\n"
                "\n"
                "auto main() -> int\n"
                "{\n"
                "    std::println(\"type shi\");\n"
                "}\n";

        if (strcmp(std, "c++98") == 0 || strcmp(std, "c++03") == 0)
            return
                "#include <iostream>\n"
                "\n"
                "int main()\n"
                "{\n"
                "    std::cout << \"type shi\\n\";\n"
                "}\n";

        return
            "#include <iostream>\n"
            "\n"
            "auto main() -> int\n"
            "{\n"
            "    std::cout << \"type shi\\n\";\n"
            "}\n";
    }

    return
        "#include <stdio.h>\n"
        "\n"
        "int main(void)\n"
        "{\n"
        "    (void) puts(\"type shi\");\n"
        "}\n";
}

static void write_main(FILE* out, const struct Config* config)
{
    (void) fputs(main_source(config), out);
}

/* fill flags with the shared warning + debug flags and return the count.
 * every generator reuses these so all four build systems compile alike. */
static size_t base_warnings(const struct Config* config, const char* flags[])
{
    size_t count = 0;

    flags[count++] = "-Wall";
    flags[count++] = "-Wextra";
    flags[count++] = "-Wshadow";
    flags[count++] = "-Wpedantic";
    flags[count++] = "-Wconversion";

    if (config->language != language_cpp)
        flags[count++] = "-Wstrict-prototypes";

    flags[count++] = "-Wsign-conversion";

    if (config->language != language_cpp)
        flags[count++] = "-Wmissing-prototypes";

    return count;
}

static size_t base_flags(const struct Config* config, const char* flags[])
{
    size_t count = base_warnings(config, flags);

    flags[count++] = "-g";
    flags[count++] = "-fno-omit-frame-pointer";

    return count;
}

static const char* cmake_language(enum Language language)
{
    if (language == language_cpp)
        return "CXX";

    if (language == language_objc)
        return "OBJC";

    return "C";
}

static void write_makefile(FILE* out, const struct Config* config)
{
    const struct Language_Info* lang = &languages[config->language];
    const char* ext = lang->extension;
    const char* obj_dir = config->use_intermediate ? config->bin_int_dir : config->bin_dir;

    char clean[2 * PATH_MAX + 16];

    if (config->use_intermediate)
        (void) snprintf(clean, sizeof clean, "rm -rf %s %s", config->bin_dir, config->bin_int_dir);
    else
        (void) snprintf(clean, sizeof clean, "rm -rf %s", config->bin_dir);

    const char* flags[16];
    size_t count = 0;

    flags[count++] = "-std=$(STD)";
    count += base_warnings(config, flags + count);
    flags[count++] = "-Isrc";

    int width = 0;

    for (size_t i = 0; i < count; i++)
        if ((int) strlen(flags[i]) > width)
            width = (int) strlen(flags[i]);

    (void) fprintf(out, "CC := %s\nSTD := %s\n\nDEBUG ?= 1\nSANITIZE ?= 1\n\nCFLAGS := ", lang->compiler, config->standard);

    for (size_t i = 0; i < count; i++)
    {
        if (i > 0)
            (void) fprintf(out, "          ");

        if (i < count - 1)
            (void) fprintf(out, "%-*s \\\n", width, flags[i]);
        else
            (void) fprintf(out, "%s\n", flags[i]);
    }

    (void) fprintf(
        out,
        "\n"
        "ifeq ($(DEBUG),1)\n"
        "CFLAGS += -g -fno-omit-frame-pointer\n"
        "else\n"
        "CFLAGS += -O2\n"
        "endif\n"
        "\n"
        "ifeq ($(SANITIZE),1)\n"
        "CFLAGS += -fsanitize=address,undefined\n"
        "LDFLAGS += -fsanitize=address,undefined\n"
        "endif\n"
        "\n"
        "TARGET := %s/%s\n"
        "SRC := $(shell find src -name '*.%s')\n"
        "OBJ := $(SRC:src/%%=%s/%%.o)\n"
        "\n"
        "all: $(TARGET)\n"
        "\n"
        "$(TARGET): $(OBJ)\n"
            "\t@mkdir -p $(@D)\n"
            "\t$(CC) $^ -o $@ $(LDFLAGS)\n"
        "\n"
        "%s/%%.%s.o: src/%%.%s\n"
            "\t@mkdir -p $(@D)\n"
            "\t$(CC) $(CFLAGS) -c $< -o $@\n"
        "\n"
        "check:\n"
            "\tbear -- make clean all\n"
            "\tcppcheck --enable=warning,style,performance,portability \\\n"
            "\t\t --project=compile_commands.json                \\\n"
            "\t\t --error-exitcode=1\n"
        "\n"
        "clean:\n"
              "\t%s\n"
        "\n"
        ".PHONY: all check clean\n",

        config->bin_dir, config->name, ext,
        obj_dir, obj_dir, ext, ext, clean);
}

static void write_cmake(FILE* out, const struct Config* config)
{
    const char* name = config->name;
    const char* ext = languages[config->language].extension;
    const char* flags[10];
    size_t count = base_flags(config, flags);

    (void) fprintf(
        out,
        "cmake_minimum_required(VERSION 3.16)\n"
        "\n"
        "project(%s %s)\n"
        "\n"
        "option(SANITIZE \"build with asan + ubsan\" ON)\n"
        "\n"
        "file(GLOB_RECURSE SOURCES CONFIGURE_DEPENDS src/*.%s)\n"
        "\n"
        "add_executable(%s ${SOURCES})\n"
        "\n"
        "target_include_directories(%s PRIVATE src)\n"
        "\n"
        "target_compile_options(%s PRIVATE\n",
        name, cmake_language(config->language),
        ext, name, name, name);

    for (size_t i = 0; i < count; i++)
        (void) fprintf(out, "    %s\n", flags[i]);

    (void) fprintf(out, "    -std=%s)\n", config->standard);

    if (config->language == language_objc)
        (void) fprintf(
            out,
            "\n"
            "target_link_libraries(%s PRIVATE \"-framework Foundation\")\n",
            name);

    (void) fprintf(
        out,
        "\n"
        "if(SANITIZE)\n"
        "    target_compile_options(%s PRIVATE -fsanitize=address,undefined)\n"
        "    target_link_options(%s PRIVATE -fsanitize=address,undefined)\n"
        "endif()\n",
        name, name);
}

static const char* meson_language(enum Language language)
{
    if (language == language_cpp)
        return "cpp";

    if (language == language_objc)
        return "objc";

    return "c";
}

static void write_meson(FILE* out, const struct Config* config)
{
    const char* name = config->name;
    const char* ext = languages[config->language].extension;
    const char* lang = meson_language(config->language);
    const char* flags[10];
    size_t count = base_flags(config, flags);

    (void) fprintf(
        out,
        "project('%s', '%s',\n"
        "    default_options: [\n"
        "        'b_sanitize=address,undefined',\n"
        "        'b_lundef=false',\n"
        "    ])\n"
        "\n"
        "sources = run_command(\n"
        "    'find', 'src', '-name', '*.%s',\n"
        "    check: true).stdout().strip().split('\\n')\n"
        "\n"
        "add_project_arguments(\n",
        name, lang, ext);

    for (size_t i = 0; i < count; i++)
        (void) fprintf(out, "    '%s',\n", flags[i]);

    (void) fprintf(
        out,
        "    '-std=%s',\n"
        "    language: '%s')\n"
        "\n"
        "inc = include_directories('src')\n"
        "\n",
        config->standard, lang);

    if (config->language == language_objc)
        (void) fprintf(
            out,
            "foundation = dependency('appleframeworks', modules: ['Foundation'])\n"
            "\n"
            "executable('%s', sources,\n"
            "    include_directories: inc,\n"
            "    dependencies: foundation)\n",
            name);
    else
        (void) fprintf(
            out,
            "executable('%s', sources,\n"
            "    include_directories: inc)\n",
            name);
}

static const char* premake_language(enum Language language)
{
    if (language == language_cpp)
        return "C++";

    return "C";
}

static void write_premake(FILE* out, const struct Config* config)
{
    const char* name = config->name;
    const char* ext = languages[config->language].extension;
    const char* obj_dir = config->use_intermediate ? config->bin_int_dir : config->bin_dir;
    const char* flags[10];
    size_t count = base_flags(config, flags);

    (void) fprintf(
        out,
        "workspace \"%s\"\n"
        "    configurations { \"debug\" }\n"
        "\n"
        "project \"%s\"\n"
        "    kind \"ConsoleApp\"\n"
        "    language \"%s\"\n"
        "    toolset \"clang\"\n"
        "\n"
        "    targetdir \"%s\"\n"
        "    targetname \"%s\"\n"
        "    objdir \"%s\"\n"
        "\n"
        "    files { \"src/**.%s\" }\n"
        "    includedirs { \"src\" }\n"
        "\n"
        "    buildoptions {\n",
        name, name, premake_language(config->language),
        config->bin_dir, name, obj_dir, ext);

    for (size_t i = 0; i < count; i++)
        (void) fprintf(out, "        \"%s\",\n", flags[i]);

    (void) fprintf(
        out,
        "        \"-std=%s\",\n"
        "        \"-fsanitize=address,undefined\",\n"
        "    }\n"
        "\n"
        "    linkoptions { \"-fsanitize=address,undefined\" }\n",
        config->standard);

    if (config->language == language_objc)
        (void) fputs(
            "\n"
            "    links { \"Foundation.framework\" }\n",
            out);
}

static void write_gitignore(FILE* out, const struct Config* config)
{
    (void) fprintf(out, "%s/\n", config->bin_dir);

    if (config->use_intermediate         && 
        (config->build == build_make     || 
         config->build == build_premake) && 
        strcmp(config->bin_int_dir, config->bin_dir) != 0)
        (void) fprintf(out, "%s/\n", config->bin_int_dir);

    if (config->build == build_premake)
        (void) fputs("Makefile\n*.make\n", out);

    if (config->use_clangd_ignore)
        (void) fputs("\n" 
                     ".clangd\n"
                     "compile_flags.txt\n"
                     "compile_commands.json\n",
                     out);
}

/* open path, hand the stream to writer, close. returns 0 on success. */
static int emit(const char* path, const struct Config* config, void (*writer)(FILE*, const struct Config*))
{
    FILE* file = fopen(path, "w");

    if (file == NULL)
    {
        error("cannot create file", path);
        return -1;
    }

    writer(file, config);

    if (fclose(file) != 0)
    {
        error("cannot write file", path);
        return -1;
    }

    return 0;
}

static int make_dir(const char* path)
{
    if (mkdir(path, 0755) == 0)
        return 0;

    if (errno == EEXIST)
        error("already exists", path);
    else
        error("cannot create directory", path);

    return -1;
}

static void print_next_steps(const struct Config* config)
{
    (void) printf("\ncreated %s (%s, %s, %s)\n\n", 
                  config->name, 
                  languages[config->language].name, 
                  config->standard, 
                  build_systems[config->build].name);

    (void) printf("  cd %s\n", config->name);

    switch (config->build)
    {
        case build_make:
            (void) printf("  make\n");
            (void) printf("  make check\n");
            break;

        case build_cmake:
            (void) printf("  cmake -B %s\n", config->bin_dir);
            (void) printf("  cmake --build %s\n", config->bin_dir);
            break;

        case build_meson:
            (void) printf("  meson setup %s\n", config->bin_dir);
            (void) printf("  meson compile -C %s\n", config->bin_dir);
            break;

        case build_premake:
            (void) printf("  premake5 gmake2\n");
            (void) printf("  make\n");
            break;

        default:
            break;
    }

    (void) printf("\n");
}

static int generate_project(const struct Config* config)
{
    char path[PATH_MAX];
    const char* build_file;
    void (*write_build)(FILE*, const struct Config*);

    switch (config->build)
    {
        case build_make:    build_file = "Makefile";       write_build = write_makefile; break;
        case build_cmake:   build_file = "CMakeLists.txt"; write_build = write_cmake;    break;
        case build_meson:   build_file = "meson.build";    write_build = write_meson;    break;
        case build_premake: build_file = "premake5.lua";   write_build = write_premake;  break;
        default:            error("unknown build system", NULL); return -1;
    }

    if (make_dir(config->name) != 0)
        return -1;

    (void) snprintf(path, sizeof path, "%s/src", config->name);

    if (make_dir(path) != 0)
        return -1;

    (void) snprintf(path, sizeof path, "%s/src/main.%s",
                    config->name, languages[config->language].extension);

    if (emit(path, config, write_main) != 0)
        return -1;

    (void) snprintf(path, sizeof path, "%s/%s", config->name, build_file);

    if (emit(path, config, write_build) != 0)
        return -1;

    (void) snprintf(path, sizeof path, "%s/.gitignore", config->name);

    if (emit(path, config, write_gitignore) != 0)
        return -1;

    if (config->use_git && git_init(config->name) != 0)
        (void) fprintf(stderr, "%s: warning: git is not installed\n", mkproj_program);

    print_next_steps(config);

    {
        char* const argv[] = { "tree", "-a", "--dirsfirst", "-I", ".git", (char*) config->name, NULL };

        if (run(argv, 0) == 127)
            (void) puts("  (tree is not installed)");
    }

    return 0;
}

int main(int argc, char** argv)
{
    struct Config config =
    {
        .name = NULL,
        .language = language_c,
        .standard = NULL,
        .build = build_make,
        .bin_dir = NULL,
        .bin_int_dir = NULL,
        .use_git = 1,
        .use_intermediate = 0,
        .use_clangd_ignore = 1,
    };

    int status = parse_args(argc, argv, &config);

    if (status < 0)
        return EXIT_SUCCESS;

    if (status > 0)
    {
        print_usage(stderr);
        return EXIT_FAILURE;
    }

    if (generate_project(&config) != 0)
        return EXIT_FAILURE;

    return EXIT_SUCCESS;
}