/*
 * 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 <stdio.h>
#include <stdlib.h>
#include <string.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;
};

struct Config
{
    const char *name;
    enum Language language;
    const char *standard;
    enum Build_System build;
    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" },
    [build_cmake]   = { .key = "cmake",   .name = "CMake" },
    [build_meson]   = { .key = "meson",   .name = "Meson" },
    [build_premake] = { .key = "premake", .name = "premake5" },
};

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"
        "              [--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"
        "      --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 *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, "-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;
    }

    return 0;
}

int main(int argc, char **argv)
{
    struct Config config =
    {
        .name = NULL,
        .language = language_c,
        .standard = NULL,
        .build = build_make,
        .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;
    }

    /* TODO: generation. for now, echo the resolved config. */
    (void) printf("name:     %s\n", config.name);
    (void) printf("language: %s\n", languages[config.language].name);
    (void) printf("standard: %s\n", config.standard);
    (void) printf("build:    %s\n", build_systems[config.build].name);
    (void) printf("git:      %s\n", config.use_git ? "yes" : "no");
    (void) printf("interm.:  %s\n", config.use_intermediate ? "yes" : "no");
    (void) printf("clangd:   %s\n", config.use_clangd_ignore ? "yes" : "no");

    return EXIT_SUCCESS;
}