//
// Created by servostar on 6/4/24.
//

#include <llvm/link/lld.h>
#include <sys/log.h>
#include <mem/cache.h>
#include <sys/col.h>

const char* get_absolute_link_path(const TargetConfig* config, const char* link_target_name) {
    INFO("resolving absolute path for link target: %s", link_target_name);

    for (guint i = 0; i < config->link_search_paths->len; i++) {
        const char* link_directory_path = g_array_index(config->link_search_paths, char*, i);

        char* path = g_build_filename(link_directory_path, link_target_name, NULL);
        char* cwd = g_get_current_dir();
        char* canonical = g_canonicalize_filename(path, cwd);

        const gboolean exists = g_file_test(canonical, G_FILE_TEST_EXISTS);
        const gboolean is_dir = g_file_test(canonical, G_FILE_TEST_IS_DIR);

        g_free(path);
        g_free(cwd);

        if (exists && !is_dir) {
            INFO("link target found at: %s", canonical);
            return canonical;
        }

        g_free(canonical);
    }

    // file not found
    return NULL;
}

TargetLinkConfig* lld_create_link_config(__attribute__((unused)) const Target* target, const TargetConfig* target_config, const Module* module) {
    DEBUG("generating link configuration");

    TargetLinkConfig* config = mem_alloc(MemoryNamespaceLld, sizeof(TargetLinkConfig));

    config->fatal_warnings = target_config->lld_fatal_warnings;
    config->object_file_names = g_array_new(FALSE, FALSE, sizeof(char*));
    config->colorize = stdout_supports_ansi_esc();

    // append build object file
    char* basename = g_strjoin(".", target_config->name, "o", NULL);
    char* filename = g_build_filename(target_config->archive_directory, basename, NULL);
    const char* target_object = get_absolute_link_path(target_config, (const char*) filename);
    if (target_object == NULL) {
        ERROR("failed to resolve path to target object: %s", filename);
        lld_delete_link_config(config);
        return NULL;
    }

    {
        // output file after linking
        basename = g_strjoin(".", target_config->name, "out", NULL);
        filename = g_build_filename(target_config->output_directory, basename, NULL);

        config->output_file = filename;
    }

    g_array_append_val(config->object_file_names, target_object);
    INFO("resolved path of target object: %s", target_object);

    // resolve absolute paths to dependent library object files
    DEBUG("resolving target dependencies...");
    for (guint i = 0; i < module->imports->len; i++) {
        const char* dependency = g_array_index(module->imports, const char*, i);

        const char* dependency_object = get_absolute_link_path(target_config, dependency);
        if (dependency_object == NULL) {
            INFO("failed to resolve path to dependency object: %s", dependency);
            print_message(Warning, "failed to resolve path to dependency object: %s", dependency);
            continue;
        }
        g_array_append_val(config->object_file_names, dependency_object);
        INFO("resolved path of target object: %s", dependency_object);
    }

    INFO("resolved %d dependencies", config->object_file_names->len);

    return config;
}

gboolean lld_generate_link_command(TargetLinkConfig* config, char** command) {
    GString* commandString = g_string_new("");

    g_string_append(commandString, "clang");

    for (guint i = 0; i < config->object_file_names->len; i++) {
        g_string_append(commandString, " ");
        g_string_append(commandString, g_array_index(config->object_file_names, char*, i));
    }

    *command = commandString->str;

    return true;
}

BackendError lld_link_target(TargetLinkConfig* config) {

    char* command = NULL;
    lld_generate_link_command(config, &command);

    print_message(Info, "invoking binary driver with: %s", command);

    if (system(command)) {
        print_message(Error, "failed generating binary...");
    }

    g_free(command);

    return SUCCESS;
}

void lld_delete_link_config(TargetLinkConfig* config) {
    for (guint i = 0; i < config->object_file_names->len; i++) {
        free((void*) g_array_index(config->object_file_names, const char*, i));
    }
    g_array_free(config->object_file_names, TRUE);
    mem_free(config);
}