#include <stdio.h>
#include <dirent.h>
#define NOH_IMPLEMENTATION
#include "noh.h"

Noh_Arena temp;

#include "path.c"
#include "users.c"

#define SV Noh_String_View
#define sv noh_sv_from_cstr

static void show_usage(char *program_name, char *error) {
    noh_log(NOH_INFO, "Usage:");
    noh_log(NOH_INFO, "%s command [args]", program_name);
    noh_log(NOH_INFO, "");
    noh_log(NOH_INFO, "Commands:");
    noh_log(NOH_INFO, "%s register library_path username password", program_name);
    noh_log(NOH_INFO, "  library_path: The path to the library where the users file and user subfolders are located.");
    noh_log(NOH_INFO, "  username: The username of the user to register.");
    noh_log(NOH_INFO, "  password: The password of the user to register.");
    noh_log(NOH_INFO, "Registers a new user, or changes their password if they already exist.");
    noh_log(NOH_INFO, "");
    noh_log(NOH_INFO, "%s delete library_path username", program_name);
    noh_log(NOH_INFO, "  library_path: The path to the library where the users file and user subfolders are located.");
    noh_log(NOH_INFO, "  username: The username of the user to delete.");
    noh_log(NOH_INFO, "Deletes a user, optionally also deleting their library folder.");
    noh_log(NOH_INFO, "");
    noh_log(NOH_INFO, "%s list library_path", program_name);
    noh_log(NOH_INFO, "  library_path: The path to the library where the users file and user subfolders are located.");
    noh_log(NOH_INFO, "Lists all users defined in the provided library path.");
    noh_log(NOH_INFO, "");
    noh_log(NOH_ERROR, "%s", error);
    exit(1);
}

bool remove_directory(char *path) {
    noh_arena_save(&temp);
    bool result = true;

    DIR *dir = opendir(path);
    if (!dir) return false;

    struct dirent *p;
    while ((p = readdir(dir))) {
        // Ignore . and .. file entries.
        if (!strcmp(p->d_name, ".") || !strcmp(p->d_name, "..")) continue;

        char *sub_path = noh_arena_sprintf(&temp, "%s/%s", path, p->d_name);

        // Delete files and recurse subfolders.
        struct stat statbuf;
        if (!stat(sub_path, &statbuf)) {
           if (S_ISDIR(statbuf.st_mode))
              result &= remove_directory(sub_path);
           else
              result &= unlink(sub_path) == 0;
        }
    }

    closedir(dir);

    if (result) result = rmdir(path);

    noh_arena_reset(&temp);
    return result;
}

/// Prompts a user with a question and returns their response.
bool prompt_user(char *question) {
    noh_arena_save(&temp);
    noh_log(NOH_INFO, noh_arena_sprintf(&temp, "%s [yn]", question));
    noh_arena_reset(&temp);

    char response;
    if (!scanf(" %c", &response)) {
        noh_log(NOH_ERROR, "Error reading response from stdin.");
        return false;
    }

    return response == 'y' || response == 'Y';
}

bool register_user(Noh_String_View library_path, Noh_String_View username, Noh_String_View password) {
    bool result = true;

    // Read the file.
    Noh_String_View file_name = noh_sv_from_cstr("users.conf");
    Noh_String users_file_path = build_path(false, &library_path, &file_name);
    noh_string_append_null(&users_file_path);

    // Build users map.
    Noh_String hashed = {0};
    Users users = {0};
    Noh_String users_file = {0};
    Noh_String user_folder_path = {0};
    if (!read_users_file(users_file_path.elems, &users_file, &users)) noh_return_defer(false);

    // Hash the password.
    hashed = hash_password(username, password);

    // Find the user in the map of users.
    for (size_t i = 0; i < users.count; i++) {
        User *user = &users.elems[i];
        if (!noh_sv_eq_ci(user->username, username)) continue;

        // The user exists. Update password after confirmation.
        if (!prompt_user("User already exists. Update password?")) {
            noh_log(NOH_INFO, "Ok, not changing anything.");
            noh_return_defer(true);
        }

        noh_log(NOH_INFO, "Updating user password.");
        user->hash = noh_sv_from_string(hashed);
        if (!write_users_file(users_file_path.elems, &users, NULL)) noh_return_defer(false);

        // Create user folder if needed.
        user_folder_path = build_path(false, &library_path, &username);
        noh_string_append_null(&user_folder_path);
        if (!noh_mkdir_if_needed(user_folder_path.elems)) noh_return_defer(false);

        noh_return_defer(true);
    }

    // User was not found, add it to the list.
    noh_log(NOH_INFO, "Adding a new user.");
    noh_da_append(&users, ((User){ .username = username, .hash = noh_sv_from_string(hashed) }));
    if (!write_users_file(users_file_path.elems, &users, NULL)) noh_return_defer(false);

    // Create user folder if needed.
    user_folder_path = build_path(false, &library_path, &username);
    noh_string_append_null(&user_folder_path);
    if (!noh_mkdir_if_needed(user_folder_path.elems)) noh_return_defer(false);

defer:
    noh_string_free(&users_file_path);
    noh_string_free(&user_folder_path);
    noh_da_free(&users);
    noh_string_free(&users_file);
    noh_string_free(&hashed);
    return result;
}

bool delete_user(Noh_String_View library_path, Noh_String_View username) {
    bool result = true;

    // Read the file.
    Noh_String_View file_name = noh_sv_from_cstr("users.conf");
    Noh_String users_file_path = build_path(false, &library_path, &file_name);
    noh_string_append_null(&users_file_path);

    // Build users map.
    Noh_String user_folder_path = {0};
    Users users = {0};
    Noh_String users_file = {0};
    if (!read_users_file(users_file_path.elems, &users_file, &users)) noh_return_defer(false);

    // Check if the user exists.
    User *user_to_delete = NULL;
    for (size_t i = 0; i < users.count; i++) {
        User *user = &users.elems[i];
        if (!noh_sv_eq_ci(user->username, username)) continue;

        user_to_delete = user;
        break;
    }

    // User does not exist, don't change anything.
    if (!user_to_delete) {
        noh_log(NOH_INFO, "User does not exist.");
        noh_return_defer(true);
    }

    // The user exists. Prompt to confirm deletion.
    if (!prompt_user("User found, delete the user?")) {
        noh_log(NOH_INFO, "Ok, not changing anything.");
        noh_return_defer(true);
    }

    noh_log(NOH_INFO, "Deleting user.");
    if (!write_users_file(users_file_path.elems, &users, user_to_delete)) noh_return_defer(false);

    // Prompt to delete the user's library folder.
    user_folder_path = build_path(false, &library_path, &username);
    noh_string_append_null(&user_folder_path);
    if (!noh_file_exists(user_folder_path.elems)) noh_return_defer(true);

    if (prompt_user("Library folder exists. Delete it?")) {
        noh_log(NOH_INFO, "Deleting library folder.");
        return remove_directory(user_folder_path.elems);
    }

defer:
    noh_string_free(&user_folder_path);
    noh_string_free(&users_file_path);
    noh_da_free(&users);
    noh_string_free(&users_file);
    return result;
}

bool list_users(Noh_String_View library_path) {
    // Read the file.
    Noh_String_View file_name = noh_sv_from_cstr("users.conf");
    Noh_String users_file_path = build_path(false, &library_path, &file_name);
    noh_string_append_null(&users_file_path);

    // Build users map.
    Users users = {0};
    Noh_String users_file = {0};
    if (!read_users_file(users_file_path.elems, &users_file, &users)) return false;

    if (users.count == 0) {
        noh_log(NOH_INFO, "No users registered.");
        noh_da_free(&users);
        noh_string_free(&users_file);
        return true;
    }

    noh_arena_save(&temp);
    noh_log(NOH_INFO, "Users:");
    for (size_t i = 0; i < users.count; i++) {
        User *user = &users.elems[i];
        noh_log(NOH_INFO, noh_arena_sprintf(&temp, "- "Nsv_Fmt, Nsv_Arg(user->username)));
    }
    noh_arena_reset(&temp);

    noh_string_free(&users_file_path);
    noh_da_free(&users);
    noh_string_free(&users_file);
    return true;
}

int main(int argc, char **argv) {
    temp = noh_arena_init(64 KB);

    // Parse input parameters.
    char *program_name = noh_shift_args(&argc, &argv);

    if (argc < 1) show_usage(program_name, "Command not provided");
    Noh_String_View command = noh_sv_from_cstr(noh_shift_args(&argc, &argv));

    if (argc < 1) show_usage(program_name, "Library path not provided.");
    Noh_String_View library_path = noh_sv_from_cstr(noh_shift_args(&argc, &argv));

    if (noh_sv_eq_ci(command, noh_sv_from_cstr("register"))) {
        if (argc < 1) show_usage(program_name, "Username not provided.");
        Noh_String_View username = noh_sv_from_cstr(noh_shift_args(&argc, &argv));

        if (argc < 1) show_usage(program_name, "Password not provided.");
        Noh_String_View password = noh_sv_from_cstr(noh_shift_args(&argc, &argv));

        return register_user(library_path, username, password) ? 0 : 1;

    } else if (noh_sv_eq_ci(command, sv("delete"))) {
        if (argc < 1) show_usage(program_name, "Username not provided.");
        Noh_String_View username = noh_sv_from_cstr(noh_shift_args(&argc, &argv));

        return delete_user(library_path, username) ? 0 : 1;

    } else if (noh_sv_eq_ci(command, sv("list"))) {
        return list_users(library_path) ? 0 : 1;

    } else {
        noh_arena_save(&temp);
        show_usage(program_name, noh_arena_sprintf(&temp, "Unknown command: "Nsv_Fmt, Nsv_Arg(command)));
        noh_arena_reset(&temp);
        return 1;
    }
}