//SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
//SPDX-License-Identifier: GPL-3.0-or-later

#include "mysql.h"

#include <fstream>
#include <iostream>

#include "mysqld_error.h"

#include "statement.h"
#include "transaction.h"
#include "database/exceptions.h"

constexpr const char* versionQuery = "SELECT value FROM system WHERE `key` = 'version'";
constexpr const char* updateQuery = "UPDATE system SET `value` = ? WHERE `key` = 'version'";
constexpr const char* registerQuery = "INSERT INTO accounts (`login`, `type`, `password`) VALUES (?, 1, ?)";
constexpr const char* lastIdQuery = "SELECT LAST_INSERT_ID() AS id";
constexpr const char* assignRoleQuery = "INSERT INTO roleBindings (`account`, `role`) SELECT ?, roles.id FROM roles WHERE roles.name = ?";
constexpr const char* selectHash = "SELECT password FROM accounts where login = ?";
constexpr const char* createSessionQuery = "INSERT INTO sessions (`owner`, `access`, `renew`, `persist`, `device`)"
                                        " SELECT accounts.id, ?, ?, true, ? FROM accounts WHERE accounts.login = ?"
                                        " RETURNING id, owner";
constexpr const char* selectSession = "SELECT id, owner, renew FROM sessions where access = ?";
constexpr const char* selectAssets = "SELECT id, owner, currency, title, icon, archived FROM assets where owner = ?";

static const std::filesystem::path buildSQLPath = "database";

DB::MySQL::MySQL():
    Interface(Type::mysql),
    connection(),
    login(),
    password(),
    database()
{
    mysql_init(&connection);
}

DB::MySQL::~MySQL() {
    mysql_close(&connection);
}

void DB::MySQL::connect(const std::string& path) {
    if (state != State::disconnected)
        return;

    MYSQL* con = &connection;
    MYSQL* res = mysql_real_connect(
        con,
        NULL,
        login.c_str(),
        password.c_str(),
        database.empty() ? NULL : database.c_str(),
        0,
        path.c_str(),
        0
    );

    if (res != con)
        throw std::runtime_error(std::string("Error changing connecting: ") + mysql_error(con));

    state = State::connected;
}

void DB::MySQL::setCredentials(const std::string& login, const std::string& password) {
    if (MySQL::login == login && MySQL::password == password)
        return;

    MySQL::login = login;
    MySQL::password = password;

    if (state == State::disconnected)
        return;

    MYSQL* con = &connection;
    int result = mysql_change_user(
        con,
        login.c_str(),
        password.c_str(),
        database.empty() ? NULL : database.c_str()
    );

    if (result != 0)
        throw std::runtime_error(std::string("Error changing credetials: ") + mysql_error(con));
}

void DB::MySQL::setDatabase(const std::string& database) {
    if (MySQL::database == database)
        return;

    MySQL::database = database;

    if (state == State::disconnected)
        return;

    MYSQL* con = &connection;
    int result = mysql_select_db(con, database.c_str());

    if (result != 0)
        throw std::runtime_error(std::string("Error changing db: ") + mysql_error(con));
}

void DB::MySQL::disconnect() {
    if (state == State::disconnected)
        return;

    MYSQL* con = &connection;
    mysql_close(con);
    mysql_init(con);            //this is ridiculous!
}

void DB::MySQL::executeFile(const std::filesystem::path& relativePath) {
    MYSQL* con = &connection;
    std::filesystem::path path = sharedPath() / relativePath;
    if (!std::filesystem::exists(path))
        throw std::runtime_error("Error executing file "
            + std::filesystem::absolute(path).string()
            + ": file doesn't exist");

    std::cout << "Executing file " << path << std::endl;
    std::ifstream inputFile(path);
    std::string query;
    while (std::getline(inputFile, query, ';')) {
        std::optional<std::string> comment = getComment(query);
        while (comment) {
            std::cout << '\t' << comment.value() << std::endl;
            comment = getComment(query);
        }
        if (query.empty())
            continue;

        int result = mysql_query(con, query.c_str());
        if (result != 0) {
            int errcode = mysql_errno(con);
            if (errcode == ER_EMPTY_QUERY)
                continue;

            throw std::runtime_error("Error executing file " + path.string() + ": " + mysql_error(con));
        }

    }
}

uint8_t DB::MySQL::getVersion() {
    MYSQL* con = &connection;
    int result = mysql_query(con, versionQuery);

    if (result != 0) {
        unsigned int errcode = mysql_errno(con);
        if (errcode == ER_NO_SUCH_TABLE)
            return 0;

        throw std::runtime_error(std::string("Error executing retreiving version: ") + mysql_error(con));
    }

    std::unique_ptr<MYSQL_RES, ResDeleter> res(mysql_store_result(con));
    if (!res)
        throw std::runtime_error(std::string("Querying version returned no result: ") + mysql_error(con));

    MYSQL_ROW row = mysql_fetch_row(res.get());
    if (row)
        return std::stoi(row[0]);
    else
        return 0;
}

void DB::MySQL::setVersion(uint8_t version) {
    std::string strVersion = std::to_string(version);
    Statement statement(&connection, updateQuery);
    statement.bind(strVersion.data(), MYSQL_TYPE_VAR_STRING);
    statement.execute();
}

void DB::MySQL::migrate(uint8_t targetVersion) {
    uint8_t currentVersion = getVersion();

    while (currentVersion < targetVersion) {
        if (currentVersion == 255)
            throw std::runtime_error("Maximum possible database version reached");

        uint8_t nextVersion = currentVersion + 1;
        std::string fileName = "migrations/m" + std::to_string(currentVersion) + ".sql";
        std::cout << "Performing migration "
            << std::to_string(currentVersion)
            << " -> "
            << std::to_string(nextVersion)
        << std::endl;
        executeFile(fileName);
        setVersion(nextVersion);
        currentVersion = nextVersion;
    }

    std::cout << "Database is now on actual version " << std::to_string(targetVersion) << std::endl;
}

std::optional<std::string> DB::MySQL::getComment(std::string& string) {
    ltrim(string);
    if (string.length() < 2)
        return std::nullopt;

    if (string[0] == '-') {
        if (string[1] == '-') {
            string.erase(0, 2);
            std::string::size_type eol = string.find('\n');
            return extract(string, 0, eol);
        }
    } else if (string[0] == '/') {
        if (string[1] == '*') {
            string.erase(0, 2);
            std::string::size_type end = 0;
            do {
                end = string.find(end, '*');
            } while (end != std::string::npos && end < string.size() - 1 && string[end + 1] == '/');
            if (end < string.size() - 1)
                end = std::string::npos;

            return extract(string, 0, end);
        }
    }

    return std::nullopt;
}

unsigned int DB::MySQL::registerAccount(const std::string& login, const std::string& hash) {
    //TODO validate filed lengths!
    MYSQL* con = &connection;
    MySQL::Transaction txn(con);

    Statement addAcc(con, registerQuery);

    std::string l = login;      //I hate copying just to please this horible API
    std::string h = hash;
    addAcc.bind(l.data(), MYSQL_TYPE_STRING);
    addAcc.bind(h.data(), MYSQL_TYPE_STRING);
    try {
        addAcc.execute();
    } catch (const Duplicate& dup) {
        throw DuplicateLogin(dup.what());
    }

    unsigned int id = lastInsertedId();
    static std::string defaultRole("default");

    Statement addRole(con, assignRoleQuery);
    addRole.bind(&id, MYSQL_TYPE_LONG, true);
    addRole.bind(defaultRole.data(), MYSQL_TYPE_STRING);
    addRole.execute();

    txn.commit();
    return id;
}

std::string DB::MySQL::getAccountHash(const std::string& login) {
    std::string l = login;
    MYSQL* con = &connection;

    Statement getHash(con, selectHash);
    getHash.bind(l.data(), MYSQL_TYPE_STRING);
    getHash.execute();

    std::vector<std::vector<std::any>> result = getHash.fetchResult();
    if (result.empty())
        throw NoLogin("Couldn't find login " + l);

    if (result[0].empty())
        throw std::runtime_error("Error with the query \"selectHash\"");

    return std::any_cast<const std::string&>(result[0][0]);
}

DB::Session DB::MySQL::createSession(const std::string& login, const std::string& access, const std::string& renew) {
    std::string l = login;
    DB::Session res;
    res.accessToken = access;
    res.renewToken = renew;
    static std::string testingDevice("Testing...");

    MYSQL* con = &connection;

    Statement session(con, createSessionQuery);
    session.bind(res.accessToken.data(), MYSQL_TYPE_STRING);
    session.bind(res.renewToken.data(), MYSQL_TYPE_STRING);
    session.bind(testingDevice.data(), MYSQL_TYPE_STRING);
    session.bind(l.data(), MYSQL_TYPE_STRING);
    session.execute();

    std::vector<std::vector<std::any>> result = session.fetchResult();
    if (result.empty())
        throw std::runtime_error("Error returning ids after insertion in sessions table");

    res.id = std::any_cast<unsigned int>(result[0][0]);
    res.owner = std::any_cast<unsigned int>(result[0][1]);

    return res;
}

unsigned int DB::MySQL::lastInsertedId() {
    MYSQL* con = &connection;
    int result = mysql_query(con, lastIdQuery);

    if (result != 0)
        throw std::runtime_error(std::string("Error executing last inserted id: ") + mysql_error(con));

    std::unique_ptr<MYSQL_RES, ResDeleter> res(mysql_store_result(con));
    if (!res)
        throw std::runtime_error(std::string("Querying last inserted id returned no result: ") + mysql_error(con));

    MYSQL_ROW row = mysql_fetch_row(res.get());
    if (row)
        return std::stoi(row[0]);
    else
        throw std::runtime_error(std::string("Querying last inserted id returned no rows"));
}
DB::Session DB::MySQL::findSession(const std::string& accessToken) {
    std::string a = accessToken;
    MYSQL* con = &connection;

    Statement session(con, selectSession);
    session.bind(a.data(), MYSQL_TYPE_STRING);
    session.execute();

    std::vector<std::vector<std::any>> result = session.fetchResult();
    if (result.empty())
        throw NoSession("Couldn't find session with token " + a);

    DB::Session res;
    res.id = std::any_cast<unsigned int>(result[0][0]);
    res.owner = std::any_cast<unsigned int>(result[0][1]);
    res.renewToken = std::any_cast<const std::string&>(result[0][2]);
    res.accessToken = a;

    return res;
}

std::vector<DB::Asset> DB::MySQL::listAssets(unsigned int owner) {
    MYSQL* con = &connection;

    Statement st(con, selectSession);
    st.bind(&owner, MYSQL_TYPE_LONG, true);
    st.execute();
    std::vector<std::vector<std::any>> res = st.fetchResult();

    std::size_t size = res.size();
    std::vector<DB::Asset> result(size);
    for (std::size_t i = 0; i < size; ++i) {
        const std::vector<std::any>& proto = res[i];
        DB::Asset& asset = result[i];
        asset.id = std::any_cast<unsigned int>(proto[0]);
        asset.owner = std::any_cast<unsigned int>(proto[1]);
        asset.currency = std::any_cast<unsigned int>(proto[2]);
        asset.title = std::any_cast<const std::string&>(proto[3]);
        asset.icon = std::any_cast<const std::string&>(proto[4]);
        asset.archived = std::any_cast<bool>(proto[5]); //TODO
    }

    return result;
}