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

#include "mysql.h"

#include <fstream>
#include <iostream>
#include <chrono>

#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, access, renew FROM sessions where access = ?";
constexpr const char* selectAssets = "SELECT id, owner, currency, title, icon, color, archived FROM assets where owner = ?";
constexpr const char* insertAsset = "INSERT INTO assets (`owner`, `currency`, `title`, `icon`, `color`, `archived`, `type`)"
                                        " VALUES (?, ?, ?, ?, ?, ?, 1)";
constexpr const char* updateAssetQuery = "UPDATE assets SET `owner` = ?, `currency` = ?, `title` = ?, `icon` = ?, `color` = ?, `archived` = ?"
                                        " WHERE `id` = ?";
constexpr const char* removeAsset = "DELETE FROM assets where `id` = ? AND `owner` = ?";
constexpr const char* selectUsedCurrencies = "SELECT DISTINCT c.id, c.code, c.title, c.manual, c.icon FROM currencies c"
                                                        " JOIN assets a ON c.id = a.currency"
                                                        " WHERE a.owner = ?";
constexpr const char* addTransactionQuery = "INSERT INTO transactions"
                                            " (`initiator`, `type`, `asset`, `parent`, `value`, `performed`)"
                                            " VALUES (?, 1, ?, ?, ?, ?)";
constexpr const char* updateTransactionQuery = "UPDATE transactions SET"
                                            " `initiator` = ?, `type` = 1, `asset` = ?,"
                                            " `parent` = ?, `value` = ?, `performed` = ?"
                                            " WHERE `id` = ?";
constexpr const char* deleteTransactionQuery = "DELETE FROM transactions where (`id` = ? OR `parent` = ?) AND `initiator` = ?";
constexpr const char* selectAllTransactions = "WITH RECURSIVE AllTransactions AS ("
            " SELECT t.id, t.initiator, t.asset, t.parent, t.value, t.modified, t.performed t.notes FROM transactions t"
            " JOIN assets a ON t.asset = a.id"
            " WHERE a.owner = ?"
            " UNION ALL"

            " SELECT t.id, t.initiator, t.asset, t.parent, t.value, t.modified, t.performed t.notes FROM transactions t"
            " JOIN AllTransactions at ON t.id = at.parent)"

        " SELECT DISTINCT id, initiator, asset, parent, value, modified, performed notes FROM AllTransactions"
        " ORDER BY performed"
        " LIMIT 100 OFFSET 0;";


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 block, comment;
    while (getBlock(inputFile, block, comment)) {
        if (!comment.empty())
            std::cout << '\t' << comment << std::endl;

        if (block.empty())
            continue;

        int result = mysql_query(con, block.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));
        }

    }
}

bool DB::MySQL::getBlock(std::ifstream& file, std::string& block, std::string& name) {
    if (file.eof())
        return false;

    block.clear();
    name.clear();

    if (file.peek() == '-') {
        file.get();
        if (file.peek() == '-') {
            file.get();
            std::getline(file, name);
        } else {
            file.unget();
        }
    }
    std::string line;
    while (!file.eof()) {
        if (file.peek() == '-') 
            return true;

        if (!std::getline(file, line))
            break;

        if (!block.empty())
            block.append(1, '\n');
        
        block += line;
    }

    return !block.empty() || !name.empty();
}

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;
}

uint32_t 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());
    }

    uint32_t 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<uint32_t>(result[0][0]);
    res.owner = std::any_cast<uint32_t>(result[0][1]);

    return res;
}

uint32_t 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);

    return DB::Session(result[0]);
}

std::vector<DB::Asset> DB::MySQL::listAssets (uint32_t owner) {
    MYSQL* con = &connection;

    Statement st(con, selectAssets);
    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)
        result[i].parse(res[i]);

    return result;
}

DB::Asset DB::MySQL::addAsset(const Asset& asset) {
    MYSQL* con = &connection;
    Asset result = asset;

    Statement add(con, insertAsset);
    add.bind(&result.owner, MYSQL_TYPE_LONG, true);
    add.bind(&result.currency, MYSQL_TYPE_LONG, true);
    add.bind(result.title.data(), MYSQL_TYPE_STRING);
    add.bind(result.icon.data(), MYSQL_TYPE_STRING);
    add.bind(&result.color, MYSQL_TYPE_LONG, true);
    add.bind(&result.archived, MYSQL_TYPE_TINY);
    add.execute();

    result.id = lastInsertedId();

    return result;
}

void DB::MySQL::updateAsset(const Asset& asset) {
    MYSQL* con = &connection;
    Asset result = asset;

    Statement update(con, updateAssetQuery);
    update.bind(&result.owner, MYSQL_TYPE_LONG, true);
    update.bind(&result.currency, MYSQL_TYPE_LONG, true);
    update.bind(result.title.data(), MYSQL_TYPE_STRING);
    update.bind(result.icon.data(), MYSQL_TYPE_STRING);
    update.bind(&result.color, MYSQL_TYPE_LONG, true);
    update.bind(&result.archived, MYSQL_TYPE_TINY);
    update.bind(&result.id, MYSQL_TYPE_LONG, true);
    update.execute();
}

bool DB::MySQL::deleteAsset(uint32_t assetId, uint32_t actorId) {
    Statement del(&connection, removeAsset);
    del.bind(&assetId, MYSQL_TYPE_LONG, true);
    del.bind(&actorId, MYSQL_TYPE_LONG, true);
    del.execute();

    if (del.affectedRows() == 0)
        return false;

    return true;
}

std::vector<DB::Currency> DB::MySQL::listUsedCurrencies(uint32_t owner) {
    Statement list(&connection, selectUsedCurrencies);
    list.bind(&owner, MYSQL_TYPE_LONG, true);
    list.execute();

    std::vector<std::vector<std::any>> res = list.fetchResult();

    std::size_t size = res.size();
    std::vector<DB::Currency> result(size);
    for (std::size_t i = 0; i < size; ++i)
        result[i].parse(res[i]);

    return result;
}

DB::Transaction DB::MySQL::addTransaction(const DB::Transaction& transaction) {
    MYSQL* con = &connection;
    DB::Transaction result = transaction;

    std::string value = std::to_string(result.value);

    Statement add(con, addTransactionQuery);
    add.bind(&result.initiator, MYSQL_TYPE_LONG, true);
    add.bind(&result.asset, MYSQL_TYPE_LONG, true);
    add.bind(&result.parent, MYSQL_TYPE_LONG, true);
    add.bind(value.data(), MYSQL_TYPE_STRING);
    add.bind(&result.performed, MYSQL_TYPE_LONG, true);
    add.execute();

    result.id = lastInsertedId();
    std::chrono::time_point currently = std::chrono::time_point_cast<std::chrono::seconds>(
        std::chrono::system_clock::now()
    );
    result.modified = currently.time_since_epoch().count();
    //todo actual value which could have changed after insertion

    return result;
}

void DB::MySQL::updateTransaction(const DB::Transaction& transaction) {
    MYSQL* con = &connection;
    DB::Transaction result = transaction;

    std::string value = std::to_string(result.value);

    Statement upd(con, updateTransactionQuery);
    upd.bind(&result.initiator, MYSQL_TYPE_LONG, true);
    upd.bind(&result.asset, MYSQL_TYPE_LONG, true);
    upd.bind(&result.parent, MYSQL_TYPE_LONG, true);
    upd.bind(value.data(), MYSQL_TYPE_STRING);
    upd.bind(&result.performed, MYSQL_TYPE_LONG, true);
    upd.bind(&result.id, MYSQL_TYPE_LONG, true);
    upd.execute();
}

bool DB::MySQL::deleteTransaction(uint32_t id, uint32_t actorId) { 
    MYSQL* con = &connection;

    Statement del(con, deleteTransactionQuery);
    del.bind(&id, MYSQL_TYPE_LONG, true);       //for actual transactions
    del.bind(&id, MYSQL_TYPE_LONG, true);       //for potential children
    del.bind(&actorId, MYSQL_TYPE_LONG, true);  //for preventing unauthorized removal, but it needs to be improved
    del.execute();                              //need to think of a parent with no children transactions...

    if (del.affectedRows() == 0)
        return false;

    return true;
}

std::vector<DB::Transaction> DB::MySQL::listTransactions(uint32_t owner) {
    MYSQL* con = &connection;

    Statement get(con, selectAllTransactions);
    get.bind(&owner, MYSQL_TYPE_LONG, true);
    get.execute();

    std::vector<std::vector<std::any>> res = get.fetchResult();
    std::size_t size = res.size();

    std::vector<DB::Transaction> result(size);
    for (std::size_t i = 0; i < size; ++i)
        result[i].parse(res[i]);

    return result;
}