// SPDX-License-Identifier: BSD-3-Clause
// SPDX-FileCopyrightText: 2020-2023 The Monero Project

#ifndef FEATHER_RESTOREHEIGHTLOOKUP_H
#define FEATHER_RESTOREHEIGHTLOOKUP_H

#include <cstdio>
#include <cstdlib>

#include "monero_seed/monero_seed.hpp"

#include "networktype.h"
#include "utils/Utils.h"

struct RestoreHeightLookup {
    NetworkType::Type type;
    QMap<time_t, int> data;
    explicit RestoreHeightLookup(NetworkType::Type type) : type(type) {}

    int dateToHeight(time_t date) {
        // restore height based on a given timestamp using a lookup
        // table. If it cannot find the date in the lookup table, it
        // will calculate the blockheight based off the last known
        // date: ((now - lastKnownDate) / blockTime) - clearance

        if (this->type == NetworkType::TESTNET) {
            return 1;
        }

        int blockTime = 120;
        int blocksPerDay = 720;
        int blockCalcClearance = blocksPerDay * 5;

        QList<time_t> values = this->data.keys();

        // If timestamp is before epoch, return genesis height.
        if (date <= values.at(0)) {
            return 1;
        }

        for (int i = 0; i != values.count(); i++) {
            if (values[i] > date) {
                if (i == 0) {
                    return 1;
                }
                return this->data[values[i-1]] - blockCalcClearance;
            }
        }

        // lookup failed, calculate blockheight from last known checkpoint
        time_t lastBlockHeightTime = values.last();
        int lastBlockHeight = this->data[lastBlockHeightTime];

        time_t deltaTime = date - lastBlockHeightTime;
        int deltaBlocks = deltaTime / blockTime;

        int blockHeight = (lastBlockHeight + deltaBlocks) - blockCalcClearance;
        return blockHeight;
    }

    time_t heightToTimestamp(int height) {
        // @TODO: most likely inefficient, refactor
        QMap<time_t, int>::iterator i;
        time_t timestamp = 0;
        int heightData = 1;
        for (i = this->data.begin(); i != this->data.end(); ++i) {
            time_t ts = i.key();
            if (i.value() > height)
                return timestamp;
            timestamp = ts;
            heightData = i.value();
        }

        while (heightData < height) {
            heightData += 720; // blocks per day
            timestamp += 86400; // seconds in day
        }

        return timestamp;
    }

    QDateTime heightToDate(int height) {
        return QDateTime::fromSecsSinceEpoch(this->heightToTimestamp(height));
    }

    static RestoreHeightLookup *fromFile(const QString &fn, NetworkType::Type type) {
        // initialize this class using a lookup table, e.g `:/assets/restore_heights_monero_mainnet.txt`/
        auto rtn = new RestoreHeightLookup(type);
        auto data= Utils::barrayToString(Utils::fileOpen(fn));

        for (const auto &line: data.split('\n')) {
            if (line.trimmed().isEmpty()) {
                continue;
            }
            auto spl = line.trimmed().split(':');
            rtn->data[(time_t)spl.at(0).toInt()] = spl.at(1).toInt();
        }
        return rtn;
    }
};

#endif //FEATHER_RESTOREHEIGHTLOOKUP_H