// config_updater.cpp — Universal INI config file updater (like insert_or_replace_option in utun)
#include "config_updater.h"
#include <QFile>
#include <QTextStream>

static std::pair<int,int> find_section_bounds(const QStringList& lines, const QString& section) {
    QString tag = "[" + section + "]";
    for (int i = 0; i < lines.size(); i++) {
        if (lines[i].trimmed() == tag) {
            int se = lines.size();
            for (int j = i + 1; j < lines.size(); j++) {
                QString t = lines[j].trimmed();
                if (t.startsWith('[') && t.endsWith(']')) { se = j; break; }
            }
            return {i, se};
        }
    }
    return {-1, -1};
}

bool config_update_in_lines(QStringList& lines, const QString& section,
                            const QString& key, const QString& value, bool replace) {
    auto bounds = find_section_bounds(lines, section);
    if (bounds.first < 0) {
        if (!lines.isEmpty() && !lines.last().trimmed().isEmpty())
            lines.append("");
        lines.append("[" + section + "]");
        lines.append(key + "=" + value);
        return true;
    }

    int si = bounds.first, se = bounds.second;
    int ki = -1;
    for (int i = si + 1; i < se; i++) {
        int eq = lines[i].indexOf('=');
        if (eq > 0 && lines[i].left(eq).trimmed() == key) { ki = i; break; }
    }

    QString newLine = key + "=" + value;

    if (replace) {
        if (ki >= 0)
            lines[ki] = newLine;
        else
            lines.insert(si + 1, newLine);
    } else {
        if (ki >= 0) {
            int lastKi = ki;
            for (int i = ki + 1; i < se; i++) {
                int eq = lines[i].indexOf('=');
                if (eq > 0 && lines[i].left(eq).trimmed() == key) lastKi = i;
            }
            lines.insert(lastKi + 1, newLine);
        } else {
            lines.insert(si + 1, newLine);
        }
    }
    return true;
}

bool config_update_option(const QString& filePath, const QString& section,
                          const QString& param, const QString& value, int flags) {
    QFile f(filePath);
    QStringList lines;

    if (f.exists()) {
        if (!f.open(QIODevice::ReadOnly | QIODevice::Text)) return false;
        QTextStream in(&f);
        while (!in.atEnd()) {
            QString line = in.readLine(0);
            if (line.endsWith('\r')) line.chop(1);
            lines.append(line);
        }
        f.close();
    }

    bool replace = (flags != CONFIG_UPDATE_APPEND);
    if (!config_update_in_lines(lines, section, param, value, replace))
        return false;

    if (!f.open(QIODevice::WriteOnly | QIODevice::Text | QIODevice::Truncate)) return false;
    QTextStream out(&f);
    for (int i = 0; i < lines.size(); i++)
        out << lines[i] << '\n';
    f.close();
    return true;
}