#include "core/Comparator.h"
#include <cstdlib>
#include <QSet>

namespace whittle {
namespace {

bool timeDiffers(std::int64_t a, std::int64_t b, std::int64_t tolNs) {
    return std::llabs(a - b) > tolNs;
}

bool sourceIsNewer(std::int64_t src, std::int64_t dst, std::int64_t tolNs) {
    return (src - dst) > tolNs;
}

QSet<QString> impliedParents(const QHash<QString, FileRecord>& source) {
    QSet<QString> out;
    for (auto it = source.constBegin(); it != source.constEnd(); ++it) {
        const QString& key = it.key();
        for (int p = key.indexOf('/'); p > 0; p = key.indexOf('/', p + 1))
            out.insert(key.left(p));
    }
    return out;
}

} 

DiffResult Comparator::compare(const QHash<QString, FileRecord>& source,
                               const QHash<QString, FileRecord>& usb,
                               const FilterSettings& f) {
    DiffResult r;

    for (auto it = source.constBegin(); it != source.constEnd(); ++it) {
        const FileRecord& s = it.value();
        const auto u = usb.constFind(it.key());

        if (u == usb.constEnd()) {
            r.sourceRows.append(s);
            r.mergeList.append(s);
            if (!s.isDir) { ++r.newFileCount; r.newBytes += s.size; }
            continue;
        }

        if (s.isDir) {
            if (f.display == FilterSettings::Display::All)
                r.sourceRows.append(s);
            continue;
        }

        const bool sizeDiff = f.compareSize && (s.size != u->size);
        const bool timeDiff = f.compareTime &&
                              timeDiffers(s.mtimeNs, u->mtimeNs, f.toleranceNs);

        if (sizeDiff || timeDiff) { ++r.diffFileCount; r.diffBytes += s.size; }
        if (sizeDiff || timeDiff || f.display == FilterSettings::Display::All)
            r.sourceRows.append(s);

        if (sourceIsNewer(s.mtimeNs, u->mtimeNs, f.toleranceNs))
            r.mergeList.append(s);
    }

    const QSet<QString> parents = impliedParents(source);
    for (auto it = usb.constBegin(); it != usb.constEnd(); ++it) {
        if (source.contains(it.key())) continue;
        if (it->isDir && parents.contains(it.key())) continue;
        r.usbOnlyRows.append(it.value());
    }

    return r;
}

}