#include "channel_occupancy.h"

namespace roro {

namespace {
// -90 dBm (barely there) -> 0.1, -40 dBm and stronger -> 1.
float weight(int rssi) {
    float w = (rssi + 90) / 50.0f;
    if (w < 0.1f) w = 0.1f;
    if (w > 1.0f) w = 1.0f;
    return w;
}
const float kSpill[] = {1.0f, 0.5f, 0.2f};  // same channel, one away, two away
}  // namespace

std::array<float, 14> channelLoad(const std::vector<ChannelSighting>& sightings) {
    std::array<float, 14> load{};
    for (auto& s : sightings) {
        if (s.channel < 1 || s.channel > 13) continue;
        for (int d = -2; d <= 2; d++) {
            int ch = s.channel + d;
            if (ch >= 1 && ch <= 13) load[ch] += weight(s.rssi) * kSpill[d < 0 ? -d : d];
        }
    }
    return load;
}

int quietestChannel(const std::array<float, 14>& load) {
    int best = 1;
    for (int ch : {6, 11})
        if (load[ch] < load[best]) best = ch;
    return best;
}

}  // namespace roro