#include "client/entity/moveable.hh"

namespace client {

static auto find_sequence_it(auto& updates,
                             const shared::tick_t& sequence) noexcept {
    return std::ranges::find_if(updates, [&sequence](const auto& update) {
        return update.tick_sequence == sequence;
    });
}

void moveable::repredict_from(const shared::tick_t& sequence) noexcept {
    // find the animate update we want to repredict starting from
    const auto find_it = find_sequence_it(this->updates, sequence);
    if (find_it == std::end(this->updates)) {
        return;
    }

    // backup current animate
    const shared::animate before_move = *this;

    // predict the next ticks starting from find_it until we run
    // out of prediction history
    for (auto it = find_it; it != std::end(this->updates); ++it) {
        const auto next_it = std::next(it);
        if (next_it == std::end(this->updates)) {
            break;
        }

        const auto viewangles = next_it->animate.get_angles();
        const auto commands = next_it->animate.get_commands();

        this->shared::animate::operator=(it->animate);
        this->commands = commands;
        this->viewangles = viewangles;
        const auto predicted = movement::move(*this, state::chunks);
        if (!predicted.has_value()) {
            break;
        }
        next_it->animate = *predicted;
        next_it->animate.get_mutable_angles() = viewangles;
        next_it->animate.get_mutable_commands() = commands;
    }
    // restore current animate
    this->shared::animate::operator=(before_move);
}

void moveable::notify(const shared::animate& animate,
                      const shared::tick_t& sequence,
                      const bool from_server) noexcept {
    this->animate::notify(animate, sequence, from_server);

    if (!from_server) { // Only repredict if we're from the server.
        return;
    }
    this->repredict_from(sequence);
}

void moveable::extrapolate() noexcept {
    // can't extrapolate if no data
    if (this->updates.empty()) {
        return;
    }

    const auto& latest_it = std::rbegin(this->updates);
    if (latest_it == std::rend(this->updates)) {
        return;
    }

    // backup current animate, load latest animate
    const shared::animate before_extrapolate = *this;
    this->shared::animate::operator=(latest_it->animate);

    // FIXED: we were writing our commands with the old commands, so we were
    // always predicting the first commands, which were always for not moving!
    this->commands = before_extrapolate.get_commands();
    this->viewangles = before_extrapolate.get_angles();

    const auto predicted = movement::move(*this, state::chunks);
    if (predicted.has_value()) {
        this->notify(*predicted, this->get_latest_sequence() + 1, false);
    }
    this->shared::animate::operator=(before_extrapolate);
}

} // namespace client