ProbabilitySelector.h

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#pragma once

#include "tree/Selector.h"
#include <vector>
#include "AI.h"
#include "common/String.h"
#include "common/Random.h"

namespace ai {

class ProbabilitySelector: public Selector {
protected:
    std::vector<float> _weights;
    float _weightSum;
public:
    ProbabilitySelector(const std::string& name, const std::string& parameters, const ConditionPtr& condition) :
            Selector(name, parameters, condition), _weightSum(0.0f) {
        std::vector<std::string> tokens;
        Str::splitString(parameters, tokens, ",");
        const int weightAmount = static_cast<int>(tokens.size());
        for (int i = 0; i < weightAmount; i++) {
            const float weight = Str::strToFloat(tokens[i]);
            _weightSum += weight;
            _weights[i] = weight;
        }
    }

    virtual ~ProbabilitySelector() {
    }

    NODE_FACTORY(ProbabilitySelector)

    TreeNodeStatus execute(const AIPtr& entity, int64_t deltaMillis) override {
        if (Selector::execute(entity, deltaMillis) == CANNOTEXECUTE)
            return CANNOTEXECUTE;

        int index = getSelectorState(entity);
        if (index == AI_NOTHING_SELECTED) {
            float rndIndex = ai::randomf(_weightSum);
            const int weightAmount = static_cast<int>(_weights.size());
            for (; index < weightAmount; ++index) {
                if (rndIndex < _weights[index])
                    break;
                rndIndex -= _weights[index];
            }
        }

        const TreeNodePtr& child = _children[index];
        const TreeNodeStatus result = child->execute(entity, deltaMillis);
        if (result == RUNNING) {
            setSelectorState(entity, index);
        } else {
            setSelectorState(entity, AI_NOTHING_SELECTED);
        }
        child->resetState(entity);

        const int size = static_cast<int>(_children.size());
        for (int i = 0; i < size; ++i) {
            if (i == index)
                continue;
            _children[i]->resetState(entity);
        }
        return state(entity, result);
    }
};

}