#include "effects/blur.hpp"

#include <algorithm>
#include <vector>

#include "effects/box_blur.hpp"
#include "effects/source_fill.hpp"

namespace effector {

const std::vector<ParamSpec>& BlurEffect::params() const {
    static const std::vector<ParamSpec> specs = {
        ParamSpec::makeInt("radius", "Radius", 8, 1, 256,
                           "Half width in pixels of the blur window."),
        ParamSpec::makeInt("passes", "Passes", 2, 1, 8,
                           "How often the box blur is repeated; more passes look more gaussian."),
        ParamSpec::makeChoice("direction", "Direction", "both", {"both", "horizontal", "vertical"},
                              "Axis the blur is applied along."),
        ParamSpec::makeBool("first_source", "Use the first image", false,
                            "Always blur the first source instead of picking one at random."),
    };
    return specs;
}

Image BlurEffect::render(const std::vector<Image>& sources, int width, int height, Rng& rng,
                         const ParamValues& values) const {
    if (width < 1 || height < 1) throw EffectError("Canvas size must be at least 1x1 pixels.");

    const int radius = static_cast<int>(std::max(1L, paramInt(values, "radius", 8)));
    const int passes = static_cast<int>(std::max(1L, paramInt(values, "passes", 2)));
    const std::string direction = paramChoice(values, "direction", "both");
    const bool firstSource = paramBool(values, "first_source", false);

    Image canvas(width, height);
    if (!sources.empty()) {
        // Every random value is drawn here, before any threading, so that a
        // seed always gives the same image.
        const std::size_t index = firstSource ? 0 : rng.below(sources.size() - 1);
        const Image& src = sources[index];
        const int sx = static_cast<int>(rng.inRange(0, std::max(0, src.width() - width)));
        const int sy = static_cast<int>(rng.inRange(0, std::max(0, src.height() - height)));
        fillFromSource(canvas, src, sx, sy);
    }

    boxBlur(canvas, radius, passes, direction);

    return canvas;
}

}  // namespace effector