#pragma once
#include "rtt.h"

NS_START

class Brush
{
public:
    int id;
    std::string m_name;
    uint16_t m_tex_id;
    glm::vec4 m_tip_color;
    float m_tip_size;
    float m_tip_spacing;
    float m_tip_flow;
    float m_tip_angle;
    float m_jitter_scale;
    float m_jitter_angle;
    float m_jitter_spread;
    float m_jitter_flow;
};

class Stroke
{
public:
    struct Sample
    {
        glm::vec2 pos;
        float size;
        float flow;
        float angle;
    };
    struct Keypoint
    {
        glm::vec2 pos;
        float pressure;
        float dist;
    };
    int m_layer;
    float m_dist;
    float m_step;
    ui::Brush m_brush;
    std::vector<Keypoint> m_keypoints;
    std::vector<Sample> m_samples;
    int m_last_kp;
    std::minstd_rand prng;
    void start(glm::vec2 pos, float pressure, const ui::Brush& brush)
    {
        m_last_kp = 0;
        m_dist = 0.f;
        m_step = glm::max(brush.m_tip_spacing * brush.m_tip_size * 30, 0.1f);
        m_brush = brush;
        add_point(pos, pressure);
    }
    void add_point(glm::vec2 pos, float pressure)
    {
        float dist = m_keypoints.empty() ? 0.f : 
            m_keypoints.back().dist + glm::distance(m_keypoints.back().pos, pos);
        m_keypoints.emplace_back();
        m_keypoints.back().pos = pos;
        m_keypoints.back().pressure = pressure;
        m_keypoints.back().dist = dist;
    }
    bool has_sample()
    {
        return m_keypoints.empty() ? false :                // no keypoints
            (m_keypoints.back().dist > (m_dist + m_step));  // check if next kp is closer than spacing
    }
    std::vector<Sample> compute_samples()
    {
        int nsamples = (int)glm::floor((m_keypoints.back().dist - m_dist) / m_step);
        std::vector<Sample> samples;
        samples.reserve(nsamples); // preallocate the estimate number of samples
        while (m_keypoints.back().dist > (m_dist + m_step))
        {
            m_dist += m_step;
            while (m_dist > m_keypoints[m_last_kp + 1].dist)
                m_last_kp++;
            const auto& A = m_keypoints[m_last_kp];
            const auto& B = m_keypoints[m_last_kp + 1]; // NOTE: this should be true when while is true
            float t = (m_dist - A.dist) / (B.dist - A.dist); // NOTE: must be A != B
            auto pos = glm::lerp(A.pos, B.pos, t);
            float pressure = glm::lerp(A.pressure, B.pressure, t);
            auto s = randomize_sample(pos, pressure);
            samples.push_back(s);
        }
        return std::move(samples);
    }
    Sample randomize_sample(const glm::vec2& pos, float pressure)
    {
        auto rnd_nor = [&] { return float((double)prng() / (double)prng.max()); };              // normalized [0, +1]
        auto rnd_neg = [&] { return float((double)prng() / (double)prng.max() * 2.0 - 1.0); };  // normalized [-1, +1]
        auto rnd_rad = [&] { return float((double)prng() / (double)prng.max() * M_PI * 2.0); }; // normalized [0, 2pi]
        auto rnd_vec = [&] { float rad = rnd_rad(); return glm::vec2(cosf(rad), sinf(rad)); };  // normalized direction vector

        Sample s;
        s.angle = (m_brush.m_tip_angle + rnd_nor() * m_brush.m_jitter_angle) * (float)(M_PI * 2.0);
        s.pos = pos + (rnd_vec() * m_brush.m_jitter_spread * 100.f);
        s.size = 100.f * m_brush.m_tip_size * (1.f - rnd_nor() * m_brush.m_jitter_scale);
        s.flow = m_brush.m_tip_flow * (1.f - rnd_nor() * m_brush.m_jitter_flow);
        return s;
    }
};

class Layer
{
public:
    RTT m_rtt;
    bool m_visible = true;
    bool m_locked = false;
    float m_alpha = 1.f;
    std::string m_name;
    bool create(int width, int height, std::string name)
    {
        m_rtt.create(width, height);
        return true;
    }
};

NS_END