#define OSH_H_IMPLEMENTATION
#include "osh.h"

#include <GL/glew.h>
#include <GLFW/glfw3.h>

#define GRAVITY 0.05
#define FLOOR_HEIGHT -0.9
#define JUMP_TIMEOUT 0.14
#define JUMP_FORCE 0.3
#define DRAG 0.98
#define PLAYER_RADIUS 0.02

#define PLAYER_COLOR 1.0, 1.0, 1.0
#define FLOOR_COLOR 0.15, 0.05, 0.05
#define BACKGROUND_COLOR 0.05, 0.05, 0.05, 1.0

void onError(const int error, const char* description) {
    (void) error;
    osh::panic("GLFW error:", description);
}

struct Vector2 {
    double x, y;

    Vector2(double x = 0, double y = 0) : x(x), y(y) {}

    Vector2 conjugate() {
        return {x, -y};
    }
    
    Vector2 operator*(double d) {
        return {x*d, y*d};
    }

    Vector2 operator*=(double d) {
        x *= d;
        y *= d;
        return *this;
    }

    Vector2 operator+(Vector2 v) {
        return {x+v.x, y+v.y};
    }

    Vector2 operator+=(Vector2 v) {
        x += v.x;
        y += v.y;
        return *this;
    }

    Vector2 operator-(Vector2 v) {
        return {x-v.x, y-v.y};
    }

    Vector2 operator-=(Vector2 v) {
        x -= v.x;
        y -= v.y;
        return *this;
    }
};

void print1(osh::Formatter auto& fmt, const Vector2& v) {
    osh::printp(fmt, '(', v.x, ", ", v.y, ')');
}

void onResize(GLFWwindow* window, int width, int height) {
        glfwGetFramebufferSize(window, &width, &height);
        glViewport(0, 0, width, height);

        glLoadIdentity();
        glOrtho(
            -double(width) / height, double(width) / height,
            -1, 1,
            0, 1);
}

void fillRect(Vector2 pos, Vector2 size) {
    glBegin(GL_POLYGON);

    glVertex2d(pos.x,           pos.y);
    glVertex2d(pos.x + size.x,  pos.y);
    glVertex2d(pos.x + size.x,  pos.y - size.y);
    glVertex2d(pos.x,           pos.y - size.y);

    glEnd();
}

void drawPoint(Vector2 pos, double radius) {
    glPointSize(radius);
    glBegin(GL_POINTS);
    glVertex2d(pos.x, pos.y);
    glEnd();
}

struct Player {
    double jumpTimeout = 0;
    Vector2 pos, vel, acc, size;

    Player() : size(PLAYER_RADIUS, PLAYER_RADIUS) {}

    void push(Vector2 force) {
        acc += force;
    }

    void jump() {
        vel.y = JUMP_FORCE;
        jumpTimeout = JUMP_TIMEOUT;
    }

    void update(double dt) {
        if (jumpTimeout > 0) {
            push({0, JUMP_FORCE});
            jumpTimeout -= dt;
        }

        vel += acc;
        vel *= DRAG;
        acc = {0, 0};

        pos += vel * dt;
        pos.y = osh::max(pos.y, FLOOR_HEIGHT + size.y);
    }

    void draw() {
        glColor3d(PLAYER_COLOR);
        fillRect(pos - size.conjugate(), size*2);

        glColor3d(1.0, 0, 0);
        drawPoint(pos, 10);
    }
};

Player player;

void onKey(GLFWwindow* window, int key, int scancode, int action, int mods) {
    (void) window;
    (void) scancode;
    (void) mods;

    if (action == GLFW_PRESS) {
        if (key == GLFW_KEY_SPACE) {
            player.jump();
        }
    }
}

int main(void) {
    glfwSetErrorCallback(onError);

    glfwInit();

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
    GLFWwindow* window = glfwCreateWindow(640, 480, "HopHop", NULL, NULL);

    glfwSetKeyCallback(window, onKey);
    glfwSetWindowSizeCallback(window, onResize);

    glfwMakeContextCurrent(window);

    if (glewInit() != GLEW_OK) {
        osh::panic("glewInit() failed");
    }

    double last = glfwGetTime();
    while (!glfwWindowShouldClose(window)) {
        double now = glfwGetTime();
        double dt = now - last;

        glfwPollEvents();

        glClearColor(BACKGROUND_COLOR);
        glClear(GL_COLOR_BUFFER_BIT);

        player.push({0, -GRAVITY});
        player.update(dt);

        player.draw();

        glColor3d(FLOOR_COLOR);
        fillRect({ -1, FLOOR_HEIGHT }, {2, 2});

        glfwSwapBuffers(window);
        last = now;
    }

    glfwDestroyWindow(window);
    glfwTerminate();
    return 0;
}