#include <stdlib.h>
#include <stdio.h>

#include "raylib.h"
#include "raymath.h"


typedef struct Config {
    int SCREEN_WIDTH;
    int SCREEN_HEIGHT;
    int ORIGIN_X;
    int ORIGIN_Y;
    char TITLE[50];
    int TARGET_FPS;
} Config;

typedef struct Line {
    Vector2 start;
    Vector2 end;
    Color color;
} Line;

typedef struct Object {
    float posX;
    float posY;
    float radius;
    Color color;
    float charge;
} Object;

typedef struct VectorField {
    int colSize;
    int rowSize;
    int spacing;
    Line **lines;
} VectorField;

void Initialize(Config config);
void InitializeVectorField(VectorField *vectorField, int colSize, int rowSize);
void doDrawing(VectorField *vectorField, int colSize, int rowSize, Object *objects, int objectNum);
void doUpdate(VectorField *vectorField, Object *objects, int objectNum);

int main(void)
{
    Config config = {
            1500,
            900,
            1500 / 2,
            900 / 2,
            "Force Field Simulator",
            60
    };
    Initialize(config);

    int spacing = 20;
    int colSize = config.SCREEN_WIDTH / spacing - 1;
    int rowSize = config.SCREEN_HEIGHT / spacing - 1;
    Line **lines = NULL;
    VectorField vectorField = {
            .colSize = colSize,
            .rowSize = rowSize,
            .spacing = spacing,
            .lines = lines
    };
    InitializeVectorField(&vectorField, colSize, rowSize);

    Object object0 = {
            .posX = (float)config.ORIGIN_X - 200,
            .posY = (float)config.ORIGIN_Y - 50,
            .radius = 20,
            .color = RED,
            .charge = 100
    };

    Object object1 = {
            .posX = (float)config.ORIGIN_X + 200,
            .posY = (float)config.ORIGIN_Y + 50,
            .radius = 20,
            .color = BLUE,
            .charge = -60
    };

//    Object object2 = {
//            .posX = (float)config.ORIGIN_X + 200,
//            .posY = (float)config.ORIGIN_Y - 100,
//            .radius = 20,
//            .color = BLUE,
//            .charge = -100
//    };

    Object objects[] = {object0, object1};
    int objectNum = sizeof(objects) / sizeof(Object);

    while (!WindowShouldClose())
    {
        doUpdate(&vectorField, objects, objectNum);
        doDrawing(&vectorField, colSize, rowSize, objects, objectNum);
    }

    CloseWindow();

    return 0;
}

void Initialize(Config config) {
    InitWindow(config.SCREEN_WIDTH, config.SCREEN_HEIGHT, config.TITLE);
    SetTargetFPS(config.TARGET_FPS);
}

void MemAllocFailed(char *source) {
    printf("Memory allocation for %s failed", source);
    exit(42);
}

//float getRndAngle() {
//    float nMax = 360;
//    return (float)rand() / ((float)RAND_MAX / nMax); // NOLINT(cert-msc30-c, cert-msc50-cpp)
//}

void InitializeVectorField(VectorField *vectorField, int colSize, int rowSize) {
    vectorField->lines = malloc(rowSize * sizeof(Line*));
    for (int i = 0; i < rowSize; i++) {
        vectorField->lines[i] = malloc(colSize * sizeof(Line));
        for (int j = 0; j < colSize; j++) {
            Vector2 start = {
                    (float)((j + 1) * vectorField->spacing),
                    (float)((i + 1) * vectorField->spacing)
            };
            Vector2 end = {start.x + 5, start.y - 5};
            Line line = {
                    .start = start,
                    .end = end,
                    .color = WHITE
            };
            vectorField->lines[i][j] = line;
        }
    }
}

void doUpdate(VectorField *vectorField, Object *objects, int objectNum) {
    float forceConstant = 2000.0f;
    float dt = GetFrameTime();
    for (int i = 0; i < vectorField->rowSize; i++) {
        for (int j = 0; j < vectorField->colSize; j++) {
            Vector2 resultant = Vector2Zero();
            for (int k = 0; k < objectNum; k++) {
                Object object = objects[k];
                Vector2 distanceVector = Vector2Subtract(vectorField->lines[i][j].start, (Vector2){object.posX, object.posY});
                float fieldStrength = forceConstant * object.charge / Vector2LengthSqr(distanceVector);
                Vector2 force = Vector2Normalize(distanceVector);
                force = Vector2Scale(force, fieldStrength);
                resultant = Vector2Add(force, resultant);
            }
            float resultantMag = Clamp(Vector2Length(resultant), -20.0f, 20.0f);
            if (fabsf(resultantMag) < 2.0f) {
                resultantMag = resultantMag >= 0 ? 2.0f : -2.0f;
            }
            resultant = Vector2Normalize(resultant);
            resultant = Vector2Scale(resultant, resultantMag);
            vectorField->lines[i][j].end = Vector2Add(vectorField->lines[i][j].start, resultant);
            float lineLength = Vector2Length(Vector2Subtract(vectorField->lines[i][j].start, vectorField->lines[i][j].end));
            Color color;
            if (lineLength >= 16) color = RED;
            else if (lineLength >= 12) color = ORANGE;
            else if (lineLength >= 8) color = YELLOW;
            else if (lineLength >= 4) color = GREEN;
            else color = GRAY;
            vectorField->lines[i][j].color = color;
        }
    }
    float speed = 20;
    objects[0].posX += speed * dt;
    objects[1].posX -= speed * dt;
}

void doDrawing(VectorField *vectorField, int colSize, int rowSize, Object *objects, int objectNum) {
    BeginDrawing();

    ClearBackground(BLACK);

    for (int i = 0; i < rowSize; i++) {
        for (int j = 0; j < colSize; j++) {
            DrawLineV(vectorField->lines[i][j].start, vectorField->lines[i][j].end, vectorField->lines[i][j].color);
        }
    }
    for (int i = 0; i < objectNum; i++) {
        Object object = objects[i];
        DrawCircle((int)object.posX, (int)object.posY, object.radius, object.color);
    }

    EndDrawing();
}