#include <raylib.h>
#include <string.h>
#include "game.h"
#include "assets.h"
#include "stdio.h"

#include "player.h"
#include "background.h"

Game game;

static inline bool EntityAllocated(const Entity* e) {
    return (e->flags & ENTITY_ALLOCATED);
}

static inline bool PhysicsEnabled(const Entity* e) {
    return EntityAllocated(e) && (e->flags & ENTITY_PHYSICS_ACTIVE);
}

static inline bool ShouldDrawEntity(const Entity* e, DrawLayer layerDrawing) {
    return EntityAllocated(e)
        && (e->flags & ENTITY_VISIBLE)
        && (layerDrawing == e->drawLayer);
}

static inline bool SameEntity(const Entity* a, const Entity* b) {
    return a->id == b->id;
}

static inline bool IsColliding(const Rectangle* a, const Rectangle* b) {
    bool collisionX = (a->x <= b->x && a->x + a->width > b->x)
        || (b->x <= a->x && b->x + b->width > a->x);

    bool collisionY = (a->y <= b->y && a->y + a->height > b->y)
        || (b->y <= a->y && b->y + b->height > a->y);

    return collisionX && collisionY;
}

static inline Rectangle GetPhysicsColliderGlobal(const Entity* e) {
    Rectangle physicsColliderGlobal = e->physicsCollider;
    physicsColliderGlobal.x += e->position.x;
    physicsColliderGlobal.y += e->position.y;

    return physicsColliderGlobal;
}

static inline Rectangle GetDrawDestinationRectGlobal(const Entity* e) {
    Rectangle destRectGlobal = e->destRect;

    destRectGlobal.x += e->position.x;
    destRectGlobal.y += e->position.y;

    return destRectGlobal;
}

void MoveAndSlide(Entity* e, float deltaTime) {
    Vector2 velocity = e->velocity;
    Rectangle physicsCollider = GetPhysicsColliderGlobal(e);

    physicsCollider.x += e->velocity.x * deltaTime;
    for (int i = 0; i < MAX_ENTITY_COUNT; i++) {
        Entity* c = &game.entities[i];

        if(!PhysicsEnabled(c) || SameEntity(c, e)) continue;
        Rectangle otherCollider = GetPhysicsColliderGlobal(c);

        if(IsColliding(&physicsCollider, &otherCollider)) {
            if (velocity.x > 0) { 
                physicsCollider.x = otherCollider.x - physicsCollider.width;
            } else {
                physicsCollider.x = otherCollider.x + otherCollider.width;
            }
        }
    }

    physicsCollider.y += e->velocity.y * deltaTime;
    for (int i = 0; i < MAX_ENTITY_COUNT; i++) {
        Entity* c = &game.entities[i];

        if(!PhysicsEnabled(c) || SameEntity(c, e)) continue;
        Rectangle otherCollider = GetPhysicsColliderGlobal(c);

        if(IsColliding(&physicsCollider, &otherCollider)) {
            if (velocity.y > 0) { 
                physicsCollider.y = otherCollider.y - physicsCollider.height;
            } else {
                physicsCollider.y = otherCollider.y + otherCollider.height;
            }
        }
    }

    e->position.x = physicsCollider.x;
    e->position.y = physicsCollider.y;
}


void AddEntity(Entity* e) {
    static int nextId = 0;

    e->id = nextId++;
    e->flags |= ENTITY_ALLOCATED;

    for(int i = 0; i < MAX_ENTITY_COUNT; i++) {
        if (!EntityAllocated(&game.entities[i])) {
            game.entities[i] = *e;
            break;
        }
    }
}

void InitGame() {
    game.paused = false;
    LoadAssets();
    
    memset(game.entities, 0, sizeof(game.entities));
}

void UpdateEntity(Entity* e, float deltaTime) {
    switch (e->type) {
        case Player_Entity:
            UpdatePlayer(e, deltaTime);
            break;

        case Background_Entity:
            UpdateBackground(e, deltaTime);
            break;
        
        default:
            break;
    }
}

void UpdateGame(float deltaTime) {
    #ifdef BEATEMUP_DEBUG
        if (IsKeyPressed(KEY_D) && IsKeyDown(KEY_ENTER)) {
            game.enableDebugOverlay = !game.enableDebugOverlay;
        }
    #endif

    for (int i = 0; i < MAX_ENTITY_COUNT; i++) {
        Entity* e = &game.entities[i];

        if (EntityAllocated(e))
            UpdateEntity(e, deltaTime);
    }
}

#ifdef BEATEMUP_DEBUG
void DebugHighlights(const Entity* e) {
    if (!PhysicsEnabled(e))
        return;

    Rectangle dstRect = GetPhysicsColliderGlobal(e);
    DrawRectangle(dstRect.x, dstRect.y, dstRect.width, dstRect.height, e->physicsColliderColor);
}
#endif

void DefaultDrawEntity(const Entity* e) {
    Rectangle srcRect = {0, 0, e->texture.width, e->texture.height};
    Vector2 origin = {0.0f, 0.0f};
    float rotation = 0.0f;
    Rectangle destRect = GetDrawDestinationRectGlobal(e);

    DrawTexturePro(e->texture, srcRect, destRect, origin, rotation, WHITE);
}

void DrawEntity(const Entity* e) {
    switch (e->type) {

        default:
            DefaultDrawEntity(e);
    }
}

void DrawGame() {
    BeginDrawing();
    ClearBackground(RAYWHITE);

    for (DrawLayer layer = Background_Layer; layer <= Foreground_Layer; layer++) {
        for (int j = 0; j < MAX_ENTITY_COUNT; j++) {
            Entity* currentEntity = &game.entities[j];

            if (ShouldDrawEntity(currentEntity, layer))
                DrawEntity(currentEntity);
        }
    }

    #ifdef BEATEMUP_DEBUG
    for (int i = 0; i < MAX_ENTITY_COUNT; i++) {
        if (game.enableDebugOverlay)
            DebugHighlights(&game.entities[i]);
    }
    #endif

    EndDrawing();
}

void AddWall(float xpos, float ypos, float width, float height) {
    Entity wall = {0};
    wall.type = Wall_Entity;

    wall.flags |= ENTITY_PHYSICS_ACTIVE;

    wall.position = (Vector2) {xpos, ypos};
    wall.physicsCollider = (Rectangle) {0, 0, width, height};

    #ifdef BEATEMUP_DEBUG
        wall.physicsColliderColor = BLUE;
    #endif
    
    AddEntity(&wall);
}