#include "systems.h"

#include "../game_state.h"

#include <raymath.h>
#include <stdlib.h>

void updateParticleEmitter(ecs_iter_t *it) {
    ParticleEmitter *emitter = ecs_field(it, ParticleEmitter, 1);
    f32 dt = GetFrameTime();

    for (i32 i = 0; i < it->count; i++) {
        ecs_entity_t entity = it->entities[i];
        if (ecs_has(ECS, entity, EmitterAttachment)) {
            EmitterAttachment attachment = *ecs_get(ECS, entity, EmitterAttachment);
            if (!ecs_is_alive(ECS, attachment.baseEntity)) {
                ecs_delete(ECS, entity);
                continue;
            }
            Vector2 pos = *ecs_get(ECS, entity, Position);
            pos = Vector2Add(pos, attachment.offset);
            emitter->pos = pos;
        }

        emitter[i].emitterElapsed += dt;
        if (emitter[i].emitterElapsed >= emitter[i].emitterLifetime)
            ecs_delete(ECS, entity);
    }
}

static inline int lerpInt(int start, int end, int amount)
{
    float result = start + amount*(end - start);

    return result;
}
bool updateParticle(const Texture2D tex, Particle *particle, f32 dt) {
    f32 alpha = particle->elapsed / particle->lifetime;

    Vector2 vel = Vector2Lerp(particle->startVel, particle->endVel, alpha);
    f32 size = Lerp(particle->startSize, particle->endSize, alpha);
    f32 rot = Lerp(particle->startRotSpeed, particle->endRotSpeed, alpha);
    Color startC = particle->startColor;
    Color endC = particle->endColor;
    Color color = {
            .r = lerpInt(startC.r, endC.r, alpha),
            .g = lerpInt(startC.g, endC.g, alpha),
            .b = lerpInt(startC.b, endC.b, alpha),
            .a = lerpInt(startC.a, endC.a, alpha)
    };

    //BeginBlendMode(particle->blend);
    f32 hSize = size * 0.5f;
    Vector2 center = particle->pos;
    Rectangle src = getTextureRect(particle->tileID);
    src.x += 0.1f;
    src.y += 0.1f;
    src.width -= 0.2f;
    src.height -= 0.2f;
    DrawTexturePro(tex, src, (Rectangle) {
            center.x,
            center.y,
            size, size
    }, (Vector2) {hSize, hSize}, rot, color);
    //EndBlendMode();

    particle->pos = Vector2Add(particle->pos, Vector2Scale(vel, dt));
    particle->elapsed += dt;
    return alpha >= 1.0f;
}
// https://stackoverflow.com/questions/13408990/how-to-generate-random-float-number-in-c
static inline f32 randFloatRange(f32 min, f32 max) {
    float scale = rand() / (float) RAND_MAX; /* [0, 1.0] */
    return min + scale * ( max - min );      /* [min, max] */
}
static inline Vector2 randVector2Range(Vector2 from, Vector2 to) {
    return (Vector2) {
            randFloatRange(from.x, to.x),
            randFloatRange(from.y, to.y)
    };
}
static inline Color randColorRange(Color from, Color to) {
    return (Color) {
            .r = GetRandomValue(from.r, to.r),
            .g = GetRandomValue(from.g, to.g),
            .b = GetRandomValue(from.b, to.b),
            .a = GetRandomValue(from.a, to.a),
    };
}
Particle spawnParticle(const ParticleEmitter *emitter) {
    const struct ParticleEmitterData *data = &emitter->data;
    return (Particle) {
            .pos = Vector2Add(emitter->pos, randVector2Range(data->minOffset, data->maxOffset)),
            .rotation = 0.0f,
            .startVel = randVector2Range(data->minStartVel, data->maxStartVel),
            .endVel = randVector2Range(data->minEndVel, data->maxEndVel),
            .startSize = randFloatRange(data->minStartSize, data->maxStartSize),
            .endSize = randFloatRange(data->minEndSize, data->maxEndSize),
            .startRotSpeed = randFloatRange(data->minStartRotSpeed, data->maxStartRotSpeed),
            .endRotSpeed = randFloatRange(data->minEndRotSpeed, data->maxEndRotSpeed),
            .startColor = randColorRange(data->minStartColor, data->maxStartColor),
            .endColor = randColorRange(data->minEndColor, data->maxEndColor),
            .blend = data->blend,
            .tileID = data->tileID,
            .elapsed = 0.0f,
            .lifetime = randFloatRange(data->minLifetime, data->maxLifetime),
    };
}

void updateAnimationState(ecs_iter_t *it) {
    Animation *anim = ecs_field(it, Animation, 1);
    TextureRegion *text = ecs_field(it, TextureRegion, 2);
    for (i32 i = 0; i < it->count; i++) {
        ecs_entity_t entity = it->entities[i];
        AnimType type = ANIM_IDLE;
        if (ecs_has(ECS, entity, Velocity)) {
            Velocity vel = *ecs_get(ECS, entity, Velocity);
            f32 len = Vector2Length(vel);
            if (len > 1.0f) {
                type = ANIM_WALK;
                text[i].flipX = vel.x < 0;
            }
        }

        if (type != anim[i].animType) {
            anim[i].animType = type;
            anim[i].sequence = entityGetAnimationSequence(anim[i].entityType, type);
            anim[i].curFrame = 0;
            anim[i].elapsed  = 0;
        }
    }
}
void updateAnimation(ecs_iter_t *it) {
    Animation     *anim    = ecs_field(it, Animation, 1);
    TextureRegion *texture = ecs_field(it, TextureRegion, 2);

    float dt = GetFrameTime();

    for (i32 i = 0; i < it->count; i++) {
        ecs_entity_t entity = it->entities[i];
        AnimationFrame    frame = anim[i].frame;
        AnimationSequence seq   = anim[i].sequence;

        anim[i].elapsed += dt;
        if (anim[i].elapsed < frame.duration) continue;

        i32 nextFrame    = (anim[i].curFrame + 1) % seq.frameCount;
        anim[i].curFrame = nextFrame;
        anim[i].frame    = entityGetAnimationFrame(anim[i].entityType, anim[i].animType, nextFrame);
        anim[i].elapsed  = 0.0f;

        texture[i].rec = getTextureRect(anim[i].frame.frame);
        if (ecs_has(ECS, entity, Owner)) {
            Owner owner = *ecs_get(ECS, entity, Owner);
            BzTileID base = anim[i].frame.frame;
            Vector2 offset = getTileOffset(base, owner.player);
            texture[i].rec.x += offset.x;
            texture[i].rec.y += offset.y;
        }
    }
}

void updateEasingSystem(ecs_iter_t *it) {
    Easing *easing = ecs_field(it, Easing, 1);

    f32 dt = GetFrameTime();

    for (i32 i = 0; i < it->count; i++) {
        ecs_entity_t entity = it->entities[i];
        if (easing[i].elapsed > easing[i].duration) {
            ecs_remove(ECS, entity, Easing);
            continue;
        }
        if (!ecs_has_id(ECS, entity, easing[i].compID))
            continue;
        easing[i].elapsed += dt;
        f32 alpha = easing[i].elapsed / easing[i].duration;
        alpha = BZ_MIN(1.0f, alpha);
        f32 prevX = easing[i].x;
        easing[i].x = bzEase(easing[i].easingFunc, alpha);

        const Easing *e = &easing[i];
        f32 x = e->x;
        // Inner
        x = e->easeStart + e->easeTarget * x + e->easeOffset;
        // Outer
        x = e->start + e->target * x + e->offset;
        easing[i].x = x;

        u8 *compData = ecs_get_mut_id(ECS, entity, easing[i].compID);
        compData += easing[i].memberOffset;
        f32 *out = (f32 *) compData;

        *out -= prevX;
        *out += x;
    }
}