#include <math.h>
#include <stdlib.h>

#include <SDL3/SDL.h>

#include "pxl8_macros.h"
#include "pxl8_vfx.h"

struct pxl8_particles {
    pxl8_particle* particles;
    u32 alive_count;
    u32 count;
    u32 max_count;

    f32 x, y;
    f32 spread_x, spread_y;

    f32 drag;
    f32 gravity_x, gravity_y;
    f32 turbulence;

    f32 spawn_rate;
    f32 spawn_timer;

    void (*render_fn)(pxl8_gfx* gfx, pxl8_particle* p, void* userdata);
    void (*spawn_fn)(pxl8_particle* p, void* userdata);
    void (*update_fn)(pxl8_particle* p, f32 dt, void* userdata);
    void* userdata;
};

void pxl8_vfx_plasma(pxl8_gfx* ctx, f32 time, f32 scale1, f32 scale2, u8 palette_offset) {
    if (!ctx || !pxl8_gfx_get_framebuffer(ctx)) return;
    
    for (i32 y = 0; y < pxl8_gfx_get_height(ctx); y++) {
        for (i32 x = 0; x < pxl8_gfx_get_width(ctx); x++) {
            f32 v1 = sinf(x * scale1 + time);
            f32 v2 = sinf(y * scale1 + time * 0.7f);
            f32 v3 = sinf((x + y) * scale2 + time * 1.3f);
            f32 v4 = sinf(sqrtf(x * x + y * y) * 0.05f + time * 0.5f);
            
            f32 v = v1 + v2 + v3 + v4;
            f32 normalized = (1.0f + v / 4.0f) * 0.5f;
            if (normalized < 0.0f) normalized = 0.0f;
            if (normalized > 1.0f) normalized = 1.0f;
            u8 color = palette_offset + (u8)(15.0f * normalized);
            
            pxl8_pixel(ctx, x, y, color);
        }
    }
}

void pxl8_vfx_raster_bars(pxl8_gfx* ctx, pxl8_raster_bar* bars, u32 bar_count, f32 time) {
    if (!ctx || !bars) return;

    for (u32 i = 0; i < bar_count; i++) {
        pxl8_raster_bar* bar = &bars[i];
        f32 y = bar->base_y + bar->amplitude * sinf(time * bar->speed + bar->phase);
        i32 y_int = (i32)y;

        for (i32 dy = 0; dy < bar->height; dy++) {
            f32 position = (f32)dy / (f32)(bar->height - 1);
            f32 distance_from_center = fabsf(position - 0.5f) * 2.0f;

            u8 color_idx;
            if (distance_from_center < 0.3f) {
                color_idx = bar->fade_color;
            } else if (distance_from_center < 0.6f) {
                color_idx = bar->fade_color - 1;
            } else if (distance_from_center < 0.8f) {
                color_idx = bar->color;
            } else {
                color_idx = bar->color - 1;
            }

            pxl8_rect_fill(ctx, 0, y_int + dy, pxl8_gfx_get_width(ctx), 1, color_idx);
        }
    }
}

void pxl8_vfx_rotozoom(pxl8_gfx* ctx, f32 angle, f32 zoom, i32 cx, i32 cy) {
    if (!ctx || !pxl8_gfx_get_framebuffer(ctx)) return;
    
    f32 cos_a = cosf(angle);
    f32 sin_a = sinf(angle);
    
    u8* temp_buffer = (u8*)SDL_malloc(pxl8_gfx_get_width(ctx) * pxl8_gfx_get_height(ctx));
    if (!temp_buffer) return;
    
    SDL_memcpy(temp_buffer, pxl8_gfx_get_framebuffer(ctx), pxl8_gfx_get_width(ctx) * pxl8_gfx_get_height(ctx));
    
    for (i32 y = 0; y < pxl8_gfx_get_height(ctx); y++) {
        for (i32 x = 0; x < pxl8_gfx_get_width(ctx); x++) {
            f32 dx = x - cx;
            f32 dy = y - cy;
            
            f32 src_x = cx + (dx * cos_a - dy * sin_a) / zoom;
            f32 src_y = cy + (dx * sin_a + dy * cos_a) / zoom;
            
            i32 sx = (i32)src_x;
            i32 sy = (i32)src_y;
            
            if (sx >= 0 && sx < pxl8_gfx_get_width(ctx) && sy >= 0 && sy < pxl8_gfx_get_height(ctx)) {
                pxl8_gfx_get_framebuffer(ctx)[y * pxl8_gfx_get_width(ctx) + x] = temp_buffer[sy * pxl8_gfx_get_width(ctx) + sx];
            }
        }
    }
    
    SDL_free(temp_buffer);
}

void pxl8_vfx_tunnel(pxl8_gfx* ctx, f32 time, f32 speed, f32 twist) {
    if (!ctx || !pxl8_gfx_get_framebuffer(ctx)) return;
    
    f32 cx = pxl8_gfx_get_width(ctx) / 2.0f;
    f32 cy = pxl8_gfx_get_height(ctx) / 2.0f;
    
    for (i32 y = 0; y < pxl8_gfx_get_height(ctx); y++) {
        for (i32 x = 0; x < pxl8_gfx_get_width(ctx); x++) {
            f32 dx = x - cx;
            f32 dy = y - cy;
            f32 dist = sqrtf(dx * dx + dy * dy);
            
            if (dist > 1.0f) {
                f32 angle = atan2f(dy, dx);
                f32 u = angle * 0.159f + twist * sinf(time * 0.5f);
                f32 v = 256.0f / dist + time * speed;
                
                u8 tx = (u8)((i32)(u * 256.0f) & 0xFF);
                u8 ty = (u8)((i32)(v * 256.0f) & 0xFF);
                u8 color = tx ^ ty;
                
                pxl8_pixel(ctx, x, y, color);
            }
        }
    }
}

void pxl8_vfx_water_ripple(pxl8_gfx* ctx, f32* height_map, i32 drop_x, i32 drop_y, f32 damping) {
    if (!ctx || !height_map) return;
    
    i32 w = pxl8_gfx_get_width(ctx);
    i32 h = pxl8_gfx_get_height(ctx);
    
    static f32* prev_height = NULL;
    if (!prev_height) {
        prev_height = (f32*)SDL_calloc(w * h, sizeof(f32));
        if (!prev_height) return;
    }
    
    if (drop_x >= 0 && drop_x < w && drop_y >= 0 && drop_y < h) {
        height_map[drop_y * w + drop_x] = 255.0f;
    }
    
    for (i32 y = 1; y < h - 1; y++) {
        for (i32 x = 1; x < w - 1; x++) {
            i32 idx = y * w + x;
            f32 sum = height_map[idx - w] + height_map[idx + w] + 
                     height_map[idx - 1] + height_map[idx + 1];
            f32 avg = sum / 2.0f;
            prev_height[idx] = (avg - prev_height[idx]) * damping;
        }
    }
    
    f32* temp = height_map;
    height_map = prev_height;
    prev_height = temp;
}

pxl8_particles* pxl8_particles_create(u32 max_count) {
    pxl8_particles* particles = SDL_calloc(1, sizeof(pxl8_particles));
    if (!particles) return NULL;

    particles->particles = SDL_calloc(max_count, sizeof(pxl8_particle));
    if (!particles->particles) {
        SDL_free(particles);
        return NULL;
    }

    particles->max_count = max_count;
    particles->drag = 0.98f;
    particles->gravity_y = 100.0f;
    particles->spawn_rate = 10.0f;

    return particles;
}

void pxl8_particles_destroy(pxl8_particles* particles) {
    if (!particles) return;
    SDL_free(particles->particles);
    SDL_free(particles);
}

void pxl8_particles_clear(pxl8_particles* particles) {
    if (!particles || !particles->particles) return;

    for (u32 i = 0; i < particles->max_count; i++) {
        particles->particles[i].life = 0;
        particles->particles[i].flags = 0;
    }
    particles->alive_count = 0;
    particles->spawn_timer = 0;
}

void pxl8_particles_emit(pxl8_particles* particles, u32 count) {
    if (!particles || !particles->particles) return;
    
    for (u32 i = 0; i < count && particles->alive_count < particles->max_count; i++) {
        for (u32 j = 0; j < particles->max_count; j++) {
            if (particles->particles[j].life <= 0) {
                pxl8_particle* p = &particles->particles[j];
                p->life = 1.0f;
                p->max_life = 1.0f;
                p->x = particles->x + (((f32)rand() / RAND_MAX) - 0.5f) * particles->spread_x;
                p->y = particles->y + (((f32)rand() / RAND_MAX) - 0.5f) * particles->spread_y;
                p->z = 0;
                p->vx = p->vy = p->vz = 0;
                p->ax = particles->gravity_x;
                p->ay = particles->gravity_y;
                p->az = 0;
                p->color = p->start_color = p->end_color = 15;
                p->size = 1.0f;
                p->angle = 0;
                p->spin = 0;
                p->flags = 1;
                
                if (particles->spawn_fn) {
                    particles->spawn_fn(p, particles->userdata);
                }
                
                particles->alive_count++;
                break;
            }
        }
    }
}

void pxl8_particles_render(pxl8_particles* particles, pxl8_gfx* gfx) {
    if (!particles || !particles->particles || !gfx) return;

    for (u32 i = 0; i < particles->max_count; i++) {
        pxl8_particle* p = &particles->particles[i];
        if (p->life > 0 && p->flags) {
            if (particles->render_fn) {
                particles->render_fn(gfx, p, particles->userdata);
            } else {
                i32 x = (i32)p->x;
                i32 y = (i32)p->y;
                if (x >= 0 && x < pxl8_gfx_get_width(gfx) && y >= 0 && y < pxl8_gfx_get_height(gfx)) {
                    pxl8_pixel(gfx, x, y, p->color);
                }
            }
        }
    }
}

void pxl8_particles_update(pxl8_particles* particles, f32 dt) {
    if (!particles || !particles->particles) return;

    if (particles->spawn_rate > 0.0f) {
        particles->spawn_timer += dt;
        f32 spawn_interval = 1.0f / particles->spawn_rate;
        u32 max_spawns_per_frame = particles->max_count / 10;
        if (max_spawns_per_frame < 1) max_spawns_per_frame = 1;
        u32 spawn_count = 0;
        while (particles->spawn_timer >= spawn_interval && spawn_count < max_spawns_per_frame) {
            pxl8_particles_emit(particles, 1);
            particles->spawn_timer -= spawn_interval;
            spawn_count++;
        }
    }
    
    for (u32 i = 0; i < particles->max_count; i++) {
        pxl8_particle* p = &particles->particles[i];
        if (p->life > 0) {
            if (particles->update_fn) {
                particles->update_fn(p, dt, particles->userdata);
            } else {
                p->vx += p->ax * dt;
                p->vy += p->ay * dt;
                p->vz += p->az * dt;
                
                p->vx *= particles->drag;
                p->vy *= particles->drag;
                p->vz *= particles->drag;
                
                p->x += p->vx * dt;
                p->y += p->vy * dt;
                p->z += p->vz * dt;
                
                p->angle += p->spin * dt;
            }
            
            p->life -= dt / p->max_life;
            if (p->life <= 0) {
                p->flags = 0;
                particles->alive_count--;
            }
        }
    }
}

void pxl8_vfx_explosion(pxl8_particles* particles, i32 x, i32 y, u32 color, f32 force) {
    if (!particles) return;

    particles->x = x;
    particles->y = y;
    particles->spread_x = particles->spread_y = 2.0f;
    particles->gravity_x = 0;
    particles->gravity_y = 200.0f;
    particles->drag = 0.95f;
    particles->update_fn = NULL;
    
    for (u32 i = 0; i < 50 && i < particles->max_count; i++) {
        pxl8_particle* p = &particles->particles[i];
        f32 angle = ((f32)rand() / RAND_MAX) * 6.28f;
        f32 speed = force * (0.5f + ((f32)rand() / RAND_MAX) * 0.5f);
        
        p->x = x;
        p->y = y;
        p->vx = cosf(angle) * speed;
        p->vy = sinf(angle) * speed;
        p->life = 1.0f;
        p->max_life = 1.0f + ((f32)rand() / RAND_MAX);
        p->color = color;
        p->flags = 1;
    }
}

static void fire_spawn(pxl8_particle* p, void* userdata) {
    uintptr_t palette_start = (uintptr_t)userdata;
    p->start_color = palette_start + 6 + (rand() % 3);
    p->end_color = palette_start;
    p->color = p->start_color;
    p->max_life = 1.5f + ((f32)rand() / RAND_MAX) * 1.5f;
    p->vy = -80.0f - ((f32)rand() / RAND_MAX) * 120.0f;
    p->vx = (((f32)rand() / RAND_MAX) - 0.5f) * 40.0f;
}

static void fire_update(pxl8_particle* p, f32 dt, void* userdata) {
    (void)userdata;
    p->vx += p->ax * dt;
    p->vy += p->ay * dt;
    p->vz += p->az * dt;
    
    p->x += p->vx * dt;
    p->y += p->vy * dt;
    p->z += p->vz * dt;
    
    f32 life_ratio = 1.0f - (p->life / p->max_life);
    if (p->start_color >= p->end_color) {
        u8 color_range = p->start_color - p->end_color;
        p->color = p->start_color - (u8)(life_ratio * color_range);
    } else {
        u8 color_range = p->end_color - p->start_color;
        p->color = p->start_color + (u8)(life_ratio * color_range);
    }
}

void pxl8_vfx_fire(pxl8_particles* particles, i32 x, i32 y, i32 width, u8 palette_start) {
    if (!particles) return;
    
    particles->x = x;
    particles->y = y;
    particles->spread_x = width;
    particles->spread_y = 4.0f;
    particles->gravity_x = 0;
    particles->gravity_y = -100.0f;
    particles->drag = 0.97f;
    particles->spawn_rate = 120.0f;
    particles->spawn_fn = fire_spawn;
    particles->update_fn = fire_update;
    particles->userdata = (void*)(uintptr_t)palette_start;
}

static void rain_spawn(pxl8_particle* p, void* userdata) {
    (void)userdata;
    p->start_color = 27 + (rand() % 3);
    p->end_color = 29;
    p->color = p->start_color;
    p->max_life = 2.0f;
    p->vy = 200.0f + ((f32)rand() / RAND_MAX) * 100.0f;
}

void pxl8_vfx_rain(pxl8_particles* particles, i32 width, f32 wind) {
    if (!particles) return;

    particles->x = width / 2.0f;
    particles->y = -10;
    particles->spread_x = width;
    particles->spread_y = 0;
    particles->gravity_x = wind;
    particles->gravity_y = 300.0f;
    particles->drag = 1.0f;
    particles->spawn_rate = 100.0f;
    particles->spawn_fn = rain_spawn;
    particles->update_fn = NULL;
}

static void smoke_spawn(pxl8_particle* p, void* userdata) {
    uintptr_t base_color = (uintptr_t)userdata;
    p->start_color = base_color;
    p->end_color = base_color + 4;
    p->color = p->start_color;
    p->max_life = 3.0f + ((f32)rand() / RAND_MAX) * 2.0f;
    p->vy = -20.0f - ((f32)rand() / RAND_MAX) * 30.0f;
    p->vx = (((f32)rand() / RAND_MAX) - 0.5f) * 20.0f;
    p->size = 1.0f + ((f32)rand() / RAND_MAX) * 2.0f;
}

void pxl8_vfx_smoke(pxl8_particles* particles, i32 x, i32 y, u8 color) {
    if (!particles) return;
    
    particles->x = x;
    particles->y = y;
    particles->spread_x = 5.0f;
    particles->spread_y = 5.0f;
    particles->gravity_x = 0;
    particles->gravity_y = -50.0f;
    particles->drag = 0.96f;
    particles->spawn_rate = 20.0f;
    particles->spawn_fn = smoke_spawn;
    particles->update_fn = NULL;
    particles->userdata = (void*)(uintptr_t)color;
}

static void snow_spawn(pxl8_particle* p, void* userdata) {
    (void)userdata;
    p->start_color = 8 + (rand() % 3);
    p->end_color = 10;
    p->color = p->start_color;
    p->max_life = 4.0f;
    p->vx = (((f32)rand() / RAND_MAX) - 0.5f) * 20.0f;
    p->vy = 30.0f + ((f32)rand() / RAND_MAX) * 20.0f;
}

void pxl8_vfx_snow(pxl8_particles* particles, i32 width, f32 wind) {
    if (!particles) return;

    particles->x = width / 2.0f;
    particles->y = -10;
    particles->spread_x = width;
    particles->spread_y = 0;
    particles->gravity_x = wind;
    particles->gravity_y = 30.0f;
    particles->drag = 1.0f;
    particles->spawn_rate = 30.0f;
    particles->spawn_fn = snow_spawn;
    particles->update_fn = NULL;
}

static void sparks_spawn(pxl8_particle* p, void* userdata) {
    uintptr_t base_color = (uintptr_t)userdata;
    p->start_color = base_color;
    p->end_color = base_color > 2 ? base_color - 2 : 0;
    p->color = p->start_color;
    p->max_life = 0.5f + ((f32)rand() / RAND_MAX) * 1.0f;
    
    f32 angle = ((f32)rand() / RAND_MAX) * 6.28f;
    f32 speed = 100.0f + ((f32)rand() / RAND_MAX) * 200.0f;
    p->vx = cosf(angle) * speed;
    p->vy = sinf(angle) * speed - 50.0f;
}

void pxl8_vfx_sparks(pxl8_particles* particles, i32 x, i32 y, u32 color) {
    if (!particles) return;
    
    particles->x = x;
    particles->y = y;
    particles->spread_x = 2.0f;
    particles->spread_y = 2.0f;
    particles->gravity_x = 0;
    particles->gravity_y = 100.0f;
    particles->drag = 0.97f;
    particles->spawn_rate = 40.0f;
    particles->spawn_fn = sparks_spawn;
    particles->update_fn = NULL;
    particles->userdata = (void*)(uintptr_t)color;
}

void pxl8_vfx_starfield(pxl8_particles* particles, f32 speed, f32 spread) {
    if (!particles) return;
    
    particles->spread_x = particles->spread_y = spread;
    particles->gravity_x = particles->gravity_y = 0;
    particles->drag = 1.0f;
    particles->spawn_rate = 0;
    particles->update_fn = NULL;
    
    for (u32 i = 0; i < particles->max_count; i++) {
        pxl8_particle* p = &particles->particles[i];
        p->x = ((f32)rand() / RAND_MAX) * spread * 2.0f - spread;
        p->y = ((f32)rand() / RAND_MAX) * spread * 2.0f - spread;
        p->z = ((f32)rand() / RAND_MAX) * spread;
        p->vz = -speed;
        p->life = 1000.0f;
        p->max_life = 1000.0f;
        p->color = 8 + (rand() % 8);
        p->flags = 1;
    }
}