/*
 * meow_ui_img.c — 图片层（B1.2）。基于 stb_image（单头文件、静态编入），
 * 解 PNG/JPEG/BMP → RGBA，统一最近邻缩放/居中裁方。
 */
#include "meow_ui.h"
#include "meow_ui_internal.h"
#include "stb_image.h"

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

struct meow_img {
    int w, h;
    unsigned char *rgba;   /* 4 通道 straight alpha */
};

static meow_img *img_alloc(int w, int h, unsigned char *rgba)
{
    if (w <= 0 || h <= 0 || !rgba) { if (rgba) stbi_image_free(rgba); return NULL; }
    meow_img *im = (meow_img *)malloc(sizeof *im);
    if (!im) { stbi_image_free(rgba); return NULL; }
    im->w = w; im->h = h; im->rgba = rgba;
    return im;
}

meow_img *meow_img_load_mem(const void *buf, int len)
{
    if (!buf || len <= 0) return NULL;
    int w = 0, h = 0, c = 0;
    unsigned char *p = stbi_load_from_memory((const unsigned char *)buf, len, &w, &h, &c, 4);
    if (!p) return NULL;
    return img_alloc(w, h, p);
}

meow_img *meow_img_load_file(const char *path)
{
    if (!path) return NULL;
    int w = 0, h = 0, c = 0;
    unsigned char *p = stbi_load(path, &w, &h, &c, 4);
    if (!p) return NULL;
    return img_alloc(w, h, p);
}

void meow_img_free(meow_img *im)
{
    if (!im) return;
    if (im->rgba) stbi_image_free(im->rgba);
    free(im);
}

int meow_img_w(meow_img *im) { return im ? im->w : 0; }
int meow_img_h(meow_img *im) { return im ? im->h : 0; }

/* 最近邻采样缩放（cover=1 居中裁方），返回 dw*dh*4 临时 RGBA 缓冲 */
static unsigned char *scale_buf(const meow_img *im, int dw, int dh, int cover)
{
    if (!im || dw <= 0 || dh <= 0) return NULL;
    unsigned char *out = (unsigned char *)malloc((size_t)dw * dh * 4);
    if (!out) return NULL;
    float s = 1.0f;
    float ox = 0.0f, oy = 0.0f;
    if (cover) {
        float sx = (float)im->w / dw, sy = (float)im->h / dh;
        s = sx > sy ? sx : sy;                 /* 铺满 → 可能外溢，居中裁 */
        float sw = im->w / s, sh = im->h / s;  /* 目标显示寸（sw×sh） */
        ox = (float)(dw - sw) * 0.5f;
        oy = (float)(dh - sh) * 0.5f;
        if (ox < 0) ox = 0; if (oy < 0) oy = 0;
        for (int dy = 0; dy < dh; dy++) {
            int syi = (int)((dy + oy) / s);
            if (syi < 0) syi = 0; if (syi >= im->h) syi = im->h - 1;
            for (int dx = 0; dx < dw; dx++) {
                int sxi = (int)((dx + ox) / s);
                if (sxi < 0) sxi = 0; if (sxi >= im->w) sxi = im->w - 1;
                memcpy(out + ((size_t)dy * dw + dx) * 4,
                       im->rgba + ((size_t)syi * im->w + sxi) * 4, 4);
            }
        }
    } else {
        for (int dy = 0; dy < dh; dy++) {
            int syi = (int)((float)dy * im->h / dh);
            if (syi >= im->h) syi = im->h - 1;
            for (int dx = 0; dx < dw; dx++) {
                int sxi = (int)((float)dx * im->w / dw);
                if (sxi >= im->w) sxi = im->w - 1;
                memcpy(out + ((size_t)dy * dw + dx) * 4,
                       im->rgba + ((size_t)syi * im->w + sxi) * 4, 4);
            }
        }
    }
    return out;
}

void meow_ui_img(int x, int y, meow_img *im)
{
    if (!im) return;
    meow_gfx_blit_rgba(x, y, im->w, im->h, im->rgba, 255);
}

void meow_ui_img_scaled(int x, int y, int w, int h, meow_img *im)
{
    if (!im) return;
    unsigned char *tmp = scale_buf(im, w, h, 0);
    if (!tmp) return;
    meow_gfx_blit_rgba(x, y, w, h, tmp, 255);
    free(tmp);
}

void meow_ui_img_alpha(int x, int y, int w, int h, meow_img *im, int alpha)
{
    if (!im) return;
    unsigned char *tmp = scale_buf(im, w, h, 0);
    if (!tmp) return;
    meow_gfx_blit_rgba(x, y, w, h, tmp, alpha);
    free(tmp);
}

void meow_ui_img_cover(int x, int y, int size, meow_img *im)
{
    if (!im) return;
    unsigned char *tmp = scale_buf(im, size, size, 1);
    if (!tmp) return;
    meow_gfx_blit_rgba(x, y, size, size, tmp, 255);
    free(tmp);
}