multiavatar 1.0.10

//! favicon 打包器：把同一头像按多个边长渲染为 PNG 并打成 zip / 单文件 ICO。
//!
//! 典型用途：网站 favicon / 应用图标包。viewBox 为正方形时各尺寸均为等比方图，
//! 非正方形视口会等比缩放并居中（边缘留透明边）。
//! ICO 格式（Vista+ PNG 内嵌）手写容器：ICONDIR 头 + 每尺寸 ICONDIRENTRY + 原始 PNG 数据。
//! ZIP 打包同样手写（stored 模式）：favicon PNG 内部已是 deflate 压缩，
//! ZIP 层再压缩收益极小，stored 即可——零 zip crate 依赖。

use crate::svg::{SvgParser, SvgRasterizer};

use super::png_writer::to_png;

/// 默认打包尺寸（favicon 常见规格）。
pub const DEFAULT_SIZES: [u32; 6] = [16, 32, 48, 64, 128, 256];

/// 打包多尺寸 PNG 为 zip 字节（默认尺寸 [DEFAULT_SIZES]）。
///
/// ZIP 结构手写：每个条目 Local File Header + 数据（stored），
/// 末尾 Central Directory + EOCD；文件名 UTF-8（flag 0x0800）。
pub fn to_zip(svg: &str, sizes: &[u32]) -> Vec<u8> {
    let sizes = if sizes.is_empty() { &DEFAULT_SIZES } else { sizes };
    let doc = SvgParser::parse(svg);
    // 先渲染全部条目：名字 + PNG 数据
    let entries: Vec<(String, Vec<u8>)> = sizes
        .iter()
        .map(|size| {
            let pixmap = SvgRasterizer::rasterize(&doc, *size).expect("favicon PNG 光栅化失败");
            (format!("avatar-{}.png", size), to_png(&pixmap))
        })
        .collect();

    // 局部头 + 数据（stored）
    let mut buf = Vec::new();
    let mut central = Vec::new();
    for (name, data) in &entries {
        let offset = buf.len() as u32;
        // ZIP 条目 CRC32 只针对文件数据（不含文件名）
        let crc = crc32fast::hash(data);
        // Local File Header：sig + ver(20) + flags(UTF8) + method(0) + time/date + crc + sizes + name_len + extra_len
        write_le32(&mut buf, 0x04034b50);
        write_le16(&mut buf, 20);
        write_le16(&mut buf, 0x0800);
        write_le16(&mut buf, 0); // stored
        write_le16(&mut buf, 0); // mod time（留空，部分解压器容忍；可用 0x0000）
        write_le16(&mut buf, 0x0021); // mod date 1980-01-01
        write_le32(&mut buf, crc);
        write_le32(&mut buf, data.len() as u32);
        write_le32(&mut buf, data.len() as u32);
        write_le16(&mut buf, name.len() as u16);
        write_le16(&mut buf, 0);
        buf.extend_from_slice(name.as_bytes());
        buf.extend_from_slice(data);
        // Central Directory Entry
        write_le32(&mut central, 0x02014b50);
        write_le16(&mut central, 20); // version made by
        write_le16(&mut central, 20); // version needed
        write_le16(&mut central, 0x0800);
        write_le16(&mut central, 0);
        write_le16(&mut central, 0);
        write_le16(&mut central, 0x0021);
        write_le32(&mut central, crc);
        write_le32(&mut central, data.len() as u32);
        write_le32(&mut central, data.len() as u32);
        write_le16(&mut central, name.len() as u16);
        write_le16(&mut central, 0);
        write_le16(&mut central, 0);
        write_le16(&mut central, 0);
        write_le16(&mut central, 0);
        write_le32(&mut central, 0);
        write_le32(&mut central, offset);
        central.extend_from_slice(name.as_bytes());
    }
    let cd_offset = buf.len() as u32;
    buf.extend_from_slice(&central);
    // EOCD
    write_le32(&mut buf, 0x06054b50);
    write_le16(&mut buf, 0); // disk
    write_le16(&mut buf, 0); // cd start disk
    write_le16(&mut buf, entries.len() as u16);
    write_le16(&mut buf, entries.len() as u16);
    write_le32(&mut buf, central.len() as u32);
    write_le32(&mut buf, cd_offset);
    write_le16(&mut buf, 0); // comment len
    buf
}

/// 打包多尺寸 PNG 为单文件 ICO 字节（默认尺寸 [DEFAULT_SIZES]）。
///
/// 结构与 PNG 内嵌 ICO（Vista+）一致：ICONDIR + ICONDIRENTRY×N + PNG 数据，
/// 浏览器与 Windows 均直接支持；大于 255 的尺寸按规范以 0 表示。
pub fn to_ico(svg: &str, sizes: &[u32]) -> Vec<u8> {
    let sizes = if sizes.is_empty() { &DEFAULT_SIZES } else { sizes };
    let doc = SvgParser::parse(svg);
    // 先渲染全部 PNG，确定每个条目的字节数与偏移
    let pngs: Vec<Vec<u8>> = sizes
        .iter()
        .map(|size| {
            let pixmap = SvgRasterizer::rasterize(&doc, *size).expect("ICO PNG 光栅化失败");
            to_png(&pixmap)
        })
        .collect();

    let mut offset: u32 = 6 + 16 * sizes.len() as u32; // ICONDIR(6B) + ICONDIRENTRY×N(16B)
    let mut bos = Vec::with_capacity(offset as usize + 64 * 1024);
    // ICONDIR：reserved=0, type=1(icon), count
    write_le16(&mut bos, 0);
    write_le16(&mut bos, 1);
    write_le16(&mut bos, sizes.len() as u16);
    for (i, size) in sizes.iter().enumerate() {
        let s = *size;
        bos.push(if s >= 256 { 0 } else { s as u8 }); // width（0 表示 256）
        bos.push(if s >= 256 { 0 } else { s as u8 }); // height（0 表示 256）
        bos.push(0); // colorCount
        bos.push(0); // reserved
        write_le16(&mut bos, 1); // planes
        write_le16(&mut bos, 32); // bitCount
        write_le32(&mut bos, pngs[i].len() as u32); // bytesInRes
        write_le32(&mut bos, offset); // imageOffset
        offset += pngs[i].len() as u32;
    }
    for png in &pngs {
        bos.extend_from_slice(png);
    }
    bos
}

fn write_le16(out: &mut Vec<u8>, v: u16) {
    out.push((v & 0xFF) as u8);
    out.push((v >> 8) as u8);
}

fn write_le32(out: &mut Vec<u8>, v: u32) {
    out.push((v & 0xFF) as u8);
    out.push((v >> 8) as u8);
    out.push((v >> 16) as u8);
    out.push((v >> 24) as u8);
}