#include "TexDecoder.h"
#include "ImageReader.h"

namespace PKG {

// TEX 文件结构：
//   [magic1:NString(16)] "TEXV0005"
//   [magic2:NString(16)] "TEXI0001"
//   [format:int32]       TexFormat
//   [flags:int32]        TexType 标志位
//   [texW:int32][texH:int32]    纹理尺寸
//   [imgW:int32][imgH:int32]    图像尺寸
//   [unk:uint32]
//   <TexImageContainer>         图像数据（TEXB 块）
Result<Tex> TexDecoder::Decode(StreamReader& reader) {
    Tex tex{};

    // 校验魔数
    auto magic1Res = reader.ReadNString(16);
    if (!magic1Res)
        return Fail<Tex>(magic1Res.error.code, magic1Res.error.message);
    tex.Magic1 = *magic1Res;
    if (tex.Magic1 != "TEXV0005")
        return Fail<Tex>(ErrorCode::BadMagic, "Invalid TEX magic1: " + tex.Magic1);

    auto magic2Res = reader.ReadNString(16);
    if (!magic2Res)
        return Fail<Tex>(magic2Res.error.code, magic2Res.error.message);
    tex.Magic2 = *magic2Res;
    if (tex.Magic2 != "TEXI0001")
        return Fail<Tex>(ErrorCode::BadMagic, "Invalid TEX magic2: " + tex.Magic2);

    // 读取头部字段
    auto formatRes = reader.ReadInt32();
    if (!formatRes) return Fail<Tex>(formatRes.error.code, formatRes.error.message);
    tex.Header.Format = static_cast<TexFormat>(*formatRes);

    auto flagsRes = reader.ReadInt32();
    if (!flagsRes) return Fail<Tex>(flagsRes.error.code, flagsRes.error.message);
    tex.Header.Flags = static_cast<TexType>(*flagsRes);

    auto texWidthRes = reader.ReadInt32();
    if (!texWidthRes) return Fail<Tex>(texWidthRes.error.code, texWidthRes.error.message);
    tex.Header.TextureWidth = *texWidthRes;

    auto texHeightRes = reader.ReadInt32();
    if (!texHeightRes) return Fail<Tex>(texHeightRes.error.code, texHeightRes.error.message);
    tex.Header.TextureHeight = *texHeightRes;

    auto imgWidthRes = reader.ReadInt32();
    if (!imgWidthRes) return Fail<Tex>(imgWidthRes.error.code, imgWidthRes.error.message);
    tex.Header.ImageWidth = *imgWidthRes;

    auto imgHeightRes = reader.ReadInt32();
    if (!imgHeightRes) return Fail<Tex>(imgHeightRes.error.code, imgHeightRes.error.message);
    tex.Header.ImageHeight = *imgHeightRes;

    auto unkRes = reader.ReadUInt32();
    if (!unkRes) return Fail<Tex>(unkRes.error.code, unkRes.error.message);
    tex.Header.UnkInt0 = *unkRes;

    // 解析标志位
    tex.IsGif = (static_cast<int>(tex.Header.Flags) & static_cast<int>(TexType::IsGif)) != 0;
    tex.IsVideoTexture = (static_cast<int>(tex.Header.Flags) & static_cast<int>(TexType::IsVideoTexture)) != 0;

    // 读取图像容器
    auto containerRes = ImageReader::ReadContainer(reader, tex.Header.Format);
    if (!containerRes)
        return Fail<Tex>(containerRes.error.code, containerRes.error.message);
    tex.ImageContainer = *containerRes;

    return Ok(std::move(tex));
}

} // namespace PKG