"""Unity 资产（.meta / .mat）文本模板与 GUID 管理。纯 stdlib，可独立测试。

模板采自 Unity 2022.3（TextureImporter serializedVersion 12 / Material 8 /
ModelImporter 22200）；升级 Unity 后如导入异常，在编辑器导出同类资产 diff 更新模板。"""
import os
import re
import uuid

XPBR_SHADER_GUID = "cab897163f45445fa34263d6670bfc9e"  # Client/Assets/Game/shader/XShader/XPbr.shader.meta

_GUID_RE = re.compile(r"^guid: ([0-9a-f]{32})", re.M)


def new_guid():
    return uuid.uuid4().hex


def guid_for(asset_path):
    """资产已有 .meta 则复用其中 guid（重复转换不破坏 Unity 引用），否则新分配。"""
    meta = asset_path + ".meta"
    if os.path.isfile(meta):
        try:
            with open(meta, "r", encoding="utf-8", errors="replace") as f:
                m = _GUID_RE.search(f.read())
        except OSError:
            m = None  # meta 损坏/不可读时按无 meta 处理，重新分配
        if m:
            return m.group(1)
    return new_guid()


def safe_name(name):
    return re.sub(r"[^0-9A-Za-z_\-]", "_", name).strip("_") or "mat"


def texture_meta(guid, srgb, max_size, alpha_is_transparency=False):
    return """fileFormatVersion: 2
guid: {guid}
TextureImporter:
  internalIDToNameTable: []
  externalObjects: {{}}
  serializedVersion: 12
  mipmaps:
    mipMapMode: 0
    enableMipMap: 1
    sRGBTexture: {srgb}
    linearTexture: 0
    fadeOut: 0
    borderMipMap: 0
    mipMapsPreserveCoverage: 0
    alphaTestReferenceValue: 0.5
    mipMapFadeDistanceStart: 1
    mipMapFadeDistanceEnd: 3
  bumpmap:
    convertToNormalMap: 0
    externalNormalMap: 0
    heightScale: 0.25
    normalMapFilter: 0
    flipGreenChannel: 0
  isReadable: 0
  streamingMipmaps: 0
  streamingMipmapsPriority: 0
  vTOnly: 0
  ignoreMipmapLimit: 0
  grayScaleToAlpha: 0
  generateCubemap: 6
  cubemapConvolution: 0
  seamlessCubemap: 0
  textureFormat: 1
  maxTextureSize: {max_size}
  textureSettings:
    serializedVersion: 2
    filterMode: 1
    aniso: 1
    mipBias: 0
    wrapU: 0
    wrapV: 0
    wrapW: 0
  nPOTScale: 1
  lightmap: 0
  compressionQuality: 50
  spriteMode: 0
  spriteExtrude: 1
  spriteMeshType: 1
  alignment: 0
  spritePivot: {{x: 0.5, y: 0.5}}
  spritePixelsToUnits: 100
  spriteBorder: {{x: 0, y: 0, z: 0, w: 0}}
  spriteGenerateFallbackPhysicsShape: 1
  alphaUsage: 1
  alphaIsTransparency: {ait}
  spriteTessellationDetail: -1
  textureType: 0
  textureShape: 1
  singleChannelComponent: 0
  flipbookRows: 1
  flipbookColumns: 1
  maxTextureSizeSet: 0
  compressionQualitySet: 0
  textureFormatSet: 0
  ignorePngGamma: 0
  applyGammaDecoding: 0
  swizzle: 50462976
  cookieLightType: 0
  platformSettings:
  - serializedVersion: 3
    buildTarget: DefaultTexturePlatform
    maxTextureSize: {max_size}
    resizeAlgorithm: 0
    textureFormat: -1
    textureCompression: 1
    compressionQuality: 50
    crunchedCompression: 0
    allowsAlphaSplitting: 0
    overridden: 0
    ignorePlatformSupport: 0
    androidETC2FallbackOverride: 0
    forceMaximumCompressionQuality_BC6H_BC7: 0
  spriteSheet:
    serializedVersion: 2
    sprites: []
    outline: []
    physicsShape: []
    bones: []
    spriteID:
    internalID: 0
    vertices: []
    indices:
    edges: []
    weights: []
    secondaryTextures: []
    nameFileIdTable: {{}}
  mipmapLimitGroupName:
  pSDRemoveMatte: 0
  userData:
  assetBundleName:
  assetBundleVariant:
""".format(guid=guid, srgb=1 if srgb else 0, max_size=max_size,
           ait=1 if alpha_is_transparency else 0)


def material_yaml(name, shader_guid, base_tex_guid, mix_tex_guid, alpha_test):
    keywords = "\n  - _ALPHATEST_ON" if alpha_test else " []"
    return """%YAML 1.1
%TAG !u! tag:unity3d.com,2011:
--- !u!21 &2100000
Material:
  serializedVersion: 8
  m_ObjectHideFlags: 0
  m_CorrespondingSourceObject: {{fileID: 0}}
  m_PrefabInstance: {{fileID: 0}}
  m_PrefabAsset: {{fileID: 0}}
  m_Name: {name}
  m_Shader: {{fileID: 4800000, guid: {shader_guid}, type: 3}}
  m_Parent: {{fileID: 0}}
  m_ModifiedSerializedProperties: 0
  m_ValidKeywords:{keywords}
  m_InvalidKeywords: []
  m_LightmapFlags: 4
  m_EnableInstancingVariants: 0
  m_DoubleSidedGI: 0
  m_CustomRenderQueue: -1
  stringTagMap: {{}}
  disabledShaderPasses: []
  m_LockedProperties:
  m_SavedProperties:
    serializedVersion: 3
    m_TexEnvs:
    - _MainTex:
        m_Texture: {{fileID: 2800000, guid: {base_tex_guid}, type: 3}}
        m_Scale: {{x: 1, y: 1}}
        m_Offset: {{x: 0, y: 0}}
    - _MixTex:
        m_Texture: {{fileID: 2800000, guid: {mix_tex_guid}, type: 3}}
        m_Scale: {{x: 1, y: 1}}
        m_Offset: {{x: 0, y: 0}}
    m_Ints: []
    m_Floats:
    - _AO: 1
    - _AlphaTest: {alpha_test}
    - _Cutoff: 0.5
    - _Metallic: 1
    - _Roughness: 1
    m_Colors:
    - _BaseColor: {{r: 1, g: 1, b: 1, a: 1}}
  m_BuildTextureStacks: []
""".format(name=name, shader_guid=shader_guid, base_tex_guid=base_tex_guid,
           mix_tex_guid=mix_tex_guid, keywords=keywords,
           alpha_test=1 if alpha_test else 0)


def material_meta(guid):
    return """fileFormatVersion: 2
guid: {guid}
NativeFormatImporter:
  externalObjects: {{}}
  mainObjectFileID: 2100000
  userData:
  assetBundleName:
  assetBundleVariant:
""".format(guid=guid)


def model_meta(guid, material_remaps):
    """material_remaps: [(fbx 内材质名, mat 文件 guid), ...]"""
    if material_remaps:
        ext = "externalObjects:\n"
        for mat_name, mat_guid in material_remaps:
            ext += ("  - first:\n"
                    "      type: UnityEngine:Material\n"
                    "      assembly: UnityEngine.CoreModule\n"
                    "      name: {n}\n"
                    "    second: {{fileID: 2100000, guid: {g}, type: 2}}\n"
                    ).format(n=mat_name, g=mat_guid)
    else:
        ext = "externalObjects: {}\n"
    return """fileFormatVersion: 2
guid: {guid}
ModelImporter:
  serializedVersion: 22200
  internalIDToNameTable: []
  {ext}  materials:
    materialImportMode: 2
    materialName: 0
    materialSearch: 1
    materialLocation: 1
  animations:
    legacyGenerateAnimations: 4
    bakeSimulation: 0
    resampleCurves: 1
    optimizeGameObjects: 0
    removeConstantScaleCurves: 0
    motionNodeName:
    animationImportErrors:
    animationImportWarnings:
    animationRetargetingWarnings:
    animationDoRetargetingWarnings: 0
    importAnimatedCustomProperties: 0
    importConstraints: 0
    animationCompression: 1
    animationRotationError: 0.5
    animationPositionError: 0.5
    animationScaleError: 0.5
    animationWrapMode: 0
    extraExposedTransformPaths: []
    extraUserProperties: []
    clipAnimations: []
    isReadable: 0
  meshes:
    lODScreenPercentages: []
    globalScale: 1
    meshCompression: 0
    addColliders: 0
    useSRGBMaterialColor: 1
    sortHierarchyByName: 1
    importPhysicalCameras: 1
    importVisibility: 1
    importBlendShapes: 1
    importCameras: 1
    importLights: 1
    nodeNameCollisionStrategy: 1
    fileIdsGeneration: 2
    swapUVChannels: 0
    generateSecondaryUV: 0
    useFileUnits: 1
    keepQuads: 0
    weldVertices: 1
    bakeAxisConversion: 0
    preserveHierarchy: 0
    skinWeightsMode: 0
    maxBonesPerVertex: 4
    minBoneWeight: 0.001
    optimizeBones: 1
    meshOptimizationFlags: -1
    indexFormat: 0
    secondaryUVAngleDistortion: 8
    secondaryUVAreaDistortion: 15.000001
    secondaryUVHardAngle: 88
    secondaryUVMarginMethod: 1
    secondaryUVMinLightmapResolution: 40
    secondaryUVMinObjectScale: 1
    secondaryUVPackMargin: 4
    useFileScale: 1
    strictVertexDataChecks: 0
  tangentSpace:
    normalSmoothAngle: 60
    normalImportMode: 0
    tangentImportMode: 3
    normalCalculationMode: 4
    legacyComputeAllNormalsFromSmoothingGroupsWhenMeshHasBlendShapes: 0
    blendShapeNormalImportMode: 1
    normalSmoothingSource: 0
  referencedClips: []
  importAnimation: 1
  humanDescription:
    serializedVersion: 3
    human: []
    skeleton: []
    armTwist: 0.5
    foreArmTwist: 0.5
    upperLegTwist: 0.5
    legTwist: 0.5
    armStretch: 0.05
    legStretch: 0.05
    feetSpacing: 0
    globalScale: 1
    rootMotionBoneName:
    hasTranslationDoF: 0
    hasExtraRoot: 0
    skeletonHasParents: 1
  lastHumanDescriptionAvatarSource: {{instanceID: 0}}
  autoGenerateAvatarMappingIfUnspecified: 1
  animationType: 2
  humanoidOversampling: 1
  avatarSetup: 0
  addHumanoidExtraRootOnlyWhenUsingAvatar: 1
  importBlendShapeDeformPercent: 1
  remapMaterialsIfMaterialImportModeIsNone: 0
  additionalBone: 0
  userData:
  assetBundleName:
  assetBundleVariant:
""".format(guid=guid, ext=ext)