#include "hecl/Backend/ProgrammableCommon.hpp"
#include <map>

namespace hecl::Backend {

const char* ProgrammableCommon::BlendFactorToDefine(BlendFactor factor, BlendFactor defaultFactor) {
  switch (factor) {
  case BlendFactor::Zero:
    return "ZERO";
  case BlendFactor::One:
    return "ONE";
  case BlendFactor::SrcColor:
    return "SRCCOLOR";
  case BlendFactor::InvSrcColor:
    return "INVSRCCOLOR";
  case BlendFactor::DstColor:
    return "DSTCOLOR";
  case BlendFactor::InvDstColor:
    return "INVDSTCOLOR";
  case BlendFactor::SrcAlpha:
    return "SRCALPHA";
  case BlendFactor::InvSrcAlpha:
    return "INVSRCALPHA";
  case BlendFactor::DstAlpha:
    return "DSTALPHA";
  case BlendFactor::InvDstAlpha:
    return "INVDSTALPHA";
  case BlendFactor::SrcColor1:
    return "SRCCOLOR1";
  case BlendFactor::InvSrcColor1:
    return "INVSRCCOLOR1";
  default:
    return BlendFactorToDefine(defaultFactor, BlendFactor::Zero);
  }
}

unsigned ProgrammableCommon::addTexCoordGen(TexGenSrc src, int uvIdx, int mtx, bool normalize) {
  for (unsigned i = 0; i < m_tcgs.size(); ++i) {
    TexCoordGen& tcg = m_tcgs[i];
    if (tcg.m_src == src && tcg.m_uvIdx == uvIdx && tcg.m_mtx == mtx && tcg.m_norm == normalize)
      return i;
  }
  m_tcgs.emplace_back();
  TexCoordGen& newTcg = m_tcgs.back();
  newTcg.m_src = src;
  newTcg.m_uvIdx = uvIdx;
  newTcg.m_mtx = mtx;
  newTcg.m_norm = normalize;
  return m_tcgs.size() - 1;
}

unsigned ProgrammableCommon::addTexSampling(unsigned mapIdx, unsigned tcgIdx) {
  for (unsigned i = 0; i < m_texSamplings.size(); ++i) {
    TexSampling& samp = m_texSamplings[i];
    if (samp.mapIdx == mapIdx && samp.tcgIdx == tcgIdx)
      return i;
  }
  m_texSamplings.emplace_back();
  TexSampling& samp = m_texSamplings.back();
  samp.mapIdx = mapIdx;
  samp.tcgIdx = tcgIdx;
  if (m_texMapEnd < mapIdx + 1)
    m_texMapEnd = mapIdx + 1;
  return m_texSamplings.size() - 1;
}

unsigned ProgrammableCommon::RecursiveTraceTexGen(const IR& ir, Diagnostics& diag, const IR::Instruction& inst, int mtx,
                                                  bool normalize) {
  if (inst.m_op != IR::OpType::Call)
    diag.reportBackendErr(inst.m_loc, "TexCoordGen resolution requires function");

  const std::string& tcgName = inst.m_call.m_name;
  if (!tcgName.compare("UV")) {
    if (inst.getChildCount() < 1)
      diag.reportBackendErr(inst.m_loc, "TexCoordGen UV(layerIdx) requires one argument");
    const IR::Instruction& idxInst = inst.getChildInst(ir, 0);
    auto& idxImm = idxInst.getImmVec();
    return addTexCoordGen(TexGenSrc::UV, int(idxImm.simd[0]), mtx, normalize);
  } else if (!tcgName.compare("Normal"))
    return addTexCoordGen(TexGenSrc::Normal, -1, mtx, normalize);
  else if (!tcgName.compare("View"))
    return addTexCoordGen(TexGenSrc::Position, -1, mtx, normalize);

  /* Otherwise treat as game-specific function */
  const IR::Instruction& tcgSrcInst = inst.getChildInst(ir, 0);
  unsigned idx = RecursiveTraceTexGen(ir, diag, tcgSrcInst, m_texMtxRefs.size(), normalize || tcgName.back() == 'N');
  TexCoordGen& tcg = m_tcgs[idx];
  m_texMtxRefs.push_back(idx);
  tcg.m_gameFunction = tcgName;
  tcg.m_gameArgs.clear();
  for (int i = 1; i < inst.getChildCount(); ++i) {
    const IR::Instruction& ci = inst.getChildInst(ir, i);
    tcg.m_gameArgs.push_back(ci.getImmVec());
  }
  return idx;
}

std::string ProgrammableCommon::RecursiveTraceColor(const IR& ir, Diagnostics& diag, const IR::Instruction& inst,
                                                    bool toSwizzle) {
  switch (inst.m_op) {
  case IR::OpType::Call: {
    const std::string& name = inst.m_call.m_name;
    bool normalize = false;
    if (!name.compare("Texture") || (normalize = true && !name.compare("TextureN"))) {
      if (inst.getChildCount() < 2)
        diag.reportBackendErr(inst.m_loc, "Texture(map, texgen) requires 2 arguments");

      const IR::Instruction& mapInst = inst.getChildInst(ir, 0);
      auto& mapImm = mapInst.getImmVec();
      unsigned mapIdx = unsigned(mapImm.simd[0]);

      const IR::Instruction& tcgInst = inst.getChildInst(ir, 1);
      unsigned texGenIdx = RecursiveTraceTexGen(ir, diag, tcgInst, -1, normalize);

      return toSwizzle ? EmitSamplingUseRaw(addTexSampling(mapIdx, texGenIdx))
                       : EmitSamplingUseRGB(addTexSampling(mapIdx, texGenIdx));
    } else if (!name.compare("ColorReg")) {
      const IR::Instruction& idxInst = inst.getChildInst(ir, 0);
      unsigned idx = unsigned(idxInst.getImmVec().simd[0]);
      return toSwizzle ? EmitColorRegUseRaw(idx) : EmitColorRegUseRGB(idx);
    } else if (!name.compare("Lighting")) {
      m_lighting = true;
      return toSwizzle ? EmitLightingRaw() : EmitLightingRGB();
    } else if (!name.compare("vec3")) {
      if (inst.getChildCount() < 3)
        diag.reportBackendErr(inst.m_loc, "vec3(r,g,b) requires 3 arguments");
      const IR::Instruction& aInst = inst.getChildInst(ir, 0);
      const IR::Instruction& bInst = inst.getChildInst(ir, 1);
      const IR::Instruction& cInst = inst.getChildInst(ir, 2);
      return EmitVec3(RecursiveTraceAlpha(ir, diag, aInst, false), RecursiveTraceAlpha(ir, diag, bInst, false),
                      RecursiveTraceAlpha(ir, diag, cInst, false));
    } else
      diag.reportBackendErr(inst.m_loc, "unable to interpret '%s'", name.c_str());
    break;
  }
  case IR::OpType::LoadImm: {
    const atVec4f& vec = inst.m_loadImm.m_immVec;
    return EmitVec3(vec);
  }
  case IR::OpType::Arithmetic: {
    ArithmeticOp op = inst.m_arithmetic.m_op;
    const IR::Instruction& aInst = inst.getChildInst(ir, 0);
    const IR::Instruction& bInst = inst.getChildInst(ir, 1);
    std::string aTrace = RecursiveTraceColor(ir, diag, aInst, false);
    std::string bTrace = RecursiveTraceColor(ir, diag, bInst, false);

    switch (op) {
    case ArithmeticOp::Add: {
      return EmitAdd(aTrace, bTrace);
    }
    case ArithmeticOp::Subtract: {
      return EmitSub(aTrace, bTrace);
    }
    case ArithmeticOp::Multiply: {
      return EmitMult(aTrace, bTrace);
    }
    case ArithmeticOp::Divide: {
      return EmitDiv(aTrace, bTrace);
    }
    default:
      diag.reportBackendErr(inst.m_loc, "invalid arithmetic op");
    }
  }
  case IR::OpType::Swizzle: {
    const IR::Instruction& aInst = inst.getChildInst(ir, 0);
    std::string aTrace = RecursiveTraceColor(ir, diag, aInst, true);
    return EmitSwizzle3(diag, inst.m_loc, aTrace, inst.m_swizzle.m_idxs);
  }
  default:
    diag.reportBackendErr(inst.m_loc, "invalid color op");
  }

  return std::string();
}

std::string ProgrammableCommon::RecursiveTraceAlpha(const IR& ir, Diagnostics& diag, const IR::Instruction& inst,
                                                    bool toSwizzle) {
  switch (inst.m_op) {
  case IR::OpType::Call: {
    const std::string& name = inst.m_call.m_name;
    bool normalize = false;
    if (!name.compare("Texture") || (normalize = true && !name.compare("TextureN"))) {
      if (inst.getChildCount() < 2)
        diag.reportBackendErr(inst.m_loc, "Texture(map, texgen) requires 2 arguments");

      const IR::Instruction& mapInst = inst.getChildInst(ir, 0);
      const atVec4f& mapImm = mapInst.getImmVec();
      unsigned mapIdx = unsigned(mapImm.simd[0]);

      const IR::Instruction& tcgInst = inst.getChildInst(ir, 1);
      unsigned texGenIdx = RecursiveTraceTexGen(ir, diag, tcgInst, -1, normalize);

      return toSwizzle ? EmitSamplingUseRaw(addTexSampling(mapIdx, texGenIdx))
                       : EmitSamplingUseAlpha(addTexSampling(mapIdx, texGenIdx));
    } else if (!name.compare("ColorReg")) {
      const IR::Instruction& idxInst = inst.getChildInst(ir, 0);
      unsigned idx = unsigned(idxInst.getImmVec().simd[0]);
      return toSwizzle ? EmitColorRegUseRaw(idx) : EmitColorRegUseAlpha(idx);
    } else if (!name.compare("Lighting")) {
      m_lighting = true;
      return toSwizzle ? EmitLightingRaw() : EmitLightingAlpha();
    } else
      diag.reportBackendErr(inst.m_loc, "unable to interpret '%s'", name.c_str());
    break;
  }
  case IR::OpType::LoadImm: {
    const atVec4f& vec = inst.m_loadImm.m_immVec;
    return EmitVal(vec.simd[0]);
  }
  case IR::OpType::Arithmetic: {
    ArithmeticOp op = inst.m_arithmetic.m_op;
    const IR::Instruction& aInst = inst.getChildInst(ir, 0);
    const IR::Instruction& bInst = inst.getChildInst(ir, 1);
    std::string aTrace = RecursiveTraceAlpha(ir, diag, aInst, false);
    std::string bTrace = RecursiveTraceAlpha(ir, diag, bInst, false);

    switch (op) {
    case ArithmeticOp::Add: {
      return EmitAdd(aTrace, bTrace);
    }
    case ArithmeticOp::Subtract: {
      return EmitSub(aTrace, bTrace);
    }
    case ArithmeticOp::Multiply: {
      return EmitMult(aTrace, bTrace);
    }
    case ArithmeticOp::Divide: {
      return EmitDiv(aTrace, bTrace);
    }
    default:
      diag.reportBackendErr(inst.m_loc, "invalid arithmetic op");
    }
  }
  case IR::OpType::Swizzle: {
    const IR::Instruction& aInst = inst.getChildInst(ir, 0);
    std::string aTrace = RecursiveTraceAlpha(ir, diag, aInst, true);
    return EmitSwizzle1(diag, inst.m_loc, aTrace, inst.m_swizzle.m_idxs);
  }
  default:
    diag.reportBackendErr(inst.m_loc, "invalid alpha op");
  }

  return std::string();
}

void ProgrammableCommon::reset(const IR& ir, Diagnostics& diag, const char* backendName) {
  m_lighting = false;
  m_texSamplings.clear();
  m_texMapEnd = 0;
  m_tcgs.clear();
  m_texMtxRefs.clear();
  m_colorExpr.clear();
  m_alphaExpr.clear();

  diag.setBackend(backendName);

  /* Final instruction is the root call by hecl convention */
  const IR::Instruction& rootCall = ir.m_instructions.back();
  if (!rootCall.m_call.m_name.compare("HECLOpaque")) {
    m_blendSrc = BlendFactor::One;
    m_blendDst = BlendFactor::Zero;
  } else if (!rootCall.m_call.m_name.compare("HECLAlpha")) {
    m_blendSrc = BlendFactor::SrcAlpha;
    m_blendDst = BlendFactor::InvSrcAlpha;
  } else if (!rootCall.m_call.m_name.compare("HECLAdditive")) {
    m_blendSrc = BlendFactor::SrcAlpha;
    m_blendDst = BlendFactor::One;
  } else {
    diag.reportBackendErr(rootCall.m_loc, "%s backend doesn't handle '%s' root", backendName,
                          rootCall.m_call.m_name.c_str());
    return;
  }

  /* Follow Color Chain */
  const IR::Instruction& colorRoot = ir.m_instructions.at(rootCall.m_call.m_argInstIdxs.at(0));
  m_colorExpr = RecursiveTraceColor(ir, diag, colorRoot, false);

  /* Follow Alpha Chain */
  if (rootCall.m_call.m_argInstIdxs.size() > 1) {
    const IR::Instruction& alphaRoot = ir.m_instructions.at(rootCall.m_call.m_argInstIdxs.at(1));
    m_alphaExpr = RecursiveTraceAlpha(ir, diag, alphaRoot, false);
  }
}

static const char SWIZZLE_CHARS[] = "rgba";

std::string ProgrammableCommon::EmitSwizzle3(Diagnostics& diag, const SourceLocation& loc, const std::string& a,
                                             const atInt8 swiz[4]) const {
  std::string retval = a + '.';
  for (int i = 0; i < 3; ++i) {
    if (swiz[i] < 0 || swiz[i] > 3)
      diag.reportBackendErr(loc, "unable to use swizzle as RGB value");
    retval += SWIZZLE_CHARS[swiz[i]];
  }
  return retval;
}

std::string ProgrammableCommon::EmitSwizzle1(Diagnostics& diag, const SourceLocation& loc, const std::string& a,
                                             const atInt8 swiz[4]) const {
  std::string retval = a + '.';
  if (swiz[0] < 0 || swiz[0] > 3)
    diag.reportBackendErr(loc, "unable to use swizzle as Alpha value");
  retval += SWIZZLE_CHARS[swiz[0]];
  return retval;
}

} // namespace hecl::Backend