//===-- lib/runtime/descriptor.cpp ------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "flang-rt/runtime/descriptor.h"
#include "ISO_Fortran_util.h"
#include "memory.h"
#include "flang-rt/runtime/allocator-registry.h"
#include "flang-rt/runtime/derived.h"
#include "flang-rt/runtime/stat.h"
#include "flang-rt/runtime/terminator.h"
#include "flang-rt/runtime/type-info.h"
#include "flang/Common/type-kinds.h"
#include "flang/Runtime/freestanding-tools.h"
#include <cassert>
#include <cstdlib>
#include <cstring>

namespace Fortran::runtime {

RT_OFFLOAD_API_GROUP_BEGIN

RT_API_ATTRS Descriptor::Descriptor(const Descriptor &that) { *this = that; }

RT_API_ATTRS Descriptor &Descriptor::operator=(const Descriptor &that) {
  runtime::memcpy(reinterpret_cast<void *>(this), &that, that.SizeInBytes());
  return *this;
}

RT_API_ATTRS void Descriptor::Establish(TypeCode t, std::size_t elementBytes,
    void *p, int rank, const SubscriptValue *extent,
    ISO::CFI_attribute_t attribute, bool addendum, int allocatorIdx) {
  Terminator terminator{__FILE__, __LINE__};
  int cfiStatus{ISO::VerifyEstablishParameters(&raw_, p, attribute, t.raw(),
      elementBytes, rank, extent, /*external=*/false)};
  if (cfiStatus != CFI_SUCCESS) {
    terminator.Crash(
        "Descriptor::Establish: CFI_establish returned %d for CFI_type_t(%d)",
        cfiStatus, t.raw());
  }
  ISO::EstablishDescriptor(
      &raw_, p, attribute, t.raw(), elementBytes, rank, extent);
  if (elementBytes == 0) {
    raw_.elem_len = 0;
    // Reset byte strides of the dimensions, since EstablishDescriptor()
    // only does that when the base address is not nullptr.
    for (int j{0}; j < rank; ++j) {
      GetDimension(j).SetByteStride(0);
    }
  }
  if (addendum) {
    SetHasAddendum();
  }
  DescriptorAddendum *a{Addendum()};
  RUNTIME_CHECK(terminator, addendum == (a != nullptr));
  if (a) {
    new (a) DescriptorAddendum{};
  }
  SetAllocIdx(allocatorIdx);
}

RT_API_ATTRS std::size_t Descriptor::BytesFor(TypeCategory category, int kind) {
  Terminator terminator{__FILE__, __LINE__};
  int bytes{common::TypeSizeInBytes(category, kind)};
  RUNTIME_CHECK(terminator, bytes > 0);
  return bytes;
}

RT_API_ATTRS void Descriptor::Establish(TypeCategory c, int kind, void *p,
    int rank, const SubscriptValue *extent, ISO::CFI_attribute_t attribute,
    bool addendum, int allocatorIdx) {
  Establish(TypeCode(c, kind), BytesFor(c, kind), p, rank, extent, attribute,
      addendum, allocatorIdx);
}

RT_API_ATTRS void Descriptor::Establish(int characterKind,
    std::size_t characters, void *p, int rank, const SubscriptValue *extent,
    ISO::CFI_attribute_t attribute, bool addendum, int allocatorIdx) {
  Establish(TypeCode{TypeCategory::Character, characterKind},
      characterKind * characters, p, rank, extent, attribute, addendum,
      allocatorIdx);
}

RT_API_ATTRS void Descriptor::Establish(const typeInfo::DerivedType &dt,
    void *p, int rank, const SubscriptValue *extent,
    ISO::CFI_attribute_t attribute, int allocatorIdx) {
  auto elementBytes{static_cast<std::size_t>(dt.sizeInBytes())};
  ISO::EstablishDescriptor(
      &raw_, p, attribute, CFI_type_struct, elementBytes, rank, extent);
  if (elementBytes == 0) {
    raw_.elem_len = 0;
    // Reset byte strides of the dimensions, since EstablishDescriptor()
    // only does that when the base address is not nullptr.
    for (int j{0}; j < rank; ++j) {
      GetDimension(j).SetByteStride(0);
    }
  }
  SetHasAddendum();
  new (Addendum()) DescriptorAddendum{&dt};
  SetAllocIdx(allocatorIdx);
}

RT_API_ATTRS void Descriptor::UncheckedScalarEstablish(
    const typeInfo::DerivedType &dt, void *p) {
  auto elementBytes{static_cast<std::size_t>(dt.sizeInBytes())};
  ISO::EstablishDescriptor(
      &raw_, p, CFI_attribute_other, CFI_type_struct, elementBytes, 0, nullptr);
  SetHasAddendum();
  new (Addendum()) DescriptorAddendum{&dt};
}

RT_API_ATTRS OwningPtr<Descriptor> Descriptor::Create(TypeCode t,
    std::size_t elementBytes, void *p, int rank, const SubscriptValue *extent,
    ISO::CFI_attribute_t attribute, bool addendum,
    const typeInfo::DerivedType *dt) {
  Terminator terminator{__FILE__, __LINE__};
  RUNTIME_CHECK(terminator, t.IsDerived() == (dt != nullptr));
  int derivedTypeLenParameters = dt ? dt->LenParameters() : 0;
  std::size_t bytes{SizeInBytes(rank, addendum, derivedTypeLenParameters)};
  Descriptor *result{
      reinterpret_cast<Descriptor *>(AllocateMemoryOrCrash(terminator, bytes))};
  if (dt) {
    result->Establish(*dt, p, rank, extent, attribute);
  } else {
    result->Establish(t, elementBytes, p, rank, extent, attribute, addendum);
  }
  return OwningPtr<Descriptor>{result};
}

RT_API_ATTRS OwningPtr<Descriptor> Descriptor::Create(TypeCategory c, int kind,
    void *p, int rank, const SubscriptValue *extent,
    ISO::CFI_attribute_t attribute) {
  return Create(
      TypeCode(c, kind), BytesFor(c, kind), p, rank, extent, attribute);
}

RT_API_ATTRS OwningPtr<Descriptor> Descriptor::Create(int characterKind,
    SubscriptValue characters, void *p, int rank, const SubscriptValue *extent,
    ISO::CFI_attribute_t attribute) {
  return Create(TypeCode{TypeCategory::Character, characterKind},
      characterKind * characters, p, rank, extent, attribute);
}

RT_API_ATTRS OwningPtr<Descriptor> Descriptor::Create(
    const typeInfo::DerivedType &dt, void *p, int rank,
    const SubscriptValue *extent, ISO::CFI_attribute_t attribute) {
  return Create(TypeCode{TypeCategory::Derived, 0}, dt.sizeInBytes(), p, rank,
      extent, attribute, /*addendum=*/true, &dt);
}

RT_API_ATTRS std::size_t Descriptor::SizeInBytes() const {
  const DescriptorAddendum *addendum{Addendum()};
  std::size_t bytes{ sizeof *this - sizeof(Dimension) + raw_.rank * sizeof(Dimension) +
      (addendum ? addendum->SizeInBytes() : 0)};
  assert (bytes <= MaxDescriptorSizeInBytes(raw_.rank,addendum) && "Descriptor must fit compiler-allocated space");
  return bytes;
}

RT_API_ATTRS std::size_t Descriptor::Elements() const {
  return InlineElements();
}

RT_API_ATTRS int Descriptor::Allocate(std::int64_t *asyncObject) {
  std::size_t elementBytes{ElementBytes()};
  if (static_cast<std::int64_t>(elementBytes) < 0) {
    // F'2023 7.4.4.2 p5: "If the character length parameter value evaluates
    // to a negative value, the length of character entities declared is zero."
    elementBytes = raw_.elem_len = 0;
  }
  std::size_t byteSize{Elements() * elementBytes};
  AllocFct alloc{allocatorRegistry.GetAllocator(MapAllocIdx())};
  // Zero size allocation is possible in Fortran and the resulting
  // descriptor must be allocated/associated. Since std::malloc(0)
  // result is implementation defined, always allocate at least one byte.
  void *p{alloc(byteSize ? byteSize : 1, asyncObject)};
  if (!p) {
    return CFI_ERROR_MEM_ALLOCATION;
  }
  // TODO: image synchronization
  raw_.base_addr = p;
  SetByteStrides();
  return 0;
}

RT_API_ATTRS void Descriptor::SetByteStrides() {
  if (int dims{rank()}) {
    std::size_t stride{ElementBytes()};
    for (int j{0}; j < dims; ++j) {
      auto &dimension{GetDimension(j)};
      dimension.SetByteStride(stride);
      stride *= dimension.Extent();
    }
  }
}

RT_API_ATTRS int Descriptor::Destroy(
    bool finalize, bool destroyPointers, Terminator *terminator) {
  if (!destroyPointers && raw_.attribute == CFI_attribute_pointer) {
    return StatOk;
  } else {
    if (auto *addendum{Addendum()}) {
      if (const auto *derived{addendum->derivedType()}) {
        if (!derived->noDestructionNeeded()) {
          runtime::Destroy(*this, finalize, *derived, terminator);
        }
      }
    }
    return Deallocate();
  }
}

RT_API_ATTRS bool Descriptor::DecrementSubscripts(
    SubscriptValue *subscript, const int *permutation) const {
  for (int j{raw_.rank - 1}; j >= 0; --j) {
    int k{permutation ? permutation[j] : j};
    const Dimension &dim{GetDimension(k)};
    if (--subscript[k] >= dim.LowerBound()) {
      return true;
    }
    subscript[k] = dim.UpperBound();
  }
  return false;
}

RT_API_ATTRS std::size_t Descriptor::ZeroBasedElementNumber(
    const SubscriptValue *subscript, const int *permutation) const {
  std::size_t result{0};
  std::size_t coefficient{1};
  for (int j{0}; j < raw_.rank; ++j) {
    int k{permutation ? permutation[j] : j};
    const Dimension &dim{GetDimension(k)};
    result += coefficient * (subscript[k] - dim.LowerBound());
    coefficient *= dim.Extent();
  }
  return result;
}

RT_API_ATTRS bool Descriptor::EstablishPointerSection(const Descriptor &source,
    const SubscriptValue *lower, const SubscriptValue *upper,
    const SubscriptValue *stride) {
  *this = source;
  raw_.attribute = CFI_attribute_pointer;
  SetAllocIdx(source.GetAllocIdx());
  int newRank{raw_.rank};
  for (int j{0}; j < raw_.rank; ++j) {
    if (!stride || stride[j] == 0) {
      if (newRank > 0) {
        --newRank;
      } else {
        return false;
      }
    }
  }
  raw_.rank = newRank;
  if (CFI_section(&raw_, &source.raw_, lower, upper, stride) != CFI_SUCCESS) {
    return false;
  }
  if (const auto *sourceAddendum = source.Addendum()) {
    if (auto *addendum{Addendum()}) {
      *addendum = *sourceAddendum;
    } else {
      return false;
    }
  }
  return true;
}

RT_API_ATTRS void Descriptor::ApplyMold(
    const Descriptor &mold, int rank, bool isMonomorphic) {
  raw_.rank = rank;
  for (int j{0}; j < rank && j < mold.raw_.rank; ++j) {
    GetDimension(j) = mold.GetDimension(j);
  }
  if (!isMonomorphic) {
    raw_.elem_len = mold.raw_.elem_len;
    raw_.type = mold.raw_.type;
    if (auto *addendum{Addendum()}) {
      if (auto *moldAddendum{mold.Addendum()}) {
        *addendum = *moldAddendum;
      } else {
        INTERNAL_CHECK(!addendum->derivedType());
      }
    }
  }
}

RT_API_ATTRS void Descriptor::Check() const {
  // TODO
}

static const char *GetTypeStr(ISO::CFI_type_t type, bool dumpRawType) {
  if (dumpRawType) {
#define CASE(x) \
  case (x): \
    return #x;
    switch (type) {
      CASE(CFI_type_signed_char)
      CASE(CFI_type_short)
      CASE(CFI_type_int)
      CASE(CFI_type_long)
      CASE(CFI_type_long_long)
      CASE(CFI_type_size_t)
      CASE(CFI_type_int8_t)
      CASE(CFI_type_int16_t)
      CASE(CFI_type_int32_t)
      CASE(CFI_type_int64_t)
      CASE(CFI_type_int128_t)
      CASE(CFI_type_int_least8_t)
      CASE(CFI_type_int_least16_t)
      CASE(CFI_type_int_least32_t)
      CASE(CFI_type_int_least64_t)
      CASE(CFI_type_int_least128_t)
      CASE(CFI_type_int_fast8_t)
      CASE(CFI_type_int_fast16_t)
      CASE(CFI_type_int_fast32_t)
      CASE(CFI_type_int_fast64_t)
      CASE(CFI_type_int_fast128_t)
      CASE(CFI_type_intmax_t)
      CASE(CFI_type_intptr_t)
      CASE(CFI_type_ptrdiff_t)
      CASE(CFI_type_half_float)
      CASE(CFI_type_bfloat)
      CASE(CFI_type_float)
      CASE(CFI_type_double)
      CASE(CFI_type_extended_double)
      CASE(CFI_type_long_double)
      CASE(CFI_type_float128)
      CASE(CFI_type_half_float_Complex)
      CASE(CFI_type_bfloat_Complex)
      CASE(CFI_type_float_Complex)
      CASE(CFI_type_double_Complex)
      CASE(CFI_type_extended_double_Complex)
      CASE(CFI_type_long_double_Complex)
      CASE(CFI_type_float128_Complex)
      CASE(CFI_type_Bool)
      CASE(CFI_type_char)
      CASE(CFI_type_cptr)
      CASE(CFI_type_struct)
      CASE(CFI_type_char16_t)
      CASE(CFI_type_char32_t)
      CASE(CFI_type_uint8_t)
      CASE(CFI_type_uint16_t)
      CASE(CFI_type_uint32_t)
      CASE(CFI_type_uint64_t)
      CASE(CFI_type_uint128_t)
    default:
      return nullptr;
    }
#undef CASE
  }
  TypeCode code{type};
  if (!code.IsValid()) {
    return "invalid";
  }
  auto categoryAndKind{code.GetCategoryAndKind()};
  if (!categoryAndKind) {
    return nullptr;
  }
  TypeCategory tcat{categoryAndKind->first};
  int kind{categoryAndKind->second};

#define CASE(cat, k) \
  case (k): \
    return #cat "(kind=" #k ")";
  switch (tcat) {
  case TypeCategory::Integer:
    switch (kind) {
      CASE(INTEGER, 1)
      CASE(INTEGER, 2)
      CASE(INTEGER, 4)
      CASE(INTEGER, 8)
      CASE(INTEGER, 16)
    }
    break;
  case TypeCategory::Unsigned:
    switch (kind) {
      CASE(UNSIGNED, 1)
      CASE(UNSIGNED, 2)
      CASE(UNSIGNED, 4)
      CASE(UNSIGNED, 8)
      CASE(UNSIGNED, 16)
    }
    break;
  case TypeCategory::Real:
    switch (kind) {
      CASE(REAL, 2)
      CASE(REAL, 3)
      CASE(REAL, 4)
      CASE(REAL, 8)
      CASE(REAL, 10)
      CASE(REAL, 16)
    }
    break;
  case TypeCategory::Complex:
    switch (kind) {
      CASE(COMPLEX, 2)
      CASE(COMPLEX, 3)
      CASE(COMPLEX, 4)
      CASE(COMPLEX, 8)
      CASE(COMPLEX, 10)
      CASE(COMPLEX, 16)
    }
    break;
  case TypeCategory::Character:
    switch (kind) {
      CASE(CHARACTER, 1)
      CASE(CHARACTER, 2)
      CASE(CHARACTER, 4)
    }
    break;
  case TypeCategory::Logical:
    switch (kind) {
      CASE(LOGICAL, 1)
      CASE(LOGICAL, 2)
      CASE(LOGICAL, 4)
      CASE(LOGICAL, 8)
    }
    break;
  case TypeCategory::Derived:
    return "DERIVED";
  }
#undef CASE
  return nullptr;
}

void Descriptor::Dump(FILE *f, bool dumpRawType) const {
  std::fprintf(f, "Descriptor @ %p:\n", reinterpret_cast<const void *>(this));
  std::fprintf(f, "  base_addr %p\n", raw_.base_addr);
  std::fprintf(f, "  elem_len  %zd\n", ElementBytes());
  std::fprintf(f, "  version   %d\n", static_cast<int>(raw_.version));
  std::fprintf(f, "  rank      %d%s\n", rank(), rank() ? "" : " (scalar)");
  int ty{static_cast<int>(raw_.type)};
  if (const char *tyStr{GetTypeStr(raw_.type, dumpRawType)}) {
    std::fprintf(f, "  type      %d \"%s\"\n", ty, tyStr);
  } else {
    std::fprintf(f, "  type      %d\n", ty);
  }
  int attr{static_cast<int>(raw_.attribute)};
  if (IsPointer()) {
    std::fprintf(f, "  attribute %d (pointer) \n", attr);
  } else if (IsAllocatable()) {
    std::fprintf(f, "  attribute %d (allocatable)\n", attr);
  } else {
    std::fprintf(f, "  attribute %d\n", attr);
  }
  std::fprintf(f, "  extra     %d\n", static_cast<int>(raw_.extra));
  std::fprintf(f, "    addendum  %d\n", static_cast<int>(HasAddendum()));
  std::fprintf(f, "    alloc_idx %d\n", static_cast<int>(GetAllocIdx()));
  for (int j{0}; j < raw_.rank; ++j) {
    std::fprintf(f, "  dim[%d] lower_bound %jd\n", j,
        static_cast<std::intmax_t>(raw_.dim[j].lower_bound));
    std::fprintf(f, "         extent      %jd\n",
        static_cast<std::intmax_t>(raw_.dim[j].extent));
    std::fprintf(f, "         sm          %jd\n",
        static_cast<std::intmax_t>(raw_.dim[j].sm));
  }
  if (const DescriptorAddendum * addendum{Addendum()}) {
    addendum->Dump(f);
  }
}

RT_API_ATTRS DescriptorAddendum &DescriptorAddendum::operator=(
    const DescriptorAddendum &that) {
  derivedType_ = that.derivedType_;
  auto lenParms{that.LenParameters()};
  for (std::size_t j{0}; j < lenParms; ++j) {
    len_[j] = that.len_[j];
  }
  return *this;
}

RT_API_ATTRS std::size_t DescriptorAddendum::SizeInBytes() const {
  return SizeInBytes(LenParameters());
}

RT_API_ATTRS std::size_t DescriptorAddendum::LenParameters() const {
  const auto *type{derivedType()};
  return type ? type->LenParameters() : 0;
}

void DescriptorAddendum::Dump(FILE *f) const {
  std::fprintf(
      f, "  derivedType @ %p\n", reinterpret_cast<const void *>(derivedType()));
  std::size_t lenParms{LenParameters()};
  for (std::size_t j{0}; j < lenParms; ++j) {
    std::fprintf(f, "  len[%zd] %jd\n", j, static_cast<std::intmax_t>(len_[j]));
  }
}

RT_OFFLOAD_API_GROUP_END

} // namespace Fortran::runtime