/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree.
 */

#include <executorch/runtime/executor/program.h>

#include <cstddef>
#include <cstdint>

#include <executorch/runtime/core/event_tracer_hooks.h>
#include <executorch/runtime/executor/memory_manager.h>
#include <executorch/runtime/executor/method.h>
#include <executorch/runtime/platform/profiler.h>
#include <executorch/schema/extended_header.h>
#include <executorch/schema/program_generated.h>

/*
 * Program verification can increase code size by ~30k. Targets that need to
 * save this space can avoid building it by passing
 * -DET_ENABLE_PROGRAM_VERIFICATION=0 on the compile line.
 */
#ifndef ET_ENABLE_PROGRAM_VERIFICATION
#define ET_ENABLE_PROGRAM_VERIFICATION 1
#endif

namespace executorch {
namespace runtime {

namespace {

/**
 * Program data must be aligned to this value to properly parse it. Must be a
 * power of 2. Note that max_align_t is the alignment that malloc() and new
 * guarantee.
 */
constexpr size_t kMinimumAlignment = alignof(std::max_align_t);

bool IsAligned(const void* data) {
  uintptr_t addr = reinterpret_cast<uintptr_t>(data);
  return addr % kMinimumAlignment == 0;
}

Result<executorch_flatbuffer::ExecutionPlan*> get_execution_plan(
    const executorch_flatbuffer::Program* program,
    const char* method_name) {
  auto execution_plans = program->execution_plan();
  for (size_t i = 0; i < execution_plans->size(); i++) {
    auto plan = execution_plans->GetMutableObject(i);
    if (std::strcmp(plan->name()->c_str(), method_name) == 0) {
      return plan;
    }
  }
  ET_LOG(Error, "No method named '%s' in program", method_name);
  return Error::InvalidArgument;
}

} // namespace

/* static */ Result<Program> Program::load(
    DataLoader* loader,
    Program::Verification verification) {
  EXECUTORCH_SCOPE_PROF("Program::load");

  // See if the program size is in the header.
  size_t program_size = 0;
  size_t segment_base_offset = 0;
  {
    EXECUTORCH_SCOPE_PROF("Program::check_header");
    Result<FreeableBuffer> header = loader->load(
        /*offset=*/0,
        ExtendedHeader::kNumHeadBytes,
        DataLoader::SegmentInfo(DataLoader::SegmentInfo::Type::Program));
    if (!header.ok()) {
      return header.error();
    }
    Result<ExtendedHeader> eh =
        ExtendedHeader::Parse(header->data(), header->size());
    if (eh.ok()) {
      // The header has the program size.
      program_size = eh->program_size;
      segment_base_offset = eh->segment_base_offset;
    } else if (eh.error() == Error::NotFound) {
      // No header; the program consumes the whole file, and there are no
      // segments.
      auto result = loader->size();
      if (!result.ok()) {
        return result.error();
      }
      program_size = result.get();
    } else {
      ET_LOG(Error, "Extended header may be corrupt");
      return eh.error();
    }
  }

  // Load the flatbuffer data as a segment.
  uint32_t prof_tok = EXECUTORCH_BEGIN_PROF("Program::load_data");
  Result<FreeableBuffer> program_data = loader->load(
      /*offset=*/0,
      program_size,
      DataLoader::SegmentInfo(DataLoader::SegmentInfo::Type::Program));
  if (!program_data.ok()) {
    return program_data.error();
  }
  EXECUTORCH_END_PROF(prof_tok);

  // Make sure the magic header matches the expected version.
  if (!executorch_flatbuffer::ProgramBufferHasIdentifier(
          program_data->data())) {
    ET_LOG(
        Error,
        "Program identifier '%.4s' != expected '%.4s'",
        flatbuffers::GetBufferIdentifier(program_data->data()),
        executorch_flatbuffer::ProgramIdentifier());
    return Error::InvalidProgram;
  }

  // Do extra verification if requested.
  if (verification == Verification::InternalConsistency) {
#if ET_ENABLE_PROGRAM_VERIFICATION
    EXECUTORCH_SCOPE_PROF("Program::verify_internal_consistency");
    flatbuffers::Verifier verifier(
        reinterpret_cast<const uint8_t*>(program_data->data()),
        program_data->size());
    bool ok = executorch_flatbuffer::VerifyProgramBuffer(verifier);
    ET_CHECK_OR_RETURN_ERROR(
        ok,
        InvalidProgram,
        "Verification failed; data may be truncated or corrupt");
#else
    ET_LOG(
        Info, "InternalConsistency verification requested but not available");
#endif
  }

  // The flatbuffer data must start at an aligned address to ensure internal
  // alignment of flatbuffer fields.
  ET_CHECK_OR_RETURN_ERROR(
      IsAligned(program_data->data()),
      InvalidArgument,
      "Program data 0x%p must be aligned to %zu",
      program_data->data(),
      kMinimumAlignment);

  // Get the pointer to the root flatbuffer table.
  const executorch_flatbuffer::Program* flatbuffer_program =
      executorch_flatbuffer::GetProgram(program_data->data());

  // Constant data may live inside the flatbuffer data (constant_buffer) or in a
  // separate segment (constant_segment). It should not be in both.
  // Check constant_segment->offsets()->size() > 1, as the offsets list will
  // always contain a placeholder value 0 for non-const tensors. If this is the
  // only offset, the constant segment is empty and does not need to be loaded.
  const auto* constant_segment = flatbuffer_program->constant_segment();
  if (constant_segment != nullptr && constant_segment->offsets() != nullptr &&
      constant_segment->offsets()->size() > 1) {
    // The constant data is inside a separate segment.
    const auto* constant_buffer = flatbuffer_program->constant_buffer();
    ET_CHECK_OR_RETURN_ERROR(
        constant_buffer == nullptr || constant_buffer->size() == 0,
        InvalidProgram,
        "constant_buffer contains %u items, "
        "constant_segment.offsets contains %u items. Only one should be used.",
        constant_buffer->size(),
        constant_segment->offsets()->size());
    const auto* segments = flatbuffer_program->segments();
    ET_CHECK_OR_RETURN_ERROR(
        segments != nullptr, InvalidProgram, "No segments in program");

    // Load constant segment.
    // TODO(T171839323): Add test for segment_index > num available segments.
    ET_CHECK_OR_RETURN_ERROR(
        constant_segment->segment_index() < segments->size(),
        InvalidProgram,
        "Constant segment index %d invalid for program segments range %d",
        constant_segment->segment_index(),
        segments->size());

    const executorch_flatbuffer::DataSegment* data_segment =
        segments->Get(constant_segment->segment_index());
    Result<FreeableBuffer> constant_segment_data = loader->load(
        segment_base_offset + data_segment->offset(),
        data_segment->size(),
        DataLoader::SegmentInfo(
            DataLoader::SegmentInfo::Type::Constant,
            constant_segment->segment_index()));
    if (!constant_segment_data.ok()) {
      return constant_segment_data.error();
    }
    // The FreeableBuffer owns the data that flatbuffer_program points into.
    // Also keep a pointer to the loader so it can load more segments when
    // necessary.
    return Program(
        loader,
        segment_base_offset,
        std::move(program_data.get()),
        flatbuffer_program,
        std::move(constant_segment_data.get()));
  } else {
    // The constant data is stored inside the flatbuffer, so this program does
    // not contain a separate segment for it.
    return Program(
        loader,
        segment_base_offset,
        std::move(program_data.get()),
        flatbuffer_program,
        /*constant_segment_data=*/FreeableBuffer{});
  }
}

size_t Program::num_methods() const {
  auto internal_program =
      static_cast<const executorch_flatbuffer::Program*>(internal_program_);
  const auto execution_plan = internal_program->execution_plan();
  if (execution_plan != nullptr) {
    return execution_plan->size();
  } else {
    return 0;
  }
}

Result<const char*> Program::get_method_name(size_t plan_index) const {
  if (plan_index >= this->num_methods()) {
    return Error::InvalidArgument;
  }
  auto internal_program =
      static_cast<const executorch_flatbuffer::Program*>(internal_program_);
  // We know that the execution plan exists because num_methods() returned > 0.
  auto name = internal_program->execution_plan()->Get(plan_index)->name();
  if (name == nullptr) {
    return Error::InvalidProgram;
  }
  return name->c_str();
}

Result<Method> Program::load_method(
    const char* method_name,
    MemoryManager* memory_manager,
    EventTracer* event_tracer) const {
  EXECUTORCH_SCOPE_PROF("Program::load_method");
  internal::event_tracer_create_event_block(event_tracer, "Default");
  internal::EventTracerProfileMethodScope event_tracer_scope =
      internal::EventTracerProfileMethodScope(
          event_tracer, "Program::load_method");
  // If we can't create a MethodMeta for the Method, the Method is corrupt;
  // Method::method_meta() assumes success, so we must fail here.
  Result<MethodMeta> meta = method_meta(method_name);
  if (!meta.ok()) {
    return meta.error();
  }

  auto plan = get_execution_plan(internal_program_, method_name);
  if (!plan.ok()) {
    return plan.error();
  }
  return Method::load(plan.get(), this, memory_manager, event_tracer);
}

Result<MethodMeta> Program::method_meta(const char* method_name) const {
  auto plan = get_execution_plan(internal_program_, method_name);
  if (!plan.ok()) {
    return plan.error();
  }
  // Check any fields whose accessors don't return Result<> in case they're
  // missing or corrupt.
  ET_CHECK_OR_RETURN_ERROR(
      plan.get()->name() != nullptr, InvalidProgram, "Missing name field");
  ET_CHECK_OR_RETURN_ERROR(
      plan.get()->non_const_buffer_sizes() != nullptr,
      InvalidProgram,
      "Missing non_const_buffer_sizes field");
  ET_CHECK_OR_RETURN_ERROR(
      plan.get()->inputs() != nullptr, InvalidProgram, "Missing inputs field");
  ET_CHECK_OR_RETURN_ERROR(
      plan.get()->outputs() != nullptr,
      InvalidProgram,
      "Missing outputs field");
  return MethodMeta(plan.get());
}

Result<const void*> Program::get_constant_buffer_data(
    size_t buffer_index,
    size_t nbytes) const {
  auto internal_program =
      static_cast<const executorch_flatbuffer::Program*>(internal_program_);

  // Constant data is either in a separate segment (constant_segment_data) and
  // loaded during Program::load, or stored inside the flatbuffer data
  // (constant_buffer).
  if (constant_segment_data_.data() != nullptr) {
    size_t num_elems = internal_program->constant_segment()->offsets()->size();
    ET_CHECK_OR_RETURN_ERROR(
        buffer_index < num_elems,
        InvalidArgument,
        "Constant segment buffer index %zu invalid for program constant segment range %zu",
        buffer_index,
        num_elems);

    // All constant data is stored in one segment, with each tensor aligned to
    // @executorch_tensor_alignment. Tensor offsets are stored in the flatbuffer
    // data in Program.constant_segment.offsets.
    // The constant data at buffer_index is located at: base address of the
    // constant segment + offset for tensor at buffer_index.
    uint64_t offset = static_cast<uint64_t>(
        (*internal_program->constant_segment()->offsets())[buffer_index]);

    size_t size = constant_segment_data_.size();
    ET_CHECK_OR_RETURN_ERROR(
        offset + nbytes <= size,
        InvalidArgument,
        "Constant segment offset %" PRIu64
        " + size_bytes %zu invalid for program constant segment size %zu",
        offset,
        nbytes,
        size);

    // Offset is wrt the beginning of the constant segment.
    return static_cast<const void*>(
        static_cast<const unsigned char*>(constant_segment_data_.data()) +
        offset);
  } else {
    // Otherwise, the constant data is stored inside Program.constant_buffer.
    size_t num_elems = internal_program->constant_buffer()->size();
    ET_CHECK_OR_RETURN_ERROR(
        buffer_index < num_elems,
        InvalidArgument,
        "Constant buffer index %zu invalid for program constant buffer range %zu",
        buffer_index,
        num_elems);

    const auto& constant_buffer = *internal_program->constant_buffer();

    ET_CHECK_OR_RETURN_ERROR(
        constant_buffer[buffer_index]->storage()->size() <= nbytes,
        InvalidArgument,
        "Constant buffer size %u larger than allocated nbytes %zu",
        constant_buffer[buffer_index]->storage()->size(),
        nbytes);

    return static_cast<const void*>(
        constant_buffer[buffer_index]->storage()->data());
  }
}

Result<const char*> Program::get_output_flattening_encoding(
    const char* method_name) const {
  auto plan = get_execution_plan(internal_program_, method_name);
  if (!plan.ok()) {
    return plan.error();
  }
  return plan.get()->container_meta_type()->encoded_out_str()->c_str();
}

Error Program::get_backend_delegate_data(
    size_t index,
    const void** out_data,
    size_t* out_size) const {
  const auto* data_list =
      static_cast<const executorch_flatbuffer::Program*>(internal_program_)
          ->backend_delegate_data();
  ET_CHECK_OR_RETURN_ERROR(
      index < data_list->size(),
      NotFound,
      "index %zu >= list size %" PRIu32,
      index,
      data_list->size());
  auto data = data_list->Get(index)->data();
  *out_data = data->data();
  *out_size = data->size();
  return Error::Ok;
}

/* static */ Program::HeaderStatus Program::check_header(
    const void* data,
    size_t size) {
  if (size < kMinHeadBytes) {
    return HeaderStatus::ShortData;
  }
  if (executorch_flatbuffer::ProgramBufferHasIdentifier(data)) {
    // The data has the same file_identifier string as the schema.fbs file
    // that this runtime was built with.
    return HeaderStatus::CompatibleVersion;
  }
  const char* id = flatbuffers::GetBufferIdentifier(data);
  if (id[0] == 'E' && id[1] == 'T') {
    // It looks like an executorch file, but not the version we expect.
    return HeaderStatus::IncompatibleVersion;
  }
  return HeaderStatus::NotPresent;
}

Result<FreeableBuffer> Program::LoadSegment(
    const DataLoader::SegmentInfo& segment_info) const {
  EXECUTORCH_SCOPE_PROF("Program::LoadSegment");
  size_t index = segment_info.segment_index;
  if (loader_ == nullptr || segment_base_offset_ == 0) {
    ET_LOG(Error, "No segments in program: requested index %zu", index);
    return Error::NotFound;
  }
  size_t num_segments = internal_program_->segments()->size();
  if (index >= num_segments) {
    ET_LOG(
        Error, "Segment index %zu out of range (>= %zu)", index, num_segments);
    return Error::NotFound;
  }
  const executorch_flatbuffer::DataSegment* segment =
      internal_program_->segments()->Get(index);
  // Could fail if offset and size are out of bound for the data, or if this
  // is reading from a file and fails, or for many other reasons depending on
  // the implementation of the loader.
  return loader_->load(
      segment_base_offset_ + segment->offset(), segment->size(), segment_info);
}

Error Program::load_mutable_subsegment_into(
    size_t mutable_data_segments_index,
    size_t offset_index,
    size_t size,
    void* buffer) const {
  EXECUTORCH_SCOPE_PROF("Program::load_subsegment_into");
  // Check that the program has segments.
  if (loader_ == nullptr || segment_base_offset_ == 0) {
    ET_LOG(Error, "No segments in program");
    return Error::NotFound;
  }

  // Check that the program has mutable data segments.
  if (internal_program_->mutable_data_segments() == nullptr) {
    ET_LOG(Error, "No mutable data segments in program");
    return Error::NotFound;
  }
  if (mutable_data_segments_index >=
      internal_program_->mutable_data_segments()->size()) {
    ET_LOG(
        Error,
        "mutable_data_segments_index %zu out of range >= %" PRIu64,
        mutable_data_segments_index,
        (uint64_t)internal_program_->mutable_data_segments()->size());
    return Error::NotFound;
  }

  // Grab the mutable data segment info.
  const auto& segment_offsets = internal_program_->mutable_data_segments()->Get(
      mutable_data_segments_index);

  // Check that the offset is valid.
  if (segment_offsets->offsets() == nullptr) {
    ET_LOG(Error, "No offsets in mutable data segment");
    return Error::NotFound;
  }
  if (offset_index >= segment_offsets->offsets()->size()) {
    ET_LOG(
        Error,
        "offset index %zu out of range >= %" PRIu64,
        offset_index,
        (uint64_t)segment_offsets->offsets()->size());
    return Error::NotFound;
  }

  // Grab the offset. Note: This offset is relative to the start of the segment,
  // so we will need to adjust when calling the loader.
  size_t offset = segment_offsets->offsets()->Get(offset_index);

  // Grab the segment index
  size_t num_segments = internal_program_->segments()->size();
  if (segment_offsets->segment_index() >= num_segments) {
    ET_LOG(
        Error,
        "Segment index %u out of range (>= %zu)",
        segment_offsets->segment_index(),
        num_segments);
    return Error::NotFound;
  }

  // Grab the segment
  auto segment =
      internal_program_->segments()->Get(segment_offsets->segment_index());

  // Check size
  if (offset + size > segment->size()) {
    ET_LOG(
        Error,
        "offset %zu + size %zu out of range > %" PRIu64,
        offset,
        size,
        segment->size());
    return Error::InvalidArgument;
  }

  DataLoader::SegmentInfo info = DataLoader::SegmentInfo(
      DataLoader::SegmentInfo::Type::Mutable,
      segment_offsets->segment_index(),
      nullptr);

  // Load the data
  return loader_->load_into(
      segment_base_offset_ + segment->offset() + offset, size, info, buffer);
}

} // namespace runtime
} // namespace executorch