// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/stack_trace.h"
#include "vm/stack_frame.h"

namespace dart {

// Count the number of frames that are on the stack.
intptr_t StackTraceUtils::CountFrames(Thread* thread,
                                      int skip_frames,
                                      const Function& async_function) {
  Zone* zone = thread->zone();
  intptr_t frame_count = 0;
  StackFrameIterator frames(ValidationPolicy::kDontValidateFrames, thread,
                            StackFrameIterator::kNoCrossThreadIteration);
  StackFrame* frame = frames.NextFrame();
  ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
  Function& function = Function::Handle(zone);
  Code& code = Code::Handle(zone);
  Bytecode& bytecode = Bytecode::Handle(zone);
  const bool async_function_is_null = async_function.IsNull();
  for (; frame != NULL; frame = frames.NextFrame()) {
    if (!frame->IsDartFrame()) {
      continue;
    }
    if (skip_frames > 0) {
      skip_frames--;
      continue;
    }
    if (frame->is_interpreted()) {
      bytecode = frame->LookupDartBytecode();
      function = bytecode.function();
      if (function.IsNull()) {
        continue;
      }
    } else {
      code = frame->LookupDartCode();
      function = code.function();
    }
    frame_count++;
    if (!async_function_is_null &&
        (async_function.raw() == function.parent_function())) {
      return frame_count;
    }
  }
  // We hit the sentinel.
  ASSERT(async_function_is_null);
  return frame_count;
}

intptr_t StackTraceUtils::CollectFrames(Thread* thread,
                                        const Array& code_array,
                                        const Array& pc_offset_array,
                                        intptr_t array_offset,
                                        intptr_t count,
                                        int skip_frames) {
  Zone* zone = thread->zone();
  StackFrameIterator frames(ValidationPolicy::kDontValidateFrames, thread,
                            StackFrameIterator::kNoCrossThreadIteration);
  StackFrame* frame = frames.NextFrame();
  ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
  Function& function = Function::Handle(zone);
  Code& code = Code::Handle(zone);
  Bytecode& bytecode = Bytecode::Handle(zone);
  Smi& offset = Smi::Handle(zone);
  intptr_t collected_frames_count = 0;
  for (; (frame != NULL) && (collected_frames_count < count);
       frame = frames.NextFrame()) {
    if (!frame->IsDartFrame()) {
      continue;
    }
    if (skip_frames > 0) {
      skip_frames--;
      continue;
    }
    if (frame->is_interpreted()) {
      bytecode = frame->LookupDartBytecode();
      function = bytecode.function();
      if (function.IsNull()) {
        continue;
      }
      offset = Smi::New(frame->pc() - bytecode.PayloadStart());
      code_array.SetAt(array_offset, bytecode);
    } else {
      code = frame->LookupDartCode();
      offset = Smi::New(frame->pc() - code.PayloadStart());
      code_array.SetAt(array_offset, code);
    }
    pc_offset_array.SetAt(array_offset, offset);
    array_offset++;
    collected_frames_count++;
  }
  return collected_frames_count;
}

intptr_t StackTraceUtils::ExtractAsyncStackTraceInfo(
    Thread* thread,
    Function* async_function,
    StackTrace* async_stack_trace_out,
    Array* async_code_array,
    Array* async_pc_offset_array) {
  if (thread->async_stack_trace() == StackTrace::null()) {
    return 0;
  }
  *async_stack_trace_out = thread->async_stack_trace();
  ASSERT(!async_stack_trace_out->IsNull());
  const StackTrace& async_stack_trace =
      StackTrace::Handle(thread->async_stack_trace());
  const intptr_t async_stack_trace_length = async_stack_trace.Length();
  // At least two entries (0: gap marker, 1: async function).
  ASSERT(async_stack_trace_length >= 2);
  // Validate the structure of this stack trace.
  *async_code_array = async_stack_trace.code_array();
  ASSERT(!async_code_array->IsNull());
  *async_pc_offset_array = async_stack_trace.pc_offset_array();
  ASSERT(!async_pc_offset_array->IsNull());
  // We start with the asynchronous gap marker.
  ASSERT(async_code_array->At(0) != Code::null());
  ASSERT(async_code_array->At(0) == StubCode::AsynchronousGapMarker().raw());
  const Object& code_object = Object::Handle(async_code_array->At(1));
  if (code_object.IsCode()) {
    *async_function = Code::Cast(code_object).function();
  } else {
    ASSERT(code_object.IsBytecode());
    *async_function = Bytecode::Cast(code_object).function();
  }
  ASSERT(!async_function->IsNull());
  ASSERT(async_function->IsAsyncFunction() ||
         async_function->IsAsyncGenerator());
  return async_stack_trace_length;
}

}  // namespace dart