// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/developer/debug/zxdb/console/commands/verb_up.h"

#include "src/developer/debug/zxdb/client/thread.h"
#include "src/developer/debug/zxdb/console/command.h"
#include "src/developer/debug/zxdb/console/command_utils.h"
#include "src/developer/debug/zxdb/console/commands/verb_down.h"
#include "src/developer/debug/zxdb/console/console.h"
#include "src/developer/debug/zxdb/console/output_buffer.h"
#include "src/developer/debug/zxdb/console/verbs.h"

namespace zxdb {

namespace {

const char kUpShortHelp[] = "up: Move up the stack";
const char kUpHelp[] =
    R"(up

  Switch the active frame to the one above (backward in time from) the current.

Examples

  up
      Move one frame up the stack

  t 1 up
      Move up the stack on thread 1
)";

Err RunVerbUp(ConsoleContext* context, const Command& cmd) {
  if (Err err = AssertStoppedThreadWithFrameCommand(context, cmd, "up"); err.has_error())
    return err;

  // This computes the frame index from the callback in case the user does "up" faster than an
  // async stack request can complete. Doing the new index computation from the callback ensures
  // that all commands are executed.
  auto on_has_frames = [weak_thread = cmd.thread()->GetWeakPtr()](const Err& err) {
    if (!weak_thread) {
      Console::get()->Output(Err("Thread destroyed."));
      return;
    }
    const Thread* thread = weak_thread.get();

    ConsoleContext* context = &Console::get()->context();
    auto id = context->GetActiveFrameIdForThread(thread);
    if (id < 0 || thread->GetStack().size() == 0) {
      Console::get()->Output(Err("No current frame."));
      return;
    }

    id += 1;

    if (static_cast<size_t>(id) >= thread->GetStack().size()) {
      Console::get()->Output(Err("At top of stack."));
      return;
    }

    context->SetActiveFrameIdForThread(thread, id);
    OutputFrameInfoForChange(thread->GetStack()[id], id);
  };

  if (cmd.thread()->GetStack().has_all_frames()) {
    on_has_frames(Err());
  } else {
    cmd.thread()->GetStack().SyncFrames(std::move(on_has_frames));
  }

  return Err();
}

}  // namespace

VerbRecord GetUpVerbRecord() {
  return VerbRecord(&RunVerbUp, {"up"}, kUpShortHelp, kUpHelp, CommandGroup::kGeneral);
}

}  // namespace zxdb