// Copyright 2018 The Flutter 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 "flutter/shell/common/isolate_configuration.h"

#include "flutter/runtime/dart_vm.h"

#ifdef ERROR
#undef ERROR
#endif

namespace shell {

IsolateConfiguration::IsolateConfiguration() = default;

IsolateConfiguration::~IsolateConfiguration() = default;

bool IsolateConfiguration::PrepareIsolate(blink::DartIsolate& isolate) {
  if (isolate.GetPhase() != blink::DartIsolate::Phase::LibrariesSetup) {
    FML_DLOG(ERROR)
        << "Isolate was in incorrect phase to be prepared for running.";
    return false;
  }

  return DoPrepareIsolate(isolate);
}

class AppSnapshotIsolateConfiguration final : public IsolateConfiguration {
 public:
  AppSnapshotIsolateConfiguration() = default;

  // |shell::IsolateConfiguration|
  bool DoPrepareIsolate(blink::DartIsolate& isolate) override {
    return isolate.PrepareForRunningFromPrecompiledCode();
  }

 private:
  FML_DISALLOW_COPY_AND_ASSIGN(AppSnapshotIsolateConfiguration);
};

class KernelIsolateConfiguration : public IsolateConfiguration {
 public:
  KernelIsolateConfiguration(std::unique_ptr<fml::Mapping> kernel)
      : kernel_(std::move(kernel)) {}

  // |shell::IsolateConfiguration|
  bool DoPrepareIsolate(blink::DartIsolate& isolate) override {
    if (blink::DartVM::IsRunningPrecompiledCode()) {
      return false;
    }
    return isolate.PrepareForRunningFromKernel(std::move(kernel_));
  }

 private:
  std::unique_ptr<fml::Mapping> kernel_;

  FML_DISALLOW_COPY_AND_ASSIGN(KernelIsolateConfiguration);
};

class KernelListIsolateConfiguration final : public IsolateConfiguration {
 public:
  KernelListIsolateConfiguration(
      std::vector<std::unique_ptr<fml::Mapping>> kernel_pieces)
      : kernel_pieces_(std::move(kernel_pieces)) {}

  // |shell::IsolateConfiguration|
  bool DoPrepareIsolate(blink::DartIsolate& isolate) override {
    if (blink::DartVM::IsRunningPrecompiledCode()) {
      return false;
    }

    for (size_t i = 0; i < kernel_pieces_.size(); i++) {
      bool last_piece = i + 1 == kernel_pieces_.size();
      if (!isolate.PrepareForRunningFromKernel(std::move(kernel_pieces_[i]),
                                               last_piece)) {
        return false;
      }
    }

    return true;
  }

 private:
  std::vector<std::unique_ptr<fml::Mapping>> kernel_pieces_;

  FML_DISALLOW_COPY_AND_ASSIGN(KernelListIsolateConfiguration);
};

std::unique_ptr<IsolateConfiguration> IsolateConfiguration::InferFromSettings(
    const blink::Settings& settings,
    fml::RefPtr<blink::AssetManager> asset_manager) {
  // Running in AOT mode.
  if (blink::DartVM::IsRunningPrecompiledCode()) {
    return CreateForAppSnapshot();
  }

  // Running from kernel snapshot.
  if (asset_manager) {
    std::unique_ptr<fml::Mapping> kernel =
        asset_manager->GetAsMapping(settings.application_kernel_asset);
    if (kernel) {
      return CreateForKernel(std::move(kernel));
    }
  }

  // Running from kernel divided into several pieces (for sharing).
  // TODO(fuchsia): Use async blobfs API once it becomes available.
  if (asset_manager) {
    std::unique_ptr<fml::Mapping> kernel_list =
        asset_manager->GetAsMapping(settings.application_kernel_list_asset);
    if (kernel_list) {
      const char* kernel_list_str =
          reinterpret_cast<const char*>(kernel_list->GetMapping());
      size_t kernel_list_size = kernel_list->GetSize();

      std::vector<std::unique_ptr<fml::Mapping>> kernel_pieces;

      size_t piece_path_start = 0;
      while (piece_path_start < kernel_list_size) {
        size_t piece_path_end = piece_path_start;
        while ((piece_path_end < kernel_list_size) &&
               (kernel_list_str[piece_path_end] != '\n')) {
          piece_path_end++;
        }

        std::string piece_path(&kernel_list_str[piece_path_start],
                               piece_path_end - piece_path_start);
        std::unique_ptr<fml::Mapping> piece =
            asset_manager->GetAsMapping(piece_path);
        if (piece == nullptr) {
          FML_LOG(ERROR) << "Failed to load: " << piece_path;
          return nullptr;
        }

        kernel_pieces.emplace_back(std::move(piece));

        piece_path_start = piece_path_end + 1;
      }
      return CreateForKernelList(std::move(kernel_pieces));
    }
  }

  return nullptr;
}

std::unique_ptr<IsolateConfiguration>
IsolateConfiguration::CreateForAppSnapshot() {
  return std::make_unique<AppSnapshotIsolateConfiguration>();
}

std::unique_ptr<IsolateConfiguration> IsolateConfiguration::CreateForKernel(
    std::unique_ptr<fml::Mapping> kernel) {
  return std::make_unique<KernelIsolateConfiguration>(std::move(kernel));
}

std::unique_ptr<IsolateConfiguration> IsolateConfiguration::CreateForKernelList(
    std::vector<std::unique_ptr<fml::Mapping>> kernel_pieces) {
  return std::make_unique<KernelListIsolateConfiguration>(
      std::move(kernel_pieces));
}

}  // namespace shell