client_filesystem.hpp

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#pragma once

 
#include <optional>
#include <span>
#include <string_view>
#include <utility>
 
#include <wowlib/core/buffer.hpp>
#include <wowlib/core/error.hpp>
#include <wowlib/core/file_key.hpp>
#include <wowlib/fs/listfile.hpp>
#include <wowlib/fs/project_directory.hpp>
#include <wowlib/fs/storage_backend.hpp>
 
namespace wowlib::fs {
  template <StorageBackend Backend, ListfileProvider Listfile = NullListfile>
  class ClientFileSystem {
  public:
    ClientFileSystem(Backend backend, Listfile listfile = {}, std::optional<ProjectDirectory> project = std::nullopt)
      : _backend(std::move(backend)), _listfile(std::move(listfile)), _project(std::move(project)) {}

    Result<FileBuffer> readFile(const FileKey& key) {
      const FileKey resolved = resolve(key);
 
      if (_project && resolved.path && _project->exists(*resolved.path)) return _project->read(*resolved.path);
 
      return _backend.readFile(resolved);
    }

    bool exists(const FileKey& key) {
      const FileKey resolved = resolve(key);
      if (_project && resolved.path && _project->exists(*resolved.path)) return true;
      return _backend.exists(resolved);
    }

    FileKey resolve(const FileKey& key) const {
      FileKey out = key;
      if (!out.fdid && out.path) out.fdid = _listfile.pathToFdid(*out.path);
      else if (!out.path && out.fdid) out.path = _listfile.fdidToPath(*out.fdid);
      return out;
    }

    Result<FileDataID> addFile(std::string_view path, std::span<const std::byte> content) {
      if (!_project)
        return makeError(ErrorCode::NotSupported, "no project directory is set; there is nowhere to add files");
 
      if (auto written = _project->write(path, content); !written) return std::unexpected(written.error());
 
      if constexpr (Backend::kind() == StorageKind::Mpq) return FileDataID{0};
      else {
        // Overwriting an already-known file keeps its id; only new paths allocate.
        if (auto existing = _listfile.pathToFdid(path)) return *existing;
        return _listfile.registerPath(path);
      }
    }

    static constexpr StorageKind kind() { return Backend::kind(); }

    Backend& backend() { return _backend; }

    Listfile& listfile() { return _listfile; }

    ProjectDirectory* project() { return _project ? &*_project : nullptr; }
 
  private:
    Backend _backend;
    Listfile _listfile;
    std::optional<ProjectDirectory> _project;
  };
}