json-validator/include/jvalidate/detail/reference_cache.h

#pragma once

#include <functional>
#include <map>
#include <optional>

#include <jvalidate/detail/pointer.h>
#include <jvalidate/detail/reference.h>

namespace jvalidate::detail {
class ReferenceCache {
private:
  std::map<Reference, RootReference, std::greater<>> to_anchor_;
  std::map<RootReference, Reference, std::greater<>> to_absolute_;

public:
  void emplace(URI const & root) {
    to_absolute_.emplace(root, root);
    to_anchor_.emplace(root, root);
  }

  Reference emplace(Reference const & absolute, RootReference const & canonical) {
    for (Reference where = absolute; not where.pointer().empty();) {
      // Recursively add all possible alternative paths that are equivalent to
      // this absolute path as valid mappings to this canonical one.
      auto it = to_absolute_.lower_bound(where.root());
      if (it == to_absolute_.end() || where.root() == it->second.root()) {
        break;
      }

      if (auto ptr = it->second.pointer(); where.pointer().starts_with(ptr)) {
        where = it->second / where.pointer().relative_to(ptr);
        to_anchor_.emplace(where, canonical);
      } else {
        break;
      }
    }

    to_anchor_.emplace(absolute, canonical);
    to_absolute_.emplace(canonical, absolute);

    return Reference(canonical);
  }

  Reference relative_to_nearest_anchor(Reference const & ref,
                                       bool for_parent_reference = false) const {
    auto it = for_parent_reference ? to_anchor_.upper_bound(ref) : to_anchor_.lower_bound(ref);
    if (it == to_anchor_.end()) {
      return ref;
    }

    auto const & [absolute, anchor] = *it;
    if (not ref.pointer().starts_with(absolute.pointer())) {
      return ref;
    }

    return Reference(anchor, ref.pointer().relative_to(absolute.pointer()));
  }

  URI actual_parent_uri(detail::Reference const & parent) const {
    // TODO(samjaffe): Think about this some more - there's something awkward here
    URI uri = relative_to_nearest_anchor(parent, true).uri();

    if (not uri.empty() || not parent.uri().empty()) {
      return uri;
    }

    if (auto it = to_anchor_.find(Reference()); it != to_anchor_.end()) {
      return it->second.uri();
    }

    return uri;
  }
};
}