#pragma once

#include <string_view>
#include <unordered_map>
#include <unordered_set>

#include <jvalidate/enum.h>
#include <jvalidate/forward.h>
#include <jvalidate/vocabulary.h>

namespace jvalidate::detail {
template <Adapter A> struct ParserContext;

template <Adapter A> class Vocabulary {
private:
  schema::Version version_;
  std::unordered_map<std::string_view, vocabulary::Metadata<A>> metadata_;
  std::unordered_set<std::string_view> permitted_;
  std::unordered_set<std::string> vocabularies_;

public:
  Vocabulary() = default;
  Vocabulary(schema::Version version,
             std::unordered_map<std::string_view, vocabulary::Metadata<A>> metadata)
      : version_(version), metadata_(std::move(metadata)) {
    for (auto const & [keyword, _] : metadata_) {
      permitted_.emplace(keyword);
    }
  }

  /**
   * @brief Reset the list of keywords that Vocabulary actually respects
   *
   * @param permitted_keywords The selection of keywords to allow for
   * searches/constraint building. Note that a constraint might be
   * registered to a null function for compatibility with this.
   *
   * @param vocabularies An optional selection of vocabulary schemas, used
   * as metadata, and deducing {@see is_format_assertion}.
   */
  void restrict(std::unordered_map<std::string, bool> const & permitted_keywords,
                std::unordered_set<std::string> const & vocabularies = {}) & {
    permitted_.clear();
    vocabularies_ = vocabularies;
    for (auto const & [keyword, _] : metadata_) {
      // We only file permitted_keywords into this Vocabulary if we have defined
      // bindings for that keyword
      if (permitted_keywords.contains(std::string(keyword))) {
        permitted_.insert(keyword);
      }
    }
    for (auto const & [keyword, required] : permitted_keywords) {
      EXPECT_M(not required || keyword.starts_with("$") || metadata_.contains(keyword),
               "Vocabulary Keyword " << keyword << " required, but not implemented");
    }
  }

  schema::Version version() const { return version_; }

  bool is_format_assertion() const {
    // In Draft07 and prior - format assertions were considered enabled by
    // default. This is - of course - problematic because very few
    // implementations actually had full support for format constraints.
    if (version_ < schema::Version::Draft2019_09) {
      return true;
    }

    // Some implementations wouldn't even bother with format constraints, and
    // others would provide implementations that either missed a number of edge
    // cases or were flat-out wrong on certain matters.
    // Therefore - starting in Draft 2019-09, the format keyword is an
    // annotation by default, instead of an assertion.
    if (version_ == schema::Version::Draft2019_09) {
      return vocabularies_.contains("/vocab/format");
    }

    // Draft 2020-12 makes this even more explicit - having separate vocabulary
    // documents for "format as assertion" and "format as annotation". Allowing
    // validators to add format constraints that are only used for annotating
    // results.
    return vocabularies_.contains("/vocab/format-assertion");
  }

  /**
   * @brief Is the given "key"word actually a keyword? As in, would
   * I expect to resolve a constraint out of it. This is a slightly more
   * lenient version of {@see is_constraint} - since it allows keywords that
   * have a null factory, as long as they've been registered (e.g. then/else).
   *
   * @param word The "key"word being looked up (e.g. "if", "properties", ...)
   */
  bool is_keyword(std::string_view word) const {
    return has(word) && metadata_.at(word).type != vocabulary::KeywordType::None;
  }

  /**
   * @brief Does the given "key"word represent a property object - that is to
   * say, an object containing some number of schemas mapped by arbitrary keys
   *
   * @param word The "key"word being looked up (e.g. "if", "properties", ...)
   */
  bool is_property_keyword(std::string_view word) const {
    return has(word) && metadata_.at(word).type == vocabulary::KeywordType::KeywordMap;
  }

  /**
   * @brief Is the given word a real constraint in the Vocabulary. In essence,
   * it must be an enabled keyword AND it must have a non-null factory function.
   *
   * @param word The "key"word being looked up (e.g. "if", "properties", ...)
   */
  bool is_constraint(std::string_view word) const { return has(word) && metadata_.at(word).make; }

  /**
   * @brief Fabricate the given constraint if real from the current context
   *
   * @param word The "key"word being looked up (e.g. "if", "properties", ...)
   *
   * @param context The current context of schema parsing, used for re-entrancy.
   *
   * @returns A pair whose first element is either a pointer to a constraint
   * (if word represents a supported constraint AND the constraint resolves to
   * something meaningful), else null.
   *
   * The second element is a boolean indicating if the constraint needs to be
   * evaluated after other constraints to use their tracking/annotations.
   * See the above comments on s_post_constraints for more info.
   */
  auto constraint(std::string_view word, ParserContext<A> const & context) const {
    return std::make_pair(is_constraint(word) ? metadata_.at(word).make(context) : nullptr,
                          has(word) && metadata_.at(word).is_post_constraint);
  }

private:
  bool has(std::string_view word) const {
    return permitted_.contains(word) && metadata_.contains(word);
  }
};
}