#pragma once

#include "bnf.h"
#include "minicc.h"

#include <cstdint>
#include <utility>

namespace Gram {

// TreeNodes are only intermediate. Terminal symbols don't get of TreeNodes
// token_id: index into token list
// node_id: index into tree node list
struct TreeNode {
 index_t parent_node_id{}; // root if parent_node_id == node_id
 index_t node_id{};

 std::string type;
 index_t variant; // bnf[type][variant]
 std::deque<std::pair<std::string, index_t>> alternatives; // [type][value] alternatives that we can consider on fail. Discard after parsing!
 std::vector<int32_t> child_ids; // < 0: terminal: token_id; >= 0: non-terminal: node_id; fill token by token
};

class Compiler
{

private:
 // The result
 index_t root_node_id{};
 std::vector<TreeNode> nodes;
 
 // Input
 std::vector<std::string> tokens;

 // Helper data
 index_t tokens_used{0}; // number of tokens used, this is also the next token index to use

 const BNF &bnf;
 const std::string& Top;

 std::map<std::string, std::set<std::string>> ReverseBNF; // possible parent types of a given type

public:
 // Tree specific
 void clear();
 
 // Node specific
 std::string GetTypeOfNode(index_t node_id) const;

 index_t TrackBack();
 
 void Validate(const std::string& Top, const BNF& bnf) const;

 void Dump();

 Compiler(const BNF& bnf, const std::string& Top);

 std::pair<index_t, std::vector<TreeNode>> compile(std::vector<Token> Tokens);
};

} // namespace Gram