/*
 * richard-atp-engine: A saturation-based automated theorem prover for first-order logic.
 * Copyright (C) 2026 Richard Qin
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */


#pragma once

/// @file term_bank.h
/// @brief Hash-consing term pool — guarantees structural sharing.

#include "atp/core/term.h"
#include "atp/core/types.h"

#include <span>

namespace atp {

/// Global term pool with hash-consing.
/// Every structurally identical term maps to the same TermId.
class TermBank {
  public:
    TermBank() = default;

    /// Create or retrieve a term. Returns the canonical TermId.
    TermId makeTerm(SymbolId symbol, std::span<const TermId> args);

    /// Create a variable term.
    TermId makeVar(SymbolId var_symbol);

    /// Look up a term by its ID.
    [[nodiscard]] const Term& getTerm(TermId id) const;

    /// Check if a TermId represents a variable.
    [[nodiscard]] bool isVariable(TermId id) const;

    /// Total number of unique terms stored.
    [[nodiscard]] size_t size() const;

  private:
    // TODO: Phase 1 implementation — flat arena + hash index
};

}  // namespace atp