/**
 * lisp-compiler: Compiles LISP using LLVM.
 * Copyright (C) 2022  Clyne Sullivan
 *
 * 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 <http://www.gnu.org/licenses/>.
 *
 * @file ast.hpp
 * @brief Abstract Syntax Tree (AST) implementation.
 */

#ifndef AST_HPP
#define AST_HPP

#include <string>
#include <vector>
#include <variant>

struct CompilerState;

namespace llvm {
    struct Value;
}

namespace AST {

using Value = llvm::Value *;

struct Node
{
    virtual ~Node() {};

    virtual Value codegen(CompilerState&) = 0;
    virtual std::string desc() {
        return "Node";
    }
};

struct Identifier : public Node
{
    std::string name;

    virtual Value codegen(CompilerState&) final;

    virtual std::string desc() final {
        return std::string("Identifier: ") + name;
    }
};

struct Literal : public Node
{
    enum Type {
        Unknown,
        Number,
    } type = Unknown;
    std::variant<int, double> value;

    virtual Value codegen(CompilerState&) final;

    virtual std::string desc() final {
        std::string str ("Literal: ");

        switch (type) {
        default:
        case Unknown:
            str += "unknown";
            break;
        case Number:
            str += std::visit([](auto&& v) { return std::to_string(v); }, value);
            break;
        }

        return str;
    }
};

struct ProcedureCall : public Node
{
    Node *callee;
    std::vector<Node *> operands;

    virtual Value codegen(CompilerState&) final;

    virtual std::string desc() final {
        std::string str ("ProcedureCall: ");
        
        str = str + "<" + (callee ? callee->desc() : "unknown") + ">";
        str += '(';
        if (!operands.empty()) {
            for (const auto& op : operands) {
                str = str + "<" + (op ? op->desc() : "unknown") + ">";
                str += ", ";
            }

            str.pop_back();
            str.pop_back();
        }
        str += ')';

        return str;
    }
};

struct LambdaExpression : public Node
{
    std::vector<Identifier *> operands;
    std::vector<Node *> body;

    virtual Value codegen(CompilerState&) final;

    virtual std::string desc() final {
        return "LambdaExpression";
    }
};

struct Conditional : public Node
{
    Node *cond;
    Node *iftrue;
    Node *iffalse;

    virtual Value codegen(CompilerState&) final;

    virtual std::string desc() final {
        return "Conditional";
    }
};

struct Definition : public Node
{
    Identifier *ident;
    Node *value;

    virtual Value codegen(CompilerState&) final;

    virtual std::string desc() final {
        return "Definition";
    }
};

struct Assignment : public Node
{
    Identifier *ident;
    Node *value;

    virtual Value codegen(CompilerState&) final;

    virtual std::string desc() final {
        return "Assignment";
    }
};

struct DerivedExpression : public Node
{
    std::string name;

    virtual Value codegen(CompilerState&) final {
        return nullptr;
    }

    virtual std::string desc() final {
        return "DerivedExpression";
    }
};

// MacroUse
// MacroBlock
// Includer

}

#endif // AST_HPP