#include "typechecker.h"
#include "ast.h"
#include "errors.h"

namespace AST {
    std::shared_ptr<types::Type> IntLiteralExpression::typecheck(
        typecheck::State&,
        typecheck::Scope&,
        std::optional<std::shared_ptr<types::Type>>
    ) {
        return std::shared_ptr<types::Type>{
            new types::FundamentalType{ types::FundamentalTypeKind::Int }
        };
    }

    std::shared_ptr<types::Type> StringLiteralExpression::typecheck(
        typecheck::State&,
        typecheck::Scope&,
        std::optional<std::shared_ptr<types::Type>>
    ) {
        auto char_ty = std::shared_ptr<types::Type>{
            new types::FundamentalType{ types::FundamentalTypeKind::Char }
        };
        auto ptr_ty = new types::PointerType{ char_ty };
        return std::shared_ptr<types::Type>{ptr_ty};
    }

    std::shared_ptr<types::Type> ValueReferenceExpression::typecheck(
        typecheck::State&,
        typecheck::Scope& scope,
        std::optional<std::shared_ptr<types::Type>>
    ) {
        return scope.symbols[this->m_name];
    }

    std::shared_ptr<types::Type> BinaryOperationExpression::typecheck(
        typecheck::State& state,
        typecheck::Scope& scope,
        std::optional<std::shared_ptr<types::Type>>
    ) {
        auto lhs_ty = this->m_lhs->typecheck(state, scope, {});
        auto rhs_ty = this->m_rhs->typecheck(state, scope, {});

        // TODO actually check binop types properly

        return lhs_ty;
    }

    std::shared_ptr<types::Type> FunctionCallExpression::typecheck(
        typecheck::State& state,
        typecheck::Scope& scope,
        std::optional<std::shared_ptr<types::Type>>
    ) {
        auto expr_ty = this->m_fn_expr->typecheck(state, scope, {});

        // TODO make sure function_ty really is a function type

        auto fn_ty = dynamic_cast<types::FunctionType*>(expr_ty.get());

        if (this->m_args.size() < fn_ty->m_param_tys.size()) {
            state.errors.push_back(CompileError("too few arguments", this->m_meta));
        }
        else if (this->m_args.size() > fn_ty->m_param_tys.size() && !fn_ty->m_vararg) {
            state.errors.push_back(CompileError("too many arguments", this->m_meta));
        }
        else {
            for (int i = 0; i < static_cast<int>(fn_ty->m_param_tys.size()); i++) {
                auto expected_param_ty = fn_ty->m_param_tys[i];
                auto param_ty = this->m_args[i]->typecheck(state, scope, expected_param_ty);

                // TODO make sure types actually match
            }
        }

        return fn_ty->m_ret_ty;
    }

    void ReturnStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
        this->m_expr->typecheck(state, scope, scope.return_ty);
    }

    void InitializationStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
        if (this->m_expr) {
            (*this->m_expr)->typecheck(state, scope, this->m_type);
        }
        scope.symbols[this->m_name] = this->m_type;
    }

    void ExpressionStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
        this->m_expr->typecheck(state, scope, {});
    }

    void IfStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
        auto bool_ty_ptr = new types::FundamentalType{ types::FundamentalTypeKind::Bool };
        this->m_condition->typecheck(state, scope, std::shared_ptr<types::Type>{ bool_ty_ptr });

        this->m_then->typecheck(state, scope);
        if (this->m_else) {
            (*this->m_else)->typecheck(state, scope);
        }
    }

    void Function::typecheck(typecheck::State& state, typecheck::Scope& scope) {
        auto return_ty = this->m_return_ty;
        std::vector<std::shared_ptr<types::Type>> param_tys{};
        for (auto& param : this->m_params) {
            param_tys.push_back(param.second);
        }

        auto function_ty = new types::FunctionType{ return_ty, param_tys, this->m_is_vararg };
        scope.symbols[this->m_name] = std::shared_ptr<types::Type>{ function_ty };

        typecheck::Scope inner{ scope };

        if (this->m_statements) {
            for (auto& statement : *this->m_statements) {
                statement->typecheck(state, inner);
            }
        }
    }
}