/*
 * Copyright (c) 2021-2024 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "unionLowering.h"
#include "varbinder/variableFlags.h"
#include "varbinder/ETSBinder.h"
#include "checker/ETSchecker.h"
#include "checker/ets/conversion.h"
#include "checker/ets/boxingConverter.h"
#include "checker/ets/unboxingConverter.h"
#include "compiler/lowering/util.h"
#include "compiler/lowering/scopesInit/scopesInitPhase.h"
#include "ir/base/classDefinition.h"
#include "ir/base/classProperty.h"
#include "ir/astNode.h"
#include "ir/expression.h"
#include "ir/opaqueTypeNode.h"
#include "ir/expressions/literals/nullLiteral.h"
#include "ir/expressions/literals/undefinedLiteral.h"
#include "ir/expressions/binaryExpression.h"
#include "ir/expressions/identifier.h"
#include "ir/expressions/memberExpression.h"
#include "ir/statements/blockStatement.h"
#include "ir/statements/classDeclaration.h"
#include "ir/statements/variableDeclaration.h"
#include "ir/ts/tsAsExpression.h"
#include "type_helper.h"
#include "public/public.h"

namespace ark::es2panda::compiler {
static ir::ClassDefinition *GetUnionFieldClass(checker::ETSChecker *checker, varbinder::VarBinder *varbinder)
{
    // Create the name for the synthetic class node
    util::UString unionFieldClassName(util::StringView(panda_file::GetDummyClassName()), checker->Allocator());
    varbinder::Variable *foundVar = nullptr;
    if ((foundVar = checker->Scope()->FindLocal(unionFieldClassName.View(),
                                                varbinder::ResolveBindingOptions::BINDINGS)) != nullptr) {
        return foundVar->Declaration()->Node()->AsClassDeclaration()->Definition();
    }
    auto *ident = checker->AllocNode<ir::Identifier>(unionFieldClassName.View(), checker->Allocator());
    auto [decl, var] = varbinder->NewVarDecl<varbinder::ClassDecl>(ident->Start(), ident->Name());
    ident->SetVariable(var);

    auto classCtx = varbinder::LexicalScope<varbinder::ClassScope>(varbinder);
    auto *classDef =
        checker->AllocNode<ir::ClassDefinition>(checker->Allocator(), ident, ir::ClassDefinitionModifiers::GLOBAL,
                                                ir::ModifierFlags::FINAL, Language(Language::Id::ETS));
    classDef->SetScope(classCtx.GetScope());
    auto *classDecl = checker->AllocNode<ir::ClassDeclaration>(classDef, checker->Allocator());
    classDef->Scope()->BindNode(classDecl);
    classDef->SetTsType(checker->GlobalETSObjectType());
    decl->BindNode(classDecl);
    var->SetScope(classDef->Scope());

    varbinder->AsETSBinder()->BuildClassDefinition(classDef);
    return classDef;
}

static varbinder::LocalVariable *CreateUnionFieldClassProperty(checker::ETSChecker *checker,
                                                               varbinder::VarBinder *varbinder,
                                                               checker::Type *fieldType,
                                                               const util::StringView &propName)
{
    auto *const allocator = checker->Allocator();
    auto *const dummyClass = GetUnionFieldClass(checker, varbinder);
    auto *classScope = dummyClass->Scope()->AsClassScope();

    // Enter the union filed class instance field scope
    auto fieldCtx = varbinder::LexicalScope<varbinder::LocalScope>::Enter(varbinder, classScope->InstanceFieldScope());

    if (auto *var = classScope->FindLocal(propName, varbinder::ResolveBindingOptions::VARIABLES); var != nullptr) {
        return var->AsLocalVariable();
    }

    // Create field name for synthetic class
    auto *fieldIdent = checker->AllocNode<ir::Identifier>(propName, allocator);

    // Create the synthetic class property node
    auto *field =
        checker->AllocNode<ir::ClassProperty>(fieldIdent, nullptr, nullptr, ir::ModifierFlags::NONE, allocator, false);

    // Add the declaration to the scope
    auto [decl, var] = varbinder->NewVarDecl<varbinder::LetDecl>(fieldIdent->Start(), fieldIdent->Name());
    var->AddFlag(varbinder::VariableFlags::PROPERTY);
    var->SetTsType(fieldType);
    fieldIdent->SetVariable(var);
    field->SetTsType(fieldType);
    decl->BindNode(field);

    ArenaVector<ir::AstNode *> fieldDecl {allocator->Adapter()};
    fieldDecl.push_back(field);
    dummyClass->AddProperties(std::move(fieldDecl));
    return var->AsLocalVariable();
}

static void HandleUnionPropertyAccess(checker::ETSChecker *checker, varbinder::VarBinder *vbind,
                                      ir::MemberExpression *expr)
{
    if (expr->PropVar() != nullptr) {
        return;
    }
    [[maybe_unused]] auto parent = expr->Parent();
    ASSERT(!(parent->IsCallExpression() && parent->AsCallExpression()->Callee() == expr &&
             parent->AsCallExpression()->Signature()->HasSignatureFlag(checker::SignatureFlags::TYPE)));
    expr->SetPropVar(
        CreateUnionFieldClassProperty(checker, vbind, expr->TsType(), expr->Property()->AsIdentifier()->Name()));
    ASSERT(expr->PropVar() != nullptr);
}

static ir::TSAsExpression *GenAsExpression(checker::ETSChecker *checker, checker::Type *const opaqueType,
                                           ir::Expression *const node, ir::AstNode *const parent)
{
    auto *const typeNode = checker->AllocNode<ir::OpaqueTypeNode>(opaqueType);
    auto *const asExpression = checker->AllocNode<ir::TSAsExpression>(node, typeNode, false);
    asExpression->SetParent(parent);
    asExpression->Check(checker);
    return asExpression;
}

/*
 *  Function that generates conversion from (union) to (primitive) type as to `as` expressions:
 *      (union) as (prim) => ((union) as (ref)) as (prim),
 *      where (ref) is some unboxable type from union constituent types.
 *  Finally, `(union) as (prim)` expression replaces union_node that came above.
 */
static ir::TSAsExpression *UnionCastToPrimitive(checker::ETSChecker *checker, checker::ETSObjectType *unboxableRef,
                                                checker::Type *unboxedPrim, ir::Expression *unionNode)
{
    auto *const unionAsRefExpression = GenAsExpression(checker, unboxableRef, unionNode, nullptr);
    return GenAsExpression(checker, unboxedPrim, unionAsRefExpression, unionNode->Parent());
}

static ir::TSAsExpression *HandleUnionCastToPrimitive(checker::ETSChecker *checker, ir::TSAsExpression *expr)
{
    auto *const unionType = expr->Expr()->TsType()->AsETSUnionType();
    auto *sourceType = unionType->FindExactOrBoxedType(checker, expr->TsType());
    if (sourceType == nullptr) {
        sourceType = unionType->AsETSUnionType()->FindTypeIsCastableToSomeType(expr->Expr(), checker->Relation(),
                                                                               expr->TsType());
    }
    if (sourceType != nullptr && expr->Expr()->GetBoxingUnboxingFlags() != ir::BoxingUnboxingFlags::NONE) {
        if (expr->TsType()->HasTypeFlag(checker::TypeFlag::ETS_PRIMITIVE)) {
            auto *const asExpr = GenAsExpression(checker, sourceType, expr->Expr(), expr);
            asExpr->SetBoxingUnboxingFlags(
                checker->GetUnboxingFlag(checker->ETSBuiltinTypeAsPrimitiveType(sourceType)));
            expr->Expr()->SetBoxingUnboxingFlags(ir::BoxingUnboxingFlags::NONE);
            expr->SetExpr(asExpr);
        }
        return expr;
    }
    auto *const unboxableUnionType = sourceType != nullptr ? sourceType : unionType->FindUnboxableType();
    auto *const unboxedUnionType = checker->ETSBuiltinTypeAsPrimitiveType(unboxableUnionType);
    auto *const node =
        UnionCastToPrimitive(checker, unboxableUnionType->AsETSObjectType(), unboxedUnionType, expr->Expr());
    node->SetParent(expr->Parent());

    return node;
}

bool UnionLowering::Perform(public_lib::Context *ctx, parser::Program *program)
{
    for (auto &[_, ext_programs] : program->ExternalSources()) {
        (void)_;
        for (auto *extProg : ext_programs) {
            Perform(ctx, extProg);
        }
    }

    checker::ETSChecker *checker = ctx->checker->AsETSChecker();

    program->Ast()->TransformChildrenRecursively(
        [checker](ir::AstNode *ast) -> ir::AstNode * {
            if (ast->IsMemberExpression() && ast->AsMemberExpression()->Object()->TsType() != nullptr) {
                auto *objType =
                    checker->GetApparentType(checker->GetNonNullishType(ast->AsMemberExpression()->Object()->TsType()));
                if (objType->IsETSUnionType()) {
                    HandleUnionPropertyAccess(checker, checker->VarBinder(), ast->AsMemberExpression());
                    return ast;
                }
            }

            if (ast->IsTSAsExpression() && ast->AsTSAsExpression()->Expr()->TsType() != nullptr &&
                ast->AsTSAsExpression()->Expr()->TsType()->IsETSUnionType() &&
                ast->AsTSAsExpression()->TsType() != nullptr &&
                ast->AsTSAsExpression()->TsType()->HasTypeFlag(checker::TypeFlag::ETS_PRIMITIVE)) {
                return HandleUnionCastToPrimitive(checker, ast->AsTSAsExpression());
            }

            return ast;
        },
        Name());

    return true;
}

bool UnionLowering::Postcondition(public_lib::Context *ctx, const parser::Program *program)
{
    bool current = !program->Ast()->IsAnyChild([checker = ctx->checker->AsETSChecker()](ir::AstNode *ast) {
        if (!ast->IsMemberExpression() || ast->AsMemberExpression()->Object()->TsType() == nullptr) {
            return false;
        }
        auto *objType =
            checker->GetApparentType(checker->GetNonNullishType(ast->AsMemberExpression()->Object()->TsType()));
        auto *parent = ast->Parent();
        if (!(parent->IsCallExpression() &&
              parent->AsCallExpression()->Signature()->HasSignatureFlag(checker::SignatureFlags::TYPE))) {
            return false;
        }
        return objType->IsETSUnionType() && ast->AsMemberExpression()->PropVar() == nullptr;
    });
    if (!current || ctx->config->options->CompilerOptions().compilationMode != CompilationMode::GEN_STD_LIB) {
        return current;
    }

    for (auto &[_, ext_programs] : program->ExternalSources()) {
        (void)_;
        for (auto *extProg : ext_programs) {
            if (!Postcondition(ctx, extProg)) {
                return false;
            }
        }
    }
    return true;
}

}  // namespace ark::es2panda::compiler