// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'binding.dart';
import 'binding_string.dart';
import 'compound.dart';
import 'type.dart';
import 'utils.dart';
import 'writer.dart';

/// A binding to a global variable
///
/// For a C global variable -
/// ```c
/// int a;
/// ```
/// The generated dart code is -
/// ```dart
/// final int a = _dylib.lookup<ffi.Int32>('a').value;
/// ```
class Global extends LookUpBinding {
  final Type type;
  final bool exposeSymbolAddress;
  final bool constant;

  Global({
    super.usr,
    super.originalName,
    required super.name,
    required this.type,
    super.dartDoc,
    this.exposeSymbolAddress = false,
    this.constant = false,
  });

  @override
  BindingString toBindingString(Writer w) {
    final s = StringBuffer();
    final globalVarName = name;
    if (dartDoc != null) {
      s.write(makeDartDoc(dartDoc!));
    }
    final pointerName = w.wrapperLevelUniqueNamer.makeUnique('_$globalVarName');
    final dartType = type.getFfiDartType(w);
    final cType = type.getCType(w);

    s.write(
        "late final ${w.ffiLibraryPrefix}.Pointer<$cType> $pointerName = ${w.lookupFuncIdentifier}<$cType>('$originalName');\n\n");
    final baseTypealiasType = type.typealiasType;
    if (baseTypealiasType is Compound) {
      if (baseTypealiasType.isOpaque) {
        s.write(
            '${w.ffiLibraryPrefix}.Pointer<$cType> get $globalVarName => $pointerName;\n\n');
      } else {
        s.write('$dartType get $globalVarName => $pointerName.ref;\n\n');
      }
    } else {
      s.write('$dartType get $globalVarName => $pointerName.value;\n\n');
      if (!constant) {
        s.write(
            'set $globalVarName($dartType value) => $pointerName.value = value;\n\n');
      }
    }

    if (exposeSymbolAddress) {
      // Add to SymbolAddress in writer.
      w.symbolAddressWriter.addSymbol(
        type: '${w.ffiLibraryPrefix}.Pointer<$cType>',
        name: name,
        ptrName: pointerName,
      );
    }

    return BindingString(type: BindingStringType.global, string: s.toString());
  }

  @override
  void addDependencies(Set<Binding> dependencies) {
    if (dependencies.contains(this)) return;

    dependencies.add(this);
    type.addDependencies(dependencies);
  }
}