import 'dart:convert';

import 'package:build/build.dart';
import 'package:code_builder/code_builder.dart';
import 'package:dart_style/dart_style.dart';
import 'recase4.0.0/recase.dart';

import 'models.dart';

final _dartfmt = DartFormatter();

Builder genFromJson(BuilderOptions options) {
  final parsedOptions = GeneratorOptions.fromOptions(options);

  return IcomoonBuilder(parsedOptions);
}

class GeneratorOptions {
  GeneratorOptions({
    required this.fontName,
    required this.selectionJsonPath,
  });

  factory GeneratorOptions.fromOptions(BuilderOptions options) {
    final config = options.config;

    assert(
      config['font_name'] != null,
      'fontName must not be null',
    );

    return GeneratorOptions(
      fontName: config['font_name'] as String,
      selectionJsonPath: config['selection_json_path'],
    );
  }

  final String fontName;
  final String? selectionJsonPath;
}

class IcomoonBuilder implements Builder {
  IcomoonBuilder(this.options);

  final GeneratorOptions options;

  @override
  Future build(BuildStep buildStep) async {
    final inputId = buildStep.inputId;

    final contents = await buildStep.readAsString(inputId);
    final selection = SelectionModel.fromJson(
      jsonDecode(contents) as Map<String, dynamic>,
    );

    final fields = selection.icons.map((icon) {
      final props = icon.properties;
      final code = props.code.toRadixString(16);
      final name = ReCase(props.name).snakeCase;

      return Field((b) => b
        ..name = name
        ..static = true
        ..modifier = FieldModifier.constant
        ..type = refer('IconData', 'package:flutter/widgets.dart')
        ..assignment = Code('IconData(0x$code, fontFamily: _kFontFam)'));
    });

    final icomoonClass = Class((b) => b
      ..name = 'Icomoon'
      ..constructors.add(Constructor((b) => b..name = '_'))
      ..fields.add(Field(
        (b) => b
          ..name = '_kFontFam'
          ..static = true
          ..modifier = FieldModifier.constant
          ..assignment = Code("'${options.fontName}'"),
      ))
      ..fields.addAll(fields));
    final content = Library(
      (b) => b.body..add(icomoonClass),
    ).accept(DartEmitter(allocator: Allocator()));

    await buildStep.writeAsString(
      buildStep.inputId.changeExtension('.dart'),
      _dartfmt.format('''
        // Generated by icomoon_selection_gen, do not modify by hand
        
        // ignore_for_file: constant_identifier_names

        $content
      '''),
    );
  }

  @override
  Map<String, List<String>> get buildExtensions => {
        '.json': ['.dart']
      };
}