main.dart

//
// Copyright 2022-2024 Picovoice Inc.
//
// You may not use this file except in compliance with the license. A copy of the license is located in the "LICENSE"
// file accompanying this source.
//
// 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.
//

import 'dart:async';
import 'dart:convert';

import 'package:cheetah_demo/cheetah_manager.dart';
import 'package:cheetah_flutter/cheetah_error.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final String accessKey =
      '{YOUR_ACCESS_KEY_HERE}'; // AccessKey obtained from Picovoice Console (https://console.picovoice.ai/)

  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();

  bool isError = false;
  String errorMessage = "";

  bool isProcessing = false;
  String transcriptText = "";
  CheetahManager? _cheetahManager;

  final ScrollController _controller = ScrollController();

  @override
  void initState() {
    super.initState();
    setState(() {
      transcriptText = "";
    });

    initCheetah();
  }

  Future<void> initCheetah() async {
    String language = "";
    try {
      final paramsString =
          await DefaultAssetBundle.of(context).loadString('assets/params.json');
      final params = json.decode(paramsString);

      language = params["language"];
    } catch (_) {
      errorCallback(CheetahException(
          "Could not find `params.json`. Ensure 'prepare_demo.dart' script was run before launching the demo."));
      return;
    }

    final String suffix = language != "en" ? "_$language" : "";
    final String modelPath = "assets/models/cheetah_params$suffix.pv";

    try {
      _cheetahManager = await CheetahManager.create(
          accessKey,
          modelPath,
          transcriptCallback,
          errorCallback);
    } on CheetahActivationException {
      errorCallback(CheetahActivationException("AccessKey activation error."));
    } on CheetahActivationLimitException {
      errorCallback(CheetahActivationLimitException(
          "AccessKey reached its device limit."));
    } on CheetahActivationRefusedException {
      errorCallback(CheetahActivationRefusedException("AccessKey refused."));
    } on CheetahActivationThrottledException {
      errorCallback(
          CheetahActivationThrottledException("AccessKey has been throttled."));
    } on CheetahException catch (ex) {
      errorCallback(ex);
    }
  }

  void transcriptCallback(String transcript) {
    bool shouldScroll =
        _controller.position.pixels == _controller.position.maxScrollExtent;

    setState(() {
      transcriptText = transcriptText + transcript;
    });

    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (shouldScroll && !_controller.position.atEdge) {
        _controller.jumpTo(_controller.position.maxScrollExtent);
      }
    });
  }

  void errorCallback(CheetahException error) {
    setState(() {
      isError = true;
      errorMessage = error.message!;
    });
  }

  Future<void> _startProcessing() async {
    if (isProcessing) {
      return;
    }

    try {
      await _cheetahManager!.startProcess();
      setState(() {
        transcriptText = "";
        isProcessing = true;
      });
    } on CheetahException catch (ex) {
      errorCallback(ex);
    }
  }

  Future<void> _stopProcessing() async {
    if (!isProcessing) {
      return;
    }

    try {
      await _cheetahManager!.stopProcess();
      setState(() {
        isProcessing = false;
      });
    } on CheetahException catch (ex) {
      errorCallback(ex);
    }
  }

  Color picoBlue = Color.fromRGBO(55, 125, 255, 1);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        key: _scaffoldKey,
        appBar: AppBar(
          title: const Text('Cheetah Demo'),
          backgroundColor: picoBlue,
        ),
        body: Column(
          children: [
            buildCheetahTextArea(context),
            buildErrorMessage(context),
            buildStartButton(context),
            footer
          ],
        ),
      ),
    );
  }

  buildStartButton(BuildContext context) {
    final ButtonStyle buttonStyle = ElevatedButton.styleFrom(
        backgroundColor: picoBlue,
        shape: CircleBorder(),
        textStyle: TextStyle(color: Colors.white));

    return Expanded(
      flex: 2,
      child: Container(
          child: SizedBox(
              width: 130,
              height: 130,
              child: ElevatedButton(
                style: buttonStyle,
                onPressed: isError
                    ? null
                    : isProcessing
                        ? _stopProcessing
                        : _startProcessing,
                child: Text(isProcessing ? "Stop" : "Start",
                    style: TextStyle(fontSize: 30)),
              ))),
    );
  }

  buildCheetahTextArea(BuildContext context) {
    return Expanded(
        flex: 6,
        child: Container(
            alignment: Alignment.topCenter,
            color: Color(0xff25187e),
            margin: EdgeInsets.all(10),
            child: SingleChildScrollView(
                controller: _controller,
                scrollDirection: Axis.vertical,
                padding: EdgeInsets.all(10),
                physics: RangeMaintainingScrollPhysics(),
                child: Align(
                    alignment: Alignment.topLeft,
                    child: Text(
                      transcriptText,
                      textAlign: TextAlign.left,
                      style: TextStyle(color: Colors.white, fontSize: 20),
                    )))));
  }

  buildErrorMessage(BuildContext context) {
    return Expanded(
        flex: isError ? 2 : 0,
        child: Container(
            alignment: Alignment.center,
            margin: EdgeInsets.only(left: 20, right: 20),
            padding: EdgeInsets.all(5),
            decoration: !isError
                ? null
                : BoxDecoration(
                    color: Colors.red, borderRadius: BorderRadius.circular(5)),
            child: !isError
                ? null
                : Text(
                    errorMessage,
                    style: TextStyle(color: Colors.white, fontSize: 18),
                  )));
  }

  Widget footer = Expanded(
      flex: 1,
      child: Container(
          alignment: Alignment.bottomCenter,
          padding: EdgeInsets.only(bottom: 20),
          child: const Text(
            "Made in Vancouver, Canada by Picovoice",
            style: TextStyle(color: Color(0xff666666)),
          )));
}