// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements.  See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You 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.

// beam-playground:
//   name: pardo-one-to-many
//   description: ParDo one-to-many example.
//   multifile: false
//   context_line: 38
//   categories:
//     - Quickstart
//   complexity: MEDIUM
//   tags:
//     - hellobeam

package main

import (
	"context"
	"github.com/apache/beam/sdks/v2/go/pkg/beam"
	"github.com/apache/beam/sdks/v2/go/pkg/beam/log"
	"github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
	"github.com/apache/beam/sdks/v2/go/pkg/beam/x/debug"
	"strings"
)

func main() {
	p, s := beam.NewPipelineWithRoot()

	// List of elements
	input := beam.Create(s, "Hello Beam", "It is awesome")

	// The applyTransform() converts [input] to [output]
	output := applyTransform(s, input)

	debug.Print(s, output)

	err := beamx.Run(context.Background(), p)

	if err != nil {
		log.Exitf(context.Background(), "Failed to execute job: %v", err)
	}
}

// The applyTransform() using ParDo with tokenize function
func applyTransform(s beam.Scope, input beam.PCollection) beam.PCollection {
	return beam.ParDo(s, tokenizeFn, input)
}

// The tokenizeFn() divides a sentence into an array of words
func tokenizeFn(input string, emit func(out string)) {
	tokens := strings.Split(input, " ")
	for _, k := range tokens {
		emit(k)
	}
}
