producer.go

package main

import (
	"bufio"
	"errors"
	"fmt"
	"os"
)

// Producer struct
type Producer struct {
	channel        chan string
	quit           chan bool
	delimiters     []string
	preAndSuffixes []string
}

// NewProducer initializer
func NewProducer(preAndSuffixesFile string, wordChannel chan string, quit chan bool) (*Producer, error) {
	producer := &Producer{
		channel:    wordChannel,
		quit:       quit,
		delimiters: []string{"-", "_", ".", ""},
	}

	contents, err := readFile(preAndSuffixesFile)
	if err != nil {
		return nil, errors.New("failed to read pre- and suffixes file")
	}

	producer.preAndSuffixes = contents

	return producer, nil
}

// ProduceWordList produces candidate bucket names to the channel.
func (p *Producer) ProduceWordList(names []string, list string) {
	for _, n := range names {
		p.channel <- n
	}

	file, err := os.Open(list)
	if err != nil {
		fmt.Fprintf(os.Stderr, "[error] %v\n", err)
		os.Exit(1)
	}

	defer file.Close()

	scanner := bufio.NewScanner(file)

	for scanner.Scan() {
		line := scanner.Text()

		for _, n := range names {
			p.Produce(n, line)
		}
	}

	close(p.channel)
}

// Produce produces candidates
func (p *Producer) Produce(name, word string) {
	for _, ca := range p.PrepareCandidateBucketNames(name, word) {
		p.channel <- ca
	}
}

// PrepareCandidateBucketNames creates all candidate pairs
func (p *Producer) PrepareCandidateBucketNames(name, word string) []string {
	result := []string{}

	for _, del := range p.delimiters {
		cand1 := fmt.Sprintf("%s%s%s", name, del, word)
		cand2 := fmt.Sprintf("%s%s%s", word, del, name)

		result = append(result, cand1)
		result = append(result, cand2)

		for _, ca := range p.preAndSuffixes {
			result = append(result, fmt.Sprintf("%s%s%s", cand1, del, ca))
			result = append(result, fmt.Sprintf("%s%s%s", ca, del, cand1))

			result = append(result, fmt.Sprintf("%s%s%s", cand2, del, ca))
			result = append(result, fmt.Sprintf("%s%s%s", ca, del, cand2))
		}
	}

	return result
}

func readFile(path string) ([]string, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, err
	}

	defer file.Close()

	var lines []string

	scanner := bufio.NewScanner(file)

	for scanner.Scan() {
		lines = append(lines, scanner.Text())
	}

	return lines, scanner.Err()
}