// Generate CSV from Google Books queries.
// authors, title, publishedDate, publisher, ISBN-13, ISBN-10, URL
package main

import (
	"bufio"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"log"
	"os"
	"strings"
)

func readFile(name string) []byte {
	in, err := os.Open(name)
	if err != nil {
		log.Fatal(err)
	}
	defer in.Close()
	body, err := io.ReadAll(in)
	if err != nil {
		log.Fatal(err)
	}

	return body
}

func write(writer *bufio.Writer, contents string) {
	_, err := writer.Write([]byte(contents))
	if err != nil {
		log.Fatal(err)
	}
}

/* Unnecessary complication.
Only one entry needs to be in memory at a time.
type Entry struct {
	authors: string
	title: string
	publishedDate: string
	isbn13: string
	isbn10: string
	url: string
}*/

func main() {
	// Read a list of file names, named after google books queries
	var fullTitle, authors, publishedDate, isbn13, isbn10, url string

	for _, title := range strings.Split(string(readFile("list")), "\n") {
		if (len(title) < 3) {
			continue
		}

		fmt.Println(title)

		// For each title, create csv file
		var out *os.File
		_, err := os.Stat(title + ".csv")
		if errors.Is(err, fs.ErrNotExist) {
			//log.Print(err)
			out, err = os.Create(title + ".csv")
			if err != nil {
				log.Fatal(err)
			}
		} else if err != nil {
			log.Fatal(err)
		} else {
			out, err = os.Open(title + ".csv")
			if err != nil {
				log.Fatal(err)
			}
		}
		defer out.Close()

		outWriter := bufio.NewWriter(out)
		//outWriter := bufio.NewWriter(os.Stdout)

		// Print CSV header
		write(outWriter, "Title, Authors, Published Date, ISBN-13, ISBN-10, URL\n")
		defer outWriter.Flush()

		// In each provided file, JSON results
		rawJson := readFile(title)
		var data interface{}
		// Parse the JSON into an associative array
		json.Unmarshal(rawJson, &data)
		// Get through the cruft
		m := data.(map[string]interface{})
		for _, subm := range m["items"].([]interface{}) {
			switch subm.(type) {
			case map[string]interface{}:
				m := subm.(map[string]interface{})
				m = m["volumeInfo"].(map[string]interface{})
				isbns := m["industryIdentifiers"].([]interface{})
				for _, v := range isbns {
					isbn := v.(map[string]interface{})
					isbnText := isbn["identifier"].(string)
					// ISBN-10 is sometimes 9 digits, ISBN-13 is always 13 digits
					if len(isbnText) == 13 {
						isbn13 = isbnText
					} else {
						isbn10 = isbnText
					}
				}

				if m["authors"] != nil {
					authorsMap := m["authors"].([]interface{})
					for i, author := range authorsMap {
						authorText := author.(string)
						if i > 0 {
							authors += " & "
							authors += authorText
						} else {
							authors = authorText
						}
					}
				}

				fullTitle = strings.Replace(m["title"].(string), ",", "", -1)
				if m["publishedDate"] != nil {
					publishedDate = m["publishedDate"].(string)
				}
				url = m["infoLink"].(string)
			default:
			}
			write(outWriter, fmt.Sprintf("%s,%s,%s,%s,%s,%s\n", fullTitle, authors, publishedDate, isbn13, isbn10, url))

		}
	}
}