transmet/news/news.go

package news

import (
	"database/sql"
	"fmt"
	"github.com/dballard/transmet/categories"
	_ "github.com/lib/pq"
	"time"
	"errors"
	"strconv"
)

type News struct {
	id          int
	Url         string
	Title       string
	Category_id int
	Date        time.Time
	Notes       string
}

const (
	SQL_NEWS_FIELDS = "id, url, title, category_id, timestamp, notes"
)

/* Storage Node containing:
 *  Name - categry name
 *  News children
 *  Category - category of this node
 *  Children - sub containers: mapped to sub categories
 */
type NewsContainer struct {
	Name     string
	News     []News
	Category *categories.Category
	Children map[int]*NewsContainer
}

/*func New(id int) *News {
	news := &News{}
	news.id = id
	return news
}*/

// Insert News item into DB
func (news *News) Insert(db *sql.DB) error {
	_, err := db.Exec("INSERT INTO news (url, title, category_id, notes) VALUES($1, $2, $3, $4)", news.Url, news.Title, news.Category_id, news.Notes)
	if err != nil {
		fmt.Println("Error inserting news: ", err)
		return err
	}
	return nil
}

// Update updatable parts of news itemn in DB
func (news *News) Update(db *sql.DB) error {
	_, err := db.Exec("UPDATE news SET title=$1, url=$2, category_id=$3, notes=$4 WHERE id=$5", news.Title, news.Url, news.Category_id, news.Notes, news.id)
	if err != nil {
		fmt.Println("Error updating news: ", err)
	}
	return err
}

func Delete(db *sql.DB, id int) error {
	_, err := db.Exec("DELETE FROM news WHERE id = $1", id)
	if err != nil {
		fmt.Println("Error deleting news: ", err)
		return err
	}

	return nil
}

func Get(db *sql.DB, id int) (*News, error) {
	rows, err := db.Query("SELECT " + SQL_NEWS_FIELDS + " FROM news WHERE id=$1", id)

	if err != nil {
		fmt.Println("Error getting news (", id, "): ", err)
		return nil, err
	}
	defer rows.Close()

	var news *News
	if rows.Next() {
		news, err = scanNews(rows)
		if err != nil {
			return nil, err
		}
	}
	return news, err
}

// Load and return in NewsContainer format all the unexported news items
func LoadPage(db *sql.DB, offset, amount int) ([]*News, int, error) {
	categories.LoadCategories(db) // required by addContainer

	rows, err := db.Query("SELECT "+SQL_NEWS_FIELDS+" FROM news order by timestamp DESC")
	if err != nil {
		fmt.Println("DB errpr reading LoadPage news: ", err)
		return nil, 0, err
	}
	defer rows.Close()

	return convertSqlToNews(rows)
}

// Load and return in NewsContainer format all the unexported news items
func Unexported(db *sql.DB) (map[int]*NewsContainer, int, error) {
	categories.LoadCategories(db) // required by addContainer

	rows, err := db.Query("SELECT "+SQL_NEWS_FIELDS+" FROM news WHERE exported is null order by category_id ASC")
	if err != nil {
		fmt.Println("DB errpr reading unexported news: ", err)
		return nil, 0, err
	}
	defer rows.Close()

	return convertSqlToNewsContainer(rows)
}

// Helper fn - formating - math
func (this *NewsContainer) HeaderDepth(start int) int {
	return start + this.Category.Depth()
}

// Mark the current batch (news.exported is null) as exported in this batch (exported = now())
func MarkExported(db *sql.DB) error {
	now := time.Now()

	_, err := db.Exec("UPDATE news SET exported=$1 WHERE exported is null", now)
	if err != nil {
		fmt.Println("DB errror: news.MarkExported():", err)
	}
	return err
}

func (news *News) Id() int {
	return news.id
}

func nullStringToString(str *sql.NullString) string {
	if str.Valid {
		return str.String
	} else {
		return ""
	}
}

func nullBoolToBool(b *sql.NullBool) bool {
	if b.Valid {
		return true
	} else {
		return false
	}
}

// Init and add a news container to the Data Structs
func addContainer(category_id int, flat, tree map[int]*NewsContainer) {
	container := &NewsContainer{Category: categories.CategoriesFlat[category_id], Name: categories.CategoriesFlat[category_id].Name, News: []News{}, Children: map[int]*NewsContainer{}}
	flat[category_id] = container
	parent := categories.CategoriesFlat[category_id].Parent
	if parent.Valid {
		if _, ok := flat[int(parent.Int64)]; !ok {
			addContainer(int(parent.Int64), flat, tree)
		}
		flat[int(parent.Int64)].Children[category_id] = container
	} else {
		tree[category_id] = container
	}
}

func scanNews(rows *sql.Rows) (*News, error) {
	news := &News{}
	var url, title, notes sql.NullString
	var category_id sql.NullInt64
	err := rows.Scan(&news.id, &url, &title, &category_id, &news.Date, &notes)
	if err != nil {
		fmt.Println("Error reading news from DB: " + err.Error())
		return nil, err
	}

	news.Url = nullStringToString(&url)
	news.Title = nullStringToString(&title)
	news.Notes = nullStringToString(&notes)

	if category_id.Valid {
		news.Category_id = int(category_id.Int64)
	} else {
		return nil, errors.New("Error reading news item from DB, no category_id for " + strconv.Itoa(news.Id()))
	}

	return news, nil
}

func convertSqlToNews(rows *sql.Rows) ([]*News, int, error) {
	news := []*News{}
	count := 0
	for rows.Next() {
		newsItem, err := scanNews(rows)

		if err != nil {
			return nil, 0, err
		}

		news = append(news, newsItem)
		count++
	}

	return news, count, nil
}

func convertSqlToNewsContainer(rows *sql.Rows) (map[int]*NewsContainer, int, error) {
	newsTree := map[int]*NewsContainer{}
	newsFlat := map[int]*NewsContainer{}
	count := 0
	for rows.Next() {
		news, err := scanNews(rows)

		if err != nil {
			return nil, 0, err
		}

		if _, ok := newsFlat[news.Category_id]; !ok {
			addContainer(news.Category_id, newsFlat, newsTree)
		}
		container := newsFlat[news.Category_id]
		container.News = append(container.News, *news)
		count++
	}

	return newsTree, count, nil
}