NetNewsWire/Frameworks/Database/ArticlesTable.swift

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//
// ArticlesTable.swift
// Evergreen
//
// Created by Brent Simmons on 5/9/16.
// Copyright © 2016 Ranchero Software, LLC. All rights reserved.
//
import Foundation
import RSCore
import RSDatabase
import RSParser
import Data
final class ArticlesTable: DatabaseTable {
let name: String
let databaseIDKey = DatabaseKey.articleID
private weak var account: Account?
private let queue: RSDatabaseQueue
private let statusesTable: StatusesTable
private let authorsLookupTable: DatabaseLookupTable
private let attachmentsLookupTable: DatabaseLookupTable
private let tagsLookupTable: DatabaseLookupTable
private let articleCache = ArticleCache()
init(name: String, account: Account, queue: RSDatabaseQueue) {
self.name = name
self.account = account
self.queue = queue
self.statusesTable = StatusesTable(name: DatabaseTableName.statuses)
let authorsTable = AuthorsTable(name: DatabaseTableName.authors)
self.authorsLookupTable = DatabaseLookupTable(name: DatabaseTableName.authorsLookup, objectIDKey: DatabaseKey.articleID, relatedObjectIDKey: DatabaseKey.authorID, relatedTable: authorsTable, relationshipName: RelationshipName.authors)
let tagsTable = TagsTable(name: DatabaseTableName.tags)
self.tagsLookupTable = DatabaseLookupTable(name: DatabaseTableName.tags, objectIDKey: DatabaseKey.articleID, relatedObjectIDKey: DatabaseKey.tagName, relatedTable: tagsTable, relationshipName: RelationshipName.tags)
let attachmentsTable = AttachmentsTable(name: DatabaseTableName.attachments)
self.attachmentsLookupTable = DatabaseLookupTable(name: DatabaseTableName.attachmentsLookup, objectIDKey: DatabaseKey.articleID, relatedObjectIDKey: DatabaseKey.attachmentID, relatedTable: attachmentsTable, relationshipName: RelationshipName.attachments)
}
// MARK: DatabaseTable Methods
func objectWithRow(_ row: FMResultSet) -> DatabaseObject? {
if let article = articleWithRow(row) {
return article as DatabaseObject
}
return nil
}
func save(_ objects: [DatabaseObject], in database: FMDatabase) {
// TODO
}
// MARK: Fetching
func fetchArticles(_ feed: Feed) -> Set<Article> {
let feedID = feed.feedID
var articles = Set<Article>()
queue.fetchSync { (database: FMDatabase!) -> Void in
articles = self.fetchArticlesForFeedID(feedID, database: database)
}
return articleCache.uniquedArticles(articles)
}
func fetchArticlesAsync(_ feed: Feed, _ resultBlock: @escaping ArticleResultBlock) {
let feedID = feed.feedID
queue.fetch { (database: FMDatabase!) -> Void in
let fetchedArticles = self.fetchArticlesForFeedID(feedID, database: database)
DispatchQueue.main.async {
let articles = self.articleCache.uniquedArticles(fetchedArticles)
resultBlock(articles)
}
}
}
func fetchUnreadArticles(for feeds: Set<Feed>) -> Set<Article> {
return fetchUnreadArticles(feeds.feedIDs())
}
// MARK: Updating
func update(_ feed: Feed, _ parsedFeed: ParsedFeed, _ completion: @escaping RSVoidCompletionBlock) {
// TODO
}
// MARK: Unread Counts
func fetchUnreadCounts(_ feeds: Set<Feed>, _ completion: @escaping UnreadCountCompletionBlock) {
// TODO
}
// MARK: Status
func mark(_ articles: Set<Article>, _ statusKey: String, _ flag: Bool) {
// Sets flag in both memory and in database.
let articleIDs = articles.flatMap { (article) -> String? in
guard let status = article.status else {
assertionFailure("Each article must have a status.")
return nil
}
if status.boolStatus(forKey: statusKey) == flag {
return nil
}
status.setBoolStatus(flag, forKey: statusKey)
return article.articleID
}
if articleIDs.isEmpty {
return
}
queue.update { (database) in
self.statusesTable.markArticleIDs(Set(articleIDs), statusKey, flag, database)
}
}
// typealias FeedCountCallback = (Int) -> Void
//
// func numberOfArticlesWithFeedID(_ feedID: String, callback: @escaping FeedCountCallback) {
//
// queue.fetch { (database: FMDatabase!)
//
// let sql = "select count(*) from articles where feedID = ?;"
// var numberOfArticles = -1
//
// if let resultSet = database.executeQuery(sql, withArgumentsIn: [feedID]) {
//
// while (resultSet.next()) {
// numberOfArticles = resultSet.long(forColumnIndex: 0)
// break
// }
// }
//
// DispatchQueue.main.async() {
// callback(numberOfArticles)
// }
// }
//
// }
}
// MARK: -
private extension ArticlesTable {
// MARK: Fetching
func attachRelatedObjects(_ articles: Set<Article>, _ database: FMDatabase) {
let articleArray = articles.map { $0 as DatabaseObject }
authorsLookupTable.attachRelatedObjects(to: articleArray, in: database)
attachmentsLookupTable.attachRelatedObjects(to: articleArray, in: database)
tagsLookupTable.attachRelatedObjects(to: articleArray, in: database)
// In theory, its impossible to have a fetched article without a status.
// Lets handle that impossibility anyway.
// Remember that, if nothing else, the user can edit the SQLite database,
// and thus could delete all their statuses.
statusesTable.ensureStatusesForArticles(articles, database)
}
func articleWithRow(_ row: FMResultSet) -> Article? {
guard let account = account else {
return nil
}
guard let article = Article(row: row, account: account) else {
return nil
}
// Note: the row is a result of a JOIN query with the statuses table,
// so we can get the status at the same time and avoid additional database lookups.
article.status = statusesTable.statusWithRow(row)
return article
}
func articlesWithResultSet(_ resultSet: FMResultSet, _ database: FMDatabase) -> Set<Article> {
let articles = resultSet.mapToSet(articleWithRow)
attachRelatedObjects(articles, database)
return articles
}
func fetchArticlesWithWhereClause(_ database: FMDatabase, whereClause: String, parameters: [AnyObject]) -> Set<Article> {
let sql = "select * from articles natural join statuses where \(whereClause);"
return articlesWithSQL(sql, parameters, database)
}
func fetchArticlesForFeedID(_ feedID: String, database: FMDatabase) -> Set<Article> {
return fetchArticlesWithWhereClause(database, whereClause: "articles.feedID = ?", parameters: [feedID as AnyObject])
}
func fetchUnreadArticles(_ feedIDs: Set<String>) -> Set<Article> {
if feedIDs.isEmpty {
return Set<Article>()
}
var articles = Set<Article>()
queue.fetchSync { (database) in
// select * from articles natural join statuses where feedID in ('http://ranchero.com/xml/rss.xml') and read=0
let parameters = feedIDs.map { $0 as AnyObject }
let placeholders = NSString.rs_SQLValueList(withPlaceholders: UInt(feedIDs.count))!
let whereClause = "feedID in \(placeholders) and read=0"
articles = self.fetchArticlesWithWhereClause(database, whereClause: whereClause, parameters: parameters)
}
return articleCache.uniquedArticles(articles)
}
func articlesWithSQL(_ sql: String, _ parameters: [AnyObject], _ database: FMDatabase) -> Set<Article> {
guard let resultSet = database.executeQuery(sql, withArgumentsIn: parameters) else {
return Set<Article>()
}
return articlesWithResultSet(resultSet, database)
}
}
// MARK: -
private struct ArticleCache {
// Main thread only unlike the other object caches.
// The cache contains a given article only until all outside references are gone.
// Cache key is articleID.
private let articlesMapTable: NSMapTable<NSString, Article> = NSMapTable.weakToWeakObjects()
func uniquedArticles(_ articles: Set<Article>) -> Set<Article> {
var articlesToReturn = Set<Article>()
for article in articles {
let articleID = article.articleID
if let cachedArticle = cachedArticle(for: articleID) {
articlesToReturn.insert(cachedArticle)
}
else {
articlesToReturn.insert(article)
addToCache(article)
}
}
// At this point, every Article must have an attached Status.
assert(articlesToReturn.eachHasAStatus())
return articlesToReturn
}
private func cachedArticle(for articleID: String) -> Article? {
return articlesMapTable.object(forKey: articleID as NSString)
}
private func addToCache(_ article: Article) {
articlesMapTable.setObject(article, forKey: article.articleID as NSString)
}
}