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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
import UIKit
protocol ImageHandler {
/// The ImageHandler will fetch the favicon with the following precedence:
/// 1. Tries to fetch from the bundle.
/// 2. Tries to fetch from the cache.
/// 3. Tries to fetch from the favicon fetcher (from the web) if there's a URL.
/// If there's no URL it fallbacks to the letter favicon.
/// 4. When all fails it returns the letter favicon.
///
/// Any time the favicon is fetched, it will be cache for future usage.
///
/// - Parameters:
/// - imageURL: The image URL, can be nil if it could not be retrieved from the site
/// - domain: The domain this favicon will be associated with
/// - Returns: The favicon image
func fetchFavicon(site: SiteImageModel) async -> UIImage
/// The ImageHandler will fetch the hero image with the following precedence
/// 1. Tries to fetch from the cache.
/// 2. Tries to fetch from the hero image fetcher (from the web).
/// 3. If all fails it throws an error
///
/// Any time the hero image is fetched, it will be cache for future usage.
/// - Parameters:
/// - siteURL: The site URL to fetch the hero image from
/// - domain: The domain this hero image will be associated with
/// - Returns: The hero image
func fetchHeroImage(site: SiteImageModel) async throws -> UIImage
/// Clears the image cache
func clearCache()
}
class DefaultImageHandler: ImageHandler {
private let bundleImageFetcher: BundleImageFetcher
private let imageCache: SiteImageCache
private let faviconFetcher: FaviconFetcher
private let letterImageGenerator: LetterImageGenerator
private let heroImageFetcher: HeroImageFetcher
init(bundleImageFetcher: BundleImageFetcher = DefaultBundleImageFetcher(),
imageCache: SiteImageCache = DefaultSiteImageCache(),
faviconFetcher: FaviconFetcher = DefaultFaviconFetcher(),
letterImageGenerator: LetterImageGenerator = DefaultLetterImageGenerator(),
heroImageFetcher: HeroImageFetcher = DefaultHeroImageFetcher()) {
self.bundleImageFetcher = bundleImageFetcher
self.imageCache = imageCache
self.faviconFetcher = faviconFetcher
self.letterImageGenerator = letterImageGenerator
self.heroImageFetcher = heroImageFetcher
}
func fetchFavicon(site: SiteImageModel) async -> UIImage {
do {
return try bundleImageFetcher.getImageFromBundle(domain: site.domain)
} catch {
return await fetchFaviconFromCache(site: site)
}
}
func fetchHeroImage(site: SiteImageModel) async throws -> UIImage {
do {
return try await imageCache.getImageFromCache(cacheKey: site.cacheKey, type: .heroImage)
} catch {
return try await fetchHeroImageFromFetcher(site: site)
}
}
func clearCache() {
Task {
await self.imageCache.clearCache()
}
}
// MARK: Private
private func fetchFaviconFromCache(site: SiteImageModel) async -> UIImage {
do {
return try await imageCache.getImageFromCache(cacheKey: site.cacheKey, type: site.expectedImageType)
} catch {
return await fetchFaviconFromFetcher(site: site)
}
}
private func fetchFaviconFromFetcher(site: SiteImageModel) async -> UIImage {
do {
guard let url = site.faviconURL else {
return await fallbackToLetterFavicon(site: site)
}
let image = try await faviconFetcher.fetchFavicon(from: url)
await imageCache.cacheImage(image: image, cacheKey: site.cacheKey, type: site.expectedImageType)
return image
} catch {
return await fallbackToLetterFavicon(site: site)
}
}
private func fetchHeroImageFromFetcher(site: SiteImageModel) async throws -> UIImage {
guard let siteURL = site.siteURL else {
throw SiteImageError.noHeroImage
}
do {
let image = try await heroImageFetcher.fetchHeroImage(from: siteURL)
await imageCache.cacheImage(image: image, cacheKey: site.cacheKey, type: .heroImage)
return image
} catch {
throw SiteImageError.noHeroImage
}
}
private func fallbackToLetterFavicon(site: SiteImageModel) async -> UIImage {
do {
let image = try await letterImageGenerator.generateLetterImage(siteString: site.cacheKey)
await imageCache.cacheImage(image: image, cacheKey: site.cacheKey, type: site.expectedImageType)
return image
} catch {
return UIImage(named: "globeLarge")?.withRenderingMode(.alwaysTemplate) ?? UIImage()
}
}
}