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MainViewModel documentation and image caching improvements

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Vicnet
2023-09-16 20:11:02 +02:00
parent fd2c67809a
commit 3504ce2a25
9 changed files with 166 additions and 71 deletions
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149
Nextcloud Cookbook iOS Client/ViewModels/MainViewModel.swift
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@@ -17,23 +17,45 @@ import UIKit
let dataStore: DataStore
let networkController: NetworkController
/// The path of an image in storage
private var localImagePath: (Int, Bool) -> (String) = { recipeId, full in
return "image\(recipeId)_\(full ? "full" : "thumb")"
}
/// The path of an image on the server
private var networkImagePath: (Int, Bool) -> (String) = { recipeId, full in
return "recipes/\(recipeId)/image?size=\(full ? "full" : "thumb")"
}
init() {
self.networkController = NetworkController()
self.dataStore = DataStore()
}
/// Try to load the category list from store or the server.
/// - Parameters
/// - needsUpdate: If true, the recipe will be loaded from the server directly, otherwise it will be loaded from store first.
func loadCategoryList(needsUpdate: Bool = false) async {
if let categoryList: [Category] = await load(localPath: "categories.data", networkPath: "categories", needsUpdate: needsUpdate) {
self.categories = categoryList
}
}
/// Try to load the recipe list from store or the server.
/// - Parameters
/// - categoryName: The name of the category containing the requested list of recipes.
/// - needsUpdate: If true, the recipe will be loaded from the server directly, otherwise it will be loaded from store first.
func loadRecipeList(categoryName: String, needsUpdate: Bool = false) async {
if let recipeList: [Recipe] = await load(localPath: "category_\(categoryName).data", networkPath: "category/\(categoryName)", needsUpdate: needsUpdate) {
recipes[categoryName] = recipeList
}
}
/// Try to load the recipe details from cache. If not found, try to load from store or the server.
/// - Parameters
/// - recipeId: The id of the recipe.
/// - needsUpdate: If true, the recipe will be loaded from the server directly, otherwise it will be loaded from cache/store first.
/// - Returns: RecipeDetail struct. If not found locally, and unable to load from server, a RecipeDetail struct containing an error message.
func loadRecipeDetail(recipeId: Int, needsUpdate: Bool = false) async -> RecipeDetail {
if !needsUpdate {
if let recipeDetail = recipeDetails[recipeId] {
@@ -47,50 +69,40 @@ import UIKit
return RecipeDetail.error()
}
/// Try to load the recipe image from cache. If not found, try to load from store or the server.
/// - Parameters
/// - recipeId: The id of a recipe.
/// - full: If true, load the full resolution image. Otherwise, load a thumbnail-sized image.
/// - needsUpdate: Determines wether the image should be loaded directly from the server, or if it should be loaded from cache/store first.
/// - Returns: The image if found locally or on the server, otherwise nil.
func loadImage(recipeId: Int, full: Bool, needsUpdate: Bool = false) async -> UIImage? {
print("loadImage(recipeId: \(recipeId), full: \(full)")
// Check if image is in image cache
if !needsUpdate, let recipeImage = imageCache[recipeId] {
if full {
if let fullImage = recipeImage.full {
return recipeImage.full
}
} else {
return recipeImage.thumb
print("loadImage(recipeId: \(recipeId), full: \(full))")
// If the image needs an update, request it from the server and overwrite the stored image
if needsUpdate {
if let data = await imageDataFromServer(recipeId: recipeId, full: full) {
guard let image = UIImage(data: data) else { return nil }
await dataStore.save(data: data.base64EncodedString(), toPath: localImagePath(recipeId, full))
imageToCache(image: image, recipeId: recipeId, full: full)
return image
}
}
// If image is not in image cache, request from local storage
do {
let localPath = "image\(recipeId)_\(full ? "full" : "thumb")"
if !needsUpdate, let data: String = try await dataStore.load(fromPath: localPath) {
print("Image data found locally. Decoding ...")
guard let dataDecoded = Data(base64Encoded: data) else { return nil }
print("Data to UIImage ...")
let image = UIImage(data: dataDecoded)
print("Done.")
return image
} else {
// If image is not in local storage, request from server
let networkPath = "recipes/\(recipeId)/image?size=full"
let request = RequestWrapper(method: .GET, path: networkPath, accept: .IMAGE)
let (data, error): (Data?, Error?) = try await networkController.sendHTTPRequest(path: request.path, request)
guard let data = data else {
print("Error receiving or decoding data.")
print("Error Message: \n", error)
return nil
}
let image = UIImage(data: data)
if image != nil {
print("Saving image loaclly ...")
try await dataStore.save(data: data.base64EncodedString(), toPath: localPath)
}
print("Done.")
return image
}
}catch {
print("An unknown error occurred.")
// Try to load image from cache
print("Attempting to load image from local storage ...")
if let image = imageFromCache(recipeId: recipeId, full: full) {
return image
}
// Try to load from store
print("Attempting to load image from server ...")
if let image = await imageFromStore(recipeId: recipeId, full: full) {
return image
}
// Try to load from the server. Store if successfull.
if let data = await imageDataFromServer(recipeId: recipeId, full: full) {
guard let image = UIImage(data: data) else { return nil }
await dataStore.save(data: data.base64EncodedString(), toPath: localImagePath(recipeId, full))
imageToCache(image: image, recipeId: recipeId, full: full)
return image
}
return nil
}
@@ -108,7 +120,7 @@ extension MainViewModel {
} else {
let request = RequestWrapper(method: .GET, path: networkPath)
let (data, error): (D?, Error?) = await networkController.sendDataRequest(request)
print(error)
print(error as Any)
if let data = data {
try await dataStore.save(data: data, toPath: localPath)
}
@@ -119,6 +131,59 @@ extension MainViewModel {
}
return nil
}
private func imageToCache(image: UIImage, recipeId: Int, full: Bool) {
if imageCache[recipeId] == nil {
imageCache[recipeId] = RecipeImage()
}
if full {
imageCache[recipeId]!.full = image
} else {
imageCache[recipeId]!.thumb = image
}
}
private func imageFromCache(recipeId: Int, full: Bool) -> UIImage? {
if imageCache[recipeId] != nil {
if full {
return imageCache[recipeId]!.full
} else {
return imageCache[recipeId]!.thumb
}
}
return nil
}
private func imageFromStore(recipeId: Int, full: Bool) async -> UIImage? {
do {
let localPath = localImagePath(recipeId, full)
if let data: String = try await dataStore.load(fromPath: localPath) {
guard let dataDecoded = Data(base64Encoded: data) else { return nil }
let image = UIImage(data: dataDecoded)
return image
}
} catch {
print("Could not find image in local storage.")
return nil
}
return nil
}
private func imageDataFromServer(recipeId: Int, full: Bool) async -> Data? {
do {
let networkPath = networkImagePath(recipeId, full)
let request = RequestWrapper(method: .GET, path: networkPath, accept: .IMAGE)
let (data, _): (Data?, Error?) = try await networkController.sendHTTPRequest(path: request.path, request)
guard let data = data else {
print("Error receiving or decoding data.")
return nil
}
return data
} catch {
print("Could not load image from server.")
}
return nil
}
}