Add LCPService.injectLicense() (#664)

Author: qnga

CHANGELOG.md

@@ -18,6 +18,7 @@ All notable changes to this project will be documented in this file. Take a look
 * Added an initializer parameter for providing a custom device identifier (contributed by [@dewantawsif](https://github.com/readium/swift-toolkit/pull/661)).
     * You must ensure the identifier is unique and stable for the device (persist and reuse across app launches).
     * Recommended: generate an app-scoped UUID and store it securely (e.g., in the Keychain); avoid hardware or advertising identifiers.
+* You can use `LCPService.injectLicenseDocument(_:in)` to insert an LCPL into a package, if you downloaded it manually instead of using `LCPService.acquirePublication()`.
 
 ### Changed
 

Sources/LCP/LCPService.swift

@@ -80,6 +80,18 @@ public final class LCPService: Loggable {
         }
     }
 
+    /// Injects a `licenseDocument` into a publication package at `url`.
+    ///
+    /// This is useful if you downloaded the publication yourself instead of using `acquirePublication`.
+    public func injectLicenseDocument(
+        _ license: LicenseDocument,
+        in url: FileURL
+    ) async -> Result<Void, LCPError> {
+        await wrap {
+            try await licenses.injectLicenseDocument(license, in: url)
+        }
+    }
+
     /// Opens the LCP license of a protected publication, to access its DRM
     /// metadata and decipher its content.
     ///

Sources/LCP/Services/LicensesService.swift

@@ -120,26 +120,47 @@ final class LicensesService: Loggable {
             onProgress: { onProgress(.percent(Float($0))) }
         ).get()
 
-        var hints = FormatHints()
-        if let type = license.link(for: .publication)?.mediaType {
-            hints.mediaTypes.append(type)
+        let format = try await injectLicenseAndGetFormat(
+            license,
+            in: download.location,
+            mediaTypeHint: download.mediaType
+        )
+
+        return LCPAcquiredPublication(
+            localURL: download.location,
+            format: format,
+            suggestedFilename: format.fileExtension.appendedToFilename(license.id),
+            licenseDocument: license
+        )
+    }
+
+    func injectLicenseDocument(
+        _ license: LicenseDocument,
+        in url: FileURL
+    ) async throws {
+        let _ = try await injectLicenseAndGetFormat(license, in: url, mediaTypeHint: nil)
+    }
+
+    private func injectLicenseAndGetFormat(
+        _ license: LicenseDocument,
+        in url: FileURL,
+        mediaTypeHint: MediaType? = nil
+    ) async throws -> Format {
+        var formatHints = FormatHints()
+        if let type = license.publicationLink.mediaType {
+            formatHints.mediaTypes.append(type)
         }
-        if let type = download.mediaType {
-            hints.mediaTypes.append(type)
+        if let type = mediaTypeHint {
+            formatHints.mediaTypes.append(type)
         }
 
-        let asset = try await assetRetriever.retrieve(url: download.location, hints: hints)
+        let asset = try await assetRetriever.retrieve(url: url, hints: formatHints)
             .mapError { LCPError.licenseContainer(ContainerError.openFailed($0)) }
             .get()
 
         try await injectLicense(license, in: asset)
 
-        return LCPAcquiredPublication(
-            localURL: download.location,
-            format: asset.format,
-            suggestedFilename: asset.format.fileExtension.appendedToFilename(license.id),
-            licenseDocument: license
-        )
+        return asset.format
     }
 
     private func readLicense(from lcpl: LicenseDocumentSource) async throws -> LicenseDocument? {