Initial implementation of APKINDEX, fetching, reading, parsing, & merging

Sources/apk/Index/ApkIndexPackage.swift

@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: Apache-2.0
+
+import Foundation
+
+struct ApkIndexPackage {
+  let indexChecksum: String  //TODO: Decode cus why not
+  let name: String
+  let version: String
+  let architecture: String?
+  let packageSize: UInt64
+  let installedSize: UInt64
+  let packageDescription: String
+  let url: String
+  let license: String
+  let origin: String?
+  let maintainer: String?
+  let buildTime: Date?
+  let commit: String?
+  let providerPriority: UInt16?
+  let dependencies: [String]  //TODO: stuff
+  let provides: [String]  //TODO: stuff
+  let installIf: [String]  //TODO: stuff
+
+  var downloadFilename: String { "\(self.name)-\(version).apk" }
+
+  //TODO: Implementation
+  //lazy var semanticVersion: (Int, Int, Int) = (0, 0, 0)
+}
+
+extension ApkIndexPackage {
+  init(raw rawEntry: ApkRawIndexEntry) throws(Self.ParseError) {
+    // Required fields
+    var indexChecksum: String? = nil
+    var name: String? = nil
+    var version: String? = nil
+    var description: String? = nil
+    var url: String? = nil
+    var license: String? = nil
+    var packageSize: UInt64? = nil
+    var installedSize: UInt64? = nil
+
+    var dependencies = [String]()
+    var provides = [String]()
+    var installIf = [String]()
+
+    // Optional fields
+    var architecture: String? = nil
+    var origin: String? = nil
+    var maintainer: String? = nil
+    var buildTime: Date? = nil
+    var commit: String? = nil
+    var providerPriority: UInt16? = nil
+
+    // Read all the raw records for this entry
+    for record in rawEntry.fields {
+      switch record.key {
+      case "P":
+        name = record.value
+      case "V":
+        version = record.value
+      case "T":
+        description = record.value
+      case "U":
+        url = record.value
+      case "L":
+        license = record.value
+      case "A":
+        architecture = record.value
+      case "D":
+        dependencies = record.value.components(separatedBy: " ")
+      case "C":
+        indexChecksum = record.value  // base64-encoded SHA1 hash prefixed with "Q1"
+      case "S":
+        guard let value = UInt64(record.value, radix: 10) else {
+          throw .badValue(key: record.key)
+        }
+        packageSize = value
+      case "I":
+        guard let value = UInt64(record.value, radix: 10) else {
+          throw .badValue(key: record.key)
+        }
+        installedSize = value
+      case "p":
+        provides = record.value.components(separatedBy: " ")
+      case "i":
+        installIf = record.value.components(separatedBy: " ")
+      case "o":
+        origin = record.value
+      case "m":
+        maintainer = record.value
+      case "t":
+        guard let timet = UInt64(record.value, radix: 10),
+            let timetInterval = TimeInterval(exactly: timet) else {
+          throw .badValue(key: record.key)
+        }
+        buildTime = Date(timeIntervalSince1970: timetInterval)
+      case "c":
+        commit = record.value
+      case "k":
+        guard let value = UInt64(record.value, radix: 10),
+            (0..<UInt64(UInt16.max)).contains(value) else {
+          throw .badValue(key: record.key)
+        }
+        providerPriority = UInt16(truncatingIfNeeded: value)
+      case "F", "M", "R", "Z", "r", "q", "a", "s", "f":
+        break // installed db entries
+      default:
+        // Safe to ignore
+        guard record.key.isLowercase else {
+          throw .badValue(key: record.key)
+        }
+      }
+    }
+
+    self.indexChecksum = try indexChecksum.unwrap(or: Self.ParseError.required(key: "C"))
+    self.name = try name.unwrap(or: Self.ParseError.required(key: "P"))
+    self.version = try version.unwrap(or: Self.ParseError.required(key: "V"))
+    self.packageDescription = try description.unwrap(or: Self.ParseError.required(key: "T"))
+    self.url = try url.unwrap(or: Self.ParseError.required(key: "U"))
+    self.license = try license.unwrap(or: Self.ParseError.required(key: "L"))
+    self.packageSize = try packageSize.unwrap(or: Self.ParseError.required(key: "S"))
+    self.installedSize = try installedSize.unwrap(or: Self.ParseError.required(key: "I"))
+
+    self.architecture = architecture
+    self.origin = origin
+    self.maintainer = maintainer
+    self.buildTime = buildTime
+    self.commit = commit
+    self.providerPriority = providerPriority
+
+    self.dependencies = dependencies
+    self.provides = provides
+    self.installIf = installIf
+  }
+
+  public enum ParseError: Error, LocalizedError {
+    case badValue(key: Character)
+    case unexpectedKey(key: Character)
+    case required(key: Character)
+
+    public var errorDescription: String? {
+      switch self {
+      case .badValue(let key):      "Bad value for key \"\(key)\""
+      case .unexpectedKey(let key): "Unexpected key \"\(key)\""
+      case .required(let key):      "Missing required key \"\(key)\""
+      }
+    }
+  }
+}
+
+extension ApkIndexPackage: CustomStringConvertible {
+  var description: String { "pkg(\(self.name))" }
+}
+
+fileprivate extension Optional {
+  func unwrap<E: Error>(or error: @autoclosure () -> E) throws(E) -> Wrapped {
+    switch self {
+    case .some(let v):
+      return v
+    case .none:
+      throw error()
+    }
+  }
+}