mac/log: fallback to system logger if no mp_log is yet available

since cocoa is initialising mpv and does several things before the mpv
core does anything and the mpv_handle was passed to the App, this can be
used to log such things before the mpv logging is available. helpful for
debugging especially bundle related things.

the logger mapping looks a bit unintuitive but error is basically yellow
what our warning is and fatal is red what our error is.

osdep/mac/app_hub.swift

@@ -22,6 +22,7 @@ class AppHub: NSObject {
 
     var mpv: OpaquePointer?
     var input: InputHelper
+    var log: LogHelper
     var option: OptionHelper?
     var event: EventHelper?
     var menu: MenuBar?
@@ -39,6 +40,7 @@ class AppHub: NSObject {
 
     private override init() {
         input = InputHelper()
+        log = LogHelper()
         super.init()
         if isApplication { menu = MenuBar(self) }
 #if HAVE_MACOS_MEDIA_PLAYER
@@ -47,6 +49,7 @@ class AppHub: NSObject {
     }
 
     @objc func initMpv(_ mpv: OpaquePointer) {
+        log.log = mp_log_new(UnsafeMutablePointer(mpv), mp_client_get_log(mpv), "app")
         option = OptionHelper(UnsafeMutablePointer(mpv), mp_client_get_global(mpv))
         input.option = option
         event = EventHelper(self, mpv)

osdep/mac/log_helper.swift

@@ -16,11 +16,20 @@
  */
 
 import Cocoa
+import os
 
 class LogHelper {
     var log: OpaquePointer?
+    let logger = Logger(subsystem: "io.mpv", category: "mpv")
 
-    init(_ log: OpaquePointer?) {
+    let loggerMapping: [Int:OSLogType] = [
+        MSGL_V: .debug,
+        MSGL_INFO: .info,
+        MSGL_WARN: .error,
+        MSGL_ERR: .fault,
+    ]
+
+    init(_ log: OpaquePointer? = nil) {
         self.log = log
     }
 
@@ -41,6 +50,11 @@ class LogHelper {
     }
 
     func send(message: String, type: Int) {
+        guard let log = log, UnsafeRawPointer(log).load(as: UInt8.self) != 0 else {
+            logger.log(level: loggerMapping[type] ?? .default, "\(message, privacy: .public)")
+            return
+        }
+
         let args: [CVarArg] = [(message as NSString).utf8String ?? "NO MESSAGE"]
         mp_msg_va(log, Int32(type), "%s\n", getVaList(args))
     }