Forumlated potentially useful json schema.

Note that this is based on an earlier state of the project, and the
terms used in this schema may differ from the current state of the project.

software/src/tonberry.schema.json

@@ -0,0 +1,53 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "definitions": {
+        "PlaybackPosition": {
+            "type": "object",
+            "properties": {
+                "position_seconds": { "type": "number" },
+                "device_uptime": { "type": "number" }
+            },
+            "required": ["position_seconds"]
+        },
+        "AudioFile": {
+            "type": "object",
+            "properties": {
+                "id": { "type": "string", "format": "uuid" },
+                "filename": { "type": "string" },
+                "size_bytes": { "type": "integer" },
+                "duration_seconds": { "type": "number" },
+                "last_played_uptime": { "type": "number" },
+                "playback_position": { "$ref": "#/definitions/PlaybackPosition" }
+            },
+            "required": ["id", "filename"]
+        },
+        "Playlist": {
+            "type": "object",
+            "properties": {
+                "id": { "type": "string", "format": "uuid" },
+                "name": { "type": "string" },
+                "audio_files": {
+                    "type": "array",
+                    "items": { "$ref": "#/definitions/AudioFile" }
+                },
+                "current_track_index": { "type": "integer", "minimum": 0 },
+                "last_played_uptime": { "type": "number" },
+                "playback_position": { "$ref": "#/definitions/PlaybackPosition" }
+            },
+            "required": ["id", "name", "audio_files"]
+        },
+        "NfcTag": {
+            "type": "object",
+            "properties": {
+                "uid": { "type": "string" },
+                "name": { "type": "string" },
+                "linked_type": {
+                    "type": "string",
+                    "enum": ["audio_file", "playlist"]
+                },
+                "linked_id": { "type": "string", "format": "uuid" }
+            },
+            "required": ["uid", "linked_type", "linked_id"]
+        }
+    }
+}