Add spec for stale file check, in regards to issue #2

Author: dark-nova

README.md

@@ -82,13 +82,25 @@ Make sure to fill in all the fields in [config.json](config.json.example).
 - `"length"`: integer; length of the digital photo frame display, in pixels
 - `"destination"`: string; must be a valid path (relative or absolute) that can be parsed by `pathlib.Path`
 
-Optional configuration:
+### Optional configuration
+
+**Quiet Hours**
 
 - `"quiet_start"`: integer; when quiet hours should start; requests (except for `GET` `QuietHours`) will not be fulfilled during this time
 - `"quiet_end"`: integer; when quiet hours should end; requests will resume
 
 ⚠ If you intend to use quiet hours, both quiet hours fields must be defined and not also be the same as each other. You cannot define only one field.
 
+**Stale File Check**
+
+- `"stale_check"`: boolean; whether to enable stale file checking (default: `false`)
+- `"stale_threshold"`: integer; how long time in hours must pass since the last file update (default: `0`)
+- `"stale_follow_quiet_hours"`: boolean; whether quiet hours should affect the check (see note below) (default: `false`)
+
+⚠ If you intend to use the stale file check, both `"stale_check"` and `stale_threshold"` must be set and not their respective default values.
+
+⚠ If `"stale_follow_quiet_hours"` is set to `true`, the file check will subtly change: it will no longer run when quiet hours are in effect, and the threshold will subtract the quiet hours that have elapsed since the last file update.
+
 ## Disclaimer
 
 This project is not affiliated with or endorsed by [Leed's] or [the Raspberry Pi Foundation][RPI]. See [LICENSE](LICENSE) for more detail.

config.json.example

@@ -3,5 +3,8 @@
     "length": 234,
     "destination": "/path/to/destination",
     "quiet_start": 21,
-    "quiet_end": 7
+    "quiet_end": 7,
+    "stale_check": false,
+    "stale_threshold": 0,
+    "stale_follow_quiet_hours": false
 }

photo_dash/config.py

@@ -78,4 +78,27 @@
 except (KeyError, ValueError):
     LOGGER.info('Quiet hours are disabled.')
     LOGGER.info('They may have been malformed or missing.')
+    LOGGER.info('To enable quiet hours, make sure both fields are filled in')
+    LOGGER.info('and both values should not be the same.')
     QUIET_HOURS = None
+
+
+try:
+    STALE_CHECK = CONFIG['stale_check']
+    STALE_THRESHOLD = CONFIG['stale_threshold']
+    if type(STALE_THRESHOLD) is not int or STALE_THRESHOLD < 1:
+        raise ValueError
+    try:
+        STALE_FOLLOW_QUIET_HOURS = CONFIG['stale_follow_quiet_hours']
+    except KeyError:
+        LOGGER.info('Quiet hours check in stale file check was not set, so')
+        LOGGER.info('quiet hours will not be checked in stale file check.')
+        STALE_FOLLOW_QUIET_HOURS = False
+except KeyError:
+    LOGGER.info('Stale file check is disabled.')
+    LOGGER.info('To enable stale file check, make sure stale_check is `true`')
+    LOGGER.info('and `stale_threshold` isn\'t 0.')
+    STALE_CHECK = False
+except ValueError:
+    LOGGER.info('Stale file check is disabled.')
+    LOGGER.info('Set `stale_threshold` a number above 0.')