This patch sets up the trigger config section of aerc.conf.
Each trigger has its own function which is called from the place where
it is triggered. Currently only the new-email trigger is implemented.
The triggers make use of format strings. For instance, in the new-email
trigger this allows the user to select the trigger command and also the
information extracted from the command and placed into their command.
To actually execute the trigger commands the keypresses are simulated.
Further triggers can be implemented in the future.
Formatting of the command is moved to a new package.
Before, we were using several IMAP-specific concepts to represent
information being displayed in the UI. Factor these structures out of
the IMAP package to make it easier for other backends to provide the
required information.
Before, the information needed to display different parts of the UI was
tightly coupled to the specific messages being sent back and forth to
the backend worker. Separating out a models package allows us to be more
specific about exactly what a backend is able to and required to
provide for the UI.
The current implementation has three classes of flags:
- readFlag
- delFlag
- flaggedFlag
The logic to check for them should be in parallel if branches rather
than in sequential if-else ladder.
