# notcoal - notmuch filters, not made from (char)coal
`notcoal` provides both a library as well as a standalone binary. The latter
can be used as an "[initial tagging](https://notmuchmail.org/initial_tagging/)"
system, the former may be integrated into a bigger e-mail client making use
of [notmuch-rs](https://github.com/vhdirk/notmuch-rs).
## What?
Takes [regex](https://github.com/rust-lang/regex) rules from a JSON file and
if any match, either adds new tags, removes tags or runs an arbitrary binaries
for further processing. Rules support AND as well as OR operations.
## Example
```json
[{
"name": "money",
"desc": "Money stuff",
"rules": [
{"from": "@(real\\.bank|gig-economy\\.career)",
"subject": ["report", "month" ]},
{"from": "no-reply@trusted\\.bank",
"subject": "statement"}
],
"op": {
"add": "€£$",
"rm": ["inbox", "unread"],
"run": ["any-binary-in-our-path-or-absolute-path", "--argument"]
}
}]
```
Here the matching expands to:
```
( from: ("@real.bank" OR "@gig-economy.career") AND subject: ("report" AND "month") )
OR
( from: "no-reply@trusted.bank" AND subject: "statement" )
```
If if this filter is applied the operations will
* add the tag `€£$`
* remove the tags `inbox` and `unread`
* run the equivalent of `/bin/sh -c 'any-binary-in-our-path-or-absolute-path --argument'`
with 3 additional environment variables:
```sh
NOTCOAL_FILTER_NAME=money
NOTCOAL_FILE_NAME=/path/to/maildir/new/filename
NOTCOAL_MSG_ID=e81cadebe7dab1cc6fac7e6a41@some-isp
```
Filters aren't only restricted to matching `from` and `subject` headers (all
of which are treated case-insensitive) but may try to match arbitrary headers.
Additionally there are the special fields `@tags`, `@path` and
(*not yet implemented*) `@body`.
The default `notcoal::filter` function loops through messages and then
tests/applies filters in the order they have been defined in. Hence, any tag
one wants to match on has to have been set by a previous matching rule.
## Standalone use for "initial tagging"
To build the standalone binary, run:
`cargo build --release --features=standalone`
The `notcoal` binary automatically extracts the location of the notmuch
database by reading `~/.notmuch-config`. The default location for rules is
`$maildir/.notmuch/hooks/notcoal-rules.json`. By default, it expects all newly
added messages (that are to be filtered) to have the `new` tag. To make sure
that's being set, edit the `.notmuch-config` to include:
```ini
[new]
tags=unread;inbox;new;
```
See `notcoal --help` for supplying alternative values. However if you're fine
with the defaults, you can just symlink `$maildir/.notmuch/hooks/post-new` to
`notcoal`!
## Thanks
[vhdirk](https://github.com/vhdirk/) for `notmuch-rs`, which made this crate
possible in the first place, [antifuchs' gmail-britta](https://github.com/antifuchs/gmail-britta/)
for inspiring the name, and [Recurse Center](https://www.recurse.com/), for
hosting a supportive community 💟