mail: Add fzfmail script

`fzfmail` allows searching, previewing, displaying and tagging mail
through the fzf interface.

mail/.config/sh/alias.d/fzfmail.sh

@@ -0,0 +1,79 @@
+#!/usr/bin/env sh
+# Fzf searching notmuch email database
+
+# Search with notmuch queries
+# You can either invoke:
+# `fzfmail` -> and then interactively create a notmuch query (not fuzzy searching)
+# or:
+# `fzfmail [notmuchquery]` -> pre-craft a query and then use fzf to filter it further, e.g.
+# fzfmail tag:archived and subject:Important and not tag:flagged
+#
+# select as many mails as you wish (ctrl-a for all current results)
+# preview mails with ?
+#
+# read with <enter>
+# re-tag with <ctrl-t>
+
+if exist fzf; then
+  # Allow fuzzy search filtering of a notmuch search query
+  fzfmail() {
+    # shellcheck disable=2016 # we only want the expression to expand when fzf preview is actually called not by the shell
+    if [ -z "$1" ]; then
+      # interactive query
+      fzfmail_mails=$(
+        printf "
+\nStart a notmuch search query:\n" |
+          fzf --multi \
+            --header "tag: | from: | to: | subject: | folder: | date: || and | not | or | near | adj || <enter> read | <ctrl-t> tag" \
+            --bind "change:reload:notmuch search {q} || true" \
+            --bind "ctrl-a:toggle-all" \
+            --bind '?:toggle-preview' \
+            --expect 'ctrl-t,esc' \
+            --preview='notmuch show --part=1 $(echo {} | cut -d" " -f1)' \
+            --preview-window hidden \
+            --phony |
+          cut -d" " -f1
+      )
+    else
+      # pre-queried fuzzy search
+      fzfmail_mails=$(
+        notmuch search "$*" |
+          fzf --multi \
+            --header "<enter> read | <ctrl-t> tag" \
+            --bind "ctrl-a:toggle-all" \
+            --bind '?:toggle-preview' \
+            --expect 'ctrl-t,esc' \
+            --preview='notmuch show --part=1 $(echo {} | cut -d" " -f1)' \
+            --preview-window hidden |
+          cut -d" " -f1
+      )
+    fi
+
+    # find out expected action
+    fzfmail_action=$(echo "$fzfmail_mails" | head -n1)
+    # quit on esc pressed -- do not do anything with selected results
+    if echo "$fzfmail_action" | grep -qe 'esc'; then return 0; fi
+
+    # get the selected mails
+    fzfmail_mails=$(echo "$fzfmail_mails" | tail -n+2)
+
+    # tag mails
+    if echo "$fzfmail_action" | grep -qe 'ctrl-t'; then
+      printf "current tags: %s\n" "$(notmuch search --output=tags "$fzfmail_mails" | tr '\n' ' ')"
+      printf "add tags with +tag; remove with -tag\n"
+      printf "apply tags: "
+      read -r fzfmail_tags
+      notmuch tag "$fzfmail_tags" -- "$fzfmail_mails"
+      return 0
+    fi
+
+    # display the mails, in semi-readable format
+    # highlight subject line in color
+    # allow moving through results with n/p
+    notmuch show "$fzfmail_mails" | sed -e 's/^\fmessage{.*$/MESSAGE:/' -e '/^\f[a-z]/d' -e 's/^Subject:/\o033[41mSubject:\o033[0m/' | less --pattern '^MESSAGE:$' -R
+
+    unset fzfmail_mails
+    unset fzfmail_action
+    unset fzfmail_tags
+  }
+fi