#!/bin/bash
# written by Johannes Weißl

# muttjump_fallback
#
# This is a fallback solution for muttjump which doesn't use any mail
# indexer to find the original mail (which is of course way slower in
# most cases).
#
# This requires two folder-hooks in .muttrc:
#
# # hack: set my_cwd to current folder path, abusing $record
# # todo: better solution?
# folder-hook . 'set my_backup_record=$record ; set record=^ ; set my_cwd=$record ; set record=$my_backup_record'

# # set macro for jumping to original message
# # needs to be set for every folder after my_cwd (see above) has been set
# # todo: better solution?
# folder-hook . 'macro generic ,J "<enter-command>push <pipe-message>\"muttjump_fallback $my_cwd $folder\"<enter><enter>" "jump to original message"'

# program paths
MUTT=${MUTT:-mutt}

function die () {
    echo -e >&2 "$0: $1"
    exit 1
}

# Check command-line arguments and STDIN
if tty -s || [ $# -gt 2 ] || [ $# -lt 1 ] ; then
    cat >&2 <<END
Usage: $0 virtual-maildir [folder] < msg

This script calls mutt, jumping to the message given in stdin.
It uses grep to search for the messages in "virtual-maildir" (a maildir
containing only symbolic links), and finds out the target through readlink.
If "virtual-maildir" contains shortcuts like '=', "folder" can be given for
expansion.
END
    exit 1
fi

# check if mutt is installed
if ! type -p $MUTT >/dev/null ; then
    die "$MUTT is not in PATH, set MUTT variable"
fi

# search for Message-ID in STDIN
tmpfile=$(mktemp)
msgid_line=$(tee "$tmpfile" | grep -i '^Message-ID: ' | head -n1)
msgid=$(echo "$msgid_line" | sed -n 's/^[^:]*: \(.*\)/\1/p')
msgsize=$(wc -c "$tmpfile")
rm -f "$tmpfile"

if [ -z "$msgid" ] ; then
    die "could not find Message-ID header in standard input"
fi
msgid_clean=$(echo "$msgid" | sed 's/^<\(.*\)>$/\1/')

maildir=$1

# If $folder is given as second argument, replace "+" or "=" in $maildir
if [ $# -gt 1 ] ; then
    folder=$2
    maildir=$(echo "$maildir" | sed "s@^[+=]@$folder/@")
fi

if [ ! -d "$maildir/cur" ] ; then
    die "directory \"$maildir\" doesn't exist or is no Maildir"
fi

# grep for Message-ID in the current Maildir
# TODO: This is definitely not what we want, but there seems to be no way
# to pass the filename of the currently selected mail to an external
# program, as this is dependent on the folder format.
num_files=$(ls -1 "$maildir"/cur/ | wc -l)
if [ $num_files -ge 100 ] ; then
    echo "Grepping through $num_files messages, this could take a while!"
fi
msgfile=$(grep -HlFx "$msgid_line" "$maildir"/cur/* | head -n1)
if [ -z "$msgfile" ] ; then
    die "could not find Message-ID in maildir:
  grep -HlFx \"Message-ID: $msgid\" \"$maildir\"/cur/*"
fi

# find out original message-file of linked message
orig_msgfile=$(readlink "$msgfile")
if [ -z "$orig_msgfile" ] ; then
    die "message \"$msgfile\" is no link to another message, aborting!"
fi

# get containing maildir of $orig_msgfile
orig_maildir=$(dirname $(dirname "$orig_msgfile"))
if [ ! -d "$orig_maildir/cur" ] ; then
    die "directory \"$orig_maildir\" doesn't exist or is no Maildir"
fi

# Close message-stdin and open terminal-stdin instead.
# mutt behaves different if STDIN is no terminal
# TODO: Find cleaner solution (e.g. mutt command-line argument?)
exec 0<&-
term="/dev/$(ps -p$$ --no-heading | awk '{print $2}')"
exec < $term

# start mutt, open original folder and jump to the original message
$MUTT -e "push <change-folder>$orig_maildir<enter><search>\"~i $msgid\"<enter>"