#!/bin/sh
VERSION="0.2.1"
usage() {
    echo "emailbook $VERSION"'
A minimalistic address book for e-mails only.

Usage: emailbook FILE [OPTIONS]

Prints all values in FILE if no option is given.

Options:
-a, --add [KEY] VALUE  Add KEY/VALUE pair to FILE. If KEY is omitted,
                       VALUE is used as key, too.
[-s, --search] QUERY   Search FILE for entries with keys or values containing QUERY.
-k, --key QUERY        Like `--search` but limit search to keys/aliases.
-v, --value QUERY      Like `--search` but limit search to values.
-p, --parse SOURCE     Parse stdin for e-mail addresses in header and add them to FILE.
                       SOURCE might be either --from, --to , --cc, --bcc, or --all.
-h, --help             Show this help.
-V, --version          Print version.
'
}

checkfilename() {
    [ $QUIET ] || [ -e "$filename" ] \
        || echo "File $filename not found. Creating it." 1>&2
}

keyexists() {
    escaped=$(echo "$*" | sed 's/[][\.|$(){}?+*^]/\\&/g')
    # also check display name with/without double quotes
    quotestoggled=$(echo "$*" | sed -E 's/^"([^"]+)"( +<[^>]+>)/\1\2/;t;s/^([^"]+?)( +<[^>]+>)/"\1"\2/')
    quotestoggledescaped=$(echo "$quotestoggled" | sed 's/[][\.|$(){}?+*^]/\\&/g')
    grep -q -E "^$escaped( :|\$)" "$filename" 2> /dev/null \
        || grep -q -E "^$quotestoggledescaped( :|\$)" "$filename" 2> /dev/null
}

addentry() {
    if keyexists "$1"; then
        [ $QUIET ] || echo "! $1 (skipped)"
    else
        [ "$2" ] && line="$1 : $2" || line="$1"
        [ $QUIET ] || echo "+ $line"
        echo "$line" >> "$filename"
    fi
}

add() {
    checkfilename
    case $# in
    1|2) addentry "$@" ;;
    *) echo "Expected one or two arguments after -a!"; exit 1 ;;
    esac
}

addfromstdin() {
    # Skip lines without "@", skip lines containing no-reply (or similar),
    # strip \r, strip leading spaces, do the following replacements:
    # "'John Doe'" <xxx> → "John Doe" <xxx>
    # 'John Doe' <xxx> → John Doe <xxx>
    # "john.doe@example.com" <john.doe@example.com> → <john.doe@example.com>
    # "<john.doe@example.com>" <john.doe@example.com> → <john.doe@example.com>
    # john.doe@example.com → <john.doe@example.com>
    grep '@' \
        | grep -v -i -E '\bnot?[_-]?reply' \
        | sed 's/\r$//' \
        | sed -E 's/^ +//g' \
        | sed -E "s/(\"?)'([^'\"]+)'(\"?)/\1\2\3/" \
        | sed -E 's/^"<?([^">]*)>?" +<\1>/<\1>/' \
        | sed -E 's/^[^<>@ ]*@[^<>@ ]+$/<\0>/' \
        | sort -u \
        | while read -r line; do addentry "$line"; done
}

searchall() {
    # show entries with matching alias first
    searchbyalias "$*"
    searchbyvalueonly "$*"
}

searchbyalias() {
    grep -i -E "$* :" "$filename" | sed -E 's/^[^:]+:\s*//'
}

searchbyvalue() {
    sed -E 's/^[^:]+:\s*//' "$filename" | grep -i -E "$*"
}

searchbyvalueonly() {
    # exclude matches found by searchbyalias
    grep -i -E -v "$* :" "$filename" | sed -E 's/^[^:]+:\s*//' | grep -i -E "$*"
}

parsefields() {
    # Find header fields starting with $1 (p.e. 'To:') plus following lines
    # starting with a space. Split entries at commas except when quoted. Skip
    # empty lines. Decode encoded strings. Squeeze double spaces.
    sed -E '/^\r?$/Q' - \
        | sed -E -n "/^$1:/{:a ; \$!N ; s/\n\s+/ / ; ta ; P ; D}" \
        | sed -E "s/^$1:\\s*//" \
        | grep -v -P '[\x80-\xFF]' \
        | awk -vFPAT='([^,"]*)("[^"]+")?([^,]*)?' -vOFS='\n' \
          '{for(i=1;i<=NF;i++) printf("%s\n",$i)}' \
        | sed -E -e '/^ *$/d' \
        | perl -CS -MEncode -ne 'print decode("MIME-Header", $_)' \
        | sed -E -e 's/  +/ /g' \
        | addfromstdin
}

parse() {
    checkfilename
    case "$1" in
    --all)  parsefields '(From|To|Cc|CC|Bcc)' ;;
    # TODO: Include References, In-Reply-To, Reply-To, Return-Path?
    --from) parsefields 'From' ;;
    --to)   parsefields 'To' ;;
    --cc)   parsefields '(Cc|CC)' ;;
    --bcc)  parsefields 'Bcc' ;;
    esac
}


case "$1" in
-h|--help|'') usage; exit ;;
-V|--version) echo "$VERSION"; exit ;;
esac

filename="$1"; shift

case "$1" in
-q|--quiet) shift; QUIET=1 ;;
esac

case "$1" in
-a|--add)     shift; add "$@" ;;
-s|--search)  shift; searchall "$*" ;;
-k|--key)     shift; searchbyalias "$*" ;;
-v|--value)   shift; searchbyvalue "$*" ;;
-p|--parse)   shift; parse "$@" ;;
*)            searchall "$*" ;;
esac