#!/bin/bash

#===============================================================================
# Flight details starting 2017-12-24
# Edinburgh (EDI) to Doha (DOH)
# Doha (DOH) to Auckland (AKL)
#
# Departure EDI: 14:55 (+0000)
# Arrival DOH:   12:55 (+0300)
# Flight time:   6hr 55min
#
# Connection:    1hr 40min
#
# Departure DOH: 02:25 (+0300)
# Arrival AKL:   05:00 (+1300)
# Flight time:   16hr 10min
#===============================================================================

minutes () {
    local hhmm="${1:?Usage: minutes time variable}"
    local -n ref="${2:?Usage: minutes time variable}"
    local hh mm

    hh=${hhmm%%:*}
    mm=${hhmm##*:}

    ref=$((hh * 60 + mm))
}

echo "Outward flights:"

dep_edi="$(date -Iminutes -d "2017-12-24 14:55")"
minutes '6:55' flight1
arr_doh=$(date -Iminutes -d "$dep_edi + $flight1 minutes")

printf "%-20s %s\n" "Leave Edinburgh at" "$(date -d "$dep_edi" '+%F %R %z')"
printf "%-20s %s\n\n" "Arrive Doha at" "$(date -d "$arr_doh" '+%F %R %z')"

minutes '1:40' doha # connection

dep_doh=$(date -Iminutes -d "$arr_doh + $doha minutes")
minutes '16:10' flight2
arr_akl=$(date -Iminutes -d "$dep_doh + $flight2 minutes")

printf "%-20s %s\n" "Leave Doha at" "$(date -d "$dep_doh" '+%F %R %z')"
printf "%-20s %s\n\n" "Arrive Auckland at" "$(date -d "$arr_akl" '+%F %R %z')"

printf "%-20s %s\n" "New Zealand time" \
    "$(TZ="Pacific/Auckland" date -d "$(date -Iminutes -d "$arr_akl")" '+%F %R %z')"

dur=$((flight1 + doha + flight2))
printf "%-20s %s\n" "Duration" "$((dur/60))hr $((dur%60))min"