#!/bin/bash

# This is a simple script that refines the output of checkupdates and
# grabs the latest news from the Arch RSS news feed. The idea is to
# have some extra info before committing to grabbing a fresh copy
# of the package database via pacman -Sy.
#
# Prerequisites: bc, xmllint

printf "Fetching data, please wait...\n\n"

CULIST=$(checkupdates)
if [[ $CULIST = "" ]]; then
    echo "No new packages"
    exit
fi

# calculate the number of packages
IFS=$'\n'
for i in $CULIST
do
    pacnum=$((pacnum+1))
done
echo "$pacnum new packages found"

# extract package names and then feed them to pacman -Si
PNAMES=""
for i in $CULIST
do
    PNAMES+=$(printf "%s" "$i" | awk '{print $1}')" "
done
IFS=''
PSI="pacman -Si $PNAMES"
PSI="$(eval "$PSI")"

# extract the relevant info from pacman -Si
PSI=$(echo "$PSI" | grep -E 'Repository|Download Size')
PSI=$(echo "$PSI" | \
      awk -F ": " '{if (NR%2 == 0) printf "%s\n", $2; else printf "%s ", $2}')

# combine pacman -Si info with the output of checkupdates
OUT=$(paste <(echo "$PSI") <(echo "$CULIST") | column -t | tr -s " ")

# calculate total download size and refine the output further
IFS=$'\n'
totsize_mb="0"
for i in $OUT
do
    cursize_bib=$(echo "$i" | cut -d ' ' -f 2,3)

    # generate appropriate conversion multipliers
    if [ "$(echo "$cursize_bib" | awk '{print $2}')" = "KiB" ]; then
        mul=0.001024
    else # assumes MiB
        mul=1.048576
    fi

    cursize_mb=$(echo "scale=1;($(echo "$cursize_bib" | \
                 awk '{print $1}')*$mul)" | bc)
    totsize_mb=$(echo "scale=1;$totsize_mb+$cursize_mb" | bc)
done

# final output for the checkupdate stage
IFS=''
printf "\n%s\n" "$(echo -e "$OUT" | cut -d ' ' --complement -f 2,3 | \
        sort -d | column -t )"
printf "\nTotal download size: %.2f MB or %.2f MiB\n" \
       "$totsize_mb" "$(echo "$totsize_mb"*0.953674 | bc)"

###############################################################################

# arch news
printf "\n==============================\n"
printf "https://www.archlinux.org/news\n"
printf "==============================\n"

# nicked from some forum, not an ideal solution, but seems to work,
# formatting has been a little bit improved here
curl -s https://www.archlinux.org/feeds/news/ | \
xmllint --xpath //item/title\ \|\ //item/pubDate /dev/stdin | \
sed -r -e "s:<title>([^<]*?)</title><pubDate>([^<]*?)</pubDate>:\2 -- \1\n:g" | \
sed -r "s:&gt;:>:" | \
sed -r "s:&lt;:<:" | \
tr -s " " | \
cut -d " " --complement -f 1,5,6 | \
head -n5 # 5 of the most recent news items seems reasonable?

# syu prompt
printf "\nLaunch sudo pacman -Syu? (y/N) "
read -r CONT
if [ "$CONT" = "y" ] || [ "$CONT" = "Y" ]; then
    printf "\n"
    sudo pacman -Syu
else
    printf "\nUpdate cancelled.\n"
fi