#!/bin/sh -u
# fetch via WWW the current temperature for a select set of Canadian cities
# ------------------------------------------------------------------
# Syntax:
#   $0 [ city_name ]
# ------------------------------------------------------------------
# Purpose: 
#   Fetch via WWW the current temperature for a select set of Canadian cities.
#   The city name can be any set of unique characters in the city name.
#   This only recognizes cities on the main Enviro Canada web page.
# ------------------------------------------------------------------
# Student Name:                   Ian! D. Allen
# Algonquin EMail Address:        alleni
# Student Number:                 000-000-000
# Course Number:                  NET 2003
# Lab Section Number:             010
# Professor Name:                 Ian Allen
# Assignment Name/Number/Date:    Exercise 5
# Comment:                        Sample solution (missing comments)
# ------------------------------------------------------------------

# Step 1 (includes all the lines above too)
PATH=/bin:/usr/bin ; export PATH
umask 022
LC_COLLATE=C ; export LC_COLLATE

# Step 2
# date
# wc /etc/passwd

# Step 3
# echo "$NOSUCHVARIABLE"

# Step 4
if [ $# -eq 0 ] ; then
    echo 1>&2 "Enter city name for weather:"
    read city || exit 1
elif [ $# -eq 1 ] ; then
    city="$1"
else
    echo 1>&2 "$0: Expecting one city name argument, found $# ($*)"
    exit 2
fi

# Step 5
if [ "$city" = "" ] ; then
    echo 1>&2 "$0: City name is empty; nothing done"
    exit 3
fi
echo "Using city name '$city'"

# Step 6
weatherURL='http://text.weatheroffice.ec.gc.ca/'

# Step 7
mainpage=mainpage.html
if [ ! -s "$mainpage" ] ; then
    wget -q -O "$mainpage" "$weatherURL"
    status=$?
    if [ ! -s "$mainpage" ] ; then
        echo 1>&2 "$0 '$city' status $status: failed to fetch '$weatherURL'"
        rm "$mainpage"
        exit 4
    fi
fi

# Step 8
englink=$( grep -B 1 "english" $mainpage | head -1 | awk -F'"' '{print $2}' )

if [ "$englink" = "" ] ; then
    echo 1>&2 "$0: '$city' Cannot find english hyperlink in '$mainpage'"
    echo 1>&2 "$0: Renamed file to '$mainpage.bak'"
    mv "$mainpage" "$mainpage".bak
    exit 5
fi
# echo "DEBUG: Found '$englink'"

# Step 9
englishURL="$weatherURL/$englink"
englishpage=englishpage.html

if [ ! -s "$englishpage" ] ; then
    wget -q -O "$englishpage" "$englishURL"
    status=$?
    if [ ! -s "$englishpage" ] ; then
        echo 1>&2 "$0 '$city' status $status: failed to fetch '$englishURL'"
        rm "$englishpage"
        exit 6
    fi
fi

# Step 10
citylink=$( grep "$city" "$englishpage" \
        | grep '/forecast/city' \
        | awk -F"'" '{print $2}'
)
if [ "$citylink" = "" ] ; then
    echo 1>&2 "$0: Cannot find '$city' in '$englishpage' from '$englishURL'"
    exit 7
fi

# Step 11
lines=$( echo "$citylink" | wc -l )
if [ $lines -ne 1 ] ; then
    echo 1>&2 "$0: City '$city' matches $lines forecasts:"
    echo 1>&2 "$citylink"
    echo 1>&2 "$0: Please be more specific"
    exit 8
fi
# echo "DEBUG: Found $citylink"

# Step 12
cityURL="$weatherURL/$citylink"
citypage=citypage.txt

lynx -dump "$cityURL" >"$citypage"
status=$?
# Step 13
if [ ! -s "$citypage" ] ; then
    echo 1>&2 "$0 lynx status $status: failed to fetch '$city' via '$cityURL'"
    rm "$citypage"
    exit 9
fi
# Step 14
if grep ERROR "$citypage" ; then
    echo 1>&2 "$0: error fetching '$city' via '$cityURL'"
    rm "$citypage"
    exit 10
fi

# Step 15
fullname=$( grep -B 4 'Currently' "$citypage" | head -1 )

# Step 16
temp=$( grep -A 1 Temperature: "$citypage" | tail -1 )

# Step 17
echo "The temperature in $fullname is $temp" | tr -s ' '