weather

#!/bin/bash

# Quick weather forecast using wttr.in
# Usage: weather                        (auto-detected location)
#        weather "new york"             (by city name)
#        weather 90210                  (by US zip code)
#        weather "SW1A 1AA" GB          (by postal code + country code)
#        weather -s                     (one-line summary)

if ! command -v curl > /dev/null 2>&1; then
  echo "Error: curl is required but not installed."
  exit 1
fi

# Percent-encode a string for safe use in a URL path segment.
# LC_ALL=C forces byte-wise iteration so multibyte UTF-8 (e.g. "München")
# is encoded as its UTF-8 bytes, correctly, regardless of the caller's locale.
urlencode() {
  local LC_ALL=C string="$1" encoded="" pos c o
  for (( pos=0; pos<${#string}; pos++ )); do
    c="${string:$pos:1}"
    case "$c" in
      [-_.~a-zA-Z0-9]) o="$c" ;;
      *) printf -v o '%%%02X' "'$c" ;;
    esac
    encoded+="$o"
  done
  printf '%s' "$encoded"
}

short=false
if [ "$1" = "-s" ] || [ "$1" = "--short" ]; then
  short=true
  shift
fi

location="${1:-}"
country="${2:-}"

if [ -n "$country" ]; then
  location="$(urlencode "$location"),$(urlencode "$country")"
elif [ -n "$location" ]; then
  location="$(urlencode "$location")"
fi

if [ "$short" = true ]; then
  curl -fs "wttr.in/${location}?format=%l:+%C+%t+%w\n" \
    || echo "Error: could not retrieve weather (bad location or network issue)."
else
  curl -fs "wttr.in/${location}?F" \
    || echo "Error: could not retrieve weather (bad location or network issue)."
fi