fetch-input

#! /usr/bin/env bash

# Copyright 2022 Ole Walkenhorst

# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
# https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
# <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
# option. This file may not be copied, modified, or distributed
# except according to those terms.

set -eu

function usage() {
	echo "Usage: $0 [-h] [-o OUTDIR] [-f FILENAME] [-y YEAR] [-d DAY]"
}

OUTDIR=inputs
FILENAME=''
CURRENTYEAR="$( date +%Y )"
YEAR="$CURRENTYEAR"
TODAY="$( date +%-d )"
DAY="$TODAY"

shopt -s extglob
while getopts ":ho:f:y:d:" opt; do
	case "$opt" in
		h) usage && exit 0;;
		o) OUTDIR="$OPTARG";;
		f) FILENAME="$OPTARG";;
		y) YEAR="$OPTARG";;
		d) DAY="${OPTARG##+(0)}";;
		:) echo "Option '$OPTARG' missing a required argument." && exit 1;;
		\?) echo "Invalid option $OPTARG" && exit 1;;
	esac
done
shift $(( OPTIND - 1 ))

if [[ "$#" -gt 0 ]]; then
	echo "Invalid positional argument $1" >&2
	exit 1
fi

if [[ "$YEAR" -lt 2015 || "$YEAR" -gt "$CURRENTYEAR" ]]; then
	echo "YEAR must be between 2015 and $CURRENTYEAR inclusive." >&2
	exit 1
fi

if [[ "$DAY" -lt 1 || "$DAY" -gt 25 ]]; then
	echo "DAY must be between 1 and 25 inclusive." >&2
	exit 1
fi

[[ -f '.env' ]] && source '.env'
cookie=${SESSION_COOKIE?SESSION_COOKIE must be set.}

response=$(curl -s "https://adventofcode.com/$YEAR/day/$DAY/input" \
                -H "Cookie: session=$cookie")

if [[ "$response" == *"Please don't repeatedly request this endpoint before it unlocks!"* ]]; then
	echo "Day $DAY is not unlocked, yet" >&2
	exit 2
fi

if [[ ! -d "$OUTDIR" ]]; then
	mkdir -p "$OUTDIR"
fi

filepath="$OUTDIR/${FILENAME:-"input.$DAY"}"
if [[ -f "$filepath" ]]; then
	echo "File already exists '$filepath'" >&2
	exit 2
fi

echo "$response" > "$filepath"
echo "Wrote '$filepath'"
exit 0