#!/bin/sh
set -eu

if [ $# -lt 3 ]; then
    echo "Error: arguments base_url, file_url and target_file required." >&2
    exit 1
fi

base_url="$1"
file_url="$2"
target_file="$3"
success=false

rm -f "$target_file"

for i in 1 2 3; do
    echo "Downloading ..." >&2
    curl -fLC - --retry 5 --retry-delay 3 -A Mozilla -o "$target_file" "$file_url"

    echo "Checking ..." >&2
    if gunzip -c "$target_file" | tar t > /dev/null; then
        success=true
        break
    fi

    if [ $i -lt 3 ]; then
        rm -f "$target_file"
        echo "Warning: invalid tarball - retrying." >&2
    else
        echo "Error: invalid tarball." >&2
    fi
done

[ "$success" = "true" ] && exit 0 || exit 1