#!/usr/bin/env zsh
# Open images from URLs by downloading them and then opening them in
# ${image_viewer}. If downloading fails, open in ${default_cmd} instead.

setopt LOCAL_OPTIONS ERR_RETURN NO_UNSET PIPE_FAIL

zmodload zsh/zutil
local -a o_help=()
zparseopts -D -K -- h=o_help
if [[ ${#o_help} -ne 0 || ! -v 1 ]]; then
    local ret=$(( ${#o_help} ^ 1 ))
    print -u $(( 1 + ${ret} )) "usage: ${0} [-h] <URL> …"
    return ${ret}
fi
local -a urls=(${@})

local default_cmd="firefox"
local image_viewer="viewnior"

for url in ${urls}; do
    if type ${image_viewer%% *} >& -; then
        local file="$(mktemp --suffix='.openwwwimg')"
        curl --silent --location --output ${file} ${url}
        if [[ ${?} -eq 0 ]]; then
            ${image_viewer} ${file}
        else
            ${default_cmd} ${url}
        fi
        rm -f ${file}
    else
        ${default_cmd} ${url}
    fi
done