#!/usr/bin/env bash
# Print the current weather as a short icon+temp string, e.g. "🌦️  +83°F".
# Caches the wttr.in response so the lock screen and waybar don't hit the
# network on every refresh. A cached value is served immediately -- even when
# stale -- and refreshed in the background, so a slow network never delays the
# lock screen's first frame. Override the location with WEATHER_CITY or edit
# CITY below.
set -u

CITY="${WEATHER_CITY:-Denver}"
CACHE_DIR="${XDG_RUNTIME_DIR:-/tmp}"
CACHE="${CACHE_DIR}/wttr.cache"
CACHE_MAX_AGE=1800 # 30 minutes
URL="https://wttr.in/${CITY}?format=%c+%t"

fetch() {
    TMP="${CACHE}.tmp.$$"
    if curl -fsS --connect-timeout 2 --max-time 5 "${URL}" > "${TMP}" 2>/dev/null; then
        mv "${TMP}" "${CACHE}"
        cat "${CACHE}"
    else
        rm -f "${TMP}" || true
        return 1
    fi
}

# Fresh cache: print it.
if [ -f "${CACHE}" ] && [ "$(( $(date +%s) - $(stat -c %Y "${CACHE}") ))" -lt "${CACHE_MAX_AGE}" ]; then
    cat "${CACHE}"
    exit 0
fi

# Stale cache: print it immediately, then refresh in the background so the
# caller never blocks. flock keeps a pile-up of refreshes from several clients
# (lock screen, waybar) from running concurrent curls.
if [ -f "${CACHE}" ]; then
    cat "${CACHE}"
    (
        exec 9>"${CACHE}.lock"
        flock -n 9 || exit 0
        fetch >/dev/null 2>&1
    ) &
    disown
    exit 0
fi

# No cache at all: fetch synchronously, but with tight timeouts.
fetch