/**
 * Build-Version-Check: Auto-Reload when a newer build is detected on the server
 *
 * Every GET API response includes the header X-Build-Time with the server's build
 * timestamp. If it's newer than the one embedded in the frontend bundle, a toast
 * is shown and the page is automatically reloaded after a short delay.
 */
import { buildTime } from "./buildInfo"
import { addToast } from "./toast"

/** Prevents multiple triggers within the same page session */
let triggered = false

const RELOAD_DELAY_MS = 3000
const STORAGE_KEY = "__build_reload__"

/**
 * Checks whether the server has a newer build than the current frontend bundle.
 * Only runs in the browser (SSR-safe).
 *
 * @param serverBuildTime - ISO timestamp from the X-Build-Time response header
 */
export function checkBuildVersion(serverBuildTime: string | null | undefined): void {
    if (!serverBuildTime || typeof window === "undefined") return
    if (triggered) return

    // Only react if the server build is actually newer
    if (serverBuildTime <= buildTime) return

    // Loop protection: if we already reloaded for this exact build, don't reload again
    // (e.g. CDN/cache still serving old bundle)
    try {
        if (sessionStorage.getItem(STORAGE_KEY) === serverBuildTime) return
    } catch (_) {
        // sessionStorage not available (e.g. privacy mode) – continue anyway
    }

    triggered = true

    // Show toast notification
    addToast("New version available – page will refresh…", "info", RELOAD_DELAY_MS + 2000)

    // Remember that we're reloading for this build timestamp
    try {
        sessionStorage.setItem(STORAGE_KEY, serverBuildTime)
    } catch (_) {
        // ignore
    }

    // Auto-reload after short delay so toast is visible
    setTimeout(() => {
        window.location.reload()
    }, RELOAD_DELAY_MS)
}