/**
 * `materialSnackbar`: the queue behind `<x-toast>`, and `window.materialToast()`.
 *
 * One snackbar at a time, as M3 shows them. Each waits its turn, stays for its timeout (paused
 * while hovered or focused, so it is never pulled away from someone reading or reaching for its
 * action) and is replaced by the next. A snackbar carrying an action has no timeout at all —
 * M3's accessibility page forbids one — unless the caller writes a timeout out.
 *
 * A `sticky` toast ("A new version is ready" with a Reload action) stays until it is answered, but
 * never holds the queue up: it is kept aside rather than queued, a toast that arrives while it shows
 * takes its place, and it comes back once the queue is empty. Only one is kept — a newer sticky
 * toast replaces it. Dismissing it, or pressing its action, lets it go.
 *
 * Two keys are watched on the whole document: Escape dismisses the snackbar while the focus is in
 * it, and Alt+G moves the focus to a snackbar that carries an action from wherever the page had it
 * — M3 asks the web for a documented shortcut of that kind, since a snackbar never takes the focus
 * on its own and a keyboard would otherwise have no way to reach the action.
 */
const DEFAULT_TIMEOUT_MS = 4000

let sequence = 0

// The listener lives here, not on the Alpine component: a toast dispatched before Alpine has
// started (on page load, straight after a redirect) would otherwise be lost. Until a host
// registers, toasts wait in `pending`.
let host = null
const pending = []

window.addEventListener('toast', (event) => (host ? host.add(event.detail) : pending.push(event.detail)))

window.materialToast = (title, options = {}) => {
    window.dispatchEvent(new CustomEvent('toast', { detail: { title, ...options } }))
}

document.addEventListener('alpine:init', () => {
    window.Alpine.data('materialSnackbar', () => ({
        queue: [],
        current: null,
        sticky: null,
        timer: null,
        remaining: 0,
        startedAt: 0,
        keys: null,

        init() {
            host = this
            pending.splice(0).forEach((detail) => this.add(detail))

            this.keys = (event) => {
                // M3: Esc dismisses the focused snackbar. Only the focused one — a key pressed
                // anywhere else on the page belongs to whatever has the focus there.
                if (event.key === 'Escape' && this.current && this.$el.contains(document.activeElement)) {
                    this.dismiss()

                    return
                }

                // M3 asks the web for a documented shortcut that moves the focus to a snackbar
                // carrying an action, and suggests Alt+G: a snackbar never takes the focus by
                // itself, so without one the keyboard cannot reach the action at all. `event.code`
                // rather than `event.key`, which Alt rewrites to another character on some layouts.
                if (event.altKey && !event.ctrlKey && !event.metaKey && event.code === 'KeyG') {
                    const action = this.$el.querySelector('[data-md-toast-action]')

                    if (action) {
                        event.preventDefault()
                        action.focus()
                    }
                }
            }

            document.addEventListener('keydown', this.keys)
        },

        destroy() {
            document.removeEventListener('keydown', this.keys)
            document.documentElement.style.removeProperty('--material-snackbar-height')

            if (host === this) {
                host = null
            }
        },

        add(detail) {
            // Livewire dispatches named arguments as the detail object; a positional dispatch
            // arrives as an array whose first entry is that object.
            const toast = Array.isArray(detail) ? detail[0] : detail
            const sticky = toast.sticky === true

            // M3 forbids a snackbar with an action from auto-dismissing: it has to wait for the
            // person to read it and reach it. A timeout written out still wins, for a caller who
            // means it; a missing one no longer falls back to the default.
            const untimed = sticky || toast.timeout === 0 || toast.timeout === null || (toast.action != null && toast.timeout === undefined)

            const entry = {
                id: ++sequence,
                type: toast.type ?? null,
                title: toast.title ?? '',
                description: toast.description ?? null,
                timeout: untimed ? 0 : (toast.timeout ?? DEFAULT_TIMEOUT_MS),
                action: toast.action ?? null,
                sticky,
            }

            if (sticky) {
                const showing = !this.current || this.current === this.sticky
                this.sticky = entry

                if (showing) {
                    this.next()
                }

                return
            }

            this.queue.push(entry)

            // A sticky toast steps aside for it, and comes back from next() once the queue is empty.
            if (!this.current || this.current === this.sticky) {
                this.next()
            }
        },

        next() {
            // Cleared and forgotten here, so a toast dismissed early never leaves its timer running
            // to cut the next one short.
            clearTimeout(this.timer)
            this.timer = null
            this.current = this.queue.shift() ?? this.sticky
            this.measure()

            if (this.current?.timeout) {
                this.remaining = this.current.timeout
                this.resume()
            }
        },

        /**
         * Publishes the snackbar's height on <html> as `--material-snackbar-height`, and clears it
         * when nothing shows. M3 puts a snackbar above a FAB, never in front of or behind one, and
         * the FAB is somewhere else in the page: a variable is the only thing the two share.
         */
        measure() {
            this.$nextTick(() => {
                const snackbar = this.$el.querySelector('[data-md-toast-snackbar]')
                const root = document.documentElement.style

                if (snackbar) {
                    root.setProperty('--material-snackbar-height', `${Math.round(snackbar.getBoundingClientRect().height)}px`)
                } else {
                    root.removeProperty('--material-snackbar-height')
                }
            })
        },

        pause() {
            if (!this.current?.timeout || !this.timer) {
                return
            }

            clearTimeout(this.timer)
            this.timer = null
            this.remaining -= performance.now() - this.startedAt
        },

        resume() {
            if (!this.current?.timeout || this.timer) {
                return
            }

            this.startedAt = performance.now()
            this.timer = setTimeout(() => {
                this.timer = null
                this.next()
            }, Math.max(this.remaining, 0))
        },

        dismiss() {
            if (this.current && this.current === this.sticky) {
                this.sticky = null
            }

            this.next()
        },

        // Closed before the handler and the event run, so a toast either of them shows is not the
        // one dismissed.
        act() {
            const action = this.current?.action

            this.dismiss()
            action?.handler?.()

            if (typeof action?.event === 'string' && action.event !== '') {
                window.dispatchEvent(new CustomEvent(action.event))
            }
        },
    }))
})