/**
 * `materialTabs`: the behaviour of `<x-tabs>` — WAI-ARIA's tabs with automatic activation.
 *
 * The arrow keys move along the tablist (mirrored on a right-to-left page), Home and End jump to
 * its ends, disabled tabs are passed over, focus follows the choice, and only the chosen tab is in
 * the Tab order. A change of tab runs in a view transition, which moves the active indicator from
 * the old tab to the new one and cross-fades the panels — unless the visitor prefers reduced motion
 * or the browser has no view transitions, when it simply changes.
 */
const reducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)')

document.addEventListener('alpine:init', () => {
    window.Alpine.data('materialTabs', () => ({
        tabs() {
            return [...this.$refs.bar.querySelectorAll('[role="tab"]:not(:disabled)')]
        },

        choose(name, focus = false) {
            const apply = () => {
                this.selected = name

                return this.$nextTick()
            }

            if (this.selected === name || reducedMotion.matches || !document.startViewTransition) {
                apply()
            } else {
                document.startViewTransition(apply)
            }

            if (focus) {
                this.$refs.bar.querySelector(`[data-md-tab="${CSS.escape(name)}"]`)?.focus()
            }
        },

        step(by) {
            const tabs = this.tabs()
            const rtl = getComputedStyle(this.$refs.bar).direction === 'rtl'
            const at = tabs.findIndex((tab) => tab.dataset.mdTab === this.selected)
            const next = tabs[(at + (rtl ? -by : by) + tabs.length) % tabs.length]

            if (next) {
                this.choose(next.dataset.mdTab, true)
            }
        },

        edge(last) {
            const tabs = this.tabs()
            const tab = last ? tabs.at(-1) : tabs[0]

            if (tab) {
                this.choose(tab.dataset.mdTab, true)
            }
        },
    }))
})