import { Controller } from '@hotwired/stimulus'
import { csrfToken } from './csrf'

// Drives the slide-in cart drawer. One instance, on the drawer root in
// checkout/drawer.blade.php.
//
// - listens on window for `bbk-cart:changed` (from bbk-add-to-cart and from
//   this drawer's own line forms) and swaps in the server-rendered cart body
// - handles the in-drawer quantity / remove forms (fetch + method spoofing)
// - re-emits `bbk-cart:updated` {count, total} after every render so the host
//   (e.g. the header bag icon) can react
// - dialog focus handling: focus moves into the panel on open, Tab is kept
//   inside it, and focus returns to whatever opened it on close
//
// Appearance is entirely CSS-driven: open state is the data-bbk-cart-state
// attribute on the root, nothing here touches styles or class lists.
export default class extends Controller {
    static targets = ['panel', 'body', 'error', 'heading', 'status']

    connect() {
        this.onChanged = this.onChanged.bind(this)
        this.onKeydown = this.onKeydown.bind(this)
        this.updateTimers = new Map() // line id -> pending debounce timer

        window.addEventListener('bbk-cart:changed', this.onChanged)
        window.addEventListener('bbk-cart:open', this.open.bind(this))
        document.addEventListener('keydown', this.onKeydown)

        // Prime the host with the count rendered server-side on page load.
        this.emitUpdated(this.element.querySelector('[data-bbk-cart-count]'))
    }

    disconnect() {
        window.removeEventListener('bbk-cart:changed', this.onChanged)
        document.removeEventListener('keydown', this.onKeydown)
        this.updateTimers.forEach((timer) => clearTimeout(timer))
    }

    onChanged(event) {
        if (event.detail?.html) this.replaceBody(event.detail.html)
        this.open()
    }

    onKeydown(event) {
        // Only the drawer instance is a dialog — the checkout page's summary
        // reuses this controller without a panel.
        if (!this.hasPanelTarget || this.element.hidden) return

        if (event.key === 'Escape') this.close()
        if (event.key === 'Tab') this.trapFocus(event)
    }

    open() {
        if (!this.element.hidden) return
        this.returnFocusTo = document.activeElement
        this.element.hidden = false
        // Next frame, so the panel transitions from its off-canvas start.
        requestAnimationFrame(() => {
            this.element.setAttribute('data-bbk-cart-state', 'open')
            if (this.hasHeadingTarget) this.headingTarget.focus({ preventScroll: true })
        })
    }

    close() {
        this.element.removeAttribute('data-bbk-cart-state')

        if (this.returnFocusTo?.isConnected) this.returnFocusTo.focus({ preventScroll: true })
        this.returnFocusTo = null

        const panel = this.panelTarget
        const done = () => {
            this.element.hidden = true
            panel.removeEventListener('transitionend', done)
        }
        panel.addEventListener('transitionend', done)
    }

    // change on a line quantity input, or submit of a line's remove form
    submit(event) {
        event.preventDefault()
        const form = event.target.closest('form')
        if (!form) return

        // A remove is a deliberate, one-shot action — only the quantity form
        // (typing, or the +/- stepper below) benefits from debouncing.
        form.classList.contains('bbk-cart-qty') ? this.scheduleSend(form) : this.send(form)
    }

    // +/- stepper buttons inside a line
    step(event) {
        event.preventDefault()
        const form = event.target.closest('form')
        const input = form.querySelector('input[type="number"]')
        const next = Math.max(0, parseInt(input.value || '0', 10) + Number(event.params.dir))
        input.value = String(next)
        this.scheduleSend(form)
    }

    // Repeated clicks (or spinner nudges) update the input instantly but only
    // send once they settle for 300ms — sending on every single click was
    // firing overlapping requests that raced each other and made the drawer
    // visibly flicker/lag under quick clicking.
    scheduleSend(form) {
        const lineId = form.closest('[data-bbk-line-id]')?.dataset.bbkLineId
        if (!lineId) return this.send(form)

        clearTimeout(this.updateTimers.get(lineId))
        this.updateTimers.set(lineId, setTimeout(() => {
            this.updateTimers.delete(lineId)
            this.send(form)
        }, 300))
    }

    async send(form) {
        this.bodyTarget.setAttribute('aria-busy', 'true')
        this.clearError()

        try {
            const response = await fetch(form.action, {
                method: 'POST',
                headers: {
                    'X-CSRF-TOKEN': csrfToken(),
                    'X-Requested-With': 'XMLHttpRequest',
                    Accept: 'application/json',
                },
                body: new FormData(form),
            })

            if (response.ok) {
                this.replaceBody(await response.text())
                return
            }

            const data = await response.json().catch(() => null)
            this.showError(data?.error)

            // The rejected quantity (typed, or from a +/- click) is left
            // sitting in the input with nothing to correct it — the update
            // never reached the cart, so the input must be put back to what
            // the cart actually still holds, not just left showing whatever
            // was rejected.
            const input = form.querySelector('[data-bbk-cart-confirmed-quantity]')
            if (input) input.value = input.dataset.bbkCartConfirmedQuantity
        } finally {
            this.bodyTarget.removeAttribute('aria-busy')
        }
    }

    // aria-modal hides the page from screen readers but doesn't stop Tab from
    // walking out of the panel into it — wrap at either end instead.
    trapFocus(event) {
        const focusable = [...this.panelTarget.querySelectorAll(
            'a[href], button:not([disabled]), input:not([disabled]):not([type="hidden"]), select:not([disabled]), textarea:not([disabled]), [tabindex]:not([tabindex="-1"])',
        )].filter((el) => !el.closest('[hidden], [aria-hidden="true"]'))

        if (!focusable.length) return

        const first = focusable[0]
        const last = focusable[focusable.length - 1]
        const active = document.activeElement

        if (event.shiftKey && (active === first || !this.panelTarget.contains(active) || (this.hasHeadingTarget && active === this.headingTarget))) {
            event.preventDefault()
            last.focus()
        } else if (!event.shiftKey && (active === last || !this.panelTarget.contains(active))) {
            event.preventDefault()
            first.focus()
        }
    }

    showError(message) {
        if (!this.hasErrorTarget || !message) return
        this.errorTarget.textContent = message
        this.errorTarget.hidden = false
    }

    clearError() {
        if (!this.hasErrorTarget) return
        this.errorTarget.hidden = true
    }

    replaceBody(html) {
        const restore = this.focusSnapshot()
        this.bodyTarget.innerHTML = html
        restore()
        this.announce()
        this.emitUpdated(this.bodyTarget.querySelector('[data-bbk-cart-count]'))
    }

    // Swapping the body destroys whatever control had focus (a qty stepper,
    // a remove button, the coupon field), dropping keyboard/screen-reader
    // users back at the top of the document. Returns a callback that, after
    // the swap, re-focuses the equivalent control in the new markup — or the
    // heading, when that control is gone (e.g. its line was just removed).
    focusSnapshot() {
        const active = document.activeElement
        if (!active || !this.bodyTarget.contains(active)) return () => {}

        let selector = null
        if (active.id) {
            selector = `#${CSS.escape(active.id)}`
        } else {
            const lineId = active.closest('[data-bbk-line-id]')?.dataset.bbkLineId
            const dir = active.dataset.bbkCartDirParam
            const control = ['bbk-cart-qty-input', 'bbk-cart-qty-btn', 'bbk-cart-item-remove']
                .find((name) => active.classList.contains(name))

            if (lineId && control) {
                selector = `[data-bbk-line-id="${CSS.escape(lineId)}"] .${control}`
                    + (dir ? `[data-bbk-cart-dir-param="${CSS.escape(dir)}"]` : '')
            }
        }

        return () => {
            const target = selector && this.bodyTarget.querySelector(selector)
            if (target) target.focus({ preventScroll: true })
            else if (this.hasHeadingTarget) this.headingTarget.focus({ preventScroll: true })
        }
    }

    // Polite "Cart updated" — cleared first so an identical message is
    // re-announced on the next update.
    announce() {
        if (!this.hasStatusTarget) return
        const message = this.statusTarget.dataset.bbkCartMessage || ''
        this.statusTarget.textContent = ''
        requestAnimationFrame(() => { this.statusTarget.textContent = message })
    }

    emitUpdated(node) {
        if (!node) return

        window.dispatchEvent(new CustomEvent('bbk-cart:updated', {
            detail: {
                count: parseInt(node.dataset.bbkCartCount || '0', 10),
                total: parseInt(node.dataset.bbkCartTotal || '0', 10),
            },
        }))
    }
}