package webui

import (
	"strconv"

	"kjol/vdom"
)

// Port of web/kit/Tutorial.tsx.
//
// Tutorial is a guided-tour / coachmark overlay: it dims the page, spotlights a
// target element, and floats a popover card with step navigation. The Solid
// source leans heavily on browser-only capabilities the neutral vdom runtime
// does not have (DOM measurement via getBoundingClientRect, portals, effects,
// timers, scroll/resize listeners, window sizing). What is ported vs. dropped:
//
//   - NOTE: calculatePopoverPosition — the viewport-aware placement math that
//     anchors and flips the popover around the target rect — is DROPPED. The
//     popover is statically centered with Tailwind instead of computed coords.
//   - NOTE: SpotlightOverlay's measured cutout (a giant box-shadow ring drawn
//     around the target's DOMRect) is APPROXIMATED by a plain dimmed backdrop,
//     which is the source's own no-target fallback.
//   - NOTE: PopoverArrow (the little triangle pointing at the target) is DROPPED,
//     since there is no target position to point at.
//   - NOTE: the fade/scale/slide transitions and the requestAnimationFrame /
//     setTimeout choreography are DROPPED; the card renders in its final state.
//   - NOTE: Solid context (TutorialProvider/useTutorial) + signals collapse to
//     plain props — the caller owns the active flag, the current-step index, and
//     the next/prev/close callbacks (read at the call site, as per kit convention).
//   - NOTE: per-step onEnter/onLeave lifecycle hooks (effect-driven) are DROPPED,
//     as is the string/function/null target union — Target here is a plain CSS
//     selector kept for reference only (nothing measures or scrolls to it).
//   - NOTE: SpotlightPadding, Placement, and Offset are retained for API parity
//     but are unused, because there is no positioning/spotlight to apply them to.

// TutorialStep is one stop in a guided tour. Content is the body VNode (the TSX
// JSXElement). Target is the CSS selector of the element the step would spotlight
// (see file NOTE — not measured here). Placement/Offset are kept for API parity
// but are not applied.
type TutorialStep struct {
	Title     string
	Content   *vdom.VNode
	Target    string
	Placement string
	Offset    int
}

// TutorialProps drives the tour overlay. CurrentStep is the active index as a
// plain value (the state that was a Solid signal now lives with the caller).
// Active gates whether the overlay renders at all. OnNext/OnPrev advance the
// tour; OnClose ends it (shared by the backdrop click, the close button, and the
// Finish button on the last step).
type TutorialProps struct {
	Steps            []TutorialStep
	CurrentStep      int
	Active           bool
	SpotlightPadding int
	OnNext           func()
	OnPrev           func()
	OnClose          func()
	Class            string
}

// tutorialOverlay is the dimmed backdrop. NOTE: this approximates SpotlightOverlay
// without the measured spotlight cutout (see file NOTE); clicking it ends the tour.
func tutorialOverlay(p TutorialProps) *vdom.VNode {
	mods := []vdom.Mod{vdom.Attr("class", "fixed inset-0 bg-black/50 z-150")}
	if p.OnClose != nil {
		mods = append(mods, vdom.On(vdom.EVENT_CLICK, p.OnClose))
	}
	return vdom.El("div", mods...)
}

// tutorialPopover renders the tooltip card (title + "X of N" + close, body,
// prev/next controls, and the step dots) for step idx. NOTE: it is statically
// centered rather than anchored to the target (see file NOTE).
func tutorialPopover(p TutorialProps, idx int) *vdom.VNode {
	step := p.Steps[idx]
	total := len(p.Steps)

	// Header: optional title + step counter, and a close button.
	headerLeft := []vdom.Mod{vdom.Attr("class", "flex items-center gap-2")}
	if step.Title != "" {
		headerLeft = append(headerLeft, vdom.El("span",
			vdom.Attr("class", "font-medium text-neutral-900"),
			vdom.Text(step.Title)))
	}
	headerLeft = append(headerLeft, vdom.El("span",
		vdom.Attr("class", "text-xs text-neutral-500"),
		vdom.Text(strconv.Itoa(idx+1)+" of "+strconv.Itoa(total))))

	closeMods := []vdom.Mod{
		vdom.Attr("type", "button"),
		vdom.Attr("class", "cursor-pointer text-neutral-400 bg-transparent border-0 p-0 leading-none transition-colors hover:text-neutral-600"),
		Icon("xmark", 18, ""),
	}
	if p.OnClose != nil {
		closeMods = append(closeMods, vdom.On(vdom.EVENT_CLICK, p.OnClose))
	}
	header := vdom.El("div", vdom.Attr("class", "flex items-center justify-between p-4 pb-2"),
		vdom.El("div", headerLeft...),
		vdom.El("button", closeMods...),
	)

	// Body content.
	bodyMods := []vdom.Mod{vdom.Attr("class", "px-4 pb-4 text-sm text-neutral-700")}
	if step.Content != nil {
		bodyMods = append(bodyMods, step.Content)
	}
	body := vdom.El("div", bodyMods...)

	// Controls: Previous on the left (hidden on the first step); Next/Finish right.
	isFirst := idx == 0
	isLast := idx == total-1

	leftMods := []vdom.Mod{}
	if !isFirst {
		leftMods = append(leftMods, Button(ButtonProps{Color: ButtonWhite, Small: true, Text: "Previous", OnClick: p.OnPrev}))
	}
	var advance *vdom.VNode
	if isLast {
		advance = Button(ButtonProps{Color: ButtonBlue, Small: true, Text: "Finish", OnClick: p.OnClose})
	} else {
		advance = Button(ButtonProps{Color: ButtonBlue, Small: true, Text: "Next", OnClick: p.OnNext})
	}
	controls := vdom.El("div", vdom.Attr("class", "flex items-center justify-between px-4 pb-4 gap-2"),
		vdom.El("div", leftMods...),
		vdom.El("div", vdom.Attr("class", "flex gap-2"), advance),
	)

	// NOTE: original card class kept verbatim; the centering utilities
	// (left/top/-translate) are the static stand-in for computed positioning.
	popMods := []vdom.Mod{
		vdom.Attr("class", cx("fixed left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2 z-200 bg-white rounded-default shadow-lg border border-neutral-200 max-w-sm", p.Class)),
		header, body, controls,
	}

	// Step dots (only when there is more than one step).
	if total > 1 {
		dotMods := []vdom.Mod{vdom.Attr("class", "flex justify-center gap-1.5 pb-3")}
		for i := 0; i < total; i++ {
			state := "bg-neutral-300"
			if i == idx {
				state = "bg-sky-600 scale-110"
			}
			dotMods = append(dotMods, vdom.El("div",
				vdom.Attr("class", cx("w-2 h-2 rounded-full transition-all duration-300 ease-in-out", state))))
		}
		popMods = append(popMods, vdom.El("div", dotMods...))
	}

	return vdom.El("div", popMods...)
}

// TutorialProvider renders children, and — when the tour is Active — the dimmed
// backdrop plus the popover card for the current step over the top. The wrapper
// uses display:contents so it does not introduce its own layout box (the Solid
// source returned a fragment). Returns just the children when inactive or empty.
//
// NOTE: unlike the Solid provider, children cannot read tour state via context;
// the caller threads Active/CurrentStep/callbacks in through TutorialProps.
func TutorialProvider(p TutorialProps, children ...*vdom.VNode) *vdom.VNode {
	mods := kids([]vdom.Mod{vdom.Attr("class", "contents")}, children)

	if p.Active && len(p.Steps) > 0 {
		idx := p.CurrentStep
		if idx < 0 {
			idx = 0
		}
		if idx > len(p.Steps)-1 {
			idx = len(p.Steps) - 1
		}
		mods = append(mods, tutorialOverlay(p), tutorialPopover(p, idx))
	}

	return vdom.El("div", mods...)
}

// StartTutorialButton is a blue button that kicks off the tour. onStart is the
// caller's start handler (which decides the starting step index). With no
// children it renders the default "Start Tutorial" label.
func StartTutorialButton(onStart func(), class string, children ...*vdom.VNode) *vdom.VNode {
	bp := ButtonProps{Color: ButtonBlue, Class: class, OnClick: onStart}
	if len(children) == 0 {
		bp.Text = "Start Tutorial"
	}
	return Button(bp, children...)
}