package app

import (
	. "kjol/vdom"
	ui "kjol/webui"
)

var chartPageDays = []string{"Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"}

// chartDemoData is a week of values; a non-zero seed reshuffles them deterministically, so
// "Shuffle" changes the chart without a data source and without a random that would differ
// between the server's render and the client's first one.
func chartDemoData(seed int) []float64 {
	base := []float64{42, 17, 63, 28, 55, 9, 71}
	if seed == 0 {
		return base
	}
	out := make([]float64, len(base))
	for i, b := range base {
		m := (int(b)*7 + seed*13) % 80
		if m < 4 {
			m = 4
		}
		out[i] = float64(m)
	}
	return out
}

//gowasm:page /wasm/chart static layout=app
func ChartPage(d Deps) func() *VNode {
	seed := NewSignal(0)
	barChart := ui.NewChart()
	areaChart := ui.NewChart()

	return func() *VNode {
		values := chartDemoData(seed.Get())

		return docPage("Rendering", "SSR & hydration",
			"A static route is rendered to HTML by the server, so the page is complete before any "+
				"WebAssembly has downloaded. The same component then runs in the browser, adopts the markup "+
				"that is already there, and takes over. One function, two runtimes.",

			docSection("the-directive", "Marking a route static",
				prose("static on the page directive is what puts a route in the server's pre-render set. Leave "+
					"it off and the route renders on the client only — which is the right choice when the page "+
					"is behind a login, or its content depends on something only the browser knows."),
				code("app/chart.go", chartSnippet),
				note("Hydration adopts, it does not rebuild",
					"The client renders the same tree the server did and walks the existing DOM alongside it, "+
						"wiring event handlers to the nodes that are already on the page. If the two trees "+
						"disagree, the CLIENT wins — a stale server binary should not be able to pin a wrong "+
						"class onto the page forever."),
			),

			docSection("charts", "A worked example: a chart",
				prose("The two charts below are webui.Chart. Their SVG — axes, rounded columns, the smoothed "+
					"area — is drawn on the SERVER and shipped in the page's HTML: view source and the marks "+
					"are already there, complete before any WebAssembly runs. That is what static buys."),
				prose("What the server cannot send is the interaction. The hover tooltip and the resize-to-fit "+
					"come alive when the WebAssembly hydrates the page — it adopts the SVG already on screen and "+
					"wires the pointer handlers to it, redrawing nothing. Server-rendered picture, client-side "+
					"behaviour, one component. Shuffle re-renders it in the browser, and no request is made."),

				Div(Attr("class", "mt-4"),
					ui.Button(ui.ButtonProps{Color: ui.ButtonPrimary, Icon: "chart-column", Text: "Shuffle data",
						OnClick: func() { seed.Set(seed.Get() + 1) }}),
				),
				Div(Attr("class", "mt-4 grid gap-4 lg:grid-cols-2"),
					Div(Attr("class", "rounded-default border border-line bg-surface p-3 shadow-xs"),
						barChart.Render(ui.ChartProps{Kind: ui.ChartBar, Labels: chartPageDays,
							Series: []ui.ChartSeries{{Name: "Requests", Data: values}}, Height: 240})),
					Div(Attr("class", "rounded-default border border-line bg-surface p-3 shadow-xs"),
						areaChart.Render(ui.ChartProps{Kind: ui.ChartArea, Smooth: true, Labels: chartPageDays,
							Series: []ui.ChartSeries{{Name: "Requests", Data: values}}, Height: 240})),
				),
			),

			docSection("api", "Reference",
				apiTable(
					apiRow{"//gowasm:page /path static", "Pre-render this route on the server, then hydrate it."},
					apiRow{"vdom.RenderHTML", "Render a tree to an HTML string. This is what the server calls."},
					apiRow{"wasmruntime.Hydrate", "Adopt server-rendered DOM instead of building it. The client's entry point for a static route."},
					apiRow{"vdom.Raw", "Insert markup verbatim — how webui.Chart's SVG string enters the tree. The reconciler clears it correctly when the element is reused."},
				),
			),
		)
	}
}

const chartSnippet = `//gowasm:page /wasm/chart static layout=app
func ChartPage(d Deps) func() *VNode {
    seed  := NewSignal(0)
    chart := ui.NewChart()          // a controller: holds hover + refs across renders

    return func() *VNode {
        return docPage("Rendering", "SSR & hydration",
            // The chart's SVG is rendered on the SERVER and shipped in the HTML.
            // On hydration the client adopts those nodes and wires the pointer
            // handlers — the hover tooltip comes alive without redrawing anything.
            chart.Render(ui.ChartProps{
                Kind:   ui.ChartBar,
                Labels: []string{"Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"},
                Series: []ui.ChartSeries{{Name: "Requests", Data: chartDemoData(seed.Get())}},
            }),
            ui.Button(ui.ButtonProps{Text: "Shuffle", OnClick: func() {
                seed.Set(seed.Get() + 1)   // a signal write re-renders, in the browser
            }}),
        )
    }
}`
