package gateway

import (
	"fmt"
	"regexp"
	"strings"
	"testing"
)

// The WebUI talks to this package through a tiny `api(path, options)` helper
// that wraps fetch(). fetch() defaults to GET when no method is given, so an
// options object without `method` silently turns a DELETE/PUT into a GET —
// the request hits the wrong branch of the handler and the user sees a
// confusing error like "use GET /api/keys" while nothing is deleted.
//
// This has now bitten twice: ab20f1b fixed delSource/delTemplate, and the very
// same pattern was still live in delKey (deleting a gateway key was impossible)
// and delAdapter. Reviewing 4000+ lines of inline JS by eye clearly does not
// catch it, so it is pinned here instead.

// apiCallRe finds the start of every api(...) call in the UI source.
var apiCallRe = regexp.MustCompile(`\bapi\(`)

// uiSource returns the embedded WebUI document.
func uiSource(t *testing.T) string {
	t.Helper()
	b, err := uiFS.ReadFile("ui/index.html")
	if err != nil {
		t.Fatalf("read embedded ui: %v", err)
	}
	return string(b)
}

// extractCall returns the source of the balanced api(...) call starting at the
// opening parenthesis index, plus the line number it starts on.
func extractCall(src string, openIdx int) (string, bool) {
	depth := 0
	for i := openIdx; i < len(src); i++ {
		switch src[i] {
		case '(':
			depth++
		case ')':
			depth--
			if depth == 0 {
				return src[openIdx : i+1], true
			}
		case '\n':
			// A call spanning more than ~25 lines is not one of ours; bail out
			// rather than scanning the rest of the document.
			if i-openIdx > 4000 {
				return "", false
			}
		}
	}
	return "", false
}

func lineOf(src string, idx int) int {
	return strings.Count(src[:idx], "\n") + 1
}

// TestUIAPICallsDeclareMethod asserts that every api() call passing an options
// object also declares an HTTP method (or is a GET that only passes an
// AbortSignal). Without this, fetch defaults to GET and mutating endpoints are
// never reached.
func TestUIAPICallsDeclareMethod(t *testing.T) {
	src := uiSource(t)
	var offenders []string
	for _, m := range apiCallRe.FindAllStringIndex(src, -1) {
		open := m[1] - 1 // index of '('
		call, ok := extractCall(src, open)
		if !ok {
			continue
		}
		// No options object at all => a plain GET, which is fine.
		if !strings.Contains(call, "{") {
			continue
		}
		if strings.Contains(call, "method:") {
			continue
		}
		// A read that only carries an AbortSignal is a deliberate GET.
		if strings.Contains(call, "signal:") && !strings.Contains(call, "body:") {
			continue
		}
		offenders = append(offenders, fmt.Sprintf("line %d: %s", lineOf(src, open), oneLine(call)))
	}
	if len(offenders) > 0 {
		t.Fatalf("api() called with an options object but no method (fetch will send GET):\n  %s",
			strings.Join(offenders, "\n  "))
	}
}

// TestUIDeleteHelpersUseDelete pins the specific helpers that remove things.
// Each must issue a DELETE; a GET here is the exact bug users reported as
// "cannot delete key: use GET /api/keys".
func TestUIDeleteHelpersUseDelete(t *testing.T) {
	src := uiSource(t)
	for _, fn := range []string{"delKey", "delAdapter", "delSource", "delTemplate"} {
		body, ok := jsFunctionBody(src, fn)
		if !ok {
			t.Errorf("helper %s() not found in the WebUI", fn)
			continue
		}
		if !strings.Contains(body, "api(") {
			t.Errorf("%s() does not call api()", fn)
			continue
		}
		if !strings.Contains(body, `method: "DELETE"`) {
			t.Errorf("%s() must issue a DELETE, got:\n%s", fn, body)
		}
	}
}

// TestUIMutatingHelpersUseWriteMethods covers the write (non-delete) helpers:
// each must declare an explicit POST/PUT/PATCH.
func TestUIMutatingHelpersUseWriteMethods(t *testing.T) {
	src := uiSource(t)
	want := map[string][]string{
		"createKey":     {`method: "POST"`},
		"putScope":      {`method: "PUT"`},
		"uploadAdapter": {`method: "POST"`},
		"saveAuto":      {`method: "PUT"`, `method: "POST"`},
	}
	for fn, methods := range want {
		body, ok := jsFunctionBody(src, fn)
		if !ok {
			continue // helper renamed or absent: the method test above still guards it
		}
		found := false
		for _, m := range methods {
			if strings.Contains(body, m) {
				found = true
				break
			}
		}
		if !found {
			t.Errorf("%s() must declare one of %v", fn, methods)
		}
	}
}

// jsFunctionBody returns the source of `function name(` / `async function name(`
// up to its closing brace, using brace balancing.
func jsFunctionBody(src, name string) (string, bool) {
	for _, prefix := range []string{"async function " + name + "(", "function " + name + "("} {
		idx := strings.Index(src, prefix)
		if idx < 0 {
			continue
		}
		open := strings.Index(src[idx:], "{")
		if open < 0 {
			continue
		}
		open += idx
		depth := 0
		for i := open; i < len(src); i++ {
			switch src[i] {
			case '{':
				depth++
			case '}':
				depth--
				if depth == 0 {
					return src[idx : i+1], true
				}
			}
		}
	}
	return "", false
}

func oneLine(s string) string {
	s = strings.Join(strings.Fields(s), " ")
	if len(s) > 140 {
		return s[:140] + "…"
	}
	return s
}

// TestUIRecordsPagingWiring guards the record table's paging plumbing. Two
// separate bugs made "scroll to the bottom" silently stop loading:
//
//  1. paintRecords rebuilt the whole table on every 5s poll whenever the row
//     count did not exceed the first screen, wiping loaded pages and resetting
//     scroll position.
//  2. IntersectionObserver only fires on TRANSITIONS. With a short list — or a
//     page whose rows all duplicated the first screen — the sentinel stayed
//     visible and never fired again.
//
// The fixes are a build-once flag, a scroll-position fallback, an initial
// viewport fill, and chaining when a page yields no new rows. None of that is
// reachable from Go, so the wiring is asserted structurally.
func TestUIRecordsPagingWiring(t *testing.T) {
	src := uiSource(t)

	paint, ok := jsFunctionBody(src, "paintRecords")
	if !ok {
		t.Fatal("paintRecords() not found")
	}
	if !strings.Contains(paint, "recsState.built") {
		t.Error("paintRecords must build the table once (recsState.built) instead of rebuilding on every poll")
	}
	if !strings.Contains(paint, "afterbegin") {
		t.Error("paintRecords must PREPEND newer rows on later polls, not rebuild the table")
	}
	if !strings.Contains(paint, "fillRecordsViewport") {
		t.Error("paintRecords must fill the viewport so the sentinel can transition")
	}

	attach, ok := jsFunctionBody(src, "attachRecsObserver")
	if !ok {
		t.Fatal("attachRecsObserver() not found")
	}
	if !strings.Contains(attach, "IntersectionObserver") {
		t.Error("attachRecsObserver must still use IntersectionObserver")
	}
	if !strings.Contains(attach, `addEventListener("scroll"`) {
		t.Error("attachRecsObserver needs a scroll fallback: an already-visible sentinel never fires again")
	}

	load, ok := jsFunctionBody(src, "loadMoreRecords")
	if !ok {
		t.Fatal("loadMoreRecords() not found")
	}
	if !strings.Contains(load, "maxChain") {
		t.Error("loadMoreRecords must chain when a page adds no new rows (the first page overlaps the first screen)")
	}
	if !strings.Contains(load, "signal: ctrl.signal") {
		t.Error("loadMoreRecords must remain abortable")
	}

	fill, ok := jsFunctionBody(src, "fillRecordsViewport")
	if !ok {
		t.Fatal("fillRecordsViewport() not found")
	}
	for _, want := range []string{"scrollHeight", "clientHeight"} {
		if !strings.Contains(fill, want) {
			t.Errorf("fillRecordsViewport must compare %s to decide whether the list overflows", want)
		}
	}

	rel, ok := jsFunctionBody(src, "releaseRecords")
	if !ok {
		t.Fatal("releaseRecords() not found")
	}
	for _, want := range []string{"observer.disconnect()", "removeEventListener", "abort()", "recsState.built = false"} {
		if !strings.Contains(rel, want) {
			t.Errorf("releaseRecords must clean up %s", want)
		}
	}
}

// TestUIThemeMatrix pins the theme system: every accent must define both a light
// and a dark variable block, so switching light/dark can never leave a theme
// half-defined (which shows up as unreadable text rather than as an error).
func TestUIThemeMatrix(t *testing.T) {
	src := uiSource(t)

	accents := []string{"sakura", "ocean", "violet", "mono"}
	for _, a := range accents {
		light := fmt.Sprintf(`html[data-accent=%q]{`, a)
		dark := fmt.Sprintf(`html[data-theme="dark"][data-accent=%q]{`, a)
		if !strings.Contains(src, light) {
			t.Errorf("accent %q has no light-mode variable block (%s)", a, light)
		}
		// sakura is the default palette: its light values live in :root, and the
		// generic dark block covers it.
		if a != "sakura" && !strings.Contains(src, dark) {
			t.Errorf("accent %q has no dark-mode variable block (%s)", a, dark)
		}
		if !strings.Contains(src, fmt.Sprintf(`data-accent="%s" title=`, a)) {
			t.Errorf("accent %q has no picker button", a)
		}
	}
}

// TestUIMonoThemeIsFlat asserts the mono theme really is pure white / pure black:
// the surfaces must be opaque and the glass/blob decoration must be switched off,
// otherwise "#ffffff" renders as a grey translucent card over a gradient mesh.
func TestUIMonoThemeIsFlat(t *testing.T) {
	src := uiSource(t)

	lightBlock, ok := cssBlock(src, `html[data-accent="mono"]{`)
	if !ok {
		t.Fatal("mono light block not found")
	}
	for _, want := range []string{"--bg-s1:#ffffff", "--card:#ffffff", "--glass:0px"} {
		if !strings.Contains(lightBlock, want) {
			t.Errorf("mono light theme must set %s, got:\n%s", want, lightBlock)
		}
	}
	if !strings.Contains(lightBlock, "--blob1:transparent") {
		t.Error("mono light theme must disable the gradient blobs")
	}

	darkBlock, ok := cssBlock(src, `html[data-theme="dark"][data-accent="mono"]{`)
	if !ok {
		t.Fatal("mono dark block not found")
	}
	for _, want := range []string{"--bg-s1:#000000", "--glass:0px"} {
		if !strings.Contains(darkBlock, want) {
			t.Errorf("mono dark theme must set %s, got:\n%s", want, darkBlock)
		}
	}
	if !strings.Contains(darkBlock, "--blob1:transparent") {
		t.Error("mono dark theme must disable the gradient blobs")
	}

	// the flat-surface overrides must exist, or backdrop-filter turns #fff grey
	for _, want := range []string{
		`html[data-accent="mono"] #bgfx .blob{display:none}`,
		`backdrop-filter:none`,
	} {
		if !strings.Contains(src, want) {
			t.Errorf("mono theme needs the flat-surface override %q", want)
		}
	}
}

// TestUICanvasColorsResolveVars guards a class of silent theme bug: Canvas 2D
// does not understand CSS var(), so assigning "var(--x)" to strokeStyle is a
// no-op that leaves the previous colour (often black) in place — invisible on a
// dark background. Theme-driven canvas colours must go through cssVar().
func TestUICanvasColorsResolveVars(t *testing.T) {
	src := uiSource(t)
	if !strings.Contains(src, "function cssVar(") {
		t.Fatal("cssVar() helper missing: canvas colours cannot resolve CSS variables without it")
	}
	for _, prop := range []string{"strokeStyle", "fillStyle"} {
		bad := fmt.Sprintf(`ctx.%s = "var(--`, prop)
		if strings.Contains(src, bad) {
			t.Errorf("ctx.%s assigned a raw CSS var(): Canvas ignores it silently, use cssVar()", prop)
		}
	}
}

// cssBlock returns the text of the CSS rule starting at selector, up to its
// closing brace.
func cssBlock(src, selector string) (string, bool) {
	i := strings.Index(src, selector)
	if i < 0 {
		return "", false
	}
	j := strings.Index(src[i:], "}")
	if j < 0 {
		return "", false
	}
	return src[i : i+j+1], true
}