package lua

import (
	"encoding/json"
	"os"
	"os/exec"
	"regexp"
	"strings"
	"testing"
)

// The billing page rendered EMPTY in production while its data endpoint returned
// 200 with real numbers. The cause was one line: render(st) referenced an
// undefined `s` for two KPI cells, so the ReferenceError aborted the whole
// render and every table stayed at its initial empty innerHTML.
//
// Nothing in the build, the tests or the API surfaced it. This file is the guard
// for the whole class: a plugin's injected UI that references an undefined name,
// or that depends on a container the page does not provide, fails silently.

// billingUI returns the injected markup for the billing plugin: the full page
// mount and the status-page element mount.
func billingUI(t *testing.T) (page string, statusElement string) {
	t.Helper()
	src, err := os.ReadFile("plugins/billing.lua")
	if err != nil {
		t.Fatalf("read billing.lua: %v", err)
	}
	// Located BY CONTENT, not by index. The plugin also uses a long string for
	// its inline SVG icon, so "the first long string" is the icon and "the
	// second" is the page — which is exactly the kind of positional assumption
	// that breaks the next time an icon or a description is added.
	page = longStringContaining(t, string(src), "billing-root")
	statusElement = longStringContaining(t, string(src), "billing-status-tile")
	return page, statusElement
}

// longStringContaining returns the [==[ ... ]==] body that contains marker.
func longStringContaining(t *testing.T, src, marker string) string {
	t.Helper()
	re := regexp.MustCompile(`(?s)\[==\[(.*?)\]==\]`)
	for _, m := range re.FindAllStringSubmatch(src, -1) {
		if strings.Contains(m[1], marker) {
			return m[1]
		}
	}
	t.Fatalf("no long string contains %q", marker)
	return ""
}

// TestBillingMountScriptExecutes is the guard for the production bug.
//
// The Billing page rendered empty while its data endpoint returned 200 with real
// numbers. Cause: render(st) referenced an undefined `s` for two KPI cells, the
// ReferenceError aborted the render, and every table kept its initial empty
// innerHTML. Nothing in the build or the API surfaced it.
//
// Two earlier attempts at a static check were both wrong: a "declared names"
// scan flagged every CSS class inside the inline HTML strings (class, div, td),
// and a CSS-selector parse of the stylesheet reported the stylesheet itself as
// broken. Static analysis of JS embedded in HTML strings is the wrong tool.
//
// So this actually RUNS the script, in node, against a minimal DOM stub, and
// fails on any thrown error. Skipped when node is unavailable, with the reason
// printed — never silently passing as if it had checked.
func TestBillingMountScriptExecutes(t *testing.T) {
	page, el := billingUI(t)
	scripts := extractScripts(page)
	if len(scripts) == 0 {
		t.Fatal("no <script> found in the billing page mount")
	}
	for i, js := range scripts {
		assertRendersAndDoesNotThrow(t, i, js)
	}
	for i, js := range extractScripts(el) {
		assertRendersAndDoesNotThrow(t, i, js)
	}
}

// assertRendersAndDoesNotThrow executes a mount script under node against a DOM
// stub and fails on EITHER a thrown/reported error OR an empty render.
//
// Checking only for exceptions is not enough, and that is the third wrong
// attempt at this guard. The plugin's render() opens with `if (!st) return;`,
// so passing the wrong field (`render(j.stateX)`) is a SILENT no-op: no throw,
// no console.error, no rejection — just an empty page. Only looking at the
// produced DOM catches that class.
func assertRendersAndDoesNotThrow(t *testing.T, idx int, js string) {
	t.Helper()
	node, err := exec.LookPath("node")
	if err != nil {
		t.Skipf("node not available (%v): cannot execute the injected script", err)
	}

	stub := `
global.window = global;
global.document = {
  getElementById: function (id) {
    if (!global.__els) global.__els = {};
    if (!global.__els[id]) global.__els[id] = {
      style: {}, dataset: {}, classList: { add: function(){}, remove: function(){} },
      // Both writes count: the Billing page fills innerHTML, the status-page
      // tile assigns textContent. Watching only one of them flagged the tile as
      // "renders nothing" — a false positive that would have taught everyone to
      // ignore this test.
      set innerHTML(v) { if (v && String(v).trim()) global.__written.push(id); this.__h = v; },
      get innerHTML() { return this.__h || ""; },
      set textContent(v) { if (v !== undefined && String(v).trim()) global.__written.push(id); this.__t = v; },
      get textContent() { return this.__t || ""; },
      set innerText(v) { if (v !== undefined && String(v).trim()) global.__written.push(id); this.__i = v; },
      get innerText() { return this.__i || ""; },
      appendChild: function(){}, querySelector: function(){ return null; },
      querySelectorAll: function(){ return []; }, addEventListener: function(){} };
    return global.__els[id];
  },
  createElement: function () { return { style: {}, dataset: {}, appendChild: function(){}, setAttribute: function(){} }; },
  addEventListener: function () {},
};
global.pluginAPI = { onTabShown: function () {} };
global.fetch = function () {
  // A payload with real numbers, so a working render produces visible output.
  return Promise.resolve({ ok: true, json: function () {
    return Promise.resolve({ plugin: "billing", state: {
      currency: "USD",
      total: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 },
      by_source: { localzen: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
      by_model: { m1: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
      by_key: { k1: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
      by_day: { "2026-01-01": { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
      degraded_reqs: 1, unpriced_reqs: 2,
    }});
  }});
};
global.__written = [];
global.__errors = [];
// The plugin's refresh() swallows its own errors so decoration can never break
// the host page — which is right, and is exactly why the production ReferenceError
// was invisible. So the trace has to come from console.error, which the plugin now
// emits. Hooking process events alone made this test pass against the very bug it
// was written for (verified by re-introducing the typo and watching it stay green).
var __realErr = console.error;
console.error = function () {
  global.__errors.push("console.error: " + Array.prototype.map.call(arguments, function (a) {
    return (a && a.message) ? a.message : String(a);
  }).join(" "));
  __realErr.apply(console, arguments);
};
process.on("uncaughtException", function (e) { global.__errors.push("uncaught: " + String(e && e.message || e)); });
process.on("unhandledRejection", function (e) { global.__errors.push("unhandled: " + String(e && e.message || e)); });
`
	// 50ms is not a guess: the plugin's IIFE kicks off refresh() which awaits a
	// fetch; a rejection lands on the microtask queue almost immediately.
	script := strings.Join([]string{
		stub, js,
		`setTimeout(function(){
   console.log("__ERRS__" + JSON.stringify({errors: global.__errors, written: global.__written}));
 }, 300);`,
	}, "\n")
	cmd := exec.Command(node, "-e", script)
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Errorf("mount script %d crashed under node: %v\n%s", idx, err, out)
		return
	}
	// The script may print other things; find the JSON we appended.
	line := ""
	for _, l := range strings.Split(string(out), "\n") {
		if i := strings.Index(l, "__ERRS__"); i >= 0 {
			line = strings.TrimSpace(l[i+len("__ERRS__"):])
		}
	}
	if line == "" {
		t.Errorf("mount script %d produced no error report — the harness did not "+
			"run to completion, so it cannot be trusted to have checked anything", idx)
		return
	}
	var report struct {
		Errors  []string `json:"errors"`
		Written []string `json:"written"`
	}
	if err := json.Unmarshal([]byte(line), &report); err != nil {
		t.Errorf("could not parse the error report %q: %v", line, err)
		return
	}
	for _, e := range report.Errors {
		t.Errorf("mount script %d reported %q — this is the failure that leaves "+
			"the Billing page blank while the API still returns data", idx, e)
	}
	if len(report.Written) == 0 {
		t.Errorf("mount script %d wrote NOTHING into any container — the page "+
			"renders empty. render() guards with `if (!st) return`, so a wrong "+
			"field name is a silent no-op: no throw, no console output, no error "+
			"anywhere. This is what the production page looked like.", idx)
	}
}

func extractScripts(html string) []string {
	re := regexp.MustCompile(`(?s)<script[^>]*>(.*?)</script>`)
	var out []string
	for _, m := range re.FindAllStringSubmatch(html, -1) {
		out = append(out, m[1])
	}
	return out
}

// TestBillingPageCoversItsData is the other half: the page declares tables for
// per-source / per-model / per-key / per-day and must actually render into them.
// A table id that is never written to is exactly how "the page loads and shows
// nothing" happens without an error.
func TestBillingPageCoversItsData(t *testing.T) {
	page, _ := billingUI(t)
	for _, id := range []string{
		"billing-kpis", "billing-by-source", "billing-by-model",
		"billing-by-key", "billing-by-day",
	} {
		if !strings.Contains(page, `id="`+id+`"`) {
			t.Errorf("the page has no container #%s", id)
		}
	}
	// Every container must be written to by the script, not just declared.
	scripts := extractScripts(page)
	all := strings.Join(scripts, "\n")
	for _, id := range []string{"billing-kpis", "billing-by-source", "billing-by-model", "billing-by-key", "billing-by-day"} {
		if !strings.Contains(all, `getElementById("`+id+`")`) {
			t.Errorf("#%s is declared but never read by the script — it stays empty forever", id)
		}
	}
}

// TestPluginIconIsNotARawEmoji guards the sidebar icon. The billing plugin
// declared icon = "💰" and the WebUI drops that verbatim into the button, while
// every native tab uses an inline SVG styled with `stroke: currentColor`. An
// emoji there renders at the wrong size and ignores the theme, so it does not
// match its neighbours — which is what the operator reported.
func TestPluginIconIsNotARawEmoji(t *testing.T) {
	icon := billingIcon(mustBillingSource(t))
	if icon == "" {
		t.Fatal("billing declares no icon; the sidebar entry would be blank")
	}
	if isEmojiIcon(icon) {
		t.Errorf("page icon is the raw emoji %q — the WebUI sidebar renders "+
			"native tabs as inline SVG (stroke: currentColor), so an emoji is the "+
			"wrong size and ignores the theme. Use an inline SVG path instead.", icon)
	}
}

// isEmojiIcon reports whether s is a pictographic emoji rather than markup or a
// text glyph. Codepoints in the pictographic blocks, plus the regional-indicator
// pair used by flags.
func isEmojiIcon(s string) bool {
	r := []rune(s)
	if len(r) == 0 {
		return false
	}
	// Anything containing '<' is markup (an inline <svg>), which is the fix.
	if strings.ContainsRune(s, '<') {
		return false
	}
	for _, c := range r {
		switch {
		case c >= 0x1F300 && c <= 0x1FAFF, // pictographs, symbols, supplemental
			c >= 0x1F000 && c <= 0x1F2FF, // mahjong/domino/cards
			c >= 0x2600 && c <= 0x27BF,   // misc symbols + dingbats
			c >= 0x2B00 && c <= 0x2BFF,   // arrows/misc symbols
			c == 0xFE0F,                  // variation selector-16
			c >= 0x1F1E6 && c <= 0x1F1FF: // regional indicators (flags)
			return true
		}
	}
	return false
}

func mustBillingSource(t *testing.T) string {
	t.Helper()
	b, err := os.ReadFile("plugins/billing.lua")
	if err != nil {
		t.Fatal(err)
	}
	return string(b)
}

// billingIcon extracts the declared page icon. It accepts BOTH a quoted string
// and a [==[ ... ]==] long string, because an inline SVG cannot be written as a
// Lua short string without escaping every quote in it.
func billingIcon(src string) string {
	if m := regexp.MustCompile(`(?m)^\s*icon\s*=\s*"([^"]*)"`).FindStringSubmatch(src); m != nil {
		return m[1]
	}
	if m := regexp.MustCompile(`(?s)\bicon\s*=\s*\[==\[(.*?)\]==\]`).FindStringSubmatch(src); m != nil {
		return m[1]
	}
	return ""
}

// TestBillingTableHeaderMatchesRowColumns catches column drift.
//
// row() gained cache columns (fresh / cache / cache%) while the header row did
// not, in the same edit. The result is a table whose cells are shifted one
// column left from "fresh" onward — so "cache%" sits under "completion" and the
// last cell has no label. It renders, it has data, and it is wrong in a way that
// takes a careful read to notice.
func TestBillingTableHeaderMatchesRowColumns(t *testing.T) {
	page, _ := billingUI(t)
	js := strings.Join(extractScripts(page), "\n")
	if !strings.Contains(js, "<th>") {
		t.Fatal("no table header found in the billing page script")
	}
	hStart := strings.Index(js, "function tableFor")
	if hStart < 0 {
		t.Fatal("no tableFor in the billing page script")
	}
	header := js[hStart:]
	th := strings.Count(header, "<th>")

	rStart := strings.Index(js, "function row")
	rEnd := strings.Index(js, "function tableFor")
	if rStart < 0 || rEnd < 0 || rEnd <= rStart {
		t.Fatal("could not isolate row()")
	}
	row := js[rStart:rEnd]
	// Each cell closes with </td>; the first cell uses <td><b>..</b></td> so
	// counting </td> is exact.
	td := strings.Count(row, "</td>")

	if th != td {
		t.Errorf("★ header declares %d columns but row() emits %d cells — the "+
			"table is misaligned from the first differing column on", th, td)
	}
}