package guards

import (
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"testing"

	"amadan.net/oficina/estilo.git/base"
	"amadan.net/oficina/estilo.git/chrome"
	estilomenu "amadan.net/oficina/estilo.git/menu"
	"amadan.net/oficina/estilo.git/theme"
)

// ourStylesheets are the CSS files this app writes. The vendored ones
// are not checked: they define their own custom properties and know
// nothing about rastrillo's.
var ourStylesheets = []string{
	"internal/sheets/static/sheets.css",
}

// tokenSources are the files that DEFINE rastrillo's tokens: the
// structural ones copied by `rastrillo doctor` and the shared palette.
var tokenSources = []string{
	"internal/sheets/static/tokens.css",
	"Estilo theme module",
}

var (
	tokenUse    = regexp.MustCompile(`var\(\s*(--rst-[a-zA-Z0-9-]+)`)
	tokenDefine = regexp.MustCompile(`(--rst-[a-zA-Z0-9-]+)\s*:`)
)

// TestEveryTokenWeUseExists is the check that would have caught five
// invented token names shipping to a canary.
//
// CSS resolves an undefined custom property to its fallback without a
// warning anywhere — no console message, no parse error, nothing in a
// Go test. So `var(--rst-border, 1px solid #ccc)` renders a plausible
// page that is simply not themed, and the only way to notice is to look
// at it in both schemes and know what you expected. That is not a gate.
//
// The five were --rst-border, --rst-text-mut, --rst-warning,
// --rst-font-mono and --rst-shell-bar-h. The real names are
// --rst-line, --rst-text-muted, --rst-tone-warning-fg and --rst-font;
// the last had no equivalent at all and the layout was measuring
// something the framework never published.
func TestEveryTokenWeUseExists(t *testing.T) {
	root := repoRoot(t)

	defined := map[string]bool{}
	for _, rel := range tokenSources {
		var body []byte
		var err error
		if rel == "Estilo theme module" {
			body = theme.CSS()
		} else {
			body, err = os.ReadFile(filepath.Join(root, rel))
		}
		if err != nil {
			t.Fatalf("guards: read %s: %v — the token sources are what `rastrillo doctor` copies; "+
				"if one moved, this test needs updating, not deleting", rel, err)
		}
		for _, m := range tokenDefine.FindAllStringSubmatch(string(body), -1) {
			defined[m[1]] = true
		}
	}
	if len(defined) == 0 {
		t.Fatal("guards: found no --rst-* definitions at all; this test is not checking anything")
	}

	var used int
	for _, rel := range ourStylesheets {
		body, err := os.ReadFile(filepath.Join(root, rel))
		if err != nil {
			t.Fatalf("guards: read %s: %v", rel, err)
		}
		var missing []string
		for _, m := range tokenUse.FindAllStringSubmatch(string(body), -1) {
			used++
			if !defined[m[1]] {
				missing = append(missing, m[1])
			}
		}
		sort.Strings(missing)
		for _, name := range dedupe(missing) {
			t.Errorf("%s: var(%s) is not defined in %s — CSS resolves an unknown "+
				"custom property to its fallback in silence, so this renders a page "+
				"that is simply not themed",
				rel, name, strings.Join(tokenSources, " or "))
		}
	}
	if used == 0 {
		t.Fatal("guards: our stylesheets reference no tokens at all; either they stopped " +
			"using the design system or this test is looking in the wrong place")
	}
}

func dedupe(in []string) []string {
	var out []string
	for i, s := range in {
		if i == 0 || s != in[i-1] {
			out = append(out, s)
		}
	}
	return out
}

// TestEveryEstiloPropertyWeUseExists is the same check for the estilo
// custom properties sheets.css reads (--estilo-float-radius and the
// rest), against the three stylesheets that define them. The same
// failure as a misspelled --rst- token: CSS takes the fallback in
// silence, so a float drawn with an estilo property nobody defines is
// simply not the suite's float.
func TestEveryEstiloPropertyWeUseExists(t *testing.T) {
	defined := map[string]bool{}
	def := regexp.MustCompile(`(--estilo-[a-zA-Z0-9-]+)\s*:`)
	for _, css := range [][]byte{base.CSS(), estilomenu.CSS(), chrome.CSS()} {
		for _, m := range def.FindAllStringSubmatch(string(css), -1) {
			defined[m[1]] = true
		}
	}
	if len(defined) == 0 {
		t.Fatal("guards: estilo defines no --estilo-* properties; this test is reading the wrong stylesheets")
	}
	use := regexp.MustCompile(`var\(\s*(--estilo-[a-zA-Z0-9-]+)`)
	for _, rel := range ourStylesheets {
		body := readRepoFile(t, repoRoot(t), rel)
		for _, m := range use.FindAllStringSubmatch(body, -1) {
			if !defined[m[1]] {
				t.Errorf("%s: var(%s) is not defined by estilo's base, menu or chrome stylesheet", rel, m[1])
			}
		}
	}
}