package tokenengine

import (
	"strings"
	"testing"

	"github.com/urpi/go-bananas/internal/domain"
)

// The aggregate contract is consumed two ways: as a stylesheet the application
// links, which can only be styled from :root, and as a stylesheet a control adopts
// into its own shadow root, where :root matches nothing because a stylesheet in the
// document does not select into a shadow tree. The bare selector forms are what make
// the second use possible, and a palette preview depends on them, so their absence is
// a silent failure: the selector still lists every palette and every preview renders
// in whatever the host's fallbacks happen to be.

// assertSelectorPair asserts that a selector list contains both halves of a pair as
// distinct comma-separated entries.
//
// The assertion is on the joined pair rather than on each half alone, because one half
// cannot tell the two forms apart: the string `[data-theme="acme"][data-mode="light"]`
// occurs inside `:root[data-theme="acme"][data-mode="light"]`, so a bare Contains
// reports a bare selector as present when only the rooted form was emitted. Joining
// them is what discriminates, because in the rooted-only list the two halves are
// separated by `:root`.
func assertSelectorPair(t *testing.T, css, want string) {
	t.Helper()
	if !strings.Contains(css, want) {
		t.Errorf("contract does not emit %q as a pair of entries, so a palette preview cannot adopt it", want)
	}
}

func TestContractEmitsBareSelectorsForPreviewScope(t *testing.T) {
	theme := testTheme()
	theme.Slug = "acme"
	theme.DefaultAppearance = domain.AppearanceDark
	css := ContractAll([]*domain.Theme{theme})

	// The palette on its own, so a preview that declares no appearance still adopts
	// the designer's choice.
	assertSelectorPair(t, css, `[data-theme="acme"], [data-bananas-theme="acme"]`)

	// Each appearance, in both attribute conventions.
	assertSelectorPair(t, css, `[data-theme="acme"][data-mode="light"], [data-bananas-theme="acme"][data-bananas-appearance="light"]`)
	assertSelectorPair(t, css, `[data-theme="acme"][data-mode="dark"], [data-bananas-theme="acme"][data-bananas-appearance="dark"]`)

	// The rooted forms have to survive: every application that links the contract
	// rather than adopting it styles itself from :root.
	assertSelectorPair(t, css, `:root[data-theme="acme"], :root[data-bananas-theme="acme"]`)
	assertSelectorPair(t, css, `:root[data-theme="acme"][data-mode="light"], :root[data-bananas-theme="acme"][data-bananas-appearance="light"]`)
}

// TestContractBareSelectorsCarryTheSameValues guards against the two forms drifting
// apart, which would mean a preview shows a different palette from the one applying
// to the page. Both forms are emitted from the same declarations, so this is a
// statement that the pairing is not an accident worth breaking.
func TestContractBareSelectorsCarryTheSameValues(t *testing.T) {
	css := ContractAll([]*domain.Theme{testTheme()})

	for _, want := range []string{
		`--bn-bg: #ffffff;`,
		`--bn-text: #0f172a;`,
		`--bn-accent: #4f46e5;`,
	} {
		if !strings.Contains(css, want) {
			t.Errorf("contract no longer emits %q", want)
		}
	}
}

// TestContractLegacyAliasesStillExist protects the compatibility promise: an
// application that already uses the unprefixed names must keep working.
func TestContractLegacyAliasesStillExist(t *testing.T) {
	css := ContractAll([]*domain.Theme{testTheme()})

	for legacy := range legacyAliases {
		if !strings.Contains(css, "--"+legacy+":") {
			t.Errorf("legacy alias --%s is no longer emitted", legacy)
		}
	}
}