package rustlang

import (
	"strings"
	"testing"

	"rickub.com/turbo-editors/turbo-core/syntax"
)

// TestTheLanguagesReferenceIsTrue holds docs/*/reference/languages.md to the
// scanner. Every row of its Rust table that no other test here covers is
// checked, so a reference claim and the code cannot drift apart quietly.
//
// The MAX_SIZE case is the one that documents a limitation rather than a
// feature: the leading-capital rule colours a SCREAMING_SNAKE_CASE constant as
// a type, the reference says so, and this is what stops somebody "fixing" it
// without also fixing the sentence.
func TestTheLanguagesReferenceIsTrue(t *testing.T) {
	tests := []struct {
		src  string
		word string
		want syntax.Class
	}{
		{"//! module doc", "//! module doc", syntax.ClassComment},
		{"/// item doc", "/// item doc", syntax.ClassComment},
		{`let s = br##"a"#b"##;`, `br##"a"#b"##`, syntax.ClassString},
		{"for i in 0..=10 {}", "..=", syntax.ClassOperator},
		{"let x = std::mem::swap;", "::", syntax.ClassPunctuation},
		{"let x: u8 = 1;", ":", syntax.ClassPunctuation},
		{"async fn f() {}", "async", syntax.ClassKeyword},
		{"let x = become;", "become", syntax.ClassKeyword},
		{"let v: Vec<u8> = vec![];", "vec!", syntax.ClassBuiltin},
		{"#![no_std]", "#![no_std]", syntax.ClassAttribute},
		{"let n = 0o77;", "0o77", syntax.ClassNumber},
		{"let n = 3.0f64;", "3.0f64", syntax.ClassNumber},
		{"let c = b'x';", "b'x'", syntax.ClassChar},
		{"fn f<'a>() {}", "'a", syntax.ClassType},
		{"let x = MAX_SIZE;", "MAX_SIZE", syntax.ClassType},
	}

	for _, test := range tests {
		t.Run(test.word, func(t *testing.T) {
			index := strings.Index(test.src, test.word)
			if index < 0 {
				t.Fatalf("%q not in %q", test.word, test.src)
			}
			got, ok := classAt(Highlight(test.src), 0, index)
			if !ok || got != test.want {
				t.Errorf("%q in %q is %v (covered %v), want %v", test.word, test.src, got, ok, test.want)
			}
		})
	}
}