use super::helpers::fixtures::get_language;
use tree_sitter::Parser;

#[test]
fn test_lookahead_iterator() {
    let mut parser = Parser::new();
    let language = get_language("rust");
    parser.set_language(&language).unwrap();

    let tree = parser.parse("struct Stuff {}", None).unwrap();

    let mut cursor = tree.walk();

    assert!(cursor.goto_first_child()); // struct
    assert!(cursor.goto_first_child()); // struct keyword

    let next_state = cursor.node().next_parse_state();
    assert_ne!(next_state, 0);
    assert_eq!(
        next_state,
        language.next_state(cursor.node().parse_state(), cursor.node().grammar_id())
    );
    assert!((next_state as usize) < language.parse_state_count());
    assert!(cursor.goto_next_sibling()); // type_identifier
    assert_eq!(next_state, cursor.node().parse_state());
    assert_eq!(cursor.node().grammar_name(), "identifier");
    assert_ne!(cursor.node().grammar_id(), cursor.node().kind_id());

    let expected_symbols = ["identifier", "block_comment", "line_comment"];
    let mut lookahead = language.lookahead_iterator(next_state).unwrap();
    assert_eq!(lookahead.language(), language);
    assert!(lookahead.iter_names().eq(expected_symbols));

    lookahead.reset_state(next_state);
    assert!(lookahead.iter_names().eq(expected_symbols));

    lookahead.reset(language.clone(), next_state);
    assert!(lookahead
        .map(|s| language.node_kind_for_id(s).unwrap())
        .eq(expected_symbols));
}

#[test]
fn test_lookahead_iterator_modifiable_only_by_mut() {
    let mut parser = Parser::new();
    let language = get_language("rust");
    parser.set_language(&language).unwrap();

    let tree = parser.parse("struct Stuff {}", None).unwrap();

    let mut cursor = tree.walk();

    assert!(cursor.goto_first_child()); // struct
    assert!(cursor.goto_first_child()); // struct keyword

    let next_state = cursor.node().next_parse_state();
    assert_ne!(next_state, 0);

    let mut lookahead = language.lookahead_iterator(next_state).unwrap();
    let _ = lookahead.next();

    let mut names = lookahead.iter_names();
    let _ = names.next();
}