@testable import PureYAML
import Testing

/// A tag shorthand using a named handle (`!handle!suffix`) must be declared by a `%TAG` directive
/// in the document that uses it; the handle does not carry across documents. The ported engine is
/// strict (official suite case QLJ7): an undeclared handle fails the parse, and the validation
/// report carries it as a parse diagnostic. These prove the error is exact: it fires for an
/// undeclared handle and stays silent for a declared one, a local tag, the secondary handle, and a
/// `!x!` that is only scalar content.
@Suite("Undefined tag handle")
struct UndefinedTagHandleTests {
    private func codes(_ yaml: String) -> [String] {
        PureYAML.validationReport(yaml).diagnostics.compactMap(\.code)
    }

    @Test("A handle not redeclared in a later document is flagged there, not in the declaring one")
    func test_handleScopeIsPerDocument() {
        let yaml = """
        %TAG !prefix! tag:example.com,2011:
        --- !prefix!A
        a: b
        --- !prefix!B
        c: d
        """
        // The ported engine is strict (official suite case QLJ7): the second document, which
        // did not redeclare the handle, fails the parse, and the report carries that failure
        // as a parse diagnostic instead of the old permissive-parse pre-pass diagnostic.
        let report = PureYAML.validationReport(yaml)
        let parseErrors = report.diagnostics.filter { $0.kind == .parse && $0.severity == .error }
        #expect(parseErrors.count == 1)
        #expect(parseErrors.first?.reason.contains("undefined tag handle") == true)
        #expect(parseErrors.first?.line == 4)
    }

    @Test("A handle redeclared for each document is accepted with no diagnostic")
    func test_redeclaredHandleIsClean() {
        let yaml = """
        %TAG !m! !my-
        --- !m!light fluorescent
        ...
        %TAG !m! !my-
        --- !m!light green
        """
        #expect(!codes(yaml).contains("undefinedTagHandle"))
    }

    @Test("A local tag, the secondary handle, and a verbatim tag are not handle references")
    func test_nonHandleTagsAreClean() {
        #expect(!codes("a: !foo bar").contains("undefinedTagHandle"))
        #expect(!codes("a: !!str x").contains("undefinedTagHandle"))
        #expect(!codes("a: !<tag:example.com,2011:x> y").contains("undefinedTagHandle"))
    }

    @Test("A bang pair inside scalar content is not a tag and is never flagged")
    func test_noFalsePositiveInScalarContent() {
        #expect(!codes("msg: hello !world! bye").contains("undefinedTagHandle"))
        #expect(!codes("quoted: \"a !x! b\"").contains("undefinedTagHandle"))
    }
}