@testable import PureYAML
import Testing

/// Verifies the ported simple-key mechanism (`save_simple_key`,
/// `remove_simple_key`, `stale_simple_keys`, flow-level push/pop) reproduces
/// libyaml's behavior.
@Suite("LibYAML Simple Key")
struct LibYAMLSimpleKeyTests {
    private func mark(line: Int, column: Int, index: Int) -> PureYAML.Parsing.Mark {
        PureYAML.Parsing.Mark(line: line, column: column, index: index)
    }

    @Test("saves a possible key, required when it sits at the block indent")
    func test_saveSimpleKeyRequiredAtIndent() throws {
        var scanner = PureYAML.Parsing.LibYAML.Scanner()
        scanner.indentEngine.rollIndent(column: 0, number: -1, type: .blockMappingStart, mark: .start)
        scanner.mark = mark(line: 1, column: 0, index: 0)
        try scanner.saveSimpleKey()
        #expect(scanner.simpleKeys.last?.possible == true)
        #expect(scanner.simpleKeys.last?.required == true)
    }

    @Test("a key not at the block indent is possible but not required")
    func test_saveSimpleKeyNotRequired() throws {
        var scanner = PureYAML.Parsing.LibYAML.Scanner()
        scanner.indentEngine.rollIndent(column: 0, number: -1, type: .blockMappingStart, mark: .start)
        scanner.mark = mark(line: 1, column: 4, index: 4)
        try scanner.saveSimpleKey()
        #expect(scanner.simpleKeys.last?.possible == true)
        #expect(scanner.simpleKeys.last?.required == false)
    }

    @Test("removing a required possible key is an error")
    func test_removeRequiredKeyThrows() throws {
        var scanner = PureYAML.Parsing.LibYAML.Scanner()
        scanner.indentEngine.rollIndent(column: 0, number: -1, type: .blockMappingStart, mark: .start)
        scanner.mark = mark(line: 1, column: 0, index: 0)
        try scanner.saveSimpleKey()
        #expect(throws: PureYAML.Parsing.LibYAML.ScannerError.self) {
            try scanner.removeSimpleKey()
        }
    }

    @Test("a non-required key on an earlier line goes stale without error")
    func test_staleNonRequiredKey() throws {
        var scanner = PureYAML.Parsing.LibYAML.Scanner()
        scanner.indentEngine.rollIndent(column: 0, number: -1, type: .blockMappingStart, mark: .start)
        scanner.mark = mark(line: 1, column: 4, index: 4)
        try scanner.saveSimpleKey()
        scanner.mark = mark(line: 2, column: 0, index: 10)
        try scanner.staleSimpleKeys()
        #expect(scanner.simpleKeys.last?.possible == false)
    }

    @Test("flow level pushes and pops a simple-key slot")
    func test_flowLevelStack() {
        var scanner = PureYAML.Parsing.LibYAML.Scanner()
        #expect(scanner.simpleKeys.count == 1)
        scanner.increaseFlowLevel(isSequence: true)
        #expect(scanner.flowLevel == 1)
        #expect(scanner.simpleKeys.count == 2)
        #expect(scanner.flowIsSequence == [true])
        scanner.decreaseFlowLevel()
        #expect(scanner.flowLevel == 0)
        #expect(scanner.simpleKeys.count == 1)
    }
}