import XCTest
import CodableCSV

/// Check support for handling bad input
final class DecodingBadInputTests: XCTestCase {
    /// Representation of a CSV row containing a couple of strings.
    private struct _Row: Codable, Equatable {
        var x: String
        var y: String
    }
}

extension DecodingBadInputTests {
    /// Tests bad quoting resulting in too many fields in a particular row
    func testBadQuoting() throws {
        let correctAnswer = [
            _Row(x: "A", y: "A A"),
            _Row(x: "B", y: "B, B"),
            _Row(x: "C", y: "C, C"),
            _Row(x: "D", y: "D D"),
        ]
        let stringAB = """
            x,y
            A,A A
            B,"B, B"
            """.appending("\n")
        let stringC_GOOD = """
            C,"C, C"
            """.appending("\n")
        // stringC_BAD fails to quote the second field which contains a comma thus making it appear to be two fields
        let stringC_BAD = """
            C,C, C
            """.appending("\n")
        let stringD = """
            D,D D
            """.appending("\n")

        let decoder = CSVDecoder {
            $0.headerStrategy = .firstLine
            $0.boolStrategy = .numeric
        }

        // using quotes properly causes a successful decode of all 4 rows
        let result_GOOD = try decoder.decode([_Row].self, from: stringAB + stringC_GOOD + stringD)
        XCTAssertEqual(correctAnswer, result_GOOD)

        // when the last field is lacking the quotes, that line and all the lines after it fail to parse.
        let result_BAD = try decoder.decode([_Row].self, from: stringAB + stringC_BAD + stringD)
        XCTAssertEqual(correctAnswer, result_BAD)
    }



    /// Tests having an ill-formed header
    func testIllFormedHeader() throws {
        let correctAnswer = [
            _Row(x: "A", y: "A A"),
            _Row(x: "B", y: "B, B"),
        ]
        let stringA_GOOD = """
            x,y
            """.appending("\n")
        // stringA_BAD has an additional, incorrect, comma after the y in the header line
        let stringA_BAD = """
            x,y,
            """.appending("\n")
        let stringB = """
            A,A A
            B,"B, B"
            """.appending("\n")

        let decoder = CSVDecoder {
            $0.headerStrategy = .firstLine
        }

        // with the correct header, everything is tickety-boo
        let result_GOOD = try decoder.decode([_Row].self, from: stringA_GOOD + stringB)
        XCTAssertEqual(correctAnswer, result_GOOD)


        // having a stray comma at the end of the header line causes no error, but no rows are processed.
        let result_BAD = try decoder.decode([_Row].self, from: stringA_BAD + stringB)
        XCTAssertEqual(correctAnswer, result_BAD)
    }


}