package lexer

import org.junit.jupiter.api.Test
import org.junit.jupiter.api.assertThrows
import org.junit.jupiter.api.Assertions.*

class ScanTests {
    @Test
    fun scan_emptyString_returns_EOF() {
        val tokens = Lexer("").scan()
        assertEquals(1, tokens.size, "Expected 1 token, got ${tokens.size}")
        assertEquals(TokenType.EOF, tokens[0].type, "Expected EOF token, got ${tokens[0].type}")
    }

    @Test
    fun scan_unknownSymbol_returns_Error() {
        assertThrows<Error> { Lexer("€").scan() }
    }

    @Test
    fun scan_dot_returns_Dot() {
        val tokens = Lexer(".").scan()
        assertEquals(2, tokens.size)
        assertEquals(TokenType.DOT, tokens[0].type, "Expected DOT token, got ${tokens[0].type}")
        assertEquals(TokenType.EOF, tokens[1].type, "Expected EOF token, got ${tokens[1].type}")
    }

    @Test
    fun scan_two_dots_returns_two_dots() {
        val tokens = Lexer("..").scan()
        assertEquals(3, tokens.size)
        assertEquals(TokenType.DOT, tokens[0].type, "Expected DOT token, got ${tokens[0].type}")
        assertEquals(TokenType.DOT, tokens[1].type, "Expected DOT token, got ${tokens[1].type}")
        assertEquals(TokenType.EOF, tokens[2].type, "Expected EOF token, got ${tokens[2].type}")
    }

    @Test
    fun scan_letter_returns_letter() {
        val tokens = Lexer("a").scan()

        assertEquals(2, tokens.size)

        assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
        assertEquals(TokenType.EOF, tokens[1].type, "Expected EOF token, got ${tokens[1].type}")

        assertEquals(0, tokens[0].position.line, "Expected line 0, got ${tokens[0].position.line}")
        assertEquals(0, tokens[0].position.column, "Expected column 0, got ${tokens[0].position.column}")
        assertEquals(1, tokens[0].position.length, "Expected length 1, got ${tokens[0].position.length}")
    }

    @Test
    fun scan_word_returns_alphanumerics() {
        val lexer = Lexer("word")
        val tokens = lexer.scan()

        assertEquals(2, tokens.size)

        assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
        assertEquals(TokenType.EOF, tokens[1].type, "Expected EOF token, got ${tokens[1].type}")

        assertEquals(4, tokens[0].position.length, "Expected length 4, got ${tokens[0].position.length}")

        assertEquals("word", tokens[0].value, "Expected 'word', got ${tokens[0].value}")
    }

    @Test
    fun scan_space_returns_nothing() {
        val lexer = Lexer(" ")
        val tokens = lexer.scan()

        assertEquals(1, tokens.size)

        assertEquals(TokenType.EOF, tokens[0].type, "Expected EOF token, got ${tokens[0].type}")
    }

    @Test
    fun scan_whitespace_various_returns_nothing() {
        val lexer = Lexer(" \t\n\r")
        val tokens = lexer.scan()

        assertEquals(1, tokens.size)

        assertEquals(TokenType.EOF, tokens[0].type, "Expected EOF token, got ${tokens[0].type}")
    }


    @Test
    fun scan_separated_words() {
        val tokens = Lexer("word1 word2").scan()

        assertEquals(3, tokens.size, "Expected 3 tokens, got ${tokens.size}")

        assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
        assertEquals("word1", tokens[0].value, "Expected 'word1', got ${tokens[0].value}")
        assertEquals(5, tokens[0].position.length, "Expected length 5, got ${tokens[0].position.length}")

        assertEquals(TokenType.ALPHANUMERIC, tokens[1].type, "Expected ALPHANUMERIC token, got ${tokens[1].type}")
        assertEquals("word2", tokens[1].value, "Expected 'word2', got ${tokens[1].value}")
        assertEquals(5, tokens[1].position.length, "Expected length 5, got ${tokens[1].position.length}")
    }

    @Test
    fun scan_multiline() {
        val tokens = Lexer(
            """
            word1
            word2
        """.trimIndent()
        ).scan()

        assertEquals(3, tokens.size, "Expected 3 tokens, got ${tokens.size}")

        assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
        assertEquals("word1", tokens[0].value, "Expected 'word1', got ${tokens[0].value}")
        assertEquals(5, tokens[0].position.length, "Expected length 5, got ${tokens[0].position.length}")

        assertEquals(TokenType.ALPHANUMERIC, tokens[1].type, "Expected ALPHANUMERIC token, got ${tokens[1].type}")
        assertEquals("word2", tokens[1].value, "Expected 'word2', got ${tokens[1].value}")
        assertEquals(5, tokens[1].position.length, "Expected length 5, got ${tokens[1].position.length}")
    }

    @Test
    fun scan_parenthesis_returns_parenthesis() {
        val lexer = Lexer("()")
        val tokens = lexer.scan()

        assertEquals(3, tokens.size)

        assertEquals(
            TokenType.LEFT_PARENTHESES,
            tokens[0].type,
            "Expected LEFT_PARENTHESES token, got ${tokens[0].type}"
        )
        assertEquals(
            TokenType.RIGHT_PARENTHESES,
            tokens[1].type,
            "Expected RIGHT_PARENTHESES token, got ${tokens[1].type}"
        )
        assertEquals(TokenType.EOF, tokens[2].type, "Expected EOF token, got ${tokens[2].type}")
    }

    @Test
    fun scan_simple_quoted_string_returns_string() {
        val lexer = Lexer("\"string\"")
        val tokens = lexer.scan()

        assertEquals(2, tokens.size)

        assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
        assertEquals(TokenType.EOF, tokens[1].type, "Expected EOF token, got ${tokens[1].type}")

        assertEquals("string", tokens[0].value, "Expected 'string', got ${tokens[0].value}")
    }

    @Test
    fun scan_quoted_string_with_space_returns_string() {
        val lexer = Lexer("\"string with space\"")
        val tokens = lexer.scan()

        assertEquals(2, tokens.size)

        assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
        assertEquals(TokenType.EOF, tokens[1].type, "Expected EOF token, got ${tokens[1].type}")

        assertEquals("string with space", tokens[0].value, "Expected 'string with space', got ${tokens[0].value}")
    }

    @Test
    fun scan_comments_returns_nothing() {
        val lexer = Lexer("% comment")
        val tokens = lexer.scan()

        assertEquals(1, tokens.size)

        assertEquals(TokenType.EOF, tokens[0].type, "Expected EOF token, got ${tokens[0].type}")
    }

    @Test
    fun scan_comment_and_sentence_returns_sentence() {
        val tokens = Lexer("""
            % comment
            sentence
        """.trimIndent()).scan()

        assertEquals(2, tokens.size)

        assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
        assertEquals("sentence", tokens[0].value, "Expected 'sentence', got ${tokens[0].value}")
    }
}