Read and parse Kindle MyClippings.txt in reverse order. Kotlin, Apache commons ReversedLinesFileReader

KindleMyClippings.kt

import org.apache.commons.io.input.ReversedLinesFileReader
import org.junit.Test
import java.io.File

class KindleMyClippings {
    class Clipping(
        val bookDetails: String,
        val date: String,
        val content: String,
    ) {

        override fun toString(): String {
            return "Clipping(" +
                    "\n\tbookDetails='$bookDetails'," +
                    "\n\tdate='$date'," +
                    "\n\tcontent='$content'" +
                    "\n)"
        }

        companion object {
            private val DATE_REGEX = Regex("(?:.+\\|)+\\s(.+)\$")

            fun fromBlock(block: ClippingBlock): Clipping {
                val dateMatch = DATE_REGEX.matchEntire(block.clippingDetails)
                checkNotNull(dateMatch) {
                    "Can't extract date from the clipping details"
                }
                val date = dateMatch.groupValues[1]

                return Clipping(
                    bookDetails = block.bookDetails,
                    date = date,
                    content = block.clippingContent,
                )
            }
        }
    }

    class ClippingBlock(
        val bookDetails: String,
        val clippingDetails: String,
        val clippingContent: String,
    ) {

        override fun toString(): String {
            return "ClippingBlock(\n\tbookDetails='$bookDetails'," +
                    "\n\tclippingDetails='$clippingDetails'," +
                    "\n\tclippingContent='$clippingContent'" +
                    "\n)"
        }

        companion object {
            const val LINES_COUNT = 4

            fun fromLinesReversed(lines: List<String>): ClippingBlock {
                require(lines.size == LINES_COUNT) {
                    "A block must contain $LINES_COUNT lines"
                }

                return ClippingBlock(
                    bookDetails = lines[3],
                    clippingDetails = lines[2],
                    clippingContent = lines[0],
                )
            }
        }
    }

    private val DIVIDER = "=========="

    @Test
    fun parseClippings() {
        val file = File("C:\\Users\\spiri\\Desktop\\My Clippings.txt")
        val clippings = mutableListOf<Clipping>()
        ReversedLinesFileReader(file, Charsets.UTF_8).use { reader ->
            var block: ClippingBlock?
            do {
                block = readNextBlock(reader)
                if (block != null) {
                    try {
                        clippings.add(Clipping.fromBlock(block))
                    } catch (e: Exception) {
                        println(block)
                        e.printStackTrace()
                    }
                }
            } while (block != null)
        }

        clippings.forEach(::println)
    }

    private fun readNextBlock(reader: ReversedLinesFileReader): ClippingBlock? {
        // Align.
        do {
            when (reader.readLine()) {
                DIVIDER -> break
                null -> return null
            }
        } while (true)

        // Read.
        val reversedBlockLines = reader.readLines(ClippingBlock.LINES_COUNT)
        return if (reversedBlockLines.size == ClippingBlock.LINES_COUNT)
            ClippingBlock.fromLinesReversed(reversedBlockLines)
        else
            null
    }
}