Initial implementation

.scalafmt.conf

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+version = 2.0.0
+maxColumn = 120
+style = defaultWithAlign
+docstrings = ScalaDoc
+assumeStandardLibraryStripMargin = true
+
+continuationIndent {
+  callSite = 2
+  defnSite = 2
+}
+
+align = more
+align.tokens.add = [{code = ":", owner = "Term.Param"}]
+
+align {
+  arrowEnumeratorGenerator = true
+  openParenCallSite = true
+  openParenDefnSite = false
+}
+
+newlines {
+  alwaysBeforeTopLevelStatements = true
+  alwaysBeforeElseAfterCurlyIf = false
+}
+
+danglingParentheses = true
+
+rewrite {
+  rules = [
+    RedundantBraces
+    RedundantParens
+    SortModifiers
+    PreferCurlyFors
+    ExpandImportSelectors
+  ]
+  sortModifiers.order = [
+    "override", "private", "protected", "final", "implicit", "sealed", "abstract", "lazy"
+  ]
+  redundantBraces.stringInterpolation = true
+}
+
+includeCurlyBraceInSelectChains = true
+optIn.breakChainOnFirstMethodDot = true
+verticalMultilineAtDefinitionSiteArityThreshold = 5
+verticalMultiline.arityThreshold = 5
+verticalMultiline.atDefnSite = true
+verticalMultiline.newlineBeforeImplicitKW = false
+project.git = true

build.sbt

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+val Http4sVersion           = "0.20.8"
+val CirceVersion            = "0.11.1"
+val LogbackVersion          = "1.2.3"
+val BetterFilesVersion      = "3.8.0"
+val DirectoryWatcherVersion = "0.9.6"
+val ScalaLoggingVersion     = "3.9.2"
+
+val root = (project in file("."))
+  .settings(
+    organization := "name.orhideous",
+    name := "twicher",
+    version := "0.1.0-SNAPSHOT",
+    scalaVersion := "2.12.8",
+    libraryDependencies ++= Seq(
+      "org.http4s"                 %% "http4s-blaze-server"            % Http4sVersion,
+      "org.http4s"                 %% "http4s-circe"                   % Http4sVersion,
+      "org.http4s"                 %% "http4s-dsl"                     % Http4sVersion,
+      "io.circe"                   %% "circe-generic"                  % CirceVersion,
+      "com.github.pathikrit"       %% "better-files"                   % BetterFilesVersion,
+      "io.methvin"                 %% "directory-watcher-better-files" % DirectoryWatcherVersion,
+      "com.typesafe.scala-logging" %% "scala-logging"                  % ScalaLoggingVersion,
+      "ch.qos.logback"             % "logback-classic"                 % LogbackVersion
+    ),
+    addCompilerPlugin("org.typelevel" %% "kind-projector"     % "0.10.3"),
+    addCompilerPlugin("com.olegpy"    %% "better-monadic-for" % "0.3.0")
+  )
+
+scalacOptions ++= Seq(
+  "-deprecation",
+  "-encoding",
+  "UTF-8",
+  "-language:higherKinds",
+  "-language:postfixOps",
+  "-feature",
+  "-Ypartial-unification",
+  "-Xfatal-warnings"
+)

project/build.properties

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+# suppress inspection "UnusedProperty" for whole file
+sbt.version=1.3.5
+

project/plugins.sbt

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+addSbtPlugin("io.github.davidgregory084" % "sbt-tpolecat" % "0.1.3")
+addSbtPlugin("io.spray" % "sbt-revolver" % "0.9.1")

src/main/resources/logback.xml

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+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>[%thread] %highlight(%-5level) %cyan(%logger{15}) - %msg %n</pattern>
+        </encoder>
+    </appender>
+    <root level="INFO">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>

src/main/scala/name/orhideous/twicher/Error.scala

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+package name.orhideous.twicher
+
+sealed trait Error extends Exception
+
+object Error {
+
+  case object NoSuchQuote extends Error
+
+}

src/main/scala/name/orhideous/twicher/Main.scala

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+package name.orhideous.twicher
+
+import cats.effect.ExitCode
+import cats.effect.IO
+import cats.effect.IOApp
+import cats.implicits._
+import name.orhideous.twicher.persistence.QuotesFileRepository
+import org.http4s.implicits._
+import org.http4s.server.Router
+import org.http4s.server.blaze._
+
+object Main extends IOApp {
+  private val host = sys.env.getOrElse("TWICHER_HOST", "0.0.0.0")
+  private val port = sys.env.getOrElse("TWICHER_PORT", "9000").toInt
+  private val dir  = sys.env.getOrElse("TWICHER_DIR", "./data")
+
+  private val repository = QuotesFileRepository(dir)
+  private val routes     = Router[IO]("/" -> Routes(repository)).orNotFound
+
+  override def run(args: List[String]): IO[ExitCode] =
+    BlazeServerBuilder[IO]
+      .bindHttp(port, host)
+      .withHttpApp(routes)
+      .serve
+      .compile
+      .drain
+      .as(ExitCode.Success)
+
+}

src/main/scala/name/orhideous/twicher/Routes.scala

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+package name.orhideous.twicher
+
+import cats.effect.IO
+import io.circe.generic.auto._
+import name.orhideous.twicher.persistence.QuotesRepository
+import org.http4s.HttpRoutes
+import org.http4s.circe.CirceEntityCodec._
+import org.http4s.dsl.Http4sDsl
+
+object Routes {
+
+  def apply(repository: QuotesRepository): HttpRoutes[IO] = {
+
+    val dsl = new Http4sDsl[IO] {}
+    import dsl._
+
+    HttpRoutes.of[IO] {
+      case GET -> Root =>
+        repository.list.flatMap(Ok(_))
+
+      case GET -> Root / "random" =>
+        repository.random.flatMap(Ok(_))
+
+      case GET -> Root / IntVar(id) =>
+        repository.read(id).flatMap(Ok(_))
+    }
+  }
+
+}

src/main/scala/name/orhideous/twicher/persistence/Quote.scala

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+package name.orhideous.twicher.persistence
+
+case class Quote(id: Int, text: String)

src/main/scala/name/orhideous/twicher/persistence/QuotesFileRepository.scala

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+package name.orhideous.twicher.persistence
+
+import java.nio.charset.Charset
+import java.nio.file.Path
+import java.nio.file.WatchEvent
+import java.util.concurrent.Executors
+
+import better.files.File
+import cats.effect.IO
+import com.typesafe.scalalogging.StrictLogging
+import io.methvin.better.files.RecursiveFileMonitor
+import name.orhideous.twicher.Error
+
+import scala.collection.concurrent.TrieMap
+import scala.concurrent.ExecutionContext
+import scala.util.Random
+
+class QuotesFileRepository(private val quotesDir: File) extends QuotesRepository with StrictLogging {
+
+  private final val cache = TrieMap.empty[Int, Quote]
+  private final val rnd   = new Random
+
+  private implicit val watcherEC: ExecutionContext =
+    ExecutionContext.fromExecutor(Executors.newFixedThreadPool(1))
+
+  private final val watcher = new RecursiveFileMonitor(quotesDir, logger = logger.underlying) {
+    override def onEvent(eventType: WatchEvent.Kind[Path], file: File, count: Int): Unit = {
+      logger.info(s"Detected change in $quotesDir, reloading")
+      reload()
+    }
+  }
+
+  watcher.start()
+  reload()
+
+  override def list: IO[Vector[Quote]] = IO.pure(cache.values.toVector)
+
+  override def random: IO[Quote] =
+    if (cache.isEmpty) {
+      IO.raiseError(Error.NoSuchQuote)
+    } else {
+      read(cache.keySet.toVector(rnd.nextInt(cache.size)))
+    }
+
+  override def read(id: Int): IO[Quote] = cache.get(id) match {
+    case Some(quote) => IO.pure(quote)
+    case None        => IO.raiseError(Error.NoSuchQuote)
+  }
+
+  private def reload(): Unit = {
+    val quotes = QuotesFileRepository.loadQuotes(quotesDir).map(q => q.id -> q).toMap
+    cache.clear()
+    cache ++= quotes
+    logger.info(s"Loaded ${quotes.size} quotes from $quotesDir")
+  }
+}
+
+object QuotesFileRepository {
+  private final val pattern = ".*(\\d+)\\.txt$".r
+
+  def apply(quotesDir: String): QuotesFileRepository = new QuotesFileRepository(File(quotesDir))
+
+  private final implicit val charset: Charset = Charset.forName("UTF-8")
+
+  private def loadQuotes(quotesDir: File): Seq[Quote] =
+    quotesDir
+      .globRegex(pattern)
+      .toSeq
+      .par
+      .map(parseFile)
+      .seq
+
+  private def parseFile(file: File): Quote = {
+    val pattern(id) = file.name
+    val text        = file.contentAsString.stripLineEnd.trim
+    Quote(id.toInt, text)
+  }
+}

src/main/scala/name/orhideous/twicher/persistence/QuotesRepository.scala

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+package name.orhideous.twicher.persistence
+
+import cats.effect.IO
+
+trait QuotesRepository {
+
+  def read(id: Int): IO[Quote]
+
+  def list: IO[Vector[Quote]]
+
+  def random: IO[Quote]
+}