WIP, beginning work on hash implementation.

adr/2023-11-26-shortform-data-model.md

@@ -77,12 +77,11 @@ but ShortForm imposes a configurable limit (10kb by default).
 CREATE TABLE assets(
     id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
     external_id UUID NOT NULL UNIQUE,
-    created_at TIMESTAMPTZ NOT NULL,
-    created_by BIGINT NOT NULL,
-    mime TEXT NOT NULL,
     title TEXT NOT NULL,
     extension TEXT NOT NULL,
-    hash TEXT NOT NULL
+    hash TEXT NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL,
+    created_by BIGINT NOT NULL
 );
 ```
 

modules/crypto/src/main/scala/gs/shortform/crypto/Sha256.scala

@@ -0,0 +1,45 @@
+package gs.shortform.crypto
+
+import java.security.MessageDigest
+import java.io.BufferedInputStream
+
+object Sha256:
+  /**
+   * Calculate the SHA-256 hash for some data.
+   *
+   * @param data The data to hash.
+   * @return The base64-encoded [[Hash]] value.
+   */
+  def calculateHash(data: Array[Byte]): Hash = 
+    val digest: MessageDigest = MessageDigest.getInstance(Sha256.Algorithm)
+    Hash.encode(digest.digest(data))
+
+  /**
+   * Consume the entire given stream and calculate its SHA-256 hash. This 
+   * function _always_ closes the underlying stream.
+   *
+   * @param data The data to hash.
+   * @return The base64-encoded [[Hash]] value.
+   */
+  def consumeToHash(data: BufferedInputStream): Hash =
+    try
+      // TODO: Need sum catz?
+      val digest: MessageDigest = MessageDigest.getInstance(Sha256.Algorithm)
+      val buffer: Array[Byte] = Array.ofDim[Byte](8192)
+      var count: Int = data.read(buffer)
+      while 
+        count > 0
+      do
+        digest.update(buffer, 0, count)
+        count = data.read(buffer)
+      
+      Hash.encode(digest.digest())
+    finally
+      data.close()
+
+  /**
+   * JCA Algorithm name for SHA-256.
+   */
+  val Algorithm: String = "SHA-256"
+
+end Sha256

modules/model/src/main/scala/gs/shortform/model/Asset.scala

@@ -0,0 +1,33 @@
+package gs.shortform.model
+
+import gs.uuid.UUID
+import gs.shortform.crypto.Hash
+
+case class Asset(
+  externalId: UUID,
+  title: Title,
+  extension: Asset.Extension,
+  hash: Hash,
+  createdAt: CreatedAt,
+  createdBy: Username
+)
+
+object Asset:
+
+  /**
+   * Represents a file extension for some [[Asset]].
+   */
+  opaque type Extension = String
+
+  object Extension:
+
+    def apply(value: String): Extension = value
+
+    given CanEqual[Extension, Extension] = CanEqual.derived
+
+    extension (ext: Extension)
+      def str(): String = ext
+
+  end Extension
+
+end Asset

modules/model/src/main/scala/gs/shortform/model/ModelError.scala

@@ -0,0 +1,25 @@
+package gs.shortform.model
+
+import gs.shortform.error.ShortFormError
+
+sealed trait ModelError extends ShortFormError
+
+object ModelError:
+
+  /**
+   * Results from a [[Tag]] failing validation for being too short.
+   *
+   * @param candidate The candidate string.
+   * @param minimumLength The minimum required length.
+   */
+  case class TagTooShort(candidate: String, minimumLength: Int) extends ModelError
+
+  /**
+   * Results from a [[Tag]] failing validation for being too long.
+   *
+   * @param candidate The candidate string.
+   * @param maximumLength The maximum required length.
+   */
+  case class TagTooLong(candidate: String, maximumLength: Int) extends ModelError
+
+end ModelError

modules/model/src/main/scala/gs/shortform/model/Post.scala

@@ -15,11 +15,13 @@ import gs.shortform.crypto.Hash
   * @param createdBy User who created this post.
   * @param title Display title for this post.
   * @param hash Hash of the primary rendered file for this post.
+  * @param tags List of [[Tag]] applied to this post.
   */
 case class Post(
   externalId: UUID,
   createdAt: CreatedAt,
   createdBy: Username,
   title: Title, 
-  hash: Hash
+  hash: Hash,
+  tags: List[Tag]
 )

modules/model/src/main/scala/gs/shortform/model/Tag.scala

@@ -0,0 +1,57 @@
+package gs.shortform.model
+
+import gs.shortform.error.ShortFormError
+
+/**
+  * Arbitrary short string which can be used to annotate [[Post]]s.
+  */
+opaque type Tag = String
+
+object Tag:
+
+  object Constraints:
+
+    /**
+     * The minimum allowed length for tags.
+     */
+    val MinimumLength: Int = 1
+
+    /**
+     * The maximum allowed length for tags.
+     */
+    val MaximumLength: Int = 32
+
+  end Constraints
+
+  /**
+   * Instantiate a new [[Tag]]. This function is unsafe.
+   *
+   * @param value The tag value.
+   * @return The new tag.
+   */
+  def apply(value: String): Tag = value
+
+  /**
+   * Validate some candidate value to instantiate a new [[Tag]].
+   *
+   * @param value The candidate string value.
+   * @return The new tag, or an error if the input was invalid.
+   */
+  def validate(value: String): Either[ShortFormError, Tag] = 
+    if value.length() < Constraints.MinimumLength then
+      Left(ModelError.TagTooShort(value, Constraints.MinimumLength))
+    else if value.length() > Constraints.MaximumLength then
+      Left(ModelError.TagTooLong(value, Constraints.MaximumLength))
+    else
+      Right(value)
+
+  given CanEqual[Tag, Tag] = CanEqual.derived
+
+  extension (title: Tag)
+    /**
+     * Render this [[Tag]] as a string.
+     */
+    def str(): String = title
+
+end Tag
+

modules/model/src/main/scala/gs/shortform/model/Username.scala

@@ -12,8 +12,9 @@ object Username:
   given CanEqual[Username, Username] = CanEqual.derived
 
   extension (title: Username)
+    /**
+     * Render this [[Username]] as a string.
+     */
     def str(): String = title
 
 end Username
-
-