From 2f6df42696f93fdab01aa38a17f5e908b606bd3a Mon Sep 17 00:00:00 2001
From: Leonetienne <leon@etiennes.de>
Date: Tue, 31 May 2022 14:25:23 +0200
Subject: [PATCH] Implement relevant methods for DataIngestionLayer

---
 GCryptCLI/include/DataIngestionLayer.h | 29 +++++++++++--
 GCryptCLI/src/DataIngestionLayer.cpp   | 60 ++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/GCryptCLI/include/DataIngestionLayer.h b/GCryptCLI/include/DataIngestionLayer.h
index 3fd24e6..1a2c13e 100644
--- a/GCryptCLI/include/DataIngestionLayer.h
+++ b/GCryptCLI/include/DataIngestionLayer.h
@@ -1,9 +1,11 @@
 #ifndef GCRYPTCLI_DATAINGESTIONLAYER_H
 #define GCRYPTCLI_DATAINGESTIONLAYER_H
 
-#include <istream>
-#include <fstream>
-#include <sstream>
+#include <iosfwd>
+#include <queue>
+#include <GCrypt/Block.h>
+
+using namespace Leonetienne::GCrypt;
 
 namespace IO {
 
@@ -13,6 +15,19 @@ namespace IO {
       //! Will initialize the ingestion
       static void Init();
 
+      //! Will attempt to read a data block.
+      //! Requires Init() to have been called
+      static void ReadBlock();
+
+      //! Have we read in all available blocks?
+      static bool ReachedEOF();
+
+      //! Will return true if there is at least one block to be GetBlock()'ed
+      static bool IsBlockReady();
+
+      //! Will return the next block in the queue
+      static Block GetNextBlock();
+
     private:
       static std::istream* in;
 
@@ -21,6 +36,14 @@ namespace IO {
       // We still have to CLOSE the file handle afterwards!
       static std::ifstream ifs;
       static std::istringstream iss;
+
+      // Indicates whether EOF has been reached
+      static bool reachedEof;
+      // Indicates whether this class is initialized
+      static bool initialized;
+
+      // All read blocks, that haven't been given out yet
+      static std::queue<Block> blocks;
   };
 }
 
diff --git a/GCryptCLI/src/DataIngestionLayer.cpp b/GCryptCLI/src/DataIngestionLayer.cpp
index 7c3f543..f4d6eec 100644
--- a/GCryptCLI/src/DataIngestionLayer.cpp
+++ b/GCryptCLI/src/DataIngestionLayer.cpp
@@ -2,6 +2,9 @@
 #include "CommandlineInterface.h"
 #include "Configuration.h"
 #include <iostream>
+#include <istream>
+#include <fstream>
+#include <sstream>
 #include <cstring>
 
 using namespace IO;
@@ -50,6 +53,9 @@ void DataIngestionLayer::Init() {
       break;
   }
 
+  initialized = true;
+  reachedEof = false;
+
   // Temporary
   std::size_t n_last_bytes_read = 0;
   char buf[64];
@@ -65,8 +71,62 @@ void DataIngestionLayer::Init() {
   return;
 }
 
+void DataIngestionLayer::ReadBlock() {
+  if (!initialized) {
+    throw std::runtime_error("Attempted to read on uninitialized DataIngestionLayer!");
+  }
+
+  if (!reachedEof) {
+    // Create buffer to read into
+    char buf[Block::BLOCK_SIZE];
+    memset(buf, 0, sizeof(buf));
+
+    // Read
+    in->read(buf, sizeof(buf));
+
+    // Fetch how much we've read
+    const std::size_t n_bytes_read = in->gcount();
+
+    // Is this fewer bytes than we requested?
+    if (n_bytes_read < sizeof(buf)) {
+      // Yes: EOF reached.
+      reachedEof = true;
+    }
+
+    // Construct a Block from this buf
+    Block block;
+    block.FromByteString(std::string(buf));
+
+    // Enqueue it
+    blocks.emplace(block);
+  }
+
+  return;
+}
+
+bool DataIngestionLayer::ReachedEOF() {
+  return reachedEof;
+}
+
+bool DataIngestionLayer::IsBlockReady() {
+  return blocks.size() > 0;
+}
+
+Block DataIngestionLayer::GetNextBlock() {
+  if (!IsBlockReady()) {
+    throw std::runtime_error("Attempted to get the next block, but there are none left!");
+  }
+
+  // Why... why not just return a T in pop()???
+  const Block popped = blocks.front();
+  blocks.pop();
+  return popped;
+}
 
 std::istream* DataIngestionLayer::in;
 std::ifstream DataIngestionLayer::ifs;
 std::istringstream DataIngestionLayer::iss;
+bool DataIngestionLayer::reachedEof = false;
+bool DataIngestionLayer::initialized = false;
+std::queue<Block> DataIngestionLayer::blocks;