From c94fc018eb9b6ce1e4f09a1eee4d5779c1ef0702 Mon Sep 17 00:00:00 2001
From: tastytea <tastytea@tastytea.de>
Date: Tue, 25 Dec 2018 23:02:19 +0100
Subject: [PATCH] Prepared functions for simple and libravatar-style
 identicons.

---
 example.cpp         |  3 ++-
 src/identiconpp.cpp | 40 ++++++++++++++++++++++++++++++++++
 src/identiconpp.hpp | 53 +++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 93 insertions(+), 3 deletions(-)

diff --git a/example.cpp b/example.cpp
index d7e6bd3..46ee738 100644
--- a/example.cpp
+++ b/example.cpp
@@ -7,6 +7,7 @@
 #include "identiconpp.hpp"
 
 using std::cout;
+using std::endl;
 using std::string;
 
 int main(int argc, char *argv[])
@@ -28,6 +29,6 @@ int main(int argc, char *argv[])
     }
 
     Identiconpp identicon(5, 5, 0xffffffff, { 0x000000ff, 0x000000 });
-
+    identicon.generate("testtest", Identiconpp::identicon_type::simple);
     return 0;
 }
diff --git a/src/identiconpp.cpp b/src/identiconpp.cpp
index fcaf2de..88d74ec 100644
--- a/src/identiconpp.cpp
+++ b/src/identiconpp.cpp
@@ -29,3 +29,43 @@ Identiconpp::Identiconpp(const uint8_t rows, const uint8_t columns,
 {
 }
 
+Identiconpp::Image Identiconpp::generate(const string &digest,
+                                         identicon_type type)
+{
+    switch (type)
+    {
+        case identicon_type::simple:
+        {
+            return generate_simple(digest);
+        }
+        case identicon_type::libravatar:
+        case identicon_type::sigil:
+        {
+            return generate_libravatar(digest);
+        }
+    }
+}
+
+Identiconpp::Image Identiconpp::generate_simple(const string &digest)
+{
+    return { 1, Magick::Image() };
+}
+
+Identiconpp::Image Identiconpp::generate_libravatar(const string &digest)
+{
+    uint8_t entropy_provided = digest.length() / 2 * 8;
+    uint8_t entropy_required = (_columns / 2 + _columns % 2) * _rows + 8;
+    ttdebug << "entropy_provided=" << std::to_string(entropy_provided)
+        << ", entropy_required=" << std::to_string(entropy_required) << '\n';
+
+    if (entropy_provided < entropy_required)
+    {
+        throw std::invalid_argument(
+            "Passed digest \"" + digest + "\" is not capable of providing " +
+            std::to_string(entropy_required) + " bits of entropy.");
+    }
+
+    // TODO: implement
+
+    return { 1, Magick::Image() };
+}
diff --git a/src/identiconpp.hpp b/src/identiconpp.hpp
index 9e90fa6..65b2f64 100644
--- a/src/identiconpp.hpp
+++ b/src/identiconpp.hpp
@@ -17,6 +17,8 @@
 #include <cstdint>
 #include <string>
 #include <vector>
+#include <tuple>
+#include <Magick++/Image.h>
 
 using std::uint8_t;
 using std::uint32_t;
@@ -31,12 +33,32 @@ using std::vector;
 class Identiconpp
 {
 public:
+    /*!
+     * @brief  Return type for images.
+     */
+    struct Image
+    {
+        uint8_t error;
+        Magick::Image data;
+    };
+
+    /*!
+     *  @brief  List of identicon types
+     *
+     *          libravatar and sigil are synonymous.
+     */
+    enum class identicon_type
+    {
+        simple,
+        libravatar,
+        sigil
+    };
+
     /*!
      *  @brief  Initialises an instance of Identiconpp.
      *
      *          The instance can be used for creating identicons with differing
-     *          image formats and sizes. Will throw `std::invalid_argument` if
-     *          an argument is invalid.
+     *          image formats and sizes.
      *
      *  @param  rows        Number of rows
      *  @param  columns     Number of columns
@@ -47,9 +69,36 @@ public:
                          const uint32_t background = 0xffffffff,
                          const vector<uint32_t> &foreground = { 0x000000ff } );
 
+    /*!
+     *  @brief  Generates identicon from digest.
+     *
+     *  @param  digest  The pre-computed digest
+     *
+     *  @return 0 and an image on success, 1 and an empty image on error.
+     */
+    Image generate(const string &digest, identicon_type type);
+
 private:
     const uint8_t _rows;
     const uint8_t _columns;
     const uint32_t _background;
     const vector<uint32_t> _foreground;
+
+    /*!
+     *  @brief  Generate simple identicon.
+     *
+     *  @param  digest  The pre-computed digest
+     *
+     *  @return 0 and an image on success, 1 and an empty image on error.
+     */
+    Image generate_simple(const string &digest);
+
+    /*!
+     *  @brief  Generate libravatar-style identicon.
+     *
+     *  @param  digest  The pre-computed digest
+     *
+     *  @return 0 and an image on success, 1 and an empty image on error.
+     */
+    Image generate_libravatar(const string &digest);
 };