From 1993ee410db04ab04efecc84bcfc4f21d60ef90c Mon Sep 17 00:00:00 2001
From: SEK1RO <vlad@sek1.ro>
Date: Mon, 16 Sep 2024 20:59:12 +0300
Subject: [PATCH] feat(base64): encode

---
 include/base/base64.hpp |  8 +++----
 src/base64.cpp          | 51 ++++++++++++++++++++++++++++++++++-------
 test/test-base64.cpp    | 20 +++++++++-------
 3 files changed, 59 insertions(+), 20 deletions(-)

diff --git a/include/base/base64.hpp b/include/base/base64.hpp
index c745128..2e37b71 100644
--- a/include/base/base64.hpp
+++ b/include/base/base64.hpp
@@ -7,12 +7,12 @@
 
 namespace base64
 {
-    bool isValid(const char *str) noexcept;
+    bool isValid(const char *str, size_t str_size) noexcept;
     bool isValid(std::string_view str) noexcept;
 
-    void encode(const uint8_t *data, uint64_t data_size, char *str) noexcept;
+    void encode(const uint8_t *data, size_t data_size, char *str, size_t str_size);
     std::string encode(std::span<const uint8_t> data) noexcept;
 
-    void decode(const char *str, uint8_t *data, uint64_t data_size);
-    std::vector<uint8_t> decode(std::string_view str);
+    void decode(const char *str, size_t str_size, uint8_t *data, size_t data_size);
+    std::vector<uint8_t> decode(std::string_view str) noexcept;
 }
\ No newline at end of file
diff --git a/src/base64.cpp b/src/base64.cpp
index aa98dbd..784cc55 100644
--- a/src/base64.cpp
+++ b/src/base64.cpp
@@ -29,9 +29,9 @@ static const int8_t b64map[] = {
 
 namespace base64
 {
-    bool isValid(const char *str) noexcept
+    bool isValid(const char *str, size_t str_size) noexcept
     {
-        return base64::isValid(std::string_view(str));
+        return base64::isValid(std::string_view(str, str_size));
     }
     bool isValid(std::string_view str) noexcept
     {
@@ -44,12 +44,47 @@ namespace base64
         }
         return baseN::isValid(sv, b64map);
     }
-    // void encode(const uint8_t *data, uint64_t data_size, char *str) noexcept
-    // {
-    // }
-    // std::string encode(std::span<const uint8_t> data) noexcept
-    // {
-    // }
+    void encode(const uint8_t *data, size_t data_size, char *str, size_t str_size)
+    {
+        if (str_size < data_size / 3 * 4 + (data_size % 3 ? 4 : 0))
+        {
+            throw std::logic_error("base64::encode: not enough allocated length");
+        }
+        for (size_t i = 0; i < data_size / 3; i++)
+        {
+            str[i * 4] = b64digits[data[i * 3] >> 2];
+            str[i * 4 + 1] = b64digits[(data[i * 3] << 4 | data[i * 3 + 1] >> 4) & 0x3F];
+            str[i * 4 + 2] = b64digits[(data[i * 3 + 1] << 2 | data[i * 3 + 2] >> 6) & 0x3F];
+            str[i * 4 + 3] = b64digits[data[i * 3 + 2] & 0x3F];
+        }
+        uint64_t last_idx = data_size / 3 * 4;
+        if (last_idx + 3 < str_size)
+        {
+            switch (data_size % 3)
+            {
+            case 1:
+                str[last_idx] = b64digits[data[data_size - 1] >> 2];
+                str[last_idx + 1] = b64digits[data[data_size - 1] << 4 & 0x30];
+                str[last_idx + 2] = '=';
+                str[last_idx + 3] = '=';
+                break;
+            case 2:
+                str[last_idx] = b64digits[data[data_size - 2] >> 2];
+                str[last_idx + 1] = b64digits[(data[data_size - 2] << 4 | data[data_size - 1] >> 4) & 0x3F];
+                str[last_idx + 2] = b64digits[data[data_size - 1] & 0x0F];
+                str[last_idx + 3] = '=';
+                break;
+            default:
+                break;
+            }
+        }
+    }
+    std::string encode(std::span<const uint8_t> data) noexcept
+    {
+        std::string str(data.size() / 3 * 4 + (data.size() % 3 ? 4 : 0), ' ');
+        base64::encode(data.data(), data.size(), str.data(), str.size());
+        return str;
+    }
     // void decode(const char *str, uint8_t *data, uint64_t data_size)
     // {
     // }
diff --git a/test/test-base64.cpp b/test/test-base64.cpp
index 0e053f5..b452011 100644
--- a/test/test-base64.cpp
+++ b/test/test-base64.cpp
@@ -13,14 +13,18 @@ TEST(base64, isValid)
     EXPECT_FALSE(isValid("1==="));
     EXPECT_FALSE(isValid("?!*"));
 }
-// TEST(base64, encode)
-// {
-// }
-// TEST(base64, encode_1e6)
-// {
-//     std::vector<uint8_t> data(1e6);
-//     encode(data);
-// }
+TEST(base64, encode)
+{
+    EXPECT_EQ(encode(hex::decode("")), "");
+    EXPECT_EQ(encode(hex::decode("04a504a5")), "BKUEpQ==");
+    EXPECT_EQ(encode(hex::decode("04a504a500")), "BKUEpQA=");
+    EXPECT_EQ(encode(hex::decode("04a504a50000")), "BKUEpQAA");
+}
+TEST(base64, encode_1e7)
+{
+    std::vector<uint8_t> data(1e7);
+    encode(data);
+}
 // TEST(base64, decode)
 // {
 // }