From fdfaf91bcf5600e610e6871e6ea3bec5c74e286f Mon Sep 17 00:00:00 2001
From: Kasey White <kwhitemsg@gmail.com>
Date: Sun, 22 May 2022 18:16:42 -0400
Subject: [PATCH] feat: create encoding for char, string, byte array

---
 crates/flat/src/encode.rs  | 40 ++++++++++++++++++
 crates/flat/src/encoder.rs | 86 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 124 insertions(+), 2 deletions(-)

diff --git a/crates/flat/src/encode.rs b/crates/flat/src/encode.rs
index b747278b..c4ccc566 100644
--- a/crates/flat/src/encode.rs
+++ b/crates/flat/src/encode.rs
@@ -20,6 +20,46 @@ impl Encode for u8 {
     }
 }
 
+impl Encode for char {
+    fn encode(&self, e: &mut Encoder) -> Result<(), String> {
+        e.char(*self)?;
+
+        Ok(())
+    }
+}
+
+impl Encode for &str {
+    fn encode(&self, e: &mut Encoder) -> Result<(), String> {
+        e.string(*self)?;
+
+        Ok(())
+    }
+}
+
+impl Encode for String {
+    fn encode(&self, e: &mut Encoder) -> Result<(), String> {
+        e.string(self)?;
+
+        Ok(())
+    }
+}
+
+impl Encode for Vec<u8> {
+    fn encode(&self, e: &mut Encoder) -> Result<(), String> {
+        e.bytes(self)?;
+
+        Ok(())
+    }
+}
+
+impl Encode for &[u8] {
+    fn encode(&self, e: &mut Encoder) -> Result<(), String> {
+        e.bytes(self)?;
+
+        Ok(())
+    }
+}
+
 impl<T, K> Encode for (T, K)
 where
     T: Encode,
diff --git a/crates/flat/src/encoder.rs b/crates/flat/src/encoder.rs
index 24b2e7a4..229efca0 100644
--- a/crates/flat/src/encoder.rs
+++ b/crates/flat/src/encoder.rs
@@ -3,7 +3,7 @@ use crate::encode::Encode;
 pub struct Encoder {
     pub buffer: Vec<u8>,
     // Int
-    used_bits: usize,
+    used_bits: i64,
     // Int
     current_byte: u8,
 }
@@ -34,7 +34,7 @@ impl Encoder {
             self.current_byte = x;
             self.next_word();
         } else {
-            todo!()
+            self.byte_unaligned(x);
         }
 
         Ok(self)
@@ -49,6 +49,30 @@ impl Encoder {
         }
     }
 
+    pub fn bytes(&mut self, arr: &[u8]) -> Result<&mut Self, String> {
+        if self.used_bits != 0 {
+            return Err("Buffer is not byte aligned".to_string());
+        }
+        self.write_blk(arr, &mut 0);
+        Ok(self)
+    }
+
+    pub fn char(&mut self, c: char) -> Result<&mut Self, String> {
+        self.word(c as u32);
+        Ok(self)
+    }
+
+    pub fn string(&mut self, s: &str) -> Result<&mut Self, String> {
+        for i in s.chars() {
+            self.one();
+            self.char(i)?;
+        }
+
+        self.zero();
+
+        Ok(self)
+    }
+
     fn zero(&mut self) -> &mut Self {
         if self.used_bits == 7 {
             self.next_word();
@@ -71,6 +95,13 @@ impl Encoder {
         self
     }
 
+    fn byte_unaligned(&mut self, x: u8) {
+        let x_shift = self.current_byte | (x >> self.used_bits);
+        self.buffer.push(x_shift);
+
+        self.current_byte = x << (8 - self.used_bits);
+    }
+
     fn next_word(&mut self) {
         self.buffer.push(self.current_byte);
 
@@ -78,6 +109,57 @@ impl Encoder {
         self.used_bits = 0;
     }
 
+    fn write_blk(&mut self, arr: &[u8], src_ptr: &mut usize) {
+        let src_len = arr.len() - *src_ptr;
+        let blk_len = src_len.min(255);
+        self.buffer.push(blk_len as u8);
+        if blk_len == 0 {
+            return;
+        }
+
+        self.buffer.extend(&arr[*src_ptr..blk_len]);
+
+        *src_ptr += blk_len;
+        self.write_blk(arr, src_ptr);
+    }
+
+    fn word(&mut self, c: u32) {
+        loop {
+            let mut w = (c & 127) as u8;
+            let c = c >> 7;
+
+            if c != 0 {
+                w |= 128;
+            }
+            self.bits(8, w);
+
+            if c == 0 {
+                break;
+            }
+        }
+    }
+
+    fn bits(&mut self, num_bits: i64, val: u8) {
+        self.used_bits += num_bits;
+        let unused_bits = 8 - self.used_bits;
+        match unused_bits {
+            x if x > 0 => {
+                self.current_byte |= val << x;
+            }
+            x if x == 0 => {
+                self.current_byte |= val;
+                self.next_word();
+            }
+            x => {
+                let used = -x;
+                self.current_byte |= val >> used;
+                self.next_word();
+                self.current_byte = val << (8 - used);
+                self.used_bits = used;
+            }
+        }
+    }
+
     pub(crate) fn filler(&mut self) {
         self.current_byte |= 1;
         self.next_word();