finished implementing png chunks

src/chunk.rs

@@ -1,7 +1,7 @@
-use std::{fmt::Display};
+use std::fmt::{write, Display};
 use crc::Crc;
 
-use crate::chunk_type::{self, ChunkType};
+use crate::chunk_type::ChunkType;
 
 struct Chunk {
     length:     u32,
@@ -11,8 +11,24 @@ struct Chunk {
 }
 
 impl Chunk {
-    fn new(chunk_type: ChunkType, data: Vec<u8>) -> Chunk {
-        todo!()
+    fn new(chunktype: ChunkType, data: Vec<u8>) -> Chunk {
+        let x25: Crc<u32> = Crc::<u32>::new(&crc::CRC_32_ISO_HDLC);
+
+        let to_hash: Vec<u8> = chunktype
+            .bytes()
+            .iter()
+            .chain(&data)
+            .copied()
+            .collect();
+
+        let crc_value = x25.checksum(&to_hash);
+
+        Chunk {
+            length: data.len() as u32,
+            chunk_type: chunktype,
+            chunk_data: data,
+            crc: crc_value,
+        }
     }
 
     fn length(&self) -> u32 {
@@ -32,11 +48,25 @@ impl Chunk {
     }
 
     fn data_as_string(&self) -> Result<String, &'static str> {
-        todo!()
+        let to_stringify: Vec<u8> = self.chunk_data.clone();
+
+        if self.length() == 0 {
+            Err("diocane")
+        } else {
+            Ok(String::from_utf8(to_stringify).unwrap())
+        }
     }
 
     fn as_bytes(&self) -> Vec<u8> {
-        todo!()
+        let bytes: Vec<u8> = self.length()
+            .to_be_bytes()
+            .iter()
+            .chain(self.chunk_type.bytes().iter())
+            .chain(self.chunk_data.iter())
+            .chain(self.crc().to_be_bytes().iter())
+            .copied().collect();
+
+        bytes
     }
 }
 
@@ -64,7 +94,7 @@ impl TryFrom<&[u8]> for Chunk {
 
         let mut chunk_data_vec: Vec<u8> = Vec::new();
 
-        for byte in &value[(slice_length - 8)..(slice_length -4)] {
+        for byte in &value[8..(slice_length -4)] {
             chunk_data_vec.push(*byte)
         }
 
@@ -83,14 +113,36 @@ impl TryFrom<&[u8]> for Chunk {
             crc: crc_from_slice,
         };
 
+        let x25: Crc<u32> = Crc::<u32>::new(&crc::CRC_32_ISO_HDLC);
+
+        let to_hash: Vec<u8> = chunk.chunk_type
+            .bytes()
+            .iter()
+            .chain(chunk.chunk_data.iter())
+            .copied()
+            .collect();
+
+        let crc_value = x25.checksum(&to_hash);
+
+        if crc_value != chunk.crc {
+            Err("Invalid bytes (probably crc is wrong)")
+        } else {
             Ok(chunk)
+        }
+
+
 
     }
 }
 
 impl Display for Chunk {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        todo!()
+        write!(f, "chunk length:{}\nchunk type: {}\n, chunk message {}\nCRC u32: {}",
+            self.length,
+            self.chunk_type,
+            self.data_as_string().unwrap(),
+            self.crc
+        )
     }
 }
 

src/chunk_type.rs

@@ -1,5 +1,5 @@
 use core::str;
-use std::{str::FromStr, u8};
+use std::str::FromStr;
 
 fn byte_to_bits(byte: u8) -> [u8; 8] {
     let mut bits = [0u8; 8];
@@ -27,7 +27,7 @@ pub struct ChunkType {
 
 impl ChunkType {
 
-    fn bytes(&self) -> [u8; 4] {
+    pub fn bytes(&self) -> [u8; 4] {
         let bytes: [u8; 4] = [
             self.ancillary_byte,
             self.private_byte,
@@ -58,7 +58,6 @@ impl ChunkType {
                 continue;
             }
         }
-
     }
 
 
@@ -68,12 +67,10 @@ impl ChunkType {
 
     fn is_public(&self) -> bool {
         self.private_byte.is_ascii_uppercase()
-
     }
 
     fn is_reserved_bit_valid(&self) -> bool {
         self.reserved_byte.is_ascii_uppercase()
-
     }
 
     fn is_safe_to_copy(&self) -> bool {
@@ -86,7 +83,6 @@ impl TryFrom<[u8; 4]> for ChunkType {
     type Error = &'static str;
 
     fn try_from(value: [u8; 4]) -> Result<Self, Self::Error> {
-
         let chunk_type = ChunkType {
             ancillary_byte:     value[0],
             private_byte:       value[1],
@@ -107,7 +103,6 @@ impl TryFrom<[u8; 4]> for ChunkType {
                 continue;
             }
         }
-
     }
 }
 
@@ -122,7 +117,6 @@ impl std::fmt::Display for ChunkType {
 
         write!(f, "{}", s)
     }
-
 }
 
 impl FromStr for ChunkType {
@@ -151,7 +145,6 @@ impl FromStr for ChunkType {
                 continue;
             }
         }
-
     }
 }