Untitled

use core::hash;
use std::fs::File;
use std::io::{BufReader, Read};
use sha3::{Digest, Sha3_256};

#[derive(Default)]
pub struct SpecialFile {
    pub path: String,
    pub blocks: Vec<FileBlock>
}

pub struct FileBlock {
    pub start_byte : usize,
    pub end_byte: usize,
    pub hash_value: String
}

pub fn generate_blocks(file_path: &str) -> SpecialFile {
    let file = File::open(file_path).unwrap();
    let mut reader = BufReader::new(file);

    const BLOCK_SIZE: usize = 4096;
    let mut buffer = [0u8; BLOCK_SIZE];

    let mut special_file = SpecialFile {
        path: file_path.to_string(),
        blocks: Vec::new()
    };
    let mut start_byte = 0usize;
    let mut end_byte;

    loop {
        let bytes_read = reader.read(&mut buffer).unwrap_or_default();
        if bytes_read == 0 {
            break; 
        }

        let mut hasher = Sha3_256::new();
        hasher.update(&buffer[..bytes_read]);
        let hash_result = hasher.finalize();
        
        end_byte = start_byte + bytes_read;        
        special_file.blocks.push(FileBlock { start_byte: start_byte, end_byte: end_byte, hash_value: hex::encode(hash_result) });
        start_byte += bytes_read

    }
    special_file
}