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use file_mmap::FileMmap;

mod flagment;

#[derive(Clone, Default, PartialEq)]
pub struct DataAddress {
    offset: i64,
    len: u64,
}
impl DataAddress {
    pub fn offset(&self) -> i64 {
        self.offset
    }
    pub fn len(&self) -> u64 {
        self.len
    }
}
pub struct Data<'a> {
    address: DataAddress,
    data: &'a VariousDataFile,
}
impl Data<'_> {
    pub fn bytes(&self) -> &[u8] {
        unsafe { self.data.bytes(&self.address) }
    }
    pub fn address(&self) -> &DataAddress {
        &self.address
    }
}

pub struct VariousDataFile {
    filemmap: FileMmap,
    fragment: flagment::Fragment,
}
impl VariousDataFile {
    pub fn new(path: &str) -> Result<Self, std::io::Error> {
        let filemmap = FileMmap::new(path, 1)?;
        let fragment = flagment::Fragment::new(&(path.to_string() + ".f"))?;
        Ok(VariousDataFile { filemmap, fragment })
    }
    pub unsafe fn bytes(&self, word: &DataAddress) -> &[u8] {
        self.filemmap
            .bytes(word.offset() as isize, word.len as usize)
    }
    pub unsafe fn offset(&self, addr: isize) -> *const i8 {
        self.filemmap.offset(addr)
    }
    pub fn insert(&mut self, target: &[u8]) -> Result<Data, std::io::Error> {
        let len = target.len() as u64;
        match self.fragment.search_blank(len) {
            Some(r) => {
                unsafe {
                    self.filemmap.write(r.string_addr, target);
                    self.fragment.release(r.fragment_id, len);
                }
                Ok(Data {
                    address: DataAddress {
                        offset: r.string_addr as i64,
                        len,
                    },
                    data: self,
                })
            }
            None => {
                let addr = self.filemmap.append(target)?;
                Ok(Data {
                    address: DataAddress {
                        offset: addr as i64,
                        len,
                    },
                    data: self,
                })
            }
        }
    }
    pub unsafe fn remove(&mut self, ystr: &DataAddress) {
        self.filemmap.write_0(ystr.offset as isize, ystr.len);
        self.fragment.insert(ystr).unwrap();
    }
}

#[test]
fn test() {
    let dir = "./vdf-test";
    if std::path::Path::new(dir).exists() {
        std::fs::remove_dir_all(dir).unwrap();
        std::fs::create_dir_all(dir).unwrap();
    } else {
        std::fs::create_dir_all(dir).unwrap();
    }
    if let Ok(mut s) = VariousDataFile::new(&(dir.to_owned() + "/test.str")) {
        let noah = s.insert(b"Noah").unwrap().address;
        let liam = s.insert(b"Liam").unwrap().address;
        let olivia = s.insert(b"Olivia").unwrap().address;

        unsafe {
            s.remove(&noah);
        }
        if let Ok(w) = s.insert(b"Renamed Noah") {
            assert_eq!(
                "Renamed Noah".to_string(),
                std::str::from_utf8(w.bytes()).unwrap().to_string()
            );
        }
        unsafe { s.remove(&liam) };
        if let Ok(w) = s.insert(b"Renamed Liam") {
            assert_eq!(
                "Renamed Liam".to_string(),
                std::str::from_utf8(w.bytes()).unwrap().to_string()
            );
        }
        unsafe { s.remove(&olivia) };
        if let Ok(w) = s.insert(b"Renamed Olivia") {
            assert_eq!(
                "Renamed Olivia".to_string(),
                std::str::from_utf8(w.bytes()).unwrap().to_string()
            );
        }
        if let Ok(w) = s.insert(b"Noah") {
            assert_eq!(
                "Noah".to_string(),
                std::str::from_utf8(w.bytes()).unwrap().to_string()
            );
        }
        if let Ok(w) = s.insert(b"Liam") {
            assert_eq!(
                "Liam".to_string(),
                std::str::from_utf8(w.bytes()).unwrap().to_string()
            );
        }
        if let Ok(w) = s.insert(b"Olivia") {
            assert_eq!(
                "Olivia".to_string(),
                std::str::from_utf8(w.bytes()).unwrap().to_string()
            );
        }
    }
}