use anyhow::{bail, Result};
use std::{
    fs::{create_dir_all, remove_file, rename, File},
    path::{PathBuf, MAIN_SEPARATOR},
    thread,
    time::{Duration, SystemTime, UNIX_EPOCH},
};

const TMP_SUFFIX: &str = ".tmp";

pub struct Item {
    pub file: File,
    pub path: PathBuf,
    // pub id: u64,
}

impl Item {
    // Constructors

    pub fn create(directory: &str) -> Result<Self> {
        loop {
            // generate file id from current unix time
            let id = SystemTime::now().duration_since(UNIX_EPOCH)?.as_secs();

            // build optimized fs path:
            // add directory separator after every digit to keep up to 10 files per directory
            let path = PathBuf::from(format!(
                "{}{MAIN_SEPARATOR}{}{TMP_SUFFIX}",
                directory.trim_end_matches(MAIN_SEPARATOR),
                id.to_string().chars().fold(String::new(), |mut acc, c| {
                    if !acc.is_empty() {
                        acc.push(MAIN_SEPARATOR);
                    }
                    acc.push(c);
                    acc
                })
            ));

            // recursively create directories
            // * parent directory is expected
            create_dir_all(path.parent().unwrap())?;

            // build `Self`
            match File::create_new(&path) {
                // make sure slot is not taken (by another thread)
                Ok(file) => {
                    return Ok(Self {
                        file,
                        path,
                        // id
                    });
                }
                Err(_) => {
                    println!("[warning] Could not init location: {:?}", path.to_str());
                    // find free slot after some delay..
                    thread::sleep(Duration::from_secs(1));
                    continue;
                }
            }
        }
    }

    // Actions

    /// Take object processed, commit its changes
    pub fn commit(self) -> Result<String> {
        match self.path.to_str() {
            Some(old) => match old.strip_suffix(TMP_SUFFIX) {
                Some(new) => {
                    rename(old, new)?;
                    Ok(new.to_string())
                }
                None => bail!("Invalid TMP suffix"), // | panic
            },
            None => bail!("Invalid Item path"), // | panic
        }
    }

    /// Cleanup object relationships
    pub fn delete(self) -> Result<()> {
        Ok(remove_file(self.path)?)
    }

    // Getters

    /* @TODO implement short links handle without slash
    pub fn alias(&self, relative: &str) -> String {} */
}