use color_eyre::{eyre::{bail, WrapErr}, Result};
use std::{
    fs,
    io::ErrorKind,
    path::{Path, PathBuf},
};

pub trait Storage {
    fn prepare(&mut self) -> Result<()>;
    fn prepare_zoom(&mut self, zoom: u32) -> Result<()>;
    fn store(&mut self, zoom: u32, x: u64, y: u64, data: &[u8]) -> Result<()>;
    fn finish(&mut self) -> Result<()>;
}

#[derive(Debug)]
pub struct Folder {
    base_dir: PathBuf,
}

impl Folder {
    pub fn new(base_dir: PathBuf) -> Self {
        Folder { base_dir }
    }
}

impl Storage for Folder {
    fn prepare(&mut self) -> Result<()> {
        let path = &self.base_dir;
        let metadata = fs::metadata(path);
        match metadata {
            Err(e) if e.kind() == ErrorKind::NotFound => {
                let parent = path.parent().unwrap_or_else(|| Path::new("/"));
                fs::create_dir(path)
                    .context(format!("Could not create output directory at {parent:?}"))?
            }
            Err(e) => Err(e).context("Error while checking output directory")?,
            Ok(m) if m.is_dir() => (),
            Ok(_) => bail!("Output directory is not a directory"),
        }
        Ok(())
    }

    fn prepare_zoom(&mut self, zoom: u32) -> Result<()> {
        let target = [&self.base_dir, &zoom.to_string().into()]
            .iter()
            .collect::<PathBuf>();
        fs::create_dir(target)?;
        Ok(())
    }

    fn store(&mut self, zoom: u32, x: u64, y: u64, data: &[u8]) -> Result<()> {
        let folder = self.base_dir.join(zoom.to_string()).join(x.to_string());
        let metadata = folder.metadata();
        match metadata {
            Err(_) => fs::create_dir(&folder)?,
            Ok(m) if !m.is_dir() => bail!("Output path is not a directory"),
            _ => {}
        }
        let file = folder.join(format!("{y}.png"));
        fs::write(file, data)?;
        Ok(())
    }

    fn finish(&mut self) -> Result<()> {
        Ok(())
    }
}