use std::{fs, path::PathBuf};

use anyhow::{bail, Result};
use directories::ProjectDirs;
use serde::{Deserialize, Serialize};

#[derive(Clone)]
pub struct Persistence {
    dirs: Option<Dirs>,
}

impl Persistence {
    pub fn new() -> Self {
        Self { dirs: init_dirs() }
    }

    pub fn save_config<T: Serialize>(&self, file: &str, data: &T) -> Result<()> {
        if let Some(dirs) = self.dirs.as_ref() {
            let bytes = serde_json::to_vec_pretty(data)?;
            let filename = dirs.config_dir.join(file).with_extension("json");
            fs::write(&filename, bytes)?;
        }
        Ok(())
    }

    pub fn load_config<T: for<'a> Deserialize<'a>>(&self, file: &str) -> Result<T> {
        let Some(dirs) = self.dirs.as_ref() else {
            bail!("config directory not found");
        };
        let filename = dirs.config_dir.join(file).with_extension("json");
        let bytes = fs::read(filename)?;
        Ok(serde_json::from_slice(&bytes)?)
    }
}

#[derive(Clone)]
struct Dirs {
    config_dir: PathBuf,
}

fn init_dirs() -> Option<Dirs> {
    let dirs = ProjectDirs::from("com", "virtual-boy", "Lemur")?;
    let config_dir = dirs.config_dir().to_path_buf();
    fs::create_dir_all(&config_dir).ok()?;
    Some(Dirs { config_dir })
}