//! Filesystem layout for zesdex's persistent and scratch data directories.

use std::path::PathBuf;
use serde::{Deserialize, Serialize};

/// Resolved paths for all data directories zesdex reads from and writes to.
///
/// Why: centralizing path computation here means every consumer agrees on
/// where memory, scratch, session images, and downloads live.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Store {
    pub base_dir: PathBuf,
    pub scratch_root: PathBuf,
    pub memory_dir: PathBuf,
    pub session_images_dir: PathBuf,
    pub download_dir: PathBuf,
}

impl Store {
    /// Compute the standard set of zesdex data directory paths.
    ///
    /// Flow: OS data dir (or `.local/share` fallback) + "zesdex" → base dir;
    /// scratch root comes from the OS temp dir instead, since it's disposable.
    ///
    /// Why: paths are computed, not created — call `ensure_dirs` before use.
    pub fn new() -> Self {
        let base = dirs::data_dir()
            .unwrap_or_else(|| PathBuf::from(".local/share"))
            .join("zesdex");
        let scratch = std::env::temp_dir().join("zesdex-scratch");
        Store {
            memory_dir: base.join("memory"),
            scratch_root: scratch,
            session_images_dir: base.join("session-images"),
            download_dir: base.join("downloads"),
            base_dir: base,
        }
    }

    /// Create all store directories (base, memory, scratch, session images, downloads) if missing.
    ///
    /// Return: `Err` on the first directory that fails to create.
    pub fn ensure_dirs(&self) -> std::io::Result<()> {
        std::fs::create_dir_all(&self.base_dir)?;
        std::fs::create_dir_all(&self.memory_dir)?;
        std::fs::create_dir_all(&self.scratch_root)?;
        std::fs::create_dir_all(&self.session_images_dir)?;
        std::fs::create_dir_all(&self.download_dir)?;
        Ok(())
    }
}