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//! Persists desktop icons' grid cells across restarts - same shape as
//! `monitor_layout.rs`, deliberately not sharing code with it (its own doc
//! comment gives the reasoning: two small, independent files beat a
//! cross-module dependency for four lines of env-var lookup).
//!
//! Only icons the user has actually dragged get an entry here - see
//! `desktop_icons::rescan`'s own doc comment for why a fresh/unmoved icon
//! deliberately has no row in this file at all.
use std::collections::HashMap;
use std::path::PathBuf;
use serde::{Deserialize, Serialize};
#[derive(Serialize, Deserialize, Default)]
struct PersistedIcons {
/// Keyed by `DesktopIcon::id` - `"home"`/`"computer"`/`"trash"`, or a
/// real `~/Desktop` filename.
icons: HashMap<String, (i32, i32)>,
}
fn state_dir() -> PathBuf {
if let Ok(p) = std::env::var("SRDWM_STATE_PATH") {
return PathBuf::from(p);
}
if let Ok(xdg) = std::env::var("XDG_STATE_HOME") {
return PathBuf::from(xdg).join("srd");
}
if let Ok(home) = std::env::var("HOME") {
return PathBuf::from(home).join(".local/state/srd");
}
PathBuf::from("state/srd")
}
fn icons_path() -> PathBuf {
state_dir().join("desktop-icons.json")
}
/// Every remembered icon cell, by icon id. Empty (not an error) if the file
/// doesn't exist yet or is unreadable/corrupt - a bad state file degrades
/// to "every icon gets its default grid slot", not a startup failure.
pub(crate) fn load() -> HashMap<String, (i32, i32)> {
let path = icons_path();
let Ok(bytes) = std::fs::read(&path) else { return HashMap::new() };
match serde_json::from_slice::<PersistedIcons>(&bytes) {
Ok(persisted) => persisted.icons,
Err(e) => {
log::warn!("desktop_icons_state: couldn't parse {path:?} ({e}); starting with default icon positions instead");
HashMap::new()
}
}
}
/// Overwrites one icon's remembered cell and rewrites the whole file --
/// read-modify-write, same reasoning as `monitor_layout.rs::save_output`:
/// a drag-and-drop is a rare, human-paced event, not a per-frame one, so
/// re-reading the small file each time costs nothing.
pub(crate) fn save_icon(id: &str, cell: (i32, i32)) {
let mut persisted = PersistedIcons { icons: load() };
persisted.icons.insert(id.to_string(), cell);
let dir = state_dir();
if let Err(e) = std::fs::create_dir_all(&dir) {
log::warn!("desktop_icons_state: couldn't create {dir:?} ({e}); this icon's position won't survive a restart");
return;
}
let Ok(bytes) = serde_json::to_vec_pretty(&persisted) else { return };
let path = icons_path();
// `.tmp`-sibling-then-rename, same crash-safety reasoning as
// `monitor_layout.rs::save_output`.
let tmp = path.with_extension("json.tmp");
if let Err(e) = std::fs::write(&tmp, &bytes) {
log::warn!("desktop_icons_state: couldn't write {tmp:?} ({e}); this icon's position won't survive a restart");
return;
}
if let Err(e) = std::fs::rename(&tmp, &path) {
log::warn!("desktop_icons_state: couldn't rename {tmp:?} to {path:?} ({e}); this icon's position won't survive a restart");
}
}
#[cfg(test)]
mod tests {
use super::*;
// Same reasoning as `monitor_layout.rs`'s own tests: only the pure JSON
// round-trip is exercised here, not `load()`/`save_icon()` themselves,
// since both touch real environment variables and the filesystem that
// parallel `cargo test` runs can't safely share.
#[test]
fn a_persisted_icon_map_survives_a_json_round_trip() {
let mut icons = HashMap::new();
icons.insert("home".to_string(), (0, 0));
icons.insert("report.txt".to_string(), (2, 3));
let persisted = PersistedIcons { icons };
let bytes = serde_json::to_vec(&persisted).unwrap();
let parsed: PersistedIcons = serde_json::from_slice(&bytes).unwrap();
assert_eq!(parsed.icons.get("home"), Some(&(0, 0)));
assert_eq!(parsed.icons.get("report.txt"), Some(&(2, 3)));
}
#[test]
fn corrupt_json_falls_back_to_an_empty_map_not_an_error() {
let result = serde_json::from_slice::<PersistedIcons>(b"not valid json");
assert!(result.is_err(), "sanity: this fixture must actually fail to parse");
}
}
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