//! Formatting + small browser helpers.

use leptos::prelude::*;
use wasm_bindgen::JsValue;

/// A window event listener that is removed when the current owner is disposed.
///
/// Leptos' `window_event_listener` returns a `WindowListenerHandle` with no
/// `Drop` impl — if the owning component is unmounted without an explicit
/// `remove()`, the listener keeps firing on `window` and panics by reading
/// the component's now-disposed signals.
pub fn owned_window_listener<E: leptos::ev::EventDescriptor + 'static>(
    event: E,
    cb: impl Fn(E::EventType) + 'static,
) where
    E::EventType: wasm_bindgen::JsCast,
{
    let handle = window_event_listener(event, cb);
    on_cleanup(move || handle.remove());
}

pub fn format_size(bytes: u64) -> String {
    const UNITS: [&str; 5] = ["B", "KB", "MB", "GB", "TB"];
    let mut v = bytes as f64;
    let mut i = 0;
    while v >= 1024.0 && i < UNITS.len() - 1 {
        v /= 1024.0;
        i += 1;
    }
    if i == 0 {
        format!("{bytes} B")
    } else {
        format!("{v:.1} {}", UNITS[i])
    }
}

/// Format an RFC 3339 timestamp as "YYYY-MM-DD HH:MM" (UTC) for display.
/// Falls back to the raw string when it cannot be parsed.
pub fn format_date(rfc3339: &str) -> String {
    let d = js_sys::Date::new(&JsValue::from_str(rfc3339));
    if d.get_time().is_nan() {
        return rfc3339.to_string();
    }
    fn pad(n: u32) -> String {
        if n < 10 {
            format!("0{n}")
        } else {
            n.to_string()
        }
    }
    format!(
        "{:04}-{}-{} {} {}",
        d.get_utc_full_year(),
        pad(d.get_utc_month() + 1),
        pad(d.get_utc_date()),
        pad(d.get_utc_hours()),
        pad(d.get_utc_minutes()),
    )
}

pub fn storage_get(key: &str) -> Option<String> {
    let w = web_sys::window()?;
    let storage_opt = w.local_storage().ok()?;
    let storage = storage_opt.as_ref()?;
    storage.get_item(key).ok().flatten()
}

pub fn storage_set(key: &str, value: &str) {
    if let Some(s) = web_sys::window().and_then(|w| w.local_storage().ok().flatten()) {
        let _ = s.set_item(key, value);
    }
}

#[derive(Clone, Copy, PartialEq, Debug)]
pub enum ViewMode {
    Grid,
    List,
}

impl ViewMode {
    const KEY: &'static str = "fbng.view";

    pub fn load() -> Self {
        match storage_get(Self::KEY).as_deref() {
            Some("list") => ViewMode::List,
            _ => ViewMode::Grid,
        }
    }

    pub fn save(self) {
        storage_set(
            Self::KEY,
            if self == ViewMode::List {
                "list"
            } else {
                "grid"
            },
        );
    }
}