/*
 * Copyright (c) 2026, Tobias Müller git@tsmr.eu
 *
 */

use chrono::{DateTime, Local, TimeZone};
use std::sync::Arc;
use tokio::sync::{RwLock, RwLockReadGuard};

use crate::error::{Result, TwonlyError};

pub(crate) fn milliseconds_to_seconds(timestamp: i64) -> i64 {
    timestamp.div_euclid(1_000)
}

pub(crate) fn current_time() -> DateTime<Local> {
    Local::now()
}

pub(crate) fn is_today(timestamp: i64) -> bool {
    Local
        .timestamp_opt(timestamp, 0)
        .single()
        .is_some_and(|date| date.date_naive() == current_time().date_naive())
}

/// Midnight of the current day in the user's timezone. Flame counters roll over
/// at the local day boundary, so every comparison against "today" has to start
/// here instead of at a UTC boundary.
pub(crate) fn start_of_local_day() -> Result<i64> {
    Ok(Local
        .from_local_datetime(
            &current_time()
                .date_naive()
                .and_hms_opt(0, 0, 0)
                .ok_or_else(|| TwonlyError::Generic("invalid local date".into()))?,
        )
        .earliest()
        .ok_or_else(|| TwonlyError::Generic("local day has no midnight".into()))?
        .timestamp())
}

pub(crate) fn new_uuid_v4() -> String {
    uuid::Uuid::new_v4().to_string()
}

/// Media and message identifiers are time-ordered so that inserting them keeps
/// the primary-key index append-only, matching what Drift generated before.
pub(crate) fn new_uuid_v7() -> String {
    uuid::Uuid::now_v7().to_string()
}

#[derive(Default, Clone)]
pub(crate) struct Shared<T>(Arc<RwLock<T>>);
impl<T> Shared<T> {
    pub(crate) fn new(value: T) -> Self {
        Self(Arc::new(RwLock::new(value)))
    }
    pub(crate) async fn get(&self) -> RwLockReadGuard<'_, T> {
        self.0.read().await
    }
    // pub(crate) async fn set(&self, value: T) {
    //     *self.0.write().await = value;
    // }
}

#[cfg(test)]
mod tests {
    use super::{current_time, is_today, milliseconds_to_seconds};

    #[test]
    fn converts_milliseconds_to_seconds() {
        assert_eq!(milliseconds_to_seconds(1_999), 1);
        assert_eq!(milliseconds_to_seconds(1_000), 1);
        assert_eq!(milliseconds_to_seconds(999), 0);
    }

    #[test]
    fn recognizes_current_day() {
        assert!(is_today(current_time().timestamp()));
        assert!(!is_today(i64::MAX));
    }
}