use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};

/// System and location information
///
/// Contains country, sunrise/sunset times, and internal API parameters.
#[derive(Debug, Clone, Deserialize, Serialize, Default, PartialEq)]
pub struct Sys {
    /// Internal parameter
    #[serde(default)]
    pub r#type: Option<u8>,

    /// Internal parameter
    #[serde(default)]
    pub id: Option<u32>,

    /// Country code (ISO 3166-1 alpha-2, e.g. "GB", "JP")
    #[serde(default)]
    pub country: Option<String>,

    /// Sunrise time (UTC Unix timestamp)
    #[serde(with = "chrono::serde::ts_seconds_option")]
    pub sunrise: Option<DateTime<Utc>>,

    /// Sunset time (UTC Unix timestamp)
    #[serde(with = "chrono::serde::ts_seconds_option")]
    pub sunset: Option<DateTime<Utc>>,

    /// Internal parameter (often used for error messages)
    #[serde(default)]
    pub message: Option<f64>,
}

impl Sys {
    /// Returns true if it's currently daytime at the location
    ///
    /// Compares current UTC time with sunrise and sunset times.
    #[must_use]
    pub fn is_daytime(&self) -> Option<bool> {
        let now = Utc::now();
        match (self.sunrise, self.sunset) {
            (Some(sunrise), Some(sunset)) => Some(now >= sunrise && now <= sunset),
            _ => None,
        }
    }

    /// Returns the duration of daylight (sunset - sunrise)
    ///
    /// Returns `None` if either sunrise or sunset data is missing.
    #[must_use]
    pub fn daylight_duration(&self) -> Option<chrono::Duration> {
        Some(self.sunset? - self.sunrise?)
    }
}