use std::fmt::Display;
use chrono::{Local, Utc, NaiveTime, offset::TimeZone};

use i3monkit::Block;
use i3monkit::ColorRGB;
use i3monkit::{Widget, WidgetUpdate};

/// The widget that shows local time
pub struct DateTimeWidget<Tz> {
    /// fmt to format the datetime, see
    /// https://docs.rs/chrono/*/chrono/format/strftime/index.html for documentation.
    fmt: String,
    tz: Tz,
    colors: Option<Vec<TimeColor>>,
}

#[derive(Clone)]
pub struct TimeColor {
    pub start: NaiveTime,
    pub color: ColorRGB,
}

impl DateTimeWidget<Local> {
    pub fn new(fmt: String) -> Self {
        DateTimeWidget::tz(fmt, Local)
    }
}

impl<Tz> DateTimeWidget<Tz>
where
    Tz: TimeZone,
    Tz::Offset: Display,
{
    pub fn tz(fmt: String, tz: Tz) -> Self {
        DateTimeWidget {
            fmt,
            tz,
            colors: None,
        }
    }
    pub fn set_colors(&mut self, colors: &[TimeColor]) {
        let mut colors = colors.to_vec();
        colors.sort_by(|l, r| l.start.cmp(&r.start));
        self.colors = Some(colors);
    }
}

impl<Tz> Widget for DateTimeWidget<Tz>
where
    Tz: TimeZone,
    Tz::Offset: Display,
{
    fn update(&mut self) -> Option<WidgetUpdate> {
        let (time, time_string) = {
            let now = Utc::now().with_timezone(&self.tz);
            (now.time(), now.format(&self.fmt).to_string())
        };
        let color = if let Some(colors) = &self.colors {
            colors
                .iter()
                .filter(|tc| tc.start < time)
                .last()
                .map(|tc| tc.color.clone())
        } else {
            None
        };

        let time_string = format!(
            r#"<span size="x-large" weight="heavy">{}</span>"#,
            time_string
        );
        let mut data = Block::new()
            .append_full_text(&time_string)
            .use_pango()
            .clone();
        if let Some(color) = color {
            data.color(color);
        }
        Some(WidgetUpdate {
            refresh_interval: std::time::Duration::from_secs(1),
            data: Some(data),
        })
    }
}