use tui::layout::Rect;

use crate::app::{self};
use std::{
    cmp::{max, min},
    time::Instant,
};

pub fn get_search_start_position(
    num_columns: usize, cursor_direction: &app::CursorDirection, cursor_bar: &mut usize,
    current_cursor_position: usize, is_force_redraw: bool,
) -> usize {
    if is_force_redraw {
        *cursor_bar = 0;
    }

    match cursor_direction {
        app::CursorDirection::Right => {
            if current_cursor_position < *cursor_bar + num_columns {
                // If, using previous_scrolled_position, we can see the element
                // (so within that and + num_rows) just reuse the current previously scrolled position
                *cursor_bar
            } else if current_cursor_position >= num_columns {
                // Else if the current position past the last element visible in the list, omit
                // until we can see that element
                *cursor_bar = current_cursor_position - num_columns;
                *cursor_bar
            } else {
                // Else, if it is not past the last element visible, do not omit anything
                0
            }
        }
        app::CursorDirection::Left => {
            if current_cursor_position <= *cursor_bar {
                // If it's past the first element, then show from that element downwards
                *cursor_bar = current_cursor_position;
            } else if current_cursor_position >= *cursor_bar + num_columns {
                *cursor_bar = current_cursor_position - num_columns;
            }
            // Else, don't change what our start position is from whatever it is set to!
            *cursor_bar
        }
    }
}

/// Calculate how many bars are to be drawn within basic mode's components.
pub fn calculate_basic_use_bars(use_percentage: f64, num_bars_available: usize) -> usize {
    std::cmp::min(
        (num_bars_available as f64 * use_percentage / 100.0).round() as usize,
        num_bars_available,
    )
}

/// Determine whether a graph x-label should be hidden.
pub fn should_hide_x_label(
    always_hide_time: bool, autohide_time: bool, timer: &mut Option<Instant>, draw_loc: Rect,
) -> bool {
    use crate::constants::*;

    if always_hide_time || (autohide_time && timer.is_none()) {
        true
    } else if let Some(time) = timer {
        if Instant::now().duration_since(*time).as_millis() < AUTOHIDE_TIMEOUT_MILLISECONDS.into() {
            false
        } else {
            *timer = None;
            true
        }
    } else {
        draw_loc.height < TIME_LABEL_HEIGHT_LIMIT
    }
}

#[cfg(test)]
mod test {

    use super::*;

    #[test]
    fn test_calculate_basic_use_bars() {
        // Testing various breakpoints and edge cases.
        assert_eq!(calculate_basic_use_bars(0.0, 15), 0);
        assert_eq!(calculate_basic_use_bars(1.0, 15), 0);
        assert_eq!(calculate_basic_use_bars(5.0, 15), 1);
        assert_eq!(calculate_basic_use_bars(10.0, 15), 2);
        assert_eq!(calculate_basic_use_bars(40.0, 15), 6);
        assert_eq!(calculate_basic_use_bars(45.0, 15), 7);
        assert_eq!(calculate_basic_use_bars(50.0, 15), 8);
        assert_eq!(calculate_basic_use_bars(100.0, 15), 15);
        assert_eq!(calculate_basic_use_bars(150.0, 15), 15);
    }

    #[test]
    fn test_should_hide_x_label() {
        use crate::constants::*;
        use std::time::{Duration, Instant};
        use tui::layout::Rect;

        let rect = Rect::new(0, 0, 10, 10);
        let small_rect = Rect::new(0, 0, 10, 6);

        let mut under_timer = Some(Instant::now());
        let mut over_timer =
            Instant::now().checked_sub(Duration::from_millis(AUTOHIDE_TIMEOUT_MILLISECONDS + 100));

        assert!(should_hide_x_label(true, false, &mut None, rect));
        assert!(should_hide_x_label(false, true, &mut None, rect));
        assert!(should_hide_x_label(false, false, &mut None, small_rect));

        assert!(!should_hide_x_label(
            false,
            true,
            &mut under_timer,
            small_rect
        ));
        assert!(under_timer.is_some());

        assert!(should_hide_x_label(
            false,
            true,
            &mut over_timer,
            small_rect
        ));
        assert!(over_timer.is_none());
    }
}