use crate::config::JustifyMode;
use crate::format;
use crate::layout::ActiveSection;

/// Distribute extra space evenly across gaps between sections.
/// Center the separator core (e.g., `|` from ` | `) within each gap.
/// Remainder chars distributed left-to-right.
pub fn justify(
    active: &[ActiveSection],
    term_width: u16,
    separator: &str,
    _mode: JustifyMode,
    color_enabled: bool,
) -> String {
    let content_width: usize = active
        .iter()
        .map(|s| format::display_width(&s.output.raw))
        .sum();

    let num_gaps = active.len().saturating_sub(1);
    if num_gaps == 0 {
        return active
            .first()
            .map(|s| s.output.ansi.clone())
            .unwrap_or_default();
    }

    let available = (term_width as usize).saturating_sub(content_width);
    let gap_width = available / num_gaps;
    let gap_remainder = available % num_gaps;

    // Extract separator core (non-space chars, e.g. "|" from " | ")
    let sep_core = separator.trim();
    let sep_core_len = format::display_width(sep_core);

    let mut output = String::new();
    for (i, sec) in active.iter().enumerate() {
        if i > 0 {
            let this_gap = gap_width + usize::from(i - 1 < gap_remainder);
            let gap_str = build_gap(sep_core, sep_core_len, this_gap);
            if color_enabled {
                output.push_str(&format!(
                    "{}{gap_str}{}",
                    crate::color::DIM,
                    crate::color::RESET
                ));
            } else {
                output.push_str(&gap_str);
            }
        }
        output.push_str(&sec.output.ansi);
    }

    output
}

/// Center the separator core within a gap of `total` columns.
fn build_gap(core: &str, core_len: usize, total: usize) -> String {
    if core.is_empty() || core_len == 0 {
        return " ".repeat(total);
    }

    let pad_total = total.saturating_sub(core_len);
    let pad_left = pad_total / 2;
    let pad_right = pad_total - pad_left;

    format!("{}{core}{}", " ".repeat(pad_left), " ".repeat(pad_right))
}