//! Waveform rendering widget: custom egui Painter-based display with playback position and click-to-seek.

use egui;

use audiofiles_core::analysis::waveform::WaveformData;

use crate::ui::theme;

/// Draw a waveform display. Returns the response for click-to-seek handling.
pub fn draw_waveform(
    ui: &mut egui::Ui,
    waveform: &WaveformData,
    playback_pos: Option<f32>,
    height: f32,
) -> egui::Response {
    let available_width = ui.available_width();
    let size = egui::vec2(available_width, height);
    let (rect, response) = ui.allocate_exact_size(size, egui::Sense::click());

    if !ui.is_rect_visible(rect) {
        return response;
    }

    let painter = ui.painter_at(rect);

    // Dark background
    painter.rect_filled(rect, 4.0, theme::bg_primary());

    // Center line (zero crossing)
    let center_y = rect.center().y;
    painter.line_segment(
        [
            egui::pos2(rect.left(), center_y),
            egui::pos2(rect.right(), center_y),
        ],
        egui::Stroke::new(0.5, theme::text_muted()),
    );

    // Draw waveform peaks
    let num_buckets = waveform.num_buckets;
    if num_buckets > 0 && !waveform.peaks.is_empty() {
        let bucket_width = rect.width() / num_buckets as f32;
        let half_height = rect.height() / 2.0;

        for i in 0..num_buckets {
            let pair_idx = i * 2;
            if pair_idx + 1 >= waveform.peaks.len() {
                break;
            }
            let min_val = waveform.peaks[pair_idx];
            let max_val = waveform.peaks[pair_idx + 1];

            let x = rect.left() + (i as f32 + 0.5) * bucket_width;
            let y_min = center_y - max_val * half_height;
            let y_max = center_y - min_val * half_height;

            painter.line_segment(
                [egui::pos2(x, y_min), egui::pos2(x, y_max)],
                egui::Stroke::new(1.0, theme::accent_green()),
            );
        }
    }

    // Playback position line
    if let Some(pos) = playback_pos {
        let x = rect.left() + pos.clamp(0.0, 1.0) * rect.width();
        painter.line_segment(
            [egui::pos2(x, rect.top()), egui::pos2(x, rect.bottom())],
            egui::Stroke::new(1.5, theme::text_primary()),
        );
    }

    response
}