//! Promo code management screen — list, create, delete codes.

use ratatui::Frame;
use ratatui::layout::{Constraint, Layout};
use ratatui::style::{Color, Modifier, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Borders, Paragraph, Row};

use super::App;
use super::widgets;

pub fn render(frame: &mut Frame, app: &App) {
    let area = frame.area();

    let title = Line::from(vec![
        Span::styled(" Makenot.work ", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw(" -- "),
        Span::styled("Promo Codes", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw(" "),
    ]);

    let block = Block::default()
        .title(title)
        .borders(Borders::ALL)
        .border_style(Style::default().fg(Color::Gray));

    let inner = block.inner(area);
    frame.render_widget(block, area);

    let chunks = Layout::vertical([
        Constraint::Length(1), // spacer
        Constraint::Length(1), // section header
        Constraint::Min(3),   // code list
        Constraint::Length(1), // status line
        Constraint::Length(1), // keybindings
    ])
    .split(inner);

    // Section header
    let count = app.promo_codes.len();
    let header = Paragraph::new(Line::from(vec![
        Span::raw("  "),
        Span::styled("Codes", Style::default().add_modifier(Modifier::BOLD)),
        if count == 0 {
            Span::raw("")
        } else {
            Span::raw(format!(" ({})", count))
        },
    ]));
    frame.render_widget(header, chunks[1]);

    // Code list
    if app.loading {
        let loading = Paragraph::new("  Loading...");
        frame.render_widget(loading, chunks[2]);
    } else if app.promo_codes.is_empty() {
        let empty = Paragraph::new("  No promo codes. Press [n] to create one.");
        frame.render_widget(empty, chunks[2]);
    } else {
        render_code_table(frame, app, chunks[2]);
    }

    // Status line
    if let Some(ref status) = app.promo_status {
        let style = if status.starts_with("Error") {
            Style::default().fg(Color::Red)
        } else {
            Style::default().fg(Color::Green)
        };
        let status_line = Paragraph::new(Line::from(vec![
            Span::raw("  "),
            Span::styled(status.as_str(), style),
        ]));
        frame.render_widget(status_line, chunks[3]);
    }

    // Keybindings
    let editing = app.promo_editing_step.is_some();
    let mut key_spans = vec![Span::raw("  ")];

    if editing {
        key_spans.extend([
            Span::styled("[Enter]", Style::default().add_modifier(Modifier::BOLD)),
            Span::raw(" Confirm  "),
            Span::styled("[Esc]", Style::default().add_modifier(Modifier::BOLD)),
            Span::raw(" Cancel"),
        ]);
    } else {
        key_spans.extend([
            Span::styled("[j/k]", Style::default().add_modifier(Modifier::BOLD)),
            Span::raw(" Nav  "),
            Span::styled("[n]", Style::default().add_modifier(Modifier::BOLD)),
            Span::raw(" New  "),
        ]);
        if !app.promo_codes.is_empty() {
            key_spans.extend([
                Span::styled("[d]", Style::default().add_modifier(Modifier::BOLD)),
                Span::raw(" Delete  "),
            ]);
        }
        key_spans.extend([
            Span::styled("[r]", Style::default().add_modifier(Modifier::BOLD)),
            Span::raw(" Refresh  "),
            Span::styled("[Esc]", Style::default().add_modifier(Modifier::BOLD)),
            Span::raw(" Back"),
        ]);
    }

    let keys = Paragraph::new(Line::from(key_spans)).style(Style::default().fg(Color::DarkGray));
    frame.render_widget(keys, chunks[4]);
}

fn render_code_table(frame: &mut Frame, app: &App, area: ratatui::layout::Rect) {
    let rows: Vec<Row> = app
        .promo_codes
        .iter()
        .enumerate()
        .map(|(i, code)| {
            let discount = format_discount(code.discount_type.as_deref(), code.discount_value);
            let scope = code
                .item_title
                .as_deref()
                .or(code.project_title.as_deref())
                .unwrap_or("All items");
            let uses = match code.max_uses {
                Some(max) => format!("{}/{}", code.use_count, max),
                None => code.use_count.to_string(),
            };

            Row::new(vec![
                format!("  {}", code.code),
                discount,
                scope.to_string(),
                uses,
            ])
            .style(widgets::selected_style(i, Some(app.selected_index)))
        })
        .collect();

    let widths = [
        Constraint::Min(16),
        Constraint::Length(12),
        Constraint::Length(20),
        Constraint::Length(10),
    ];

    widgets::render_table(frame, area, &["  Code", "Discount", "Scope", "Uses"], &widths, rows);
}

fn format_discount(dtype: Option<&str>, value: Option<i32>) -> String {
    match (dtype, value) {
        (Some("percentage"), Some(v)) => format!("{}% off", v),
        (Some("fixed"), Some(v)) => format!("${}.{:02} off", v / 100, v % 100),
        _ => "Free".to_string(),
    }
}