//! Analytics dashboard — revenue chart, stats, top projects, transactions, export.

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

use crate::format;

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

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

    let range_label = match app.analytics_range.as_str() {
        "7d" => "7 days",
        "30d" => "30 days",
        "90d" => "90 days",
        "all" => "All time",
        _ => &app.analytics_range,
    };

    let title = Line::from(vec![
        Span::styled(" Makenot.work ", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw(" -- "),
        Span::styled("Analytics", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw(format!(" ({}) ", range_label)),
    ]);

    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(3), // stat cards
        Constraint::Length(1), // spacer
        Constraint::Min(6),   // chart or transactions
        Constraint::Length(1), // status
        Constraint::Length(1), // keybindings
    ])
    .split(inner);

    // Stat cards
    render_stat_cards(frame, app, chunks[1]);

    // Main content area
    if app.loading {
        let loading = Paragraph::new("  Loading...");
        frame.render_widget(loading, chunks[3]);
    } else if app.analytics_show_transactions {
        render_transactions(frame, app, chunks[3]);
    } else {
        render_chart_and_projects(frame, app, chunks[3]);
    }

    // Status line
    if let Some(ref status) = app.analytics_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[4]);
    }

    // Keybindings
    let key_spans = vec![
        Span::raw("  "),
        Span::styled("[1-4]", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw(" Range  "),
        Span::styled("[t]", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw(" Transactions  "),
        Span::styled("[e]", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw(" Export CSV  "),
        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[5]);
}

fn render_stat_cards(frame: &mut Frame, app: &App, area: ratatui::layout::Rect) {
    let stat_chunks = Layout::horizontal([
        Constraint::Ratio(1, 3),
        Constraint::Ratio(1, 3),
        Constraint::Ratio(1, 3),
    ])
    .split(area);

    let data = &app.analytics_data;

    let stats = [
        (
            "Revenue",
            format::format_cents(data.as_ref().map(|d| d.current_revenue_cents).unwrap_or(0)),
            data.as_ref().map(|d| pct_change(d.current_revenue_cents, d.previous_revenue_cents)),
        ),
        (
            "Sales",
            data.as_ref().map(|d| d.current_sales.to_string()).unwrap_or_else(|| "--".into()),
            data.as_ref().map(|d| pct_change(d.current_sales, d.previous_sales)),
        ),
        (
            "Followers",
            data.as_ref().map(|d| d.current_followers.to_string()).unwrap_or_else(|| "--".into()),
            data.as_ref().map(|d| pct_change(d.current_followers, d.previous_followers)),
        ),
    ];

    for (i, (label, value, change)) in stats.iter().enumerate() {
        let block = Block::default()
            .borders(Borders::ALL)
            .border_style(Style::default().fg(Color::DarkGray));
        let inner = block.inner(stat_chunks[i]);
        frame.render_widget(block, stat_chunks[i]);

        let mut spans = vec![
            Span::styled(
                format!(" {value}"),
                Style::default().add_modifier(Modifier::BOLD),
            ),
            Span::styled(format!(" {label}"), Style::default().fg(Color::DarkGray)),
        ];

        if let Some(Some((text, positive))) = change {
            let color = if *positive { Color::Green } else { Color::Red };
            spans.push(Span::styled(format!(" {text}"), Style::default().fg(color)));
        }

        let text = Paragraph::new(Line::from(spans));
        frame.render_widget(text, inner);
    }
}

fn render_chart_and_projects(frame: &mut Frame, app: &App, area: ratatui::layout::Rect) {
    let chunks = Layout::vertical([
        Constraint::Length(1), // chart header
        Constraint::Min(4),   // chart
        Constraint::Length(1), // spacer
        Constraint::Length(1), // projects header
        Constraint::Min(2),   // projects table
    ])
    .split(area);

    // Chart header
    let header = Paragraph::new(Line::from(vec![
        Span::raw("  "),
        Span::styled("Revenue", Style::default().add_modifier(Modifier::BOLD)),
    ]));
    frame.render_widget(header, chunks[0]);

    // Revenue bar chart
    if let Some(ref data) = app.analytics_data {
        if data.buckets.is_empty() {
            let empty = Paragraph::new("  No revenue data for this period.");
            frame.render_widget(empty, chunks[1]);
        } else {
            let max_val = data.buckets.iter().map(|b| b.revenue_cents).max().unwrap_or(1).max(1);

            let bars: Vec<Bar> = data
                .buckets
                .iter()
                .map(|b| {
                    Bar::default()
                        .value(b.revenue_cents as u64)
                        .label(Line::from(b.label.clone()))
                        .text_value(if b.revenue_cents > 0 {
                            format::format_cents(b.revenue_cents)
                        } else {
                            String::new()
                        })
                        .style(Style::default().fg(Color::Cyan))
                })
                .collect();

            let chart = BarChart::default()
                .data(BarGroup::default().bars(&bars))
                .bar_width(
                    (chunks[1].width as usize)
                        .checked_div(bars.len().max(1))
                        .unwrap_or(3)
                        .clamp(1, 8) as u16,
                )
                .bar_gap(1)
                .max(max_val as u64);

            frame.render_widget(chart, chunks[1]);
        }
    } else {
        let empty = Paragraph::new("  No data.");
        frame.render_widget(empty, chunks[1]);
    }

    // Projects header
    let proj_header = Paragraph::new(Line::from(vec![
        Span::raw("  "),
        Span::styled("Top Projects", Style::default().add_modifier(Modifier::BOLD)),
    ]));
    frame.render_widget(proj_header, chunks[3]);

    // Top projects
    if let Some(ref data) = app.analytics_data {
        if data.top_projects.is_empty() {
            let empty = Paragraph::new("  No project revenue yet.");
            frame.render_widget(empty, chunks[4]);
        } else {
            let rows: Vec<Row> = data
                .top_projects
                .iter()
                .map(|p| {
                    Row::new(vec![
                        format!("  {}", p.title),
                        format::format_cents(p.revenue_cents),
                    ])
                })
                .collect();

            let widths = [Constraint::Min(20), Constraint::Length(12)];
            widgets::render_table(frame, chunks[4], &["  Project", "Revenue"], &widths, rows);
        }
    }
}

fn render_transactions(frame: &mut Frame, app: &App, area: ratatui::layout::Rect) {
    let chunks = Layout::vertical([
        Constraint::Length(1), // header
        Constraint::Min(3),   // table
    ])
    .split(area);

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

    if app.transactions.is_empty() {
        let empty = Paragraph::new("  No transactions.");
        frame.render_widget(empty, chunks[1]);
    } else {
        let rows: Vec<Row> = app
            .transactions
            .iter()
            .enumerate()
            .map(|(i, tx)| {
                let title = tx.item_title.as_deref().unwrap_or("--");
                let amount = format::format_cents(tx.amount_cents as i64);
                let date = tx.created_at.get(..10).unwrap_or(&tx.created_at);

                Row::new(vec![
                    format!("  {}", title),
                    amount,
                    tx.status.clone(),
                    date.to_string(),
                ])
                .style(widgets::selected_style(i, Some(app.selected_index)))
            })
            .collect();

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

        widgets::render_table(frame, chunks[1], &["  Item", "Amount", "Status", "Date"], &widths, rows);
    }
}

fn pct_change(current: i64, previous: i64) -> Option<(String, bool)> {
    if previous == 0 {
        if current > 0 {
            return Some(("+inf%".to_string(), true));
        }
        return None;
    }
    let change = ((current - previous) as f64 / previous as f64 * 100.0).round() as i64;
    if change == 0 {
        None
    } else {
        let text = if change > 0 {
            format!("+{}%", change)
        } else {
            format!("{}%", change)
        };
        Some((text, change > 0))
    }
}