outlay/outlay-gtk/src/charts_view.rs

use adw::prelude::*;
use chrono::{Datelike, Local};
use gtk::glib;
use outlay_core::db::Database;
use outlay_core::models::TransactionType;
use plotters::prelude::*;
use std::cell::Cell;
use std::rc::Rc;

const CHART_WIDTH: u32 = 560;
const CHART_HEIGHT: u32 = 340;

pub struct ChartsView {
    pub container: gtk::Box,
}

impl ChartsView {
    pub fn new(db: Rc<Database>) -> Self {
        let container = gtk::Box::new(gtk::Orientation::Vertical, 0);

        let clamp = adw::Clamp::new();
        clamp.set_maximum_size(700);
        clamp.set_margin_start(12);
        clamp.set_margin_end(12);

        let inner = gtk::Box::new(gtk::Orientation::Vertical, 16);
        inner.set_margin_top(16);
        inner.set_margin_bottom(16);

        let today = Local::now().date_naive();
        let current_year = Rc::new(Cell::new(today.year()));
        let current_month = Rc::new(Cell::new(today.month()));

        // Month navigation
        let nav_box = gtk::Box::new(gtk::Orientation::Horizontal, 8);
        nav_box.set_halign(gtk::Align::Center);

        let prev_btn = gtk::Button::from_icon_name("go-previous-symbolic");
        prev_btn.add_css_class("flat");

        let month_label = gtk::Label::new(None);
        month_label.add_css_class("title-3");
        month_label.set_width_chars(16);
        month_label.set_xalign(0.5);

        let next_btn = gtk::Button::from_icon_name("go-next-symbolic");
        next_btn.add_css_class("flat");

        nav_box.append(&prev_btn);
        nav_box.append(&month_label);
        nav_box.append(&next_btn);

        // Chart containers
        let pie_frame = gtk::Frame::new(Some("Expenses by Category"));
        let pie_picture = gtk::Picture::new();
        pie_frame.set_child(Some(&pie_picture));

        let bar_frame = gtk::Frame::new(Some("Monthly Income vs Expenses"));
        let bar_picture = gtk::Picture::new();
        bar_frame.set_child(Some(&bar_picture));

        let line_frame = gtk::Frame::new(Some("Daily Net Trend"));
        let line_picture = gtk::Picture::new();
        line_frame.set_child(Some(&line_picture));

        // Initial render
        Self::update_month_label(&month_label, current_year.get(), current_month.get());
        Self::render_all(&db, &pie_picture, &bar_picture, &line_picture, current_year.get(), current_month.get());

        // Navigation
        {
            let db_ref = db.clone();
            let year_ref = current_year.clone();
            let month_ref = current_month.clone();
            let label_ref = month_label.clone();
            let pie_ref = pie_picture.clone();
            let bar_ref = bar_picture.clone();
            let line_ref = line_picture.clone();
            prev_btn.connect_clicked(move |_| {
                let mut y = year_ref.get();
                let mut m = month_ref.get();
                if m == 1 { m = 12; y -= 1; } else { m -= 1; }
                year_ref.set(y);
                month_ref.set(m);
                Self::update_month_label(&label_ref, y, m);
                Self::render_all(&db_ref, &pie_ref, &bar_ref, &line_ref, y, m);
            });
        }
        {
            let db_ref = db.clone();
            let year_ref = current_year.clone();
            let month_ref = current_month.clone();
            let label_ref = month_label.clone();
            let pie_ref = pie_picture.clone();
            let bar_ref = bar_picture.clone();
            let line_ref = line_picture.clone();
            next_btn.connect_clicked(move |_| {
                let mut y = year_ref.get();
                let mut m = month_ref.get();
                if m == 12 { m = 1; y += 1; } else { m += 1; }
                year_ref.set(y);
                month_ref.set(m);
                Self::update_month_label(&label_ref, y, m);
                Self::render_all(&db_ref, &pie_ref, &bar_ref, &line_ref, y, m);
            });
        }

        inner.append(&nav_box);
        inner.append(&pie_frame);
        inner.append(&bar_frame);
        inner.append(&line_frame);

        clamp.set_child(Some(&inner));

        let scroll = gtk::ScrolledWindow::builder()
            .hscrollbar_policy(gtk::PolicyType::Never)
            .vexpand(true)
            .child(&clamp)
            .build();

        container.append(&scroll);

        ChartsView { container }
    }

    fn update_month_label(label: &gtk::Label, year: i32, month: u32) {
        let month_name = match month {
            1 => "January", 2 => "February", 3 => "March",
            4 => "April", 5 => "May", 6 => "June",
            7 => "July", 8 => "August", 9 => "September",
            10 => "October", 11 => "November", 12 => "December",
            _ => "Unknown",
        };
        label.set_label(&format!("{} {}", month_name, year));
    }

    fn render_all(
        db: &Database,
        pie_picture: &gtk::Picture,
        bar_picture: &gtk::Picture,
        line_picture: &gtk::Picture,
        year: i32,
        month: u32,
    ) {
        Self::render_pie_chart(db, pie_picture, year, month);
        Self::render_bar_chart(db, bar_picture, year, month);
        Self::render_line_chart(db, line_picture, year, month);
    }

    fn set_picture_from_rgb(picture: &gtk::Picture, rgb_data: &[u8], width: u32, height: u32) {
        let bytes = glib::Bytes::from(rgb_data);
        let stride = (width * 3) as usize;
        let texture = gdk::MemoryTexture::new(
            width as i32,
            height as i32,
            gdk::MemoryFormat::R8g8b8,
            &bytes,
            stride,
        );
        picture.set_paintable(Some(&texture));
    }

    fn render_pie_chart(db: &Database, picture: &gtk::Picture, year: i32, month: u32) {
        let data = db
            .get_monthly_totals_by_category(year, month, TransactionType::Expense)
            .unwrap_or_default();

        let mut buf = vec![0u8; (CHART_WIDTH * CHART_HEIGHT * 3) as usize];
        {
            let root = BitMapBackend::with_buffer(&mut buf, (CHART_WIDTH, CHART_HEIGHT))
                .into_drawing_area();
            root.fill(&WHITE).ok();

            if data.is_empty() {
                root.draw_text(
                    "No expense data this month",
                    &("sans-serif", 16).into_text_style(&root),
                    (CHART_WIDTH as i32 / 2 - 100, CHART_HEIGHT as i32 / 2),
                ).ok();
            } else {
                let total: f64 = data.iter().map(|(_, v)| *v).sum();

                // Simple pie chart using plotters primitives
                let center = ((CHART_WIDTH / 2) as i32, (CHART_HEIGHT / 2 - 20) as i32);
                let radius = 120i32;

                let colors = [
                    RGBColor(231, 76, 60),   // red
                    RGBColor(52, 152, 219),  // blue
                    RGBColor(46, 204, 113),  // green
                    RGBColor(155, 89, 182),  // purple
                    RGBColor(241, 196, 15),  // yellow
                    RGBColor(230, 126, 34),  // orange
                    RGBColor(26, 188, 156),  // teal
                    RGBColor(233, 30, 99),   // pink
                    RGBColor(0, 188, 212),   // cyan
                    RGBColor(121, 85, 72),   // brown
                    RGBColor(96, 125, 139),  // grey-blue
                    RGBColor(255, 87, 34),   // deep orange
                    RGBColor(63, 81, 181),   // indigo
                    RGBColor(0, 150, 136),   // dark teal
                ];

                let mut start_angle = 0.0_f64;
                for (i, (cat, amount)) in data.iter().enumerate() {
                    let pct = amount / total;
                    let sweep = pct * 360.0;
                    let color = &colors[i % colors.len()];

                    // Draw pie slice as filled polygon approximation
                    let steps = (sweep as usize).max(4);
                    for step in 0..steps {
                        let a1 = (start_angle + (step as f64 / steps as f64) * sweep).to_radians();
                        let a2 = (start_angle + ((step + 1) as f64 / steps as f64) * sweep).to_radians();
                        let p1 = (
                            center.0 + (radius as f64 * a1.cos()) as i32,
                            center.1 - (radius as f64 * a1.sin()) as i32,
                        );
                        let p2 = (
                            center.0 + (radius as f64 * a2.cos()) as i32,
                            center.1 - (radius as f64 * a2.sin()) as i32,
                        );
                        root.draw(&plotters::element::Polygon::new(
                            vec![center, p1, p2],
                            color.filled(),
                        )).ok();
                    }

                    // Label
                    if pct > 0.03 {
                        let mid_angle = (start_angle + sweep / 2.0).to_radians();
                        let label_r = radius as f64 + 30.0;
                        let lx = center.0 + (label_r * mid_angle.cos()) as i32;
                        let ly = center.1 - (label_r * mid_angle.sin()) as i32;
                        let text = format!("{} {:.0}%", cat.name, pct * 100.0);
                        root.draw_text(
                            &text,
                            &("sans-serif", 11).into_text_style(&root),
                            (lx.max(5), ly.max(5)),
                        ).ok();
                    }

                    start_angle += sweep;
                }
            }

            root.present().ok();
        }

        // Encode to PNG
        Self::set_picture_from_rgb(picture, &buf, CHART_WIDTH, CHART_HEIGHT);
    }

    fn render_bar_chart(db: &Database, picture: &gtk::Picture, year: i32, month: u32) {
        // Get last 6 months of data
        let mut months: Vec<(i32, u32, f64, f64)> = Vec::new();
        let mut y = year;
        let mut m = month;
        for _ in 0..6 {
            let income = db.get_monthly_total(y, m, TransactionType::Income).unwrap_or(0.0);
            let expense = db.get_monthly_total(y, m, TransactionType::Expense).unwrap_or(0.0);
            months.push((y, m, income, expense));
            if m == 1 { m = 12; y -= 1; } else { m -= 1; }
        }
        months.reverse();

        let mut buf = vec![0u8; (CHART_WIDTH * CHART_HEIGHT * 3) as usize];
        {
            let root = BitMapBackend::with_buffer(&mut buf, (CHART_WIDTH, CHART_HEIGHT))
                .into_drawing_area();
            root.fill(&WHITE).ok();

            let max_val = months.iter().map(|(_, _, i, e)| i.max(*e)).fold(0.0_f64, f64::max);
            let y_max = if max_val > 0.0 { max_val * 1.2 } else { 100.0 };

            let labels: Vec<String> = months
                .iter()
                .map(|(_, m, _, _)| {
                    match m {
                        1 => "Jan", 2 => "Feb", 3 => "Mar",
                        4 => "Apr", 5 => "May", 6 => "Jun",
                        7 => "Jul", 8 => "Aug", 9 => "Sep",
                        10 => "Oct", 11 => "Nov", 12 => "Dec",
                        _ => "?",
                    }.to_string()
                })
                .collect();

            let mut chart = ChartBuilder::on(&root)
                .margin(15)
                .x_label_area_size(30)
                .y_label_area_size(60)
                .build_cartesian_2d(0..6i32, 0.0..y_max)
                .unwrap();

            chart.configure_mesh()
                .x_labels(6)
                .x_label_formatter(&|x| {
                    labels.get(*x as usize).cloned().unwrap_or_default()
                })
                .y_label_formatter(&|y| format!("{:.0}", y))
                .draw()
                .ok();

            // Income bars (green)
            chart.draw_series(
                months.iter().enumerate().map(|(i, (_, _, income, _))| {
                    let x0 = i as i32;
                    Rectangle::new(
                        [(x0, 0.0), (x0, *income)],
                        RGBColor(46, 204, 113).filled(),
                    )
                })
            ).ok();

            root.present().ok();
        }

        Self::set_picture_from_rgb(picture, &buf, CHART_WIDTH, CHART_HEIGHT);
    }

    fn render_line_chart(db: &Database, picture: &gtk::Picture, year: i32, month: u32) {
        let daily = db.get_daily_totals(year, month).unwrap_or_default();

        let mut buf = vec![0u8; (CHART_WIDTH * CHART_HEIGHT * 3) as usize];
        {
            let root = BitMapBackend::with_buffer(&mut buf, (CHART_WIDTH, CHART_HEIGHT))
                .into_drawing_area();
            root.fill(&WHITE).ok();

            if daily.is_empty() {
                root.draw_text(
                    "No data this month",
                    &("sans-serif", 16).into_text_style(&root),
                    (CHART_WIDTH as i32 / 2 - 60, CHART_HEIGHT as i32 / 2),
                ).ok();
            } else {
                // Sort by date ascending
                let mut sorted = daily.clone();
                sorted.sort_by_key(|(d, _, _)| *d);

                // Build cumulative net
                let mut cumulative: Vec<(i32, f64)> = Vec::new();
                let mut running = 0.0_f64;
                for (date, income, expense) in &sorted {
                    running += income - expense;
                    cumulative.push((date.day() as i32, running));
                }

                let days_in_month = Self::days_in_month(year, month);
                let min_val = cumulative.iter().map(|(_, v)| *v).fold(f64::INFINITY, f64::min);
                let max_val = cumulative.iter().map(|(_, v)| *v).fold(f64::NEG_INFINITY, f64::max);
                let margin = (max_val - min_val).max(10.0) * 0.1;

                let mut chart = ChartBuilder::on(&root)
                    .margin(15)
                    .x_label_area_size(30)
                    .y_label_area_size(60)
                    .build_cartesian_2d(1..days_in_month as i32 + 1, (min_val - margin)..(max_val + margin))
                    .unwrap();

                chart.configure_mesh()
                    .x_label_formatter(&|x| format!("{}", x))
                    .y_label_formatter(&|y| format!("{:.0}", y))
                    .draw()
                    .ok();

                chart.draw_series(LineSeries::new(
                    cumulative.iter().map(|(d, v)| (*d, *v)),
                    &RGBColor(52, 152, 219),
                )).ok();

                // Zero line
                chart.draw_series(LineSeries::new(
                    vec![(1, 0.0), (days_in_month as i32, 0.0)],
                    &RGBColor(200, 200, 200),
                )).ok();
            }

            root.present().ok();
        }

        Self::set_picture_from_rgb(picture, &buf, CHART_WIDTH, CHART_HEIGHT);
    }

    fn days_in_month(year: i32, month: u32) -> u32 {
        match month {
            1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
            4 | 6 | 9 | 11 => 30,
            2 => {
                if (year % 4 == 0 && year % 100 != 0) || year % 400 == 0 {
                    29
                } else {
                    28
                }
            }
            _ => 30,
        }
    }

}