use ratatui::layout::Constraint;
use ratatui::layout::Direction;
use ratatui::layout::Layout;
use ratatui::prelude::*;
use ratatui::style::Modifier;
use ratatui::style::Style;
use ratatui::style::Stylize;
use ratatui::widgets::Block;
use ratatui::widgets::BorderType;
use ratatui::widgets::Borders;
use ratatui::widgets::Clear;
use ratatui::widgets::List;
use ratatui::widgets::ListItem;
use ratatui::widgets::ListState;
use ratatui::widgets::Padding;
use ratatui::widgets::Paragraph;
use std::sync::OnceLock;

use crate::app::App;
use chrono::Local;
use chrono::Utc;
use codex_cloud_tasks_api::TaskStatus;

pub fn draw(frame: &mut Frame, app: &mut App) {
    let area = frame.area();
    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Min(1),    // list
            Constraint::Length(2), // two-line footer (help + status)
        ])
        .split(area);
    if app.new_task.is_some() {
        draw_new_task_page(frame, chunks[0], app);
        draw_footer(frame, chunks[1], app);
    } else {
        draw_list(frame, chunks[0], app);
        draw_footer(frame, chunks[1], app);
    }

    if app.diff_overlay.is_some() {
        draw_diff_overlay(frame, area, app);
    }
    if app.env_modal.is_some() {
        draw_env_modal(frame, area, app);
    }
}

// ===== Overlay helpers (geometry + styling) =====
static ROUNDED: OnceLock<bool> = OnceLock::new();

fn rounded_enabled() -> bool {
    *ROUNDED.get_or_init(|| {
        std::env::var("CODEX_TUI_ROUNDED")
            .ok()
            .map(|v| v == "1")
            .unwrap_or(true)
    })
}

fn overlay_outer(area: Rect) -> Rect {
    let outer_v = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Percentage(10),
            Constraint::Percentage(80),
            Constraint::Percentage(10),
        ])
        .split(area)[1];
    Layout::default()
        .direction(Direction::Horizontal)
        .constraints([
            Constraint::Percentage(10),
            Constraint::Percentage(80),
            Constraint::Percentage(10),
        ])
        .split(outer_v)[1]
}

fn overlay_block() -> Block<'static> {
    let base = Block::default().borders(Borders::ALL);
    let base = if rounded_enabled() {
        base.border_type(BorderType::Rounded)
    } else {
        base
    };
    base.padding(Padding::new(2, 2, 1, 1))
}

fn overlay_content(area: Rect) -> Rect {
    overlay_block().inner(area)
}

pub fn draw_new_task_page(frame: &mut Frame, area: Rect, app: &mut App) {
    use ratatui::widgets::Wrap;

    let title_spans = {
        let mut spans: Vec<ratatui::text::Span> = vec!["New Task".magenta().bold()];
        if let Some(id) = app
            .new_task
            .as_ref()
            .and_then(|p| p.env_id.as_ref())
            .cloned()
        {
            spans.push("  • ".into());
            // Try to map id to label
            let label = app
                .environments
                .iter()
                .find(|r| r.id == id)
                .and_then(|r| r.label.clone())
                .unwrap_or(id);
            spans.push(label.dim());
        } else {
            spans.push("  • ".into());
            spans.push("Env: none (press ctrl-o to choose)".red());
        }
        spans
    };
    let block = Block::default()
        .borders(Borders::ALL)
        .title(Line::from(title_spans));

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

    // Clamp composer height between 3 and 6 rows for readability.
    let desired = app
        .new_task
        .as_ref()
        .map(|p| p.composer.desired_height(content.width))
        .unwrap_or(3)
        .clamp(3, 6);

    // Anchor the composer to the bottom-left by allocating a flexible spacer
    // above it and a fixed `desired`-height area for the composer.
    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Min(1), Constraint::Length(desired)])
        .split(content);
    let composer_area = rows[1];

    if let Some(page) = app.new_task.as_ref() {
        page.composer.render_ref(composer_area, frame.buffer_mut());
        // Composer renders its own footer hints; no extra row here.
    }

    // Place cursor where composer wants it
    if let Some(page) = app.new_task.as_ref() {
        if let Some((x, y)) = page.composer.cursor_pos(composer_area) {
            frame.set_cursor(x, y);
        }
    }
}

fn draw_list(frame: &mut Frame, area: Rect, app: &mut App) {
    let items: Vec<ListItem> = app.tasks.iter().map(|t| render_task_item(app, t)).collect();

    // Selection reflects the actual task index (no artificial spacer item).
    let mut state = ListState::default().with_selected(Some(app.selected));
    // Dim task list when a modal/overlay is active to emphasize focus.
    let dim_bg = app.env_modal.is_some() || app.diff_overlay.is_some();
    // Dynamic title includes current environment filter
    let suffix_span = if let Some(ref id) = app.env_filter {
        let label = app
            .environments
            .iter()
            .find(|r| &r.id == id)
            .and_then(|r| r.label.clone())
            .unwrap_or_else(|| "Selected".to_string());
        format!(" • {}", label).dim()
    } else {
        " • All".dim()
    };
    // Percent scrolled based on selection position in the list (0% at top, 100% at bottom).
    let percent_span = if app.tasks.len() <= 1 {
        "  • 0%".dim()
    } else {
        let p = ((app.selected as f32) / ((app.tasks.len() - 1) as f32) * 100.0).round() as i32;
        format!("  • {}%", p.clamp(0, 100)).dim()
    };
    let title_line = {
        let base = Line::from(vec!["Cloud Tasks".into(), suffix_span, percent_span]);
        if dim_bg {
            base.style(Style::default().add_modifier(Modifier::DIM))
        } else {
            base
        }
    };
    let block = Block::default().borders(Borders::ALL).title(title_line);
    // Render the outer block first
    frame.render_widget(block.clone(), area);
    // Draw list inside with a persistent top spacer row
    let inner = block.inner(area);
    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Length(1), Constraint::Min(1)])
        .split(inner);
    let mut list = List::new(items)
        .highlight_symbol("› ")
        .highlight_style(Style::default().bold());
    if dim_bg {
        list = list.style(Style::default().add_modifier(Modifier::DIM));
    }
    frame.render_stateful_widget(list, rows[1], &mut state);

    // In-box spinner during initial/refresh loads
    if app.refresh_inflight {
        draw_centered_spinner(frame, inner, &mut app.throbber, "Loading tasks…");
    }
}

fn draw_footer(frame: &mut Frame, area: Rect, app: &mut App) {
    let mut help = vec![
        "↑/↓".dim(),
        ": Move  ".dim(),
        "r".dim(),
        ": Refresh  ".dim(),
        "Enter".dim(),
        ": Open  ".dim(),
    ];
    // Apply hint; show disabled note when overlay is open without a diff.
    if let Some(ov) = app.diff_overlay.as_ref() {
        if !ov.can_apply {
            help.push("a".dim());
            help.push(": Apply (disabled)  ".dim());
        } else {
            help.push("a".dim());
            help.push(": Apply  ".dim());
        }
    } else {
        help.push("a".dim());
        help.push(": Apply  ".dim());
    }
    help.push("o : Set Env  ".dim());
    if app.new_task.is_some() {
        help.push("(editing new task)  ".dim());
    } else {
        help.push("n : New Task  ".dim());
    }
    help.extend(vec!["q".dim(), ": Quit  ".dim()]);
    // Split footer area into two rows: help+spinner (top) and status (bottom)
    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Length(1), Constraint::Length(1)])
        .split(area);

    // Top row: help text + spinner at right
    let top = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([Constraint::Fill(1), Constraint::Length(18)])
        .split(rows[0]);
    let para = Paragraph::new(Line::from(help));
    // Draw help text; avoid clearing the whole footer area every frame.
    frame.render_widget(para, top[0]);
    // Right side: spinner or clear the spinner area if idle to prevent stale glyphs.
    if app.refresh_inflight || app.details_inflight || app.env_loading {
        draw_inline_spinner(frame, top[1], &mut app.throbber, "Loading…");
    } else {
        frame.render_widget(Clear, top[1]);
    }

    // Bottom row: status/log text across full width (single-line; sanitize newlines)
    let mut status_line = app.status.replace('\n', " ");
    if status_line.len() > 2000 {
        // hard cap to avoid TUI noise
        status_line.truncate(2000);
        status_line.push_str("…");
    }
    // Clear the status row to avoid trailing characters when the message shrinks.
    frame.render_widget(Clear, rows[1]);
    let status = Paragraph::new(status_line);
    frame.render_widget(status, rows[1]);
}

fn draw_diff_overlay(frame: &mut Frame, area: Rect, app: &mut App) {
    // Centered overlay rect (deduped geometry) and padded content via helpers.
    let inner = overlay_outer(area);

    if app.diff_overlay.is_none() {
        return;
    }
    let is_error = if let Some(overlay) = app.diff_overlay.as_ref() {
        !overlay.can_apply
            && overlay
                .sd
                .wrapped_lines()
                .first()
                .map(|s| s.trim_start().starts_with("Task failed:"))
                .unwrap_or(false)
    } else {
        false
    };
    let can_apply = app
        .diff_overlay
        .as_ref()
        .map(|o| o.can_apply)
        .unwrap_or(false);
    let title = app
        .diff_overlay
        .as_ref()
        .map(|o| o.title.clone())
        .unwrap_or_default();
    // Ensure ScrollableDiff knows geometry using padded content area.
    let content_area = overlay_content(inner);
    if let Some(ov) = app.diff_overlay.as_mut() {
        ov.sd.set_width(content_area.width);
        ov.sd.set_viewport(content_area.height);
    }

    // Optional percent scrolled label
    let pct_opt = app
        .diff_overlay
        .as_ref()
        .and_then(|o| o.sd.percent_scrolled());
    let mut title_spans: Vec<ratatui::text::Span> = if is_error {
        vec![
            "Details ".magenta(),
            "[FAILED]".red().bold(),
            " ".into(),
            title.clone().magenta(),
        ]
    } else if can_apply {
        vec!["Diff: ".magenta(), title.clone().magenta()]
    } else {
        vec!["Details: ".magenta(), title.clone().magenta()]
    };
    if let Some(p) = pct_opt {
        title_spans.push("  • ".dim());
        title_spans.push(format!("{}%", p).dim());
    }
    let block = overlay_block().title(Line::from(title_spans));
    frame.render_widget(Clear, inner);
    frame.render_widget(block.clone(), inner);

    let styled_lines: Vec<Line<'static>> = if can_apply {
        let raw = app.diff_overlay.as_ref().map(|o| o.sd.wrapped_lines());
        raw.unwrap_or(&[])
            .iter()
            .map(|l| style_diff_line(l))
            .collect()
    } else {
        // Basic markdown styling for assistant messages
        let mut in_code = false;
        let raw = app.diff_overlay.as_ref().map(|o| o.sd.wrapped_lines());
        raw.unwrap_or(&[])
            .iter()
            .map(|raw| {
                if raw.trim_start().starts_with("```") {
                    in_code = !in_code;
                    return Line::from(raw.to_string().cyan());
                }
                if in_code {
                    return Line::from(raw.to_string().cyan());
                }
                let s = raw.trim_start();
                if s.starts_with("### ") || s.starts_with("## ") || s.starts_with("# ") {
                    return Line::from(raw.to_string().magenta().bold());
                }
                if s.starts_with("- ") || s.starts_with("* ") {
                    let rest = &s[2..];
                    return Line::from(vec!["• ".into(), rest.to_string().into()]);
                }
                Line::from(raw.to_string())
            })
            .collect()
    };
    let raw_empty = app
        .diff_overlay
        .as_ref()
        .map(|o| o.sd.wrapped_lines().is_empty())
        .unwrap_or(true);
    if app.details_inflight && raw_empty {
        // Show a centered spinner while loading details
        draw_centered_spinner(frame, content_area, &mut app.throbber, "Loading details…");
    } else {
        // We pre-wrapped lines in ScrollableDiff; do not enable Paragraph-level wrapping here.
        let scroll = app
            .diff_overlay
            .as_ref()
            .map(|o| o.sd.state.scroll)
            .unwrap_or(0);
        let content = Paragraph::new(Text::from(styled_lines)).scroll((scroll, 0));
        frame.render_widget(content, content_area);
    }
}

fn style_diff_line(raw: &str) -> Line<'static> {
    use ratatui::style::Color;
    use ratatui::style::Modifier;
    use ratatui::style::Style;
    use ratatui::text::Span;

    if raw.starts_with("@@") {
        return Line::from(vec![Span::styled(
            raw.to_string(),
            Style::default()
                .fg(Color::Magenta)
                .add_modifier(Modifier::BOLD),
        )]);
    }
    if raw.starts_with("+++") || raw.starts_with("---") {
        return Line::from(vec![Span::styled(
            raw.to_string(),
            Style::default().add_modifier(Modifier::DIM),
        )]);
    }
    if raw.starts_with('+') {
        return Line::from(vec![Span::styled(
            raw.to_string(),
            Style::default().fg(Color::Green),
        )]);
    }
    if raw.starts_with('-') {
        return Line::from(vec![Span::styled(
            raw.to_string(),
            Style::default().fg(Color::Red),
        )]);
    }
    Line::from(vec![Span::raw(raw.to_string())])
}

fn render_task_item(app: &App, t: &codex_cloud_tasks_api::TaskSummary) -> ListItem<'static> {
    let status = match t.status {
        TaskStatus::Ready => "READY".green(),
        TaskStatus::Pending => "PENDING".magenta(),
        TaskStatus::Applied => "APPLIED".blue(),
        TaskStatus::Error => "ERROR".red(),
    };

    // Title line: [STATUS] Title
    let title = Line::from(vec![
        "[".into(),
        status,
        "] ".into(),
        t.title.clone().into(),
    ]);

    // Meta line: environment label and relative time (dim)
    let mut meta: Vec<ratatui::text::Span> = Vec::new();
    if let Some(lbl) = t.environment_label.as_ref().filter(|s| !s.is_empty()) {
        meta.push(lbl.clone().dim());
    }
    let when = format_relative_time(t.updated_at).dim();
    if !meta.is_empty() {
        meta.push("  ".into());
        meta.push("•".dim());
        meta.push("  ".into());
    }
    meta.push(when);
    let meta_line = Line::from(meta);

    // Subline: summary when present; otherwise show "no diff"
    let sub = if t.summary.files_changed > 0
        || t.summary.lines_added > 0
        || t.summary.lines_removed > 0
    {
        let adds = t.summary.lines_added;
        let dels = t.summary.lines_removed;
        let files = t.summary.files_changed;
        Line::from(vec![
            format!("+{}", adds).green(),
            "/".into(),
            format!("−{}", dels).red(),
            " ".into(),
            "•".dim(),
            " ".into(),
            format!("{}", files).into(),
            " ".into(),
            "files".dim(),
        ])
    } else {
        Line::from("no diff".to_string().dim())
    };

    // Insert a blank spacer line after the summary to separate tasks
    let spacer = Line::from("");
    ListItem::new(vec![title, meta_line, sub, spacer])
}

fn format_relative_time(ts: chrono::DateTime<Utc>) -> String {
    let now = Utc::now();
    let mut secs = (now - ts).num_seconds();
    if secs < 0 {
        secs = 0;
    }
    if secs < 60 {
        return format!("{}s ago", secs);
    }
    let mins = secs / 60;
    if mins < 60 {
        return format!("{}m ago", mins);
    }
    let hours = mins / 60;
    if hours < 24 {
        return format!("{}h ago", hours);
    }
    let local = ts.with_timezone(&Local);
    local.format("%b %e %H:%M").to_string()
}

fn draw_inline_spinner(
    frame: &mut Frame,
    area: Rect,
    state: &mut throbber_widgets_tui::ThrobberState,
    label: &str,
) {
    use ratatui::style::Style;
    use throbber_widgets_tui::BRAILLE_EIGHT;
    use throbber_widgets_tui::Throbber;
    use throbber_widgets_tui::WhichUse;
    let w = Throbber::default()
        .label(label)
        .style(Style::default().cyan())
        .throbber_style(Style::default().magenta().bold())
        .throbber_set(BRAILLE_EIGHT)
        .use_type(WhichUse::Spin);
    frame.render_stateful_widget(w, area, state);
}

fn draw_centered_spinner(
    frame: &mut Frame,
    area: Rect,
    state: &mut throbber_widgets_tui::ThrobberState,
    label: &str,
) {
    // Center a 1xN throbber within the given rect
    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Percentage(50),
            Constraint::Length(1),
            Constraint::Percentage(49),
        ])
        .split(area);
    let cols = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([
            Constraint::Percentage(50),
            Constraint::Length(18),
            Constraint::Percentage(50),
        ])
        .split(rows[1]);
    draw_inline_spinner(frame, cols[1], state, label);
}

fn style_diff_fragment(src_line: &str, fragment: &str) -> Line<'static> {
    if src_line.starts_with("@@") {
        return Line::from(fragment.to_string().magenta().bold());
    }
    if src_line.starts_with("diff --git ") || src_line.starts_with("index ") {
        return Line::from(fragment.to_string().dim());
    }
    if src_line.starts_with("+++") || src_line.starts_with("---") {
        return Line::from(fragment.to_string().dim());
    }
    match src_line.as_bytes().first().copied() {
        Some(b'+') => Line::from(fragment.to_string().green()),
        Some(b'-') => Line::from(fragment.to_string().red()),
        _ => Line::from(fragment.to_string()),
    }
}

pub fn draw_env_modal(frame: &mut Frame, area: Rect, app: &mut App) {
    use ratatui::widgets::Wrap;

    // Use shared overlay geometry and padding.
    let inner = overlay_outer(area);

    // Title: primary only; move long hints to a subheader inside content.
    let title = Line::from(vec!["Select Environment".magenta().bold()]);
    let block = overlay_block().title(title);

    frame.render_widget(Clear, inner);
    frame.render_widget(block.clone(), inner);
    let content = overlay_content(inner);

    if app.env_loading {
        draw_centered_spinner(frame, content, &mut app.throbber, "Loading environments…");
        return;
    }

    // Layout: subheader + search + results list
    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(1), // subheader
            Constraint::Length(1), // search
            Constraint::Min(1),    // list
        ])
        .split(content);

    // Subheader with usage hints (dim cyan)
    let subheader = Paragraph::new(Line::from(
        "Type to search, Enter select, Esc cancel; r refresh"
            .cyan()
            .dim(),
    ))
    .wrap(Wrap { trim: true });
    frame.render_widget(subheader, rows[0]);

    let query = app
        .env_modal
        .as_ref()
        .map(|m| m.query.clone())
        .unwrap_or_default();
    let ql = query.to_lowercase();
    let search = Paragraph::new(format!("Search: {}", query)).wrap(Wrap { trim: true });
    frame.render_widget(search, rows[1]);

    // Filter environments by query (case-insensitive substring over label/id/hints)
    let envs: Vec<&crate::app::EnvironmentRow> = app
        .environments
        .iter()
        .filter(|e| {
            if ql.is_empty() {
                return true;
            }
            let mut hay = String::new();
            if let Some(l) = &e.label {
                hay.push_str(&l.to_lowercase());
                hay.push(' ');
            }
            hay.push_str(&e.id.to_lowercase());
            if let Some(h) = &e.repo_hints {
                hay.push(' ');
                hay.push_str(&h.to_lowercase());
            }
            hay.contains(&ql)
        })
        .collect();

    let mut items: Vec<ListItem> = Vec::new();
    items.push(ListItem::new(Line::from("All Environments (Global)")));
    for env in envs.iter() {
        let primary = env.label.clone().unwrap_or_else(|| "<unnamed>".to_string());
        let mut spans: Vec<ratatui::text::Span> = vec![primary.into()];
        if env.is_pinned {
            spans.push("  ".into());
            spans.push("PINNED".magenta().bold());
        }
        spans.push("  ".into());
        spans.push(env.id.clone().dim());
        if let Some(hint) = &env.repo_hints {
            spans.push("  ".into());
            spans.push(hint.clone().dim());
        }
        items.push(ListItem::new(Line::from(spans)));
    }

    let sel_desired = app.env_modal.as_ref().map(|m| m.selected).unwrap_or(0);
    let sel = sel_desired.min(envs.len());
    let mut list_state = ListState::default().with_selected(Some(sel));
    let list = List::new(items)
        .highlight_symbol("› ")
        .highlight_style(Style::default().bold())
        .block(Block::default().borders(Borders::NONE));
    frame.render_stateful_widget(list, rows[2], &mut list_state);
}