use ratatui::{
    layout::{Alignment, Constraint, Direction, Layout, Rect},
    style::{Color, Modifier, Style},
    text::{Line, Span},
    widgets::{Block, Borders, Clear, List, ListItem, Paragraph},
    Frame,
};

use crate::{
    app::{App, LogViewDayOrder, LogViewGrouping, LogViewPeriod, LogViewSelection, NewEntryMode, Screen},
    state::{AppState, TimeItem},
};

const ACTIVE_COLOR: Color = Color::Green;
const INACTIVE_COLOR: Color = Color::Yellow;

pub fn render(frame: &mut Frame, app: &App) {
    match app.current_screen {
        Screen::Main => render_main(frame, app),
        Screen::Help => render_help(frame, app),
        Screen::ConfigHelp => render_config_help(frame, app),
        Screen::NewEntry => render_new_entry(frame, app),
        Screen::ReassignProject => render_reassign_project(frame, app),
        Screen::LogView => render_log_view(frame, app),
        Screen::LogViewHelp => render_log_view_help(frame, app),
    }
}

fn render_main(frame: &mut Frame, app: &App) {
    // Calculate layout - accounting for bottom bar if needed
    let show_bottom_bar = app.config.show_help_hint;
    let has_status = app.status_message.is_some();
    let bottom_height = if show_bottom_bar {
        if has_status {
            2
        } else {
            1
        }
    } else {
        if has_status {
            1
        } else {
            0
        }
    };

    let constraints = if bottom_height > 0 {
        vec![
            Constraint::Min(3), // At least 3 lines for each section
            Constraint::Min(3),
            Constraint::Min(3),
            Constraint::Length(bottom_height), // Command bar + optional status
        ]
    } else {
        vec![Constraint::Min(3), Constraint::Min(3), Constraint::Min(3)]
    };

    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints(constraints)
        .split(frame.size());

    let main_height = if bottom_height > 0 {
        chunks[0].height + chunks[1].height + chunks[2].height
    } else {
        frame.size().height
    };

    let section_height = main_height / 3;

    // Create sections with equal height
    let sections = vec![
        Rect::new(0, 0, frame.size().width, section_height),
        Rect::new(0, section_height, frame.size().width, section_height),
        Rect::new(0, section_height * 2, frame.size().width, section_height),
    ];

    // Render main sections
    render_section(
        frame,
        sections[0],
        "Permanent Items",
        &app.state.permanent_items,
        app.state.current_pane == 0,
        app.state.selected_indices[0],
        &app.state,
    );

    render_section(
        frame,
        sections[1],
        "Recurring Items",
        &app.state.recurring_items,
        app.state.current_pane == 1,
        app.state.selected_indices[1],
        &app.state,
    );

    render_section(
        frame,
        sections[2],
        "Ad-Hoc Items",
        &app.state.recent_items,
        app.state.current_pane == 2,
        app.state.selected_indices[2],
        &app.state,
    );

    // Render bottom bar if needed
    if bottom_height > 0 {
        let bottom_area = chunks[3];
        render_bottom_bar(frame, bottom_area, app);
    }
}

fn render_new_entry(frame: &mut Frame, app: &App) {
    let area = centered_rect(60, 6, frame.size());
    frame.render_widget(Clear, area);

    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Length(3), Constraint::Length(3)])
        .split(area);

    // Tag input (first)
    let tag_block = Block::default()
        .title("Tag")
        .borders(Borders::ALL)
        .style(
            Style::default().fg(if matches!(app.new_entry_mode, NewEntryMode::Task) {
                ACTIVE_COLOR
            } else {
                Color::White
            }),
        );

    let tag_text = Paragraph::new(app.new_entry_project.as_str()).block(tag_block);

    frame.render_widget(tag_text, chunks[0]);

    // Project input (second)
    let project_block = Block::default()
        .title("Project")
        .borders(Borders::ALL)
        .style(
            Style::default().fg(if matches!(app.new_entry_mode, NewEntryMode::Project) {
                ACTIVE_COLOR
            } else {
                Color::White
            }),
        );

    let project_text = Paragraph::new(app.new_entry_buffer.as_str()).block(project_block);

    frame.render_widget(project_text, chunks[1]);

    // Render command bar
    let bar_area = Rect::new(0, frame.size().height - 1, frame.size().width, 1);

    let command_text = match app.new_entry_mode {
        NewEntryMode::Task => "Enter tag, press Enter to continue",
        NewEntryMode::Project => "Enter project, press Enter to save",
    };

    let command_bar = Paragraph::new(command_text)
        .style(Style::default().fg(Color::White))
        .alignment(Alignment::Left);

    frame.render_widget(command_bar, bar_area);
}

fn render_bottom_bar(frame: &mut Frame, area: Rect, app: &App) {
    // Split the bottom bar into left (tracking indicator) and right (help/status)
    let chunks = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([Constraint::Percentage(70), Constraint::Percentage(30)])
        .split(area);

    // Left side: Tracking indicator (only when actively tracking)
    if let Some((active_item, _)) = &app.state.active_timer {
        let tracking_text = if !active_item.tags.is_empty() {
            format!("❯❯ Tracking {} [{}] ❯❯", active_item.tags.join(", "), active_item.name)
        } else {
            format!("❯❯ Tracking {} ❯❯", active_item.name)
        };

        let tracking = Paragraph::new(tracking_text)
            .alignment(Alignment::Left)
            .style(Style::default().fg(ACTIVE_COLOR).add_modifier(Modifier::BOLD));
        frame.render_widget(tracking, chunks[0]);
    }
    // No else - show nothing when not tracking

    // Right side: Status message or help hint
    if let Some((ref message, _)) = app.status_message {
        let text = Paragraph::new(message.as_str())
            .style(Style::default().fg(Color::Yellow))
            .alignment(Alignment::Right);
        frame.render_widget(text, chunks[1]);
    } else if app.config.show_help_hint {
        render_help_hint(frame, chunks[1]);
    }
}

fn render_help_hint(frame: &mut Frame, area: Rect) {
    let help_hint = Paragraph::new("(?) for help")
        .alignment(Alignment::Right)
        .style(Style::default().fg(Color::DarkGray));
    frame.render_widget(help_hint, area);
}

fn render_help_command_bar(frame: &mut Frame) {
    let commands = vec![("c", "configuration help"), ("q/ESC", "back")];

    let command_text = format!(
        "  {}",
        commands
            .iter()
            .map(|(key, desc)| format!("{} ({})", key, desc))
            .collect::<Vec<_>>()
            .join(" · ")
    );

    let bar_area = Rect::new(
        0,
        frame.size().height.saturating_sub(1),
        frame.size().width,
        1,
    );

    let command_bar = Paragraph::new(command_text)
        .style(Style::default().fg(Color::White))
        .alignment(Alignment::Left);

    frame.render_widget(command_bar, bar_area);
}

fn render_help(frame: &mut Frame, app: &App) {
    let width = frame.size().width.saturating_sub(4).min(60);
    let area = centered_rect(width, frame.size().height.saturating_sub(2), frame.size());

    frame.render_widget(Clear, area);

    let help_text = vec![
        "WAT - Watson Time Tracker Interface",
        "",
        "This tool helps you track time using Watson with a convenient interface.",
        "",
        "The interface is divided into three sections:",
        "1. Permanent Items: Configured tasks that are always available",
        "2. Recurring Items: Frequently used tasks that you might return to",
        "3. Ad-Hoc Items: One-off tasks and quick entries",
        "",
        "Navigation:",
        "- j/k or ↑/↓: Move selection up/down",
        "- h/l or ←/→: Switch between panes",
        "- Ctrl+n/Ctrl+p: Switch between panes",
        "- Enter: Start/stop time tracking for selected item",
        "- n: Create a new task in the current section",
        "",
        "Main Commands:",
        "Enter      - Start/stop timer",
        "d          - Delete task from list",
        "p          - Reassign project name",
        "v          - View Watson log",
        "Ctrl+e     - Edit tasks config file",
        "c          - Edit app config file",
        "n          - New task",
        "q          - Quit",
        "?          - Show/hide this help (ESC also works)",
        "",
        "Log View (press 'v'):",
        "Once in log view, you can:",
        "- Switch time periods: d (day), w (week), m (month)",
        "- Toggle grouping: g (by date or by project)",
        "- Toggle day order: r (newest first ↔ oldest first)",
        "- Change selection: h/l (entry → project → day → all)",
        "- Navigate: j/k to move through selections",
        "- Edit entry: e (entry level only)",
        "- Delete entry: x (entry level only)",
        "- Copy to clipboard: c (works at all levels)",
        "- Press ? for detailed log view help",
    ];

    let text = help_text.join("\n");

    let block = Block::default()
        .title("Help (j/k to scroll)")
        .borders(Borders::ALL)
        .style(Style::default().fg(Color::White));

    let paragraph = Paragraph::new(text)
        .block(block)
        .style(Style::default().fg(Color::White))
        .scroll((app.help_scroll as u16, 0))
        .wrap(ratatui::widgets::Wrap { trim: true });

    frame.render_widget(paragraph, area);
    render_help_command_bar(frame);
}

fn render_config_help(frame: &mut Frame, app: &App) {
    let width = frame.size().width.saturating_sub(4).min(60);
    let area = centered_rect(width, frame.size().height.saturating_sub(2), frame.size());

    frame.render_widget(Clear, area);

    let help_text = vec![
        "WAT Configuration",
        "",
        "Configuration file location:",
        "  ~/.config/wat/config.yaml",
        "",
        "Available options:",
        "",
        "show_help_hint: true/false",
        "  Default: true",
        "  Shows '(?) for help' hint in the bottom-right corner",
        "",
        "projects: [list of project names]",
        "  Default: [] (empty)",
        "  List of available project names shown when reassigning",
        "  Example: [\"work\", \"personal\", \"client-a\"]",
        "",
        "strict_projects: true/false",
        "  Default: false",
        "  When true, only allows projects from the 'projects' list",
        "  When false, any project name can be used",
        "",
        "Example configuration:",
        "---",
        "show_help_hint: true",
        "strict_projects: false",
        "projects:",
        "  - work",
        "  - personal",
        "  - open-source",
        "",
        "Note: The config file is created automatically on first run.",
        "Edit it with 'c' from the main screen or manually with your editor.",
    ];

    let text = help_text.join("\n");

    let block = Block::default()
        .title("Configuration Help (j/k to scroll)")
        .borders(Borders::ALL)
        .style(Style::default().fg(Color::White));

    let paragraph = Paragraph::new(text)
        .block(block)
        .style(Style::default().fg(Color::White))
        .scroll((app.help_scroll as u16, 0))
        .wrap(ratatui::widgets::Wrap { trim: true });

    frame.render_widget(paragraph, area);
    render_help_command_bar(frame);
}

fn render_section(
    frame: &mut Frame,
    area: Rect,
    title: &str,
    items: &[TimeItem],
    is_active: bool,
    selected: usize,
    _state: &AppState,
) {
    let border_color = if is_active {
        ACTIVE_COLOR
    } else {
        INACTIVE_COLOR
    };

    let block = Block::default()
        .borders(Borders::ALL)
        .title(title)
        .style(Style::default().fg(border_color));

    let items: Vec<ListItem> = items
        .iter()
        .enumerate()
        .map(|(i, item)| {
            let style = if i == selected && is_active {
                Style::default()
                    .fg(border_color)
                    .add_modifier(Modifier::REVERSED)
            } else {
                Style::default()
            };

            let line = if !item.tags.is_empty() {
                // Display as: tag [project]
                format!("{} [{}]", item.tags.join(", "), item.name)
            } else {
                // No tags, just show project
                item.name.clone()
            };

            ListItem::new(Line::from(vec![Span::styled(line, style)]))
        })
        .collect();

    let list = List::new(items).block(block);
    frame.render_widget(list, area);
}

fn centered_rect(width: u16, height: u16, r: Rect) -> Rect {
    let x = (r.width.saturating_sub(width)) / 2;
    let y = (r.height.saturating_sub(height)) / 2;

    Rect {
        x: r.x + x,
        y: r.y + y,
        width: width.min(r.width),
        height: height.min(r.height),
    }
}

fn render_reassign_project(frame: &mut Frame, app: &App) {
    let area = centered_rect(60, 5, frame.size());
    frame.render_widget(Clear, area);

    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Length(3), Constraint::Length(2)])
        .split(area);

    // Get current item to show in title
    let items = match app.state.current_pane {
        0 => &app.state.permanent_items,
        1 => &app.state.recurring_items,
        2 => &app.state.recent_items,
        _ => &app.state.permanent_items,
    };

    let current_item_display = items
        .get(app.state.selected_indices[app.state.current_pane])
        .map(|item| {
            if !item.tags.is_empty() {
                format!("{} [{}]", item.tags.join(", "), item.name)
            } else {
                item.name.clone()
            }
        })
        .unwrap_or_default();

    // Project input
    let project_block = Block::default()
        .title(format!("Reassign Project for: {}", current_item_display))
        .borders(Borders::ALL)
        .style(Style::default().fg(ACTIVE_COLOR));

    let project_text = if !app.config.projects.is_empty() {
        format!(
            "{} (available: {})",
            app.reassign_project_buffer,
            app.config.projects.join(", ")
        )
    } else {
        app.reassign_project_buffer.clone()
    };

    let project_paragraph = Paragraph::new(project_text).block(project_block);

    frame.render_widget(project_paragraph, chunks[0]);

    // Help text
    let help_text = Paragraph::new("Enter new project name, press Enter to save, Esc to cancel")
        .style(Style::default().fg(Color::DarkGray))
        .alignment(Alignment::Center);

    frame.render_widget(help_text, chunks[1]);
}

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

    // Create the main content area (leave space for command bar at bottom)
    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Min(3), Constraint::Length(1)])
        .split(area);

    let period_str = match app.log_view_period {
        LogViewPeriod::Day => "Day",
        LogViewPeriod::Week => "Week",
        LogViewPeriod::Month => "Month",
    };

    let grouping_str = match app.log_view_grouping {
        LogViewGrouping::ByDate => "by Date",
        LogViewGrouping::ByProject => "by Project",
    };

    let order_str = match app.log_view_day_order {
        LogViewDayOrder::Chronological => "↑",
        LogViewDayOrder::ReverseChronological => "↓",
    };

    let title = format!("Watson Log - {} View ({}) [{}]", period_str, grouping_str, order_str);

    let block = Block::default()
        .title(title)
        .borders(Borders::ALL)
        .style(Style::default().fg(ACTIVE_COLOR));

    // Build list items with selection highlighting based on selection level
    let items: Vec<ListItem> = {
        // Pre-calculate which line indices should be highlighted
        let mut selected_date = String::new();
        let mut selected_project = String::new();
        let mut frame_count = 0;
        let mut selected_line_start = 0;
        let mut selected_line_end = 0;

        // First pass: find the date/project containing the selected frame
        let mut current_date = String::new();
        let mut current_project = String::new();

        // Determine what counts as an entry based on grouping mode
        let is_by_project = matches!(app.log_view_grouping, LogViewGrouping::ByProject);

        for (_idx, line) in app.log_view_content.iter().enumerate() {
            if !line.starts_with('\t') && !line.is_empty() && !line.starts_with("  ") {
                current_date = line.clone();
            } else if line.starts_with("  ") && !line.starts_with("\t") {
                current_project = line.clone();
            }

            // Only count actual entries (not all tab-indented lines)
            let is_entry = if is_by_project {
                line.starts_with("\t\t")  // Double tab for ByProject
            } else {
                line.starts_with('\t') && !line.starts_with("\t\t")  // Single tab for ByDate
            };

            if is_entry {
                if frame_count == app.log_view_selected {
                    selected_date = current_date.clone();
                    selected_project = current_project.clone();
                    break;
                }
                frame_count += 1;
            }
        }

        // Second pass: determine the range of lines to highlight
        match app.log_view_selection_level {
            LogViewSelection::Entry => {
                // Just find the specific entry line
                frame_count = 0;
                for (idx, line) in app.log_view_content.iter().enumerate() {
                    let is_entry = if is_by_project {
                        line.starts_with("\t\t")
                    } else {
                        line.starts_with('\t') && !line.starts_with("\t\t")
                    };

                    if is_entry {
                        if frame_count == app.log_view_selected {
                            selected_line_start = idx;
                            selected_line_end = idx;
                            break;
                        }
                        frame_count += 1;
                    }
                }
            }
            LogViewSelection::Project => {
                // Find the range of the selected project (within the same day)
                let mut in_target_project = false;
                current_date = String::new();

                for (idx, line) in app.log_view_content.iter().enumerate() {
                    if !line.starts_with('\t') && !line.is_empty() && !line.starts_with("  ") {
                        current_date = line.clone();
                        if in_target_project {
                            break; // End of project group
                        }
                    } else if line.starts_with("  ") && !line.starts_with("\t") {
                        if current_date == selected_date && line == &selected_project {
                            selected_line_start = idx;
                            in_target_project = true;
                        } else if in_target_project {
                            break; // Different project
                        }
                    } else if in_target_project && line.starts_with('\t') {
                        selected_line_end = idx;
                    }
                }
            }
            LogViewSelection::Day => {
                // Find the range of the selected day
                let mut in_target_day = false;

                for (idx, line) in app.log_view_content.iter().enumerate() {
                    if !line.starts_with('\t') && !line.is_empty() && !line.starts_with("  ") {
                        if line == &selected_date {
                            selected_line_start = idx;
                            in_target_day = true;
                        } else if in_target_day {
                            break; // End of day
                        }
                    } else if in_target_day && !line.is_empty() {
                        selected_line_end = idx;
                    }
                }
            }
            LogViewSelection::All => {
                // Select everything
                selected_line_start = 0;
                selected_line_end = app.log_view_content.len().saturating_sub(1);
            }
        }

        // Third pass: render with highlighting
        app.log_view_content
            .iter()
            .enumerate()
            .map(|(idx, line)| {
                let is_selected = idx >= selected_line_start && idx <= selected_line_end;

                let style = if is_selected {
                    Style::default()
                        .fg(ACTIVE_COLOR)
                        .add_modifier(Modifier::REVERSED)
                } else {
                    Style::default().fg(Color::White)
                };

                ListItem::new(Line::from(vec![Span::styled(line.clone(), style)]))
            })
            .collect()
    };

    let list = List::new(items).block(block);
    frame.render_widget(list, chunks[0]);

    // Render help hint at bottom if enabled
    if app.config.show_help_hint {
        render_help_hint(frame, chunks[1]);
    }
}

fn render_log_view_help(frame: &mut Frame, app: &App) {
    let width = frame.size().width.saturating_sub(4).min(60);
    let area = centered_rect(width, frame.size().height.saturating_sub(2), frame.size());

    frame.render_widget(Clear, area);

    let help_text = vec![
        "Watson Log Viewer Help",
        "",
        "This view displays your Watson time tracking logs with various options",
        "for viewing and managing your tracked time.",
        "",
        "Time Periods:",
        "- d: Switch to Day view (current day)",
        "- w: Switch to Week view (current week)",
        "- m: Switch to Month view (current month)",
        "",
        "Grouping:",
        "- g: Toggle between grouping by Date or by Project",
        "  - By Date: Shows all entries chronologically",
        "  - By Project: Groups entries by project within each date",
        "",
        "Day Order:",
        "- r: Toggle day order between newest first (↓) and oldest first (↑)",
        "  - Days are shown in the chosen order",
        "  - Entries within each day are always chronological (earliest to latest)",
        "",
        "Navigation:",
        "- j/k or ↑/↓: Navigate selection",
        "  - At Entry level: Move to next/previous entry",
        "  - At Project level: Jump to next/previous project group",
        "  - At Day level: Jump to next/previous day",
        "  - At All level: No navigation (entire view selected)",
        "- h/l or ←/→: Change selection level",
        "  - l (right): Zoom in (All → Day → Project → Entry)",
        "  - h (left): Zoom out (Entry → Project → Day → All)",
        "- PageUp/PageDown: Jump 10 entries (Entry level only)",
        "",
        "Selection Levels (use h/l to change):",
        "- Entry: Select individual entry (can edit/delete/copy)",
        "- Project: Select whole project group (can copy only)",
        "- Day: Select entire day (can copy only)",
        "- All: Select entire view/period (can copy only)",
        "",
        "Actions:",
        "- e: Edit the selected entry (Entry level only)",
        "- x: Delete the selected entry (Entry level only)",
        "- c: Copy selection to clipboard (works at all levels)",
        "     Copies based on current selection level",
        "",
        "Other:",
        "- ?: Show/hide this help",
        "- q or ESC: Return to main screen",
        "",
        "Tip: Use h/l to quickly select larger blocks for copying!",
    ];

    let text = help_text.join("\n");

    let block = Block::default()
        .title("Log View Help (j/k to scroll)")
        .borders(Borders::ALL)
        .style(Style::default().fg(Color::White));

    let paragraph = Paragraph::new(text)
        .block(block)
        .style(Style::default().fg(Color::White))
        .scroll((app.help_scroll as u16, 0))
        .wrap(ratatui::widgets::Wrap { trim: true });

    frame.render_widget(paragraph, area);

    // Render command bar
    let bar_area = Rect::new(
        0,
        frame.size().height.saturating_sub(1),
        frame.size().width,
        1,
    );

    let command_bar = Paragraph::new("  q/ESC/? (back to log view)")
        .style(Style::default().fg(Color::White))
        .alignment(Alignment::Left);

    frame.render_widget(command_bar, bar_area);
}