use crate::app::methods::messages::MessageMethods;
use crate::app::App;
use crate::message_grouping::{group_messages, MessageGroup};
use crate::tdlib::TdClientTrait;
use crate::ui::components;
use ratatui::{
    layout::Rect,
    style::{Color, Style},
    text::{Line, Span},
    widgets::{Block, Borders, Paragraph},
    Frame,
};

/// Информация о строке после переноса: текст и позиция в оригинале.
pub(crate) struct WrappedLine {
    pub text: String,
}

/// Разбивает текст на строки с учётом максимальной ширины.
pub(crate) fn wrap_text_with_offsets(text: &str, max_width: usize) -> Vec<WrappedLine> {
    if max_width == 0 {
        return vec![WrappedLine { text: text.to_string() }];
    }

    let mut result = Vec::new();
    let mut current_line = String::new();
    let mut current_width = 0;

    let chars: Vec<char> = text.chars().collect();
    let mut word_start = 0;
    let mut in_word = false;

    for (i, ch) in chars.iter().enumerate() {
        if ch.is_whitespace() {
            if in_word {
                let word: String = chars[word_start..i].iter().collect();
                let word_width = word.chars().count();

                if current_width == 0 {
                    current_line = word;
                    current_width = word_width;
                } else if current_width + 1 + word_width <= max_width {
                    current_line.push(' ');
                    current_line.push_str(&word);
                    current_width += 1 + word_width;
                } else {
                    result.push(WrappedLine { text: current_line });
                    current_line = word;
                    current_width = word_width;
                }
                in_word = false;
            }
        } else if !in_word {
            word_start = i;
            in_word = true;
        }
    }

    if in_word {
        let word: String = chars[word_start..].iter().collect();
        let word_width = word.chars().count();

        if current_width == 0 {
            current_line = word;
        } else if current_width + 1 + word_width <= max_width {
            current_line.push(' ');
            current_line.push_str(&word);
        } else {
            result.push(WrappedLine { text: current_line });
            current_line = word;
        }
    }

    if !current_line.is_empty() {
        result.push(WrappedLine { text: current_line });
    }

    if result.is_empty() {
        result.push(WrappedLine { text: String::new() });
    }

    result
}

/// Рендерит список сообщений с группировкой по дате/отправителю и автоскроллом.
pub(super) fn render_message_list<T: TdClientTrait>(f: &mut Frame, area: Rect, app: &mut App<T>) {
    let content_width = area.width.saturating_sub(2) as usize;
    let mut lines: Vec<Line> = Vec::new();

    let selected_msg_id = app.get_selected_message().map(|m| m.id());
    let mut selected_msg_line: Option<usize> = None;

    #[cfg(feature = "images")]
    let mut deferred_images: Vec<components::DeferredImageRender> = Vec::new();

    let current_messages = app.td_client.current_chat_messages();
    let grouped = group_messages(&current_messages);
    let mut is_first_date = true;
    let mut is_first_sender = true;

    for group in grouped {
        match group {
            MessageGroup::DateSeparator(date) => {
                lines.extend(components::render_date_separator(date, content_width, is_first_date));
                is_first_date = false;
                is_first_sender = true;
            }
            MessageGroup::SenderHeader { is_outgoing, sender_name } => {
                lines.extend(components::render_sender_header(
                    is_outgoing,
                    &sender_name,
                    content_width,
                    is_first_sender,
                ));
                is_first_sender = false;
            }
            MessageGroup::Message(msg) => {
                let is_selected = selected_msg_id == Some(msg.id());
                if is_selected {
                    selected_msg_line = Some(lines.len());
                }

                let bubble_lines = components::render_message_bubble(
                    msg,
                    app.config(),
                    content_width,
                    selected_msg_id,
                    app.playback_state.as_ref(),
                );

                #[cfg(feature = "images")]
                if let Some(photo) = msg.photo_info() {
                    if let crate::tdlib::PhotoDownloadState::Downloaded(path) =
                        &photo.download_state
                    {
                        let inline_width =
                            content_width.min(crate::constants::INLINE_IMAGE_MAX_WIDTH);
                        let img_height = components::calculate_image_height(
                            photo.width,
                            photo.height,
                            inline_width,
                        );
                        let img_width = inline_width as u16;
                        let bubble_len = bubble_lines.len();
                        let placeholder_start = lines.len() + bubble_len - img_height as usize;

                        deferred_images.push(components::DeferredImageRender {
                            message_id: msg.id(),
                            photo_path: path.clone(),
                            line_offset: placeholder_start,
                            x_offset: 0,
                            width: img_width,
                            height: img_height,
                        });
                    }
                }

                lines.extend(bubble_lines);
            }
            MessageGroup::Album(album_messages) => {
                #[cfg(feature = "images")]
                {
                    let is_selected = album_messages
                        .iter()
                        .any(|m| selected_msg_id == Some(m.id()));
                    if is_selected {
                        selected_msg_line = Some(lines.len());
                    }

                    let (bubble_lines, album_deferred) = components::render_album_bubble(
                        &album_messages,
                        app.config(),
                        content_width,
                        selected_msg_id,
                    );

                    for mut d in album_deferred {
                        d.line_offset += lines.len();
                        deferred_images.push(d);
                    }

                    lines.extend(bubble_lines);
                }
                #[cfg(not(feature = "images"))]
                {
                    for msg in &album_messages {
                        let is_selected = selected_msg_id == Some(msg.id());
                        if is_selected {
                            selected_msg_line = Some(lines.len());
                        }
                        lines.extend(components::render_message_bubble(
                            msg,
                            app.config(),
                            content_width,
                            selected_msg_id,
                            app.playback_state.as_ref(),
                        ));
                    }
                }
            }
        }
    }

    if lines.is_empty() {
        lines.push(Line::from(Span::styled("Нет сообщений", Style::default().fg(Color::Gray))));
    }

    let visible_height = area.height.saturating_sub(2) as usize;
    let total_lines = lines.len();
    let base_scroll = total_lines.saturating_sub(visible_height);

    let scroll_offset = if app.is_selecting_message() {
        if let Some(selected_line) = selected_msg_line {
            if selected_line < visible_height / 2 {
                0
            } else if selected_line > total_lines.saturating_sub(visible_height / 2) {
                base_scroll
            } else {
                selected_line.saturating_sub(visible_height / 2)
            }
        } else {
            base_scroll.saturating_sub(app.message_scroll_offset)
        }
    } else {
        base_scroll.saturating_sub(app.message_scroll_offset)
    } as u16;

    let messages_widget = Paragraph::new(lines)
        .block(Block::default().borders(Borders::ALL))
        .scroll((scroll_offset, 0));
    f.render_widget(messages_widget, area);

    #[cfg(feature = "images")]
    render_deferred_images(f, area, app, &deferred_images, visible_height, scroll_offset);
}

#[cfg(feature = "images")]
fn render_deferred_images<T: TdClientTrait>(
    f: &mut Frame,
    area: Rect,
    app: &mut App<T>,
    deferred_images: &[components::DeferredImageRender],
    visible_height: usize,
    scroll_offset: u16,
) {
    use ratatui_image::StatefulImage;

    let should_render_images = app
        .last_image_render_time
        .map(|t| t.elapsed() > std::time::Duration::from_millis(66))
        .unwrap_or(true);

    if deferred_images.is_empty() || !should_render_images {
        return;
    }

    let content_x = area.x + 1;
    let content_y = area.y + 1;

    for d in deferred_images {
        let y_in_content = d.line_offset as i32 - scroll_offset as i32;

        if y_in_content < 0 || y_in_content as usize >= visible_height {
            continue;
        }

        let img_y = content_y + y_in_content as u16;
        let remaining_height = (content_y + visible_height as u16).saturating_sub(img_y);

        if d.height > remaining_height {
            continue;
        }

        let img_rect = Rect::new(content_x + d.x_offset, img_y, d.width, d.height);

        if let Some(renderer) = &mut app.inline_image_renderer {
            let _ = renderer.load_image(d.message_id, &d.photo_path);

            if let Some(protocol) = renderer.get_protocol(&d.message_id) {
                f.render_stateful_widget(StatefulImage::default(), img_rect, protocol);
            }
        }
    }

    app.last_image_render_time = Some(std::time::Instant::now());
}