//! Shared UI components and state management for TUI applications
//!
//! This module contains reusable UI components that can be shared between
//! different TUI applications (chat, code, etc.)

/// Application state
pub use crate::state::AppState;

/// Input modes for TUI applications
pub use crate::state::InputMode;

/// Represents which panel is currently focused
pub use crate::state::FocusedPanel;

/// Auto-scroll state manager for scrollable panels
pub use crate::state::AutoScroll;

/// Visual selection state for text selection
pub use crate::state::VisualSelection;

use serde::{Deserialize, Serialize};

/// How role labels should be rendered alongside chat messages.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum RoleLabelDisplay {
    Inline,
    Above,
    None,
}

/// Extract text from a selection range in a list of lines
pub fn extract_text_from_selection(
    lines: &[String],
    start: (usize, usize),
    end: (usize, usize),
) -> Option<String> {
    if lines.is_empty() || start.0 >= lines.len() {
        return None;
    }

    let start_row = start.0;
    let start_col = start.1;
    let end_row = end.0.min(lines.len() - 1);
    let end_col = end.1;

    if start_row == end_row {
        // Single line selection
        let line = &lines[start_row];
        let chars: Vec<char> = line.chars().collect();
        let start_c = start_col.min(chars.len());
        let end_c = end_col.min(chars.len());

        if start_c >= end_c {
            return None;
        }

        let selected: String = chars[start_c..end_c].iter().collect();
        Some(selected)
    } else {
        // Multi-line selection
        let mut result = Vec::new();

        // First line: from start_col to end
        let first_line = &lines[start_row];
        let first_chars: Vec<char> = first_line.chars().collect();
        let start_c = start_col.min(first_chars.len());
        if start_c < first_chars.len() {
            result.push(first_chars[start_c..].iter().collect::<String>());
        }

        // Middle lines: entire lines
        for row in (start_row + 1)..end_row {
            if row < lines.len() {
                result.push(lines[row].clone());
            }
        }

        // Last line: from start to end_col
        if end_row < lines.len() && end_row > start_row {
            let last_line = &lines[end_row];
            let last_chars: Vec<char> = last_line.chars().collect();
            let end_c = end_col.min(last_chars.len());
            if end_c > 0 {
                result.push(last_chars[..end_c].iter().collect::<String>());
            }
        }

        if result.is_empty() {
            None
        } else {
            Some(result.join("\n"))
        }
    }
}

/// Cursor position for navigating scrollable content
pub use crate::state::CursorPosition;

/// Word boundary detection for navigation
pub fn find_next_word_boundary(line: &str, col: usize) -> Option<usize> {
    let chars: Vec<char> = line.chars().collect();

    if col >= chars.len() {
        return Some(chars.len());
    }

    let mut pos = col;
    let is_word_char = |c: char| c.is_alphanumeric() || c == '_';

    // Skip current word
    if is_word_char(chars[pos]) {
        while pos < chars.len() && is_word_char(chars[pos]) {
            pos += 1;
        }
    } else {
        // Skip non-word characters
        while pos < chars.len() && !is_word_char(chars[pos]) {
            pos += 1;
        }
    }

    Some(pos)
}

pub fn find_word_end(line: &str, col: usize) -> Option<usize> {
    let chars: Vec<char> = line.chars().collect();

    if col >= chars.len() {
        return Some(chars.len());
    }

    let mut pos = col;
    let is_word_char = |c: char| c.is_alphanumeric() || c == '_';

    // If on a word character, move to end of current word
    if is_word_char(chars[pos]) {
        while pos < chars.len() && is_word_char(chars[pos]) {
            pos += 1;
        }
        // Move back one to be ON the last character
        pos = pos.saturating_sub(1);
    } else {
        // Skip non-word characters
        while pos < chars.len() && !is_word_char(chars[pos]) {
            pos += 1;
        }
        // Now on first char of next word, move to its end
        while pos < chars.len() && is_word_char(chars[pos]) {
            pos += 1;
        }
        pos = pos.saturating_sub(1);
    }

    Some(pos)
}

pub fn find_prev_word_boundary(line: &str, col: usize) -> Option<usize> {
    let chars: Vec<char> = line.chars().collect();

    if col == 0 || chars.is_empty() {
        return Some(0);
    }

    let mut pos = col.min(chars.len());
    let is_word_char = |c: char| c.is_alphanumeric() || c == '_';

    // Move back one position first
    pos = pos.saturating_sub(1);

    // Skip non-word characters
    while pos > 0 && !is_word_char(chars[pos]) {
        pos -= 1;
    }

    // Skip word characters to find start of word
    while pos > 0 && is_word_char(chars[pos - 1]) {
        pos -= 1;
    }

    Some(pos)
}

use crate::theme::Theme;
use async_trait::async_trait;
use std::io::stdout;

pub fn show_mouse_cursor() {
    let mut stdout = stdout();
    crossterm::execute!(stdout, crossterm::cursor::Show).ok();
}

pub fn hide_mouse_cursor() {
    let mut stdout = stdout();
    crossterm::execute!(stdout, crossterm::cursor::Hide).ok();
}

pub fn apply_theme_to_string(s: &str, _theme: &Theme) -> String {
    // This is a placeholder. In a real implementation, you'd parse the string
    // and apply colors based on syntax or other rules.
    s.to_string()
}

/// A trait for abstracting UI interactions like confirmations.
#[async_trait]
pub trait UiController: Send + Sync {
    async fn confirm(&self, prompt: &str) -> bool;
}

/// A no-op UI controller for non-interactive contexts.
pub struct NoOpUiController;

#[async_trait]
impl UiController for NoOpUiController {
    async fn confirm(&self, _prompt: &str) -> bool {
        false // Always decline in non-interactive mode
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_auto_scroll() {
        let mut scroll = AutoScroll {
            content_len: 100,
            ..Default::default()
        };

        // Test on_viewport with stick_to_bottom
        scroll.on_viewport(10);
        assert_eq!(scroll.scroll, 90);

        // Test user scroll up
        scroll.on_user_scroll(-10, 10);
        assert_eq!(scroll.scroll, 80);
        assert!(!scroll.stick_to_bottom);

        // Test jump to bottom
        scroll.jump_to_bottom(10);
        assert!(scroll.stick_to_bottom);
        assert_eq!(scroll.scroll, 90);
    }

    #[test]
    fn test_visual_selection() {
        let mut selection = VisualSelection::new();
        assert!(!selection.is_active());

        selection.start_at((0, 0));
        assert!(selection.is_active());

        selection.extend_to((2, 5));
        let normalized = selection.get_normalized();
        assert_eq!(normalized, Some(((0, 0), (2, 5))));

        selection.clear();
        assert!(!selection.is_active());
    }

    #[test]
    fn test_extract_text_single_line() {
        let lines = vec!["Hello World".to_string()];
        let result = extract_text_from_selection(&lines, (0, 0), (0, 5));
        assert_eq!(result, Some("Hello".to_string()));
    }

    #[test]
    fn test_extract_text_multi_line() {
        let lines = vec![
            "First line".to_string(),
            "Second line".to_string(),
            "Third line".to_string(),
        ];
        let result = extract_text_from_selection(&lines, (0, 6), (2, 5));
        assert_eq!(result, Some("line\nSecond line\nThird".to_string()));
    }

    #[test]
    fn test_word_boundaries() {
        let line = "hello world test";
        assert_eq!(find_next_word_boundary(line, 0), Some(5));
        assert_eq!(find_next_word_boundary(line, 5), Some(6));
        assert_eq!(find_next_word_boundary(line, 6), Some(11));

        assert_eq!(find_prev_word_boundary(line, 16), Some(12));
        assert_eq!(find_prev_word_boundary(line, 11), Some(6));
        assert_eq!(find_prev_word_boundary(line, 6), Some(0));
    }
}