imp-tui 0.2.0

use crate::theme::Theme;
use crate::views::editor::{
    clamp_cursor_to_boundary, cursor_visual_position_for_text, wrapped_lines_for_width,
};
use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::style::{Modifier, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Borders, Widget};

/// Selection state for a single option in the ask overlay.
#[derive(Debug, Clone)]
pub struct AskOption {
    pub label: String,
    pub description: Option<String>,
    pub checked: bool, // only used in multi-select mode
}

/// The mode of the ask overlay.
#[derive(Debug, Clone, PartialEq)]
pub enum AskMode {
    SingleSelect,
    MultiSelect,
    FreeText,
}

/// State for the ask overlay bar.
#[derive(Debug, Clone)]
pub struct AskState {
    pub question: String,
    pub context: String,
    pub options: Vec<AskOption>,
    pub mode: AskMode,
    pub cursor: usize,       // highlighted option index
    pub input: String,       // user's typed text
    pub input_cursor: usize, // cursor position in input
    pub input_active: bool,  // true when user is typing (options dimmed)
    pub placeholder: String,
    pub editor_cursor: usize,
}

impl AskState {
    fn normalized_option_cursor(&self) -> usize {
        if self.options.is_empty() {
            0
        } else {
            self.cursor.min(self.options.len() - 1)
        }
    }

    fn normalize_option_cursor(&mut self) {
        self.cursor = self.normalized_option_cursor();
    }

    fn normalized_input_cursor(&self) -> usize {
        clamp_cursor_to_boundary(&self.input, self.input_cursor)
    }

    pub fn new(question: String, context: String, options: Vec<AskOption>, multi: bool) -> Self {
        Self::with_placeholder(question, context, options, multi, String::new())
    }

    pub fn with_placeholder(
        question: String,
        context: String,
        options: Vec<AskOption>,
        multi: bool,
        placeholder: String,
    ) -> Self {
        let input_active = options.is_empty();
        let mode = if options.is_empty() {
            AskMode::FreeText
        } else if multi {
            AskMode::MultiSelect
        } else {
            AskMode::SingleSelect
        };
        Self {
            question,
            context,
            options,
            mode,
            cursor: 0,
            input: String::new(),
            input_cursor: 0,
            input_active,
            placeholder,
            editor_cursor: 0,
        }
    }

    pub fn sync_from_editor(&mut self, text: &str, cursor: usize) {
        self.input = text.to_string();
        self.input_cursor = clamp_cursor_to_boundary(&self.input, cursor);
        self.editor_cursor = self.input_cursor;
        self.normalize_option_cursor();
        self.input_active = !self.input.is_empty() || self.options.is_empty();
    }

    pub fn height(&self, width: u16) -> u16 {
        let w = width.max(1);
        let mut h: u16 = wrapped_lines_for_width(&self.question, w).len() as u16;
        if !self.context.is_empty() {
            h += wrapped_lines_for_width(&self.context, w).len() as u16;
        }
        if !self.options.is_empty() {
            h += self.options.len() as u16; // one per option
            h += 1; // blank line between options and input
        }
        // Input line(s) — account for "❯ " prefix
        let input_w = w.saturating_sub(2).max(1);
        h += wrapped_lines_for_width(&self.input, input_w).len() as u16;
        h += 1; // hint line
        h
    }

    /// Height needed to render this prompt, including its border.
    pub fn prompt_height(&self, width: u16) -> u16 {
        self.height(width).saturating_add(2)
    }

    /// Cursor position inside the ask prompt area.
    pub fn cursor_screen_position(&self, area: Rect) -> (u16, u16) {
        if area.width == 0 || area.height == 0 {
            return (area.x, area.y);
        }

        let inner_x = area.x.saturating_add(1);
        let inner_y = area.y.saturating_add(1);
        let inner_width = area.width.saturating_sub(2).max(1);

        let mut input_row = inner_y
            .saturating_add(wrapped_lines_for_width(&self.question, inner_width).len() as u16);
        if !self.context.is_empty() {
            input_row = input_row
                .saturating_add(wrapped_lines_for_width(&self.context, inner_width).len() as u16);
        }
        if !self.options.is_empty() {
            input_row = input_row
                .saturating_add(self.options.len() as u16)
                .saturating_add(1);
        }

        let (visual_row, visual_col) = cursor_visual_position_for_text(
            &self.input,
            self.normalized_input_cursor(),
            inner_width.saturating_sub(2),
        );

        let max_x = area.x.saturating_add(area.width.saturating_sub(2));
        let max_y = area.y.saturating_add(area.height.saturating_sub(2));
        (
            (inner_x + 2 + visual_col as u16).min(max_x),
            (input_row + visual_row as u16).min(max_y),
        )
    }

    /// Move cursor up.
    pub fn cursor_up(&mut self) {
        if !self.options.is_empty() {
            self.input_active = false;
            if self.cursor > 0 {
                self.cursor -= 1;
            } else {
                self.cursor = self.options.len() - 1;
            }
        }
    }

    /// Move cursor down.
    pub fn cursor_down(&mut self) {
        if !self.options.is_empty() {
            self.input_active = false;
            if self.cursor < self.options.len() - 1 {
                self.cursor += 1;
            } else {
                self.cursor = 0;
            }
        }
    }

    /// Toggle checkbox in multi-select mode.
    pub fn toggle_current(&mut self) {
        if self.mode == AskMode::MultiSelect && !self.input_active {
            self.normalize_option_cursor();
            if let Some(opt) = self.options.get_mut(self.cursor) {
                opt.checked = !opt.checked;
            }
        }
    }

    /// Tab: copy highlighted option text into the input editor.
    pub fn tab_to_edit(&mut self) {
        if !self.options.is_empty() && !self.input_active {
            self.normalize_option_cursor();
            if let Some(option) = self.options.get(self.cursor) {
                self.input = option.label.clone();
                self.input_cursor = self.input.len();
                self.editor_cursor = self.input_cursor;
                self.input_active = true;
            }
        }
    }

    /// Toggle or quick-select by number (1-9).
    pub fn quick_select(&mut self, n: usize) -> bool {
        if n == 0 || n > self.options.len() || self.input_active {
            return false;
        }

        self.cursor = n - 1;
        if self.mode == AskMode::MultiSelect {
            self.toggle_current();
            false
        } else {
            true
        }
    }

    /// Insert a character into the input.
    pub fn type_char(&mut self, ch: char) {
        self.input_active = true;
        let cursor = self.normalized_input_cursor();
        self.input.insert(cursor, ch);
        self.input_cursor = cursor + ch.len_utf8();
        self.editor_cursor = self.input_cursor;
    }

    /// Backspace in the input.
    pub fn backspace(&mut self) {
        self.input_cursor = self.normalized_input_cursor();
        self.editor_cursor = self.input_cursor;
        if self.input_cursor > 0 && !self.input.is_empty() {
            let prev = self.input[..self.input_cursor]
                .char_indices()
                .next_back()
                .map(|(i, _)| i)
                .unwrap_or(0);
            self.input.drain(prev..self.input_cursor);
            self.input_cursor = prev;
            self.editor_cursor = prev;
        }
        // If input is now empty and we have options, go back to option mode
        if self.input.is_empty() && !self.options.is_empty() {
            self.input_active = false;
        }
    }

    /// Get the final answer when Enter is pressed.
    pub fn confirm(&self) -> AskResult {
        if self.input_active && !self.input.is_empty() {
            // User typed custom text
            return AskResult::Text(self.input.clone());
        }

        match self.mode {
            AskMode::FreeText => AskResult::Text(self.input.clone()),
            AskMode::SingleSelect => {
                if self.options.is_empty() {
                    AskResult::Text(self.input.clone())
                } else {
                    AskResult::Selected(vec![self.normalized_option_cursor()])
                }
            }
            AskMode::MultiSelect => {
                let selected: Vec<usize> = self
                    .options
                    .iter()
                    .enumerate()
                    .filter(|(_, o)| o.checked)
                    .map(|(i, _)| i)
                    .collect();
                if selected.is_empty() {
                    // If nothing checked, use the highlighted one
                    AskResult::Selected(vec![self.normalized_option_cursor()])
                } else {
                    AskResult::Selected(selected)
                }
            }
        }
    }
}

/// Result of the ask interaction.
#[derive(Debug)]
pub enum AskResult {
    Selected(Vec<usize>),
    Text(String),
}

/// Widget that renders the ask overlay bar.
pub struct AskBar<'a> {
    state: &'a AskState,
    theme: &'a Theme,
}

impl<'a> AskBar<'a> {
    pub fn new(state: &'a AskState, theme: &'a Theme) -> Self {
        Self { state, theme }
    }
}

impl Widget for AskBar<'_> {
    fn render(self, area: Rect, buf: &mut Buffer) {
        if area.height < 3 || area.width < 4 {
            return;
        }

        let s = self.state;
        let theme = self.theme;
        let dim = theme.muted_style();
        let highlight = theme.accent_style().add_modifier(Modifier::BOLD);
        let normal = theme.style();
        let question_style = theme.header_style().add_modifier(Modifier::BOLD);

        let block = Block::default()
            .title(" ask ")
            .borders(Borders::ALL)
            .border_style(Style::default().fg(theme.accent));
        let inner = block.inner(area);
        block.render(area, buf);

        if inner.height == 0 || inner.width == 0 {
            return;
        }

        let mut y = inner.y;
        let w = inner.width as usize;

        // Question (word-wrapped)
        let question_wrapped = wrapped_lines_for_width(&s.question, inner.width);
        for ql in &question_wrapped {
            if y >= inner.y + inner.height {
                return;
            }
            buf.set_line(
                inner.x,
                y,
                &Line::from(Span::styled(ql.clone(), question_style)),
                inner.width,
            );
            y += 1;
        }

        // Context (if any, word-wrapped)
        if !s.context.is_empty() {
            let context_wrapped = wrapped_lines_for_width(&s.context, inner.width);
            for cl in &context_wrapped {
                if y >= inner.y + inner.height {
                    return;
                }
                buf.set_line(
                    inner.x,
                    y,
                    &Line::from(Span::styled(cl.clone(), dim)),
                    inner.width,
                );
                y += 1;
            }
        }

        // Options
        if !s.options.is_empty() {
            for (i, opt) in s.options.iter().enumerate() {
                if y >= inner.y + inner.height {
                    break;
                }

                let is_highlighted = i == s.cursor && !s.input_active;

                let prefix = match s.mode {
                    AskMode::MultiSelect => {
                        if opt.checked {
                            "[x] "
                        } else {
                            "[ ] "
                        }
                    }
                    AskMode::SingleSelect => {
                        if is_highlighted {
                            " ❯ "
                        } else {
                            "   "
                        }
                    }
                    AskMode::FreeText => "",
                };

                let num = format!("[{}] ", i + 1);
                let label = &opt.label;
                let desc = opt.description.as_deref().unwrap_or("");

                let style = if s.input_active {
                    dim // dim all options when user is typing
                } else if is_highlighted {
                    highlight
                } else {
                    normal
                };

                let mut spans = vec![
                    Span::styled(prefix, style),
                    Span::styled(label.to_string(), style),
                ];
                if !desc.is_empty() {
                    spans.push(Span::styled(format!(" — {desc}"), dim));
                }
                // Right-align the number hint
                let content_len: usize = spans.iter().map(|s| s.content.len()).sum();
                let num_hint_style = if s.input_active {
                    dim
                } else {
                    theme.muted_style()
                };
                if content_len + num.len() + 1 < w {
                    let padding = w - content_len - num.len();
                    spans.push(Span::raw(" ".repeat(padding)));
                    spans.push(Span::styled(num, num_hint_style));
                }

                buf.set_line(inner.x, y, &Line::from(spans), inner.width);
                y += 1;
            }

            // Blank line before input
            y += 1;
        }

        // Input line
        if y < inner.y + inner.height {
            let cursor_char = if s.input_active { "│" } else { " " };
            let available_width = inner.width.saturating_sub(2);
            let mut rendered_any = false;

            if s.input.is_empty() {
                let placeholder = if !s.placeholder.is_empty() {
                    s.placeholder.clone()
                } else {
                    "type to answer freely…".to_string()
                };
                let line = Line::from(vec![
                    Span::styled("❯ ", Style::default().fg(theme.accent)),
                    Span::styled(placeholder, dim),
                    Span::styled(cursor_char, Style::default().fg(theme.accent)),
                ]);
                buf.set_line(inner.x, y, &line, inner.width);
                y += 1;
                rendered_any = true;
            } else {
                let lines = wrapped_lines_for_width(&s.input, available_width);
                let (visual_row, visual_col) =
                    cursor_visual_position_for_text(&s.input, s.editor_cursor, available_width);
                for (idx, input_line) in lines.iter().enumerate() {
                    if y >= inner.y + inner.height {
                        break;
                    }
                    let is_cursor_row = idx == visual_row;
                    let mut line_text = input_line.clone();
                    if is_cursor_row {
                        let insert_at = visual_col.min(line_text.chars().count());
                        let byte_idx = char_to_byte_idx(&line_text, insert_at);
                        line_text.insert_str(byte_idx, cursor_char);
                    }
                    let prefix = if idx == 0 { "❯ " } else { "  " };
                    let line = Line::from(vec![
                        Span::styled(prefix, Style::default().fg(theme.accent)),
                        Span::styled(line_text, normal),
                    ]);
                    buf.set_line(inner.x, y, &line, inner.width);
                    y += 1;
                    rendered_any = true;
                }
            }

            if !rendered_any {
                let line = Line::from(vec![
                    Span::styled("❯ ", Style::default().fg(theme.accent)),
                    Span::styled(cursor_char, Style::default().fg(theme.accent)),
                ]);
                buf.set_line(inner.x, y, &line, inner.width);
                y += 1;
            }
        }

        // Hint line
        if y < inner.y + inner.height {
            let hints = match s.mode {
                AskMode::FreeText => "Enter: send  Esc: skip",
                AskMode::SingleSelect => "↑↓: navigate  Tab: edit  Enter: pick  Esc: skip",
                AskMode::MultiSelect => {
                    "↑↓: navigate  Space: toggle  Tab: edit  Enter: confirm  Esc: skip"
                }
            };
            buf.set_line(
                inner.x,
                y,
                &Line::from(Span::styled(hints, dim)),
                inner.width,
            );
        }
    }
}

fn char_to_byte_idx(s: &str, char_idx: usize) -> usize {
    s.char_indices()
        .nth(char_idx)
        .map(|(idx, _)| idx)
        .unwrap_or(s.len())
}

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

    #[test]
    fn single_select_confirm() {
        let opts = vec![
            AskOption {
                label: "React".into(),
                description: None,
                checked: false,
            },
            AskOption {
                label: "Svelte".into(),
                description: None,
                checked: false,
            },
        ];
        let mut state = AskState::new("Pick one".into(), String::new(), opts, false);
        assert_eq!(state.mode, AskMode::SingleSelect);

        state.cursor_down();
        let result = state.confirm();
        assert!(matches!(result, AskResult::Selected(v) if v == vec![1]));
    }

    #[test]
    fn multi_select_toggle() {
        let opts = vec![
            AskOption {
                label: "A".into(),
                description: None,
                checked: false,
            },
            AskOption {
                label: "B".into(),
                description: None,
                checked: false,
            },
            AskOption {
                label: "C".into(),
                description: None,
                checked: false,
            },
        ];
        let mut state = AskState::new("Pick".into(), String::new(), opts, true);
        assert_eq!(state.mode, AskMode::MultiSelect);

        state.toggle_current(); // toggle A
        state.cursor_down();
        state.cursor_down();
        state.toggle_current(); // toggle C

        let result = state.confirm();
        assert!(matches!(result, AskResult::Selected(v) if v == vec![0, 2]));
    }

    #[test]
    fn free_text_input() {
        let mut state = AskState::new("What color?".into(), String::new(), vec![], false);
        assert_eq!(state.mode, AskMode::FreeText);
        assert!(state.input_active);

        state.type_char('r');
        state.type_char('e');
        state.type_char('d');

        let result = state.confirm();
        assert!(matches!(result, AskResult::Text(t) if t == "red"));
    }

    #[test]
    fn tab_copies_option_to_input() {
        let opts = vec![AskOption {
            label: "React".into(),
            description: None,
            checked: false,
        }];
        let mut state = AskState::new("Pick".into(), String::new(), opts, false);

        state.tab_to_edit();
        assert!(state.input_active);
        assert_eq!(state.input, "React");

        // Modify it
        state.type_char('!');
        let result = state.confirm();
        assert!(matches!(result, AskResult::Text(t) if t == "React!"));
    }

    #[test]
    fn typing_activates_input_mode() {
        let opts = vec![AskOption {
            label: "A".into(),
            description: None,
            checked: false,
        }];
        let mut state = AskState::new("Pick".into(), String::new(), opts, false);
        assert!(!state.input_active);

        state.type_char('c');
        assert!(state.input_active);
        assert_eq!(state.input, "c");
    }

    #[test]
    fn backspace_returns_to_option_mode() {
        let opts = vec![AskOption {
            label: "A".into(),
            description: None,
            checked: false,
        }];
        let mut state = AskState::new("Pick".into(), String::new(), opts, false);

        state.type_char('x');
        assert!(state.input_active);

        state.backspace();
        assert!(!state.input_active); // back to option mode
    }

    #[test]
    fn quick_select_confirms_single_select() {
        let opts = vec![
            AskOption {
                label: "A".into(),
                description: None,
                checked: false,
            },
            AskOption {
                label: "B".into(),
                description: None,
                checked: false,
            },
        ];
        let mut state = AskState::new("Pick".into(), String::new(), opts, false);

        assert!(state.quick_select(2));
        assert_eq!(state.cursor, 1);
    }

    #[test]
    fn quick_select_toggles_multi_select_without_confirming() {
        let opts = vec![
            AskOption {
                label: "A".into(),
                description: None,
                checked: false,
            },
            AskOption {
                label: "B".into(),
                description: None,
                checked: false,
            },
        ];
        let mut state = AskState::new("Pick".into(), String::new(), opts, true);

        assert!(!state.quick_select(2));
        assert_eq!(state.cursor, 1);
        assert!(state.options[1].checked);
    }

    #[test]
    fn height_calculation() {
        let opts = vec![
            AskOption {
                label: "A".into(),
                description: None,
                checked: false,
            },
            AskOption {
                label: "B".into(),
                description: None,
                checked: false,
            },
        ];
        let state = AskState::new("Q".into(), "ctx".into(), opts, false);
        // question(1) + context(1) + 2 options(2) + blank(1) + input(1) + hints(1) = 7
        // Use a wide width so nothing wraps
        assert_eq!(state.height(100), 7);
    }

    #[test]
    fn tab_to_edit_clamps_stale_option_cursor() {
        let opts = vec![AskOption {
            label: "React".into(),
            description: None,
            checked: false,
        }];
        let mut state = AskState::new("Pick".into(), String::new(), opts, false);
        state.cursor = 99;

        state.tab_to_edit();

        assert_eq!(state.input, "React");
        assert_eq!(state.input_cursor, state.input.len());
        assert_eq!(state.editor_cursor, state.input.len());
    }

    #[test]
    fn sync_from_editor_clamps_invalid_utf8_boundary() {
        let mut state = AskState::new("Pick".into(), String::new(), vec![], false);

        state.sync_from_editor("éx", 1);

        assert_eq!(state.input_cursor, 0);
        assert_eq!(state.editor_cursor, 0);
    }

    #[test]
    fn confirm_clamps_stale_selected_cursor() {
        let opts = vec![AskOption {
            label: "Only".into(),
            description: None,
            checked: false,
        }];
        let mut state = AskState::new("Pick".into(), String::new(), opts, false);
        state.cursor = 42;

        let result = state.confirm();
        assert!(matches!(result, AskResult::Selected(v) if v == vec![0]));
    }

    #[test]
    fn cursor_screen_position_handles_tiny_area_and_stale_cursor() {
        let mut state = AskState::new("Q".into(), String::new(), vec![], false);
        state.input = "abc".into();
        state.input_cursor = usize::MAX;
        state.editor_cursor = usize::MAX;

        let (x, y) = state.cursor_screen_position(Rect::new(3, 4, 0, 0));
        assert_eq!((x, y), (3, 4));

        let (x, y) = state.cursor_screen_position(Rect::new(3, 4, 1, 1));
        assert_eq!((x, y), (3, 4));
    }
}