//! Code editor panel
//!
//! Provides a multi-line text editor for writing Geolog code.

use eframe::egui;

use crate::gui::state::GuiState;

/// Code editor panel
pub struct EditorPanel {
    /// Whether to show line numbers
    show_line_numbers: bool,
}

impl EditorPanel {
    pub fn new() -> Self {
        Self {
            show_line_numbers: true,
        }
    }

    pub fn show(&mut self, ui: &mut egui::Ui, state: &mut GuiState) {
        // Header with title and buttons
        ui.horizontal(|ui| {
            ui.heading("Editor");

            ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
                if ui.button("Clear").clicked() {
                    state.editor_content.clear();
                }

                if ui.button("Run").clicked() {
                    state.execute_editor();
                }

                // Show current file if any
                if let Some(path) = &state.current_file {
                    ui.label(format!(
                        "{}",
                        path.file_name()
                            .map(|s| s.to_string_lossy())
                            .unwrap_or_default()
                    ));
                }
            });
        });

        ui.separator();

        // Editor area with syntax highlighting
        egui::ScrollArea::vertical()
            .auto_shrink([false, false])
            .show(ui, |ui| {
                self.show_editor_content(ui, state);
            });
    }

    fn show_editor_content(&mut self, ui: &mut egui::Ui, state: &mut GuiState) {
        // Use a monospace font for code
        let font_id = egui::FontId::monospace(14.0);

        // Calculate line numbers if needed
        let line_count = state.editor_content.lines().count().max(1);
        let line_number_width = if self.show_line_numbers {
            let digits = (line_count as f32).log10().floor() as usize + 1;
            digits.max(2) as f32 * 10.0 + 8.0
        } else {
            0.0
        };

        ui.horizontal(|ui| {
            // Line numbers column
            if self.show_line_numbers {
                ui.allocate_ui_with_layout(
                    egui::vec2(line_number_width, ui.available_height()),
                    egui::Layout::top_down(egui::Align::RIGHT),
                    |ui| {
                        ui.style_mut().visuals.override_text_color =
                            Some(egui::Color32::GRAY);

                        for i in 1..=line_count {
                            ui.label(
                                egui::RichText::new(format!("{}", i))
                                    .font(font_id.clone())
                                    .color(egui::Color32::GRAY),
                            );
                        }
                    },
                );

                ui.separator();
            }

            // Main editor area
            let text_edit = egui::TextEdit::multiline(&mut state.editor_content)
                .font(font_id)
                .code_editor()
                .desired_width(f32::INFINITY)
                .desired_rows(20)
                .lock_focus(true);

            let response = ui.add(text_edit);

            // Handle keyboard shortcuts
            if response.has_focus() {
                let modifiers = ui.input(|i| i.modifiers);
                if modifiers.ctrl || modifiers.command {
                    if ui.input(|i| i.key_pressed(egui::Key::Enter)) {
                        state.execute_editor();
                    }
                }
            }
        });
    }
}

impl Default for EditorPanel {
    fn default() -> Self {
        Self::new()
    }
}

/// Simple syntax highlighting for Geolog code
/// Returns a layouter function for egui's code_editor
#[allow(dead_code)]
fn geolog_highlighter(
    _ui: &egui::Ui,
    text: &str,
    _wrap_width: f32,
) -> egui::text::LayoutJob {
    let mut job = egui::text::LayoutJob::default();

    let keywords = [
        "theory", "instance", "query", "forall", "exists", "Sort", "Prop", "true", "false",
    ];

    let font_id = egui::FontId::monospace(14.0);
    let default_color = egui::Color32::WHITE;
    let keyword_color = egui::Color32::from_rgb(86, 156, 214); // Blue
    let comment_color = egui::Color32::from_rgb(106, 153, 85); // Green
    let string_color = egui::Color32::from_rgb(206, 145, 120); // Orange

    let mut chars = text.char_indices().peekable();

    while let Some((i, c)) = chars.next() {
        // Check for comments
        if c == '/' && chars.peek().map(|(_, c)| *c) == Some('/') {
            // Line comment - consume until end of line
            let start = i;
            while let Some((_, c)) = chars.next() {
                if c == '\n' {
                    break;
                }
            }
            let end = chars.peek().map(|(i, _)| *i).unwrap_or(text.len());
            job.append(
                &text[start..end],
                0.0,
                egui::TextFormat::simple(font_id.clone(), comment_color),
            );
            continue;
        }

        // Check for strings
        if c == '"' {
            let start = i;
            while let Some((_, c)) = chars.next() {
                if c == '"' {
                    break;
                }
                if c == '\\' {
                    chars.next(); // Skip escaped character
                }
            }
            let end = chars.peek().map(|(i, _)| *i).unwrap_or(text.len());
            job.append(
                &text[start..end],
                0.0,
                egui::TextFormat::simple(font_id.clone(), string_color),
            );
            continue;
        }

        // Check for identifiers/keywords
        if c.is_alphabetic() || c == '_' {
            let start = i;
            while chars.peek().map(|(_, c)| c.is_alphanumeric() || *c == '_') == Some(true) {
                chars.next();
            }
            let end = chars.peek().map(|(i, _)| *i).unwrap_or(text.len());
            let word = &text[start..end];

            let color = if keywords.contains(&word) {
                keyword_color
            } else {
                default_color
            };

            job.append(
                word,
                0.0,
                egui::TextFormat::simple(font_id.clone(), color),
            );
            continue;
        }

        // Default: single character
        job.append(
            &text[i..i + c.len_utf8()],
            0.0,
            egui::TextFormat::simple(font_id.clone(), default_color),
        );
    }

    job
}