use eframe::egui;
use egui_code_editor::{CodeEditor, ColorTheme, Syntax};
use std::collections::BTreeSet;

/// Returns a [`Syntax`] definition for the Rhai scripting language.
///
/// Keyword sets are sourced from the official
/// [rhaiscript/sublime-rhai](https://github.com/rhaiscript/sublime-rhai) grammar (MPL-2.0).
pub(crate) fn rhai_syntax() -> Syntax {
    Syntax {
        language: "Rhai",
        case_sensitive: true,
        comment: "//",
        comment_multiline: ["/*", "*/"],
        hyperlinks: BTreeSet::new(),
        keywords: BTreeSet::from([
            "if", "else", "switch", "for", "in", "loop", "do", "while", "until", "break",
            "continue", "return", "throw", "try", "catch", "let", "const", "fn", "import",
            "export", "as", "private",
        ]),
        // Boolean literals and context keywords get a distinct type color.
        types: BTreeSet::from(["true", "false", "this", "global"]),
        // Built-in Rhai functions highlighted as special identifiers.
        special: BTreeSet::from([
            "print",
            "debug",
            "type_of",
            "is_def_var",
            "is_def_fn",
            "is_shared",
            "call",
            "curry",
            "eval",
        ]),
    }
}

/// Renders the script code editor and header bar inside `ui`.
///
/// Returns `true` when the user clicks "Back", signalling the caller to save
/// `content` back to `board.scripts` and close the editor.
pub(crate) fn show(ui: &mut egui::Ui, name: &str, content: &mut String) -> bool {
    let mut done = false;

    ui.horizontal(|ui| {
        if ui.button("◄ Back").clicked() {
            done = true;
        }
        ui.label(format!("Editing: {name}"));
    });
    ui.separator();

    CodeEditor::default()
        .id_source("script_editor")
        .with_rows(30)
        .with_fontsize(14.0)
        .with_theme(ColorTheme::GRUVBOX)
        .with_syntax(rhai_syntax())
        .show(ui, content);

    done
}