use std::path::{Path, PathBuf};

use rfd::FileDialog;
use winit::window::Window;

const DEFAULT_FILE_NAME: &str = "map.json";

/// Show the platform-native Save dialog. The caller owns the returned path and
/// decides when to write, which keeps dialogs entirely out of unit tests.
pub fn choose_map_save_path(window: &Window, current: Option<&Path>) -> Option<PathBuf> {
    let mut dialog = map_dialog(window, "Сохранить карту");
    if let Some(directory) = starting_directory(current) {
        dialog = dialog.set_directory(directory);
    }
    let suggested_name = current
        .and_then(Path::file_name)
        .and_then(|name| name.to_str())
        .unwrap_or(DEFAULT_FILE_NAME);
    dialog
        .set_file_name(suggested_name)
        .save_file()
        .map(ensure_json_extension)
}

/// Show the platform-native Open dialog for one versioned JSON map.
pub fn choose_map_open_path(window: &Window, current: Option<&Path>) -> Option<PathBuf> {
    let mut dialog = map_dialog(window, "Открыть карту");
    if let Some(directory) = starting_directory(current) {
        dialog = dialog.set_directory(directory);
    }
    dialog.pick_file()
}

fn map_dialog(window: &Window, title: &str) -> FileDialog {
    FileDialog::new()
        .set_parent(window)
        .set_title(title)
        .add_filter("Карта Ray Marching (JSON)", &["json"])
}

fn starting_directory(current: Option<&Path>) -> Option<PathBuf> {
    current
        .and_then(|path| {
            if path.is_dir() {
                Some(path)
            } else {
                path.parent()
            }
        })
        .filter(|path| !path.as_os_str().is_empty())
        .map(Path::to_owned)
        .or_else(|| std::env::current_dir().ok())
}

pub(crate) fn ensure_json_extension(mut path: PathBuf) -> PathBuf {
    let is_json = path
        .extension()
        .and_then(|extension| extension.to_str())
        .is_some_and(|extension| extension.eq_ignore_ascii_case("json"));
    if !is_json {
        path.set_extension("json");
    }
    path
}

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

    #[test]
    fn save_path_gets_one_json_extension() {
        assert_eq!(
            ensure_json_extension(PathBuf::from("level")),
            PathBuf::from("level.json")
        );
        assert_eq!(
            ensure_json_extension(PathBuf::from("level.JSON")),
            PathBuf::from("level.JSON")
        );
        assert_eq!(
            ensure_json_extension(PathBuf::from("level.txt")),
            PathBuf::from("level.json")
        );
    }
}