use crate::{settings_content::SettingsContent, settings_store::SettingsStore};
use collections::HashSet;
use fs::{Fs, PathEventKind};
use futures::{StreamExt, channel::mpsc};
use gpui::{App, BackgroundExecutor, ReadGlobal};
use std::{path::PathBuf, sync::Arc, time::Duration};

pub const EMPTY_THEME_NAME: &str = "empty-theme";

/// Settings for visual tests that use proper fonts instead of Courier.
/// Uses Helvetica Neue for UI (sans-serif) and Menlo for code (monospace),
/// which are available on all macOS systems.
#[cfg(any(test, feature = "test-support"))]
pub fn visual_test_settings() -> String {
    let mut value =
        crate::parse_json_with_comments::<serde_json::Value>(crate::default_settings().as_ref())
            .unwrap();
    util::merge_non_null_json_value_into(
        serde_json::json!({
            "ui_font_family": ".SystemUIFont",
            "ui_font_features": {},
            "ui_font_size": 14,
            "ui_font_fallback": [],
            "buffer_font_family": "Menlo",
            "buffer_font_features": {},
            "buffer_font_size": 14,
            "buffer_font_fallbacks": [],
            "theme": EMPTY_THEME_NAME,
        }),
        &mut value,
    );
    value.as_object_mut().unwrap().remove("languages");
    serde_json::to_string(&value).unwrap()
}

#[cfg(any(test, feature = "test-support"))]
pub fn test_settings() -> String {
    let mut value =
        crate::parse_json_with_comments::<serde_json::Value>(crate::default_settings().as_ref())
            .unwrap();
    #[cfg(not(target_os = "windows"))]
    util::merge_non_null_json_value_into(
        serde_json::json!({
            "ui_font_family": "Courier",
            "ui_font_features": {},
            "ui_font_size": 14,
            "ui_font_fallback": [],
            "buffer_font_family": "Courier",
            "buffer_font_features": {},
            "buffer_font_size": 14,
            "buffer_font_fallbacks": [],
            "theme": EMPTY_THEME_NAME,
        }),
        &mut value,
    );
    #[cfg(target_os = "windows")]
    util::merge_non_null_json_value_into(
        serde_json::json!({
            "ui_font_family": "Courier New",
            "ui_font_features": {},
            "ui_font_size": 14,
            "ui_font_fallback": [],
            "buffer_font_family": "Courier New",
            "buffer_font_features": {},
            "buffer_font_size": 14,
            "buffer_font_fallbacks": [],
            "theme": EMPTY_THEME_NAME,
        }),
        &mut value,
    );
    value.as_object_mut().unwrap().remove("languages");
    serde_json::to_string(&value).unwrap()
}

pub fn watch_config_file(
    executor: &BackgroundExecutor,
    fs: Arc<dyn Fs>,
    path: PathBuf,
) -> (mpsc::UnboundedReceiver<String>, gpui::Task<()>) {
    let (tx, rx) = mpsc::unbounded();
    let task = executor.spawn(async move {
        let (events, _) = fs.watch(&path, Duration::from_millis(100)).await;
        futures::pin_mut!(events);

        let contents = fs.load(&path).await.unwrap_or_default();
        if tx.unbounded_send(contents).is_err() {
            return;
        }

        loop {
            if events.next().await.is_none() {
                break;
            }

            if let Ok(contents) = fs.load(&path).await
                && tx.unbounded_send(contents).is_err()
            {
                break;
            }
        }
    });
    (rx, task)
}

pub fn watch_config_dir(
    executor: &BackgroundExecutor,
    fs: Arc<dyn Fs>,
    dir_path: PathBuf,
    config_paths: HashSet<PathBuf>,
) -> mpsc::UnboundedReceiver<String> {
    let (tx, rx) = mpsc::unbounded();
    executor
        .spawn(async move {
            for file_path in &config_paths {
                if fs.metadata(file_path).await.is_ok_and(|v| v.is_some())
                    && let Ok(contents) = fs.load(file_path).await
                    && tx.unbounded_send(contents).is_err()
                {
                    return;
                }
            }

            let (events, _) = fs.watch(&dir_path, Duration::from_millis(100)).await;
            futures::pin_mut!(events);

            while let Some(event_batch) = events.next().await {
                for event in event_batch {
                    if config_paths.contains(&event.path) {
                        match event.kind {
                            Some(PathEventKind::Removed) => {
                                if tx.unbounded_send(String::new()).is_err() {
                                    return;
                                }
                            }
                            Some(PathEventKind::Created) | Some(PathEventKind::Changed) => {
                                if let Ok(contents) = fs.load(&event.path).await
                                    && tx.unbounded_send(contents).is_err()
                                {
                                    return;
                                }
                            }
                            _ => {}
                        }
                    }
                }
            }
        })
        .detach();

    rx
}

pub fn update_settings_file(
    fs: Arc<dyn Fs>,
    cx: &App,
    update: impl 'static + Send + FnOnce(&mut SettingsContent, &App),
) {
    SettingsStore::global(cx).update_settings_file(fs, update);
}