// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

#[cfg(feature = "semver")]
use crate::semver_compat::semver_compat_string;

use crate::SingleInstanceCallback;
use tauri::{
    plugin::{self, TauriPlugin},
    AppHandle, Config, Manager, RunEvent, Runtime,
};
use zbus::{
    blocking::{connection::Builder, Connection},
    interface,
};

struct ConnectionHandle(Connection);

struct SingleInstanceDBus<R: Runtime> {
    callback: Box<SingleInstanceCallback<R>>,
    app_handle: AppHandle<R>,
}

#[interface(name = "org.SingleInstance.DBus")]
impl<R: Runtime> SingleInstanceDBus<R> {
    fn execute_callback(&mut self, argv: Vec<String>, cwd: String) {
        (self.callback)(&self.app_handle, argv, cwd);
    }
}

#[cfg(feature = "semver")]
fn dbus_id(config: &Config, version: semver::Version) -> (String, bool) {
    let mut override_id = crate::OVERRIDE_DBUS_ID.try_lock();
    while override_id.is_err() {
        override_id = crate::OVERRIDE_DBUS_ID.try_lock();
    }
    let override_id = override_id.unwrap();
    if let Some(ovr_id) = override_id.as_ref() {
        return (ovr_id.to_owned(), true);
    }
    let mut id = config.identifier.replace(['.', '-'], "_");
    id.push('_');
    id.push_str(semver_compat_string(version).as_str());
    (id, false)
}

// Return a bool in order to indicate that the DBUS ID was set at runtime
#[cfg(not(feature = "semver"))]
fn dbus_id(config: &Config) -> (String, bool) {
    let mut override_id = crate::OVERRIDE_DBUS_ID.try_lock();
    while override_id.is_err() {
        override_id = crate::OVERRIDE_DBUS_ID.try_lock();
    }
    let override_id = override_id.unwrap();
    if let Some(ovr_id) = override_id.as_ref() {
        return (ovr_id.to_owned(), true);
    }

    // Check whether a custom DBUS_ID is present at compile time.
    let custom_id = std::option_env!("DBUS_ID");
    match custom_id {
        Some(id) => (id.to_string(), false),
        None => (config.identifier.clone(), false),
    }
}

fn dbus_path(config: &Config) -> String {
    // Check whether a custom DBUS_ID is present at compile time.
    let custom_id = std::option_env!("DBUS_ID");
    match custom_id {
        Some(id) => id.to_string().replace(['.', '-'], "_"),
        None => config.identifier.replace(['.', '-'], "_"),
    }
}

pub fn init<R: Runtime>(f: Box<SingleInstanceCallback<R>>) -> TauriPlugin<R> {
    plugin::Builder::new("single-instance")
        .setup(|app, _api| {
            #[cfg(feature = "semver")]
            let id = dbus_id(app.config(), app.package_info().version.clone());
            #[cfg(not(feature = "semver"))]
            let (id, is_id_custom) = dbus_id(app.config());

            let single_instance_dbus = SingleInstanceDBus {
                callback: f,
                app_handle: app.clone(),
            };

            let path = dbus_path(app.config());
            let dbus_path = format!("/{path}/SingleInstance");
            let dbus_name = if is_id_custom {
                id
            } else {
                format!("{id}.SingleInstance")
            };

            match Builder::session()
                .unwrap()
                .name(dbus_name.as_str())
                .unwrap()
                .replace_existing_names(false)
                .allow_name_replacements(false)
                .serve_at(dbus_path.as_str(), single_instance_dbus)
                .unwrap()
                .build()
            {
                Ok(connection) => {
                    app.manage(ConnectionHandle(connection));
                }
                Err(zbus::Error::NameTaken) => {
                    if let Ok(connection) = Connection::session() {
                        let _ = connection.call_method(
                            Some(dbus_name.as_str()),
                            dbus_path.as_str(),
                            Some("org.SingleInstance.DBus"),
                            "ExecuteCallback",
                            &(
                                std::env::args().collect::<Vec<String>>(),
                                std::env::current_dir()
                                    .unwrap_or_default()
                                    .to_str()
                                    .unwrap_or_default(),
                            ),
                        );
                    }
                    app.cleanup_before_exit();
                    std::process::exit(0);
                }
                _ => {}
            }

            Ok(())
        })
        .on_event(|app, event| {
            if let RunEvent::Exit = event {
                destroy(app);
            }
        })
        .build()
}

pub fn destroy<R: Runtime, M: Manager<R>>(manager: &M) {
    if let Some(connection) = manager.try_state::<ConnectionHandle>() {
        #[cfg(feature = "semver")]
        let id = dbus_id(
            manager.config(),
            manager.app_handle().package_info().version.clone(),
        );
        #[cfg(not(feature = "semver"))]
        let (id, is_id_custom) = dbus_id(manager.config());

        let dbus_name = if is_id_custom {
            id.clone()
        } else {
            format!("{id}.SingleInstance",)
        };
        let _ = connection.0.release_name(dbus_name);
    }
}