// Take a look at the license at the top of the repository in the LICENSE file.

use std::{boxed::Box as Box_, mem::transmute};

use glib::{
    prelude::*,
    signal::{connect_raw, SignalHandlerId},
    translate::*,
    ExitCode, GString,
};

use crate::{Application, File};

pub trait ApplicationExtManual {
    /// Runs the application.
    ///
    /// This function is intended to be run from `main()` and its return value
    /// is intended to be returned by `main()`. Although you are expected to pass
    /// the `argc`, `argv` parameters from `main()` to this function, it is possible
    /// to pass [`None`] if `argv` is not available or commandline handling is not
    /// required. Note that on Windows, `argc` and `argv` are ignored, and
    /// `g_win32_get_command_line()` is called internally (for proper support
    /// of Unicode commandline arguments).
    ///
    /// [`Application`][crate::Application] will attempt to parse the commandline arguments. You
    /// can add commandline flags to the list of recognised options by way of
    /// `g_application_add_main_option_entries()`. After this, the
    /// [`handle-local-options`][struct@crate::Application#handle-local-options] signal is emitted, from which the
    /// application can inspect the values of its `GOptionEntrys`.
    ///
    /// [`handle-local-options`][struct@crate::Application#handle-local-options] is a good place to handle options
    /// such as `--version`, where an immediate reply from the local process is
    /// desired (instead of communicating with an already-running instance).
    /// A [`handle-local-options`][struct@crate::Application#handle-local-options] handler can stop further processing
    /// by returning a non-negative value, which then becomes the exit status of
    /// the process.
    ///
    /// What happens next depends on the flags: if
    /// [`ApplicationFlags::HANDLES_COMMAND_LINE`][crate::ApplicationFlags::HANDLES_COMMAND_LINE] was specified then the remaining
    /// commandline arguments are sent to the primary instance, where a
    /// [`command-line`][struct@crate::Application#command-line] signal is emitted. Otherwise, the
    /// remaining commandline arguments are assumed to be a list of files.
    /// If there are no files listed, the application is activated via the
    /// [`activate`][struct@crate::Application#activate] signal. If there are one or more files, and
    /// [`ApplicationFlags::HANDLES_OPEN`][crate::ApplicationFlags::HANDLES_OPEN] was specified then the files are opened
    /// via the [`open`][struct@crate::Application#open] signal.
    ///
    /// If you are interested in doing more complicated local handling of the
    /// commandline then you should implement your own [`Application`][crate::Application] subclass
    /// and override `local_command_line()`. In this case, you most likely want
    /// to return [`true`] from your `local_command_line()` implementation to
    /// suppress the default handling. See
    /// [gapplication-example-cmdline2.c][https://gitlab.gnome.org/GNOME/glib/-/blob/HEAD/gio/tests/gapplication-example-cmdline2.c]
    /// for an example.
    ///
    /// If, after the above is done, the use count of the application is zero
    /// then the exit status is returned immediately. If the use count is
    /// non-zero then the default main context is iterated until the use count
    /// falls to zero, at which point 0 is returned.
    ///
    /// If the [`ApplicationFlags::IS_SERVICE`][crate::ApplicationFlags::IS_SERVICE] flag is set, then the service will
    /// run for as much as 10 seconds with a use count of zero while waiting
    /// for the message that caused the activation to arrive. After that,
    /// if the use count falls to zero the application will exit immediately,
    /// except in the case that [`ApplicationExt::set_inactivity_timeout()`][crate::prelude::ApplicationExt::set_inactivity_timeout()] is in
    /// use.
    ///
    /// This function sets the prgname (`g_set_prgname()`), if not already set,
    /// to the basename of argv[0].
    ///
    /// Much like `g_main_loop_run()`, this function will acquire the main context
    /// for the duration that the application is running.
    ///
    /// Since 2.40, applications that are not explicitly flagged as services
    /// or launchers (ie: neither [`ApplicationFlags::IS_SERVICE`][crate::ApplicationFlags::IS_SERVICE] or
    /// [`ApplicationFlags::IS_LAUNCHER`][crate::ApplicationFlags::IS_LAUNCHER] are given as flags) will check (from the
    /// default handler for local_command_line) if "--gapplication-service"
    /// was given in the command line. If this flag is present then normal
    /// commandline processing is interrupted and the
    /// [`ApplicationFlags::IS_SERVICE`][crate::ApplicationFlags::IS_SERVICE] flag is set. This provides a "compromise"
    /// solution whereby running an application directly from the commandline
    /// will invoke it in the normal way (which can be useful for debugging)
    /// while still allowing applications to be D-Bus activated in service
    /// mode. The D-Bus service file should invoke the executable with
    /// "--gapplication-service" as the sole commandline argument. This
    /// approach is suitable for use by most graphical applications but
    /// should not be used from applications like editors that need precise
    /// control over when processes invoked via the commandline will exit and
    /// what their exit status will be.
    /// ## `argv`
    ///
    ///  the argv from `main()`, or [`None`]
    ///
    /// # Returns
    ///
    /// the exit status
    #[doc(alias = "g_application_run")]
    fn run(&self) -> ExitCode;
    #[doc(alias = "g_application_run")]
    fn run_with_args<S: AsRef<str>>(&self, args: &[S]) -> ExitCode;
    /// The ::open signal is emitted on the primary instance when there are
    /// files to open. See [`ApplicationExt::open()`][crate::prelude::ApplicationExt::open()] for more information.
    /// ## `files`
    /// an array of `GFiles`
    /// ## `hint`
    /// a hint provided by the calling instance
    fn connect_open<F: Fn(&Self, &[File], &str) + 'static>(&self, f: F) -> SignalHandlerId;

    /// Increases the use count of `self`.
    ///
    /// Use this function to indicate that the application has a reason to
    /// continue to run. For example, [`ApplicationExtManual::hold()`][crate::prelude::ApplicationExtManual::hold()] is called by GTK+
    /// when a toplevel window is on the screen.
    ///
    /// To cancel the hold, call [`ApplicationExtManual::release()`][crate::prelude::ApplicationExtManual::release()].
    #[doc(alias = "g_application_hold")]
    fn hold(&self) -> ApplicationHoldGuard;

    /// Increases the busy count of `self`.
    ///
    /// Use this function to indicate that the application is busy, for instance
    /// while a long running operation is pending.
    ///
    /// The busy state will be exposed to other processes, so a session shell will
    /// use that information to indicate the state to the user (e.g. with a
    /// spinner).
    ///
    /// To cancel the busy indication, use [`ApplicationExtManual::unmark_busy()`][crate::prelude::ApplicationExtManual::unmark_busy()].
    ///
    /// The application must be registered before calling this function.
    #[doc(alias = "g_application_mark_busy")]
    fn mark_busy(&self) -> ApplicationBusyGuard;
}

impl<O: IsA<Application>> ApplicationExtManual for O {
    fn run(&self) -> ExitCode {
        self.run_with_args(&std::env::args().collect::<Vec<_>>())
    }

    fn run_with_args<S: AsRef<str>>(&self, args: &[S]) -> ExitCode {
        let argv: Vec<&str> = args.iter().map(|a| a.as_ref()).collect();
        let argc = argv.len() as i32;
        let exit_code = unsafe {
            ffi::g_application_run(self.as_ref().to_glib_none().0, argc, argv.to_glib_none().0)
        };
        ExitCode::from(exit_code)
    }

    fn connect_open<F: Fn(&Self, &[File], &str) + 'static>(&self, f: F) -> SignalHandlerId {
        unsafe extern "C" fn open_trampoline<P, F: Fn(&P, &[File], &str) + 'static>(
            this: *mut ffi::GApplication,
            files: *const *mut ffi::GFile,
            n_files: libc::c_int,
            hint: *mut libc::c_char,
            f: glib::ffi::gpointer,
        ) where
            P: IsA<Application>,
        {
            let f: &F = &*(f as *const F);
            let files: Vec<File> = FromGlibContainer::from_glib_none_num(files, n_files as usize);
            f(
                Application::from_glib_borrow(this).unsafe_cast_ref(),
                &files,
                &GString::from_glib_borrow(hint),
            )
        }
        unsafe {
            let f: Box_<F> = Box_::new(f);
            connect_raw(
                self.as_ptr() as *mut _,
                b"open\0".as_ptr() as *const _,
                Some(transmute::<_, unsafe extern "C" fn()>(
                    open_trampoline::<Self, F> as *const (),
                )),
                Box_::into_raw(f),
            )
        }
    }

    fn hold(&self) -> ApplicationHoldGuard {
        unsafe {
            ffi::g_application_hold(self.as_ref().to_glib_none().0);
        }
        ApplicationHoldGuard(self.as_ref().downgrade())
    }

    fn mark_busy(&self) -> ApplicationBusyGuard {
        unsafe {
            ffi::g_application_mark_busy(self.as_ref().to_glib_none().0);
        }
        ApplicationBusyGuard(self.as_ref().downgrade())
    }
}

#[derive(Debug)]
#[must_use = "if unused the Application will immediately be released"]
pub struct ApplicationHoldGuard(glib::WeakRef<Application>);

impl Drop for ApplicationHoldGuard {
    #[inline]
    fn drop(&mut self) {
        if let Some(application) = self.0.upgrade() {
            unsafe {
                ffi::g_application_release(application.to_glib_none().0);
            }
        }
    }
}

#[derive(Debug)]
#[must_use = "if unused the Application will immediately be unmarked busy"]
pub struct ApplicationBusyGuard(glib::WeakRef<Application>);

impl Drop for ApplicationBusyGuard {
    #[inline]
    fn drop(&mut self) {
        if let Some(application) = self.0.upgrade() {
            unsafe {
                ffi::g_application_unmark_busy(application.to_glib_none().0);
            }
        }
    }
}