//! Routines for controlling module-device-restore.

// This file is part of the PulseAudio Rust language binding.
//
// Copyright (c) 2017 Lyndon Brown
//
// This library is free software; you can redistribute it and/or modify it under the terms of the
// GNU Lesser General Public License as published by the Free Software Foundation; either version
// 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
// even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License along with this library;
// if not, see <http://www.gnu.org/licenses/>.

use std;
use capi;
use std::os::raw::c_void;
use std::ptr::null_mut;
use super::{ContextInternal, Context};
use callbacks::ListResult;
use capi::pa_ext_device_restore_info as InfoInternal;

/// Stores information about one device in the device database that is maintained by
/// module-device-manager.
#[derive(Debug)]
pub struct Info {
    /// Device type sink or source?
    pub dtype: ::def::Device,
    /// The device index.
    pub index: u32,
    /// A set of formats.
    pub formats: Vec<::format::Info>,
}

impl Info {
    fn new_from_raw(p: *const InfoInternal) -> Self {
        assert!(!p.is_null());
        let src = unsafe { p.as_ref().unwrap() };

        let mut formats_vec = Vec::with_capacity(src.n_formats as usize);
        assert!(src.n_formats == 0 || !src.formats.is_null());
        for i in 0..src.n_formats as isize {
            let indexed_ptr = unsafe { (*src.formats.offset(i)) as *mut ::format::InfoInternal };
            if !indexed_ptr.is_null() {
                formats_vec.push(::format::Info::from_raw_weak(indexed_ptr));
            }
        }

        Info {
            dtype: src.dtype,
            index: src.index,
            formats: formats_vec,
        }
    }
}

/// A wrapper object providing device restore routines to a context.
/// Note: Saves a copy of active multi-use closure callbacks, which it frees on drop.
pub struct DeviceRestore {
    context: *mut ContextInternal,
    /// Multi-use callback closure pointers
    cb_ptrs: CallbackPointers,
}

/// Holds copies of callback closure pointers, for those that are "multi-use" (may be fired multiple
/// times), for freeing at the appropriate time.
#[derive(Default)]
struct CallbackPointers {
    subscribe: SubscribeCb,
}

type SubscribeCb = ::callbacks::MultiUseCallback<FnMut(::def::Device, u32),
    extern "C" fn(*mut ContextInternal, ::def::Device, u32, *mut c_void)>;

impl Context {
    /// Returns a device restore object linked to the current context, giving access to device
    /// restore routines. See [`::context::ext_device_restore`](ext_device_restore/index.html).
    pub fn device_restore(&self) -> DeviceRestore {
        unsafe { capi::pa_context_ref(self.ptr) };
        DeviceRestore::from_raw(self.ptr)
    }
}

impl DeviceRestore {
    /// Create a new `DeviceManager` from an existing
    /// [`ContextInternal`](../struct.ContextInternal.html) pointer.
    fn from_raw(context: *mut ContextInternal) -> Self {
        Self { context: context, cb_ptrs: Default::default() }
    }

    /// Test if this extension module is available in the server.
    ///
    /// The callback must accept an integer, which indicates version.
    pub fn test<F>(&mut self, callback: F) -> ::operation::Operation
        where F: FnMut(u32) + 'static
    {
        let cb_data: *mut c_void = {
            // WARNING: Type must be explicit here, else compiles but seg faults :/
            let boxed: *mut Box<FnMut(u32)> =
                Box::into_raw(Box::new(Box::new(callback)));
            boxed as *mut c_void
        };
        let ptr = unsafe { capi::pa_ext_device_restore_test(self.context,
            Some(super::ext_test_cb_proxy), cb_data) };
        assert!(!ptr.is_null());
        ::operation::Operation::from_raw(ptr)
    }

    /// Subscribe to changes in the device database.
    ///
    /// The callback must accept a `bool`, which indicates success.
    pub fn subscribe<F>(&mut self, enable: bool, callback: F) -> ::operation::Operation
        where F: FnMut(bool) + 'static
    {
        let cb_data: *mut c_void = {
            // WARNING: Type must be explicit here, else compiles but seg faults :/
            let boxed: *mut Box<FnMut(bool)> = Box::into_raw(Box::new(Box::new(callback)));
            boxed as *mut c_void
        };
        let ptr = unsafe { capi::pa_ext_device_restore_subscribe(self.context, enable as i32,
            Some(super::success_cb_proxy), cb_data) };
        assert!(!ptr.is_null());
        ::operation::Operation::from_raw(ptr)
    }

    /// Set the subscription callback that is called when [`subscribe`](#method.subscribe) was
    /// called.
    ///
    /// The callback must accept two parameters, firstly a [`::def::Device`] variant, and secondly an
    /// integer index.
    ///
    /// [`::def::Device`]: ../../def/enum.Device.html
    pub fn set_subscribe_cb<F>(&mut self, callback: F)
        where F: FnMut(::def::Device, u32) + 'static
    {
        let saved = &mut self.cb_ptrs.subscribe;
        *saved = SubscribeCb::new(Some(Box::new(callback)));
        let (cb_fn, cb_data) = saved.get_capi_params(ext_subscribe_cb_proxy);
        unsafe { capi::pa_ext_device_restore_set_subscribe_cb(self.context, cb_fn, cb_data); }
    }

    /// Read the formats for all present devices from the device database.
    pub fn read_formats_all<F>(&mut self, callback: F) -> ::operation::Operation
        where F: FnMut(ListResult<&Info>) + 'static
    {
        let cb_data: *mut c_void = {
            // WARNING: Type must be explicit here, else compiles but seg faults :/
            let boxed: *mut Box<FnMut(ListResult<&Info>)> =
                Box::into_raw(Box::new(Box::new(callback)));
            boxed as *mut c_void
        };
        let ptr = unsafe { capi::pa_ext_device_restore_read_formats_all(self.context,
            Some(read_list_cb_proxy), cb_data) };
        assert!(!ptr.is_null());
        ::operation::Operation::from_raw(ptr)
    }

    /// Read an entry from the device database.
    pub fn read_formats<F>(&mut self, type_: ::def::Device, index: u32, callback: F
        ) -> ::operation::Operation
        where F: FnMut(ListResult<&Info>) + 'static
    {
        let cb_data: *mut c_void = {
            // WARNING: Type must be explicit here, else compiles but seg faults :/
            let boxed: *mut Box<FnMut(ListResult<&Info>)> =
                Box::into_raw(Box::new(Box::new(callback)));
            boxed as *mut c_void
        };
        let ptr = unsafe { capi::pa_ext_device_restore_read_formats(self.context, type_, index,
            Some(read_list_cb_proxy), cb_data) };
        assert!(!ptr.is_null());
        ::operation::Operation::from_raw(ptr)
    }

    /// Read an entry from the device database.
    ///
    /// The callback must accept a `bool`, which indicates success.
    pub fn save_formats<F>(&mut self, type_: ::def::Device, index: u32,
        formats: &mut [&mut ::format::Info], callback: F) -> ::operation::Operation
        where F: FnMut(bool) + 'static
    {
        // Capture array of pointers to the above ::format::InfoInternal objects
        let mut format_ptrs: Vec<*mut capi::pa_format_info> = Vec::with_capacity(formats.len());
        for format in formats {
            format_ptrs.push(unsafe { std::mem::transmute(&format.ptr) });
        }

        let cb_data: *mut c_void = {
            // WARNING: Type must be explicit here, else compiles but seg faults :/
            let boxed: *mut Box<FnMut(bool)> = Box::into_raw(Box::new(Box::new(callback)));
            boxed as *mut c_void
        };
        let ptr = unsafe {
            capi::pa_ext_device_restore_save_formats(self.context, type_, index,
                format_ptrs.len() as u8, format_ptrs.as_ptr(), Some(super::success_cb_proxy),
                cb_data)
        };
        assert!(!ptr.is_null());
        ::operation::Operation::from_raw(ptr)
    }
}

impl Drop for DeviceRestore {
    fn drop(&mut self) {
        unsafe { capi::pa_context_unref(self.context) };
        self.context = null_mut::<ContextInternal>();
    }
}

/// Proxy for the extension subscribe callback.
/// Warning: This is for multi-use cases! It does **not** destroy the actual closure callback, which
/// must be accomplished separately to avoid a memory leak.
extern "C"
fn ext_subscribe_cb_proxy(_: *mut ContextInternal, type_: ::def::Device, index: u32,
    userdata: *mut c_void)
{
    assert!(!userdata.is_null());
    // Note, does NOT destroy closure callback after use - only handles pointer
    let callback = unsafe { &mut *(userdata as *mut Box<FnMut(::def::Device, u32)>) };
    callback(type_, index);
}

/// Proxy for read list callbacks.
/// Warning: This is for list cases only! On EOL it destroys the actual closure callback.
extern "C"
fn read_list_cb_proxy(_: *mut ContextInternal, i: *const InfoInternal, eol: i32,
    userdata: *mut c_void)
{
    assert!(!userdata.is_null());
    match eol {
        0 => { // Give item to real callback, do NOT destroy it
            assert!(!i.is_null());
            let callback = unsafe { &mut *(userdata as *mut Box<FnMut(ListResult<&Info>)>) };
            let obj = Info::new_from_raw(i);
            callback(ListResult::Item(&obj));
        },
        _ => { // End-of-list or failure, signal to real callback, do now destroy it
            let mut callback = unsafe {
                Box::from_raw(userdata as *mut Box<FnMut(ListResult<&Info>)>)
            };
            callback(match eol < 0 { false => ListResult::End, true => ListResult::Error });
        },
    }
}