package ble

import "C"

import (
	"encoding/binary"
	"fmt"
	"runtime"
	"sync"
	"time"
	"unsafe"

	"git.wow.st/gmp/ble/gatt"
	"git.wow.st/gmp/ble/ns"
)

type BLE struct {
	state       ns.CBManagerState
	events      chan interface{}
	peripherals Peripherals
	cd          *ns.CBDelegate
	cm          *ns.CBCentralManager

	ready, wantScan bool
	sync.Mutex

	connections Connections
}

var cdLookup map[unsafe.Pointer]*BLE
var pdLookup map[unsafe.Pointer]*BLE
var pcache map[unsafe.Pointer]*Peripheral


type State string

type Peripheral struct {
	Name       string
	RSSI       int
	Identifier string

	p *ns.CBPeripheral
}

func peripheralName(p *ns.CBPeripheral) string {
	var ret string
	nsname := p.Name()
	if nsname.Ptr() != nil {
		ret = nsname.String()
	}
	return ret
}

func newPeripheral(x *ns.CBPeripheral) Peripheral {
	if pcache == nil {
		pcache = make(map[unsafe.Pointer]*Peripheral)
	} else {
		if ret,ok := pcache[x.Ptr()]; ok {
			return *ret
		}
	}
	ret := Peripheral{
		Name:       peripheralName(x),
		Identifier: x.Identifier().UUIDString().String(),
		p:          x,
	}
	pcache[x.Ptr()] = &ret
	return ret
}

type PeripheralListItem struct {
	p    Peripheral
	seen time.Time
}

type Peripherals struct {
	items []PeripheralListItem
	sync.Mutex
}

type ConnectionListItem struct {
	p     Peripheral
	state chan string
}

type Connections struct {
	items []ConnectionListItem
	close chan struct{}
	sync.Mutex
}

func (c *Connections) UpdateState(p Peripheral, s string) {
	var ch chan string
	c.Lock()
	for _, item := range c.items {
		if p.Identifier == item.p.Identifier {
			ch = item.state
		}
	}
	c.Unlock()
	ch <- s
}

func (ps *Peripherals) Add(x Peripheral) bool {
	ps.Lock()
	defer ps.Unlock()
	found := false
	for n, item := range ps.items {
		if item.p.Identifier == x.Identifier {
			item.p = x
			item.seen = time.Now()
			ps.items[n] = item
			found = true
			break
		}
	}
	if found {
		return false
	}
	//take ownership of this Objective-C object
	x.p.Retain()
	runtime.SetFinalizer(x.p, nil)
	x.p.GC()
	item := PeripheralListItem{p: x, seen: time.Now()}
	ps.items = append(ps.items, item)
	return true
}

func (cs *Connections) Add(x ConnectionListItem) bool {
	cs.Lock()
	defer cs.Unlock()
	found := false
	for _, item := range cs.items {
		if item.p.Identifier == x.p.Identifier {
			// are we allowed to have multiple connections to the same peripheral?
			return false
		}
	}
	if found {
		return false
	}
	cs.items = append(cs.items, x)
	return true
}

type UpdateStateEvent struct {
	State string
}

type DiscoverPeripheralEvent struct {
	Peripheral Peripheral
}

type DiscoverServiceEvent struct {
	Peripheral Peripheral
	Gatt gatt.Service
	Service *ns.CBService
}

type DiscoverCharacteristicEvent struct {
	Peripheral Peripheral
	Gatt gatt.Characteristic
	Service *ns.CBService
	Characteristic *ns.CBCharacteristic
}

type UpdateValueEvent struct {
	Data []byte
}

type ConnectEvent struct {
	Peripheral Peripheral
}
type ConnectTimeoutEvent struct {
	Peripheral Peripheral
}

type UpdageValueEvent struct {
	Peripheral Peripheral
	Characteristic gatt.Characteristic
}

func (b *BLE) Events() chan interface{} {
	return b.events
}

func stringState(x ns.CBManagerState) string {
	switch x {
	case (ns.CBManagerState)(ns.CBManagerStateResetting):
		return "resetting"
	case (ns.CBManagerState)(ns.CBManagerStateUnsupported):
		return "unsupported"
	case (ns.CBManagerState)(ns.CBManagerStateUnauthorized):
		return "unauthorized"
	case (ns.CBManagerState)(ns.CBManagerStatePoweredOff):
		return "powered off"
	case (ns.CBManagerState)(ns.CBManagerStatePoweredOn):
		return "powered on"
	case (ns.CBManagerState)(ns.CBManagerStateUnknown):
		return "unknown"
	default:
		return "no state"
	}
}

func (b *BLE) State() string {
	b.Lock()
	defer b.Unlock()
	return stringState(b.state)
}

func (b *BLE) setState(x ns.CBManagerState) {
	b.Lock()
	defer b.Unlock()
	b.state = x
	if b.ready && b.wantScan {
		fmt.Printf("Go: Scanning\n")
		b.cm.ScanForPeripheralsWithServices(nil, nil)
		b.wantScan = false
	}
}

func (b *BLE) Scan() {
	b.Lock()
	defer b.Unlock()
	if b.state != (ns.CBManagerState)(ns.CBManagerStatePoweredOn) {
		b.wantScan = true
	} else {
		b.peripherals.Lock()
		b.peripherals.items = b.peripherals.items[:0]
		b.peripherals.Unlock()
		fmt.Printf("Go: Scanning\n")
		b.cm.ScanForPeripheralsWithServices(nil, nil)
	}
}

func (b *BLE) StopScan() {
	b.Lock()
	if !b.ready {
		b.Unlock()
		return
	}
	b.Unlock()
	fmt.Printf("Go: stopping scan\n")
	b.cm.StopScan()
}

func CancelConnection(p Peripheral) {
	b := pdLookup[p.p.Ptr()]
	b.connections.Lock()
	var ch chan string;
	for _, item := range b.connections.items {
		if item.p.Identifier == p.Identifier {
			ch = item.state
			break
		}
	}
	b.connections.Unlock()
	if ch != nil {
		ch <- "cancel"
	}
}

func connectTracker(b *BLE, x ConnectionListItem) bool {
	fmt.Printf("connectTracker(): %s\n", x.p.Name)
	b.connections.Lock()
	for _, item := range b.connections.items {
		if item.p.Identifier == x.p.Identifier {
			fmt.Printf("connectTracker(): already connecting to %s\n", x.p.Name)
			b.connections.Unlock()
			return true
		}
	}
	b.connections.items = append(b.connections.items, x)
	b.connections.Unlock()
	fmt.Printf("BLE.Connect(): calling cm.ConnectPeripheral(%p)\n", x.p.p.Ptr())
	b.cm.ConnectPeripheral(x.p.p, nil)

	cancel := func() {
		b.cm.CancelPeripheralConnection(x.p.p)
		b.connections.Lock()
		for n, item := range b.connections.items {
			if item.p.Identifier == x.p.Identifier {
				b.connections.items = append(b.connections.items[:n], b.connections.items[n+1:]...)
			}
		}
		b.connections.Unlock()
	}

	go func() {
		tick := time.NewTicker(time.Second * 5)
		select {
		case <-b.connections.close:
			fmt.Printf("connectTracker(): Closing connection to %s\n", x.p.Name)
			b.cm.CancelPeripheralConnection(x.p.p)
		case <-tick.C:
			fmt.Printf("connectTracker(): Connection to %s timed out\n", x.p.Name)
			cancel()
			b.events <- ConnectTimeoutEvent{x.p}
		case state := <-x.state:
			if state == "cancel" {
				cancel()
			}
			fmt.Printf("connectTracker(): state %s\n", state)
		}
	}()
	return true
}

func (b *BLE) Connect(p Peripheral) bool {
	b.Lock()
	if !b.ready {
		b.Unlock()
		fmt.Printf("--BLE not ready\n")
		return false
	}
	b.Unlock()
	if p.p == nil {
		fmt.Printf("RetrievePeripheralsWithIdentifiers\n")
		ps := b.cm.RetrievePeripheralsWithIdentifiers(ns.NSArrayWithObjects(ns.NSUUIDAlloc().InitWithUUIDString(ns.NSStringWithGoString(p.Identifier))))
		if x := (int)(ps.Count()); x > 0 {
			fmt.Printf("--found %d\n", x)
			cbp := ps.ObjectAtIndex(0).CBPeripheral()
//NOTE: ns.ObjectAtIndex() calls SetFinalizer for us, which will be a problem
//later when we call GC(), so we first clear the finalizer here.
			runtime.SetFinalizer(cbp, nil)
			p = newPeripheral(cbp)
		} else {
			fmt.Printf("--none found\n")
			return false
		}
	}
	item := ConnectionListItem{p, make(chan string)}
	fmt.Printf("BLE.Connect() calling connectTracker\n")
	return connectTracker(b, item)
}

func Disconnect(p Peripheral) {
	b := pdLookup[p.p.Ptr()]
	found := false
	b.connections.Lock()
	for i, item := range b.connections.items {
		if item.p.Identifier == p.Identifier {
			found = true
			b.connections.items = append(b.connections.items[:i], b.connections.items[i+1:]...)
			break
		}
	}
	b.connections.Unlock()
	if !found {
		return
	}
	b.cm.CancelPeripheralConnection(p.p)
}

func updateState(c *ns.CBCentralManager) {
	b := cdLookup[c.Ptr()]
	st := c.CBManager.State()
	if st == (ns.CBManagerState)(ns.CBManagerStatePoweredOn) {
		b.ready = true
		b.connections.close = make(chan struct{})
	} else {
		if b.ready {
			close(b.connections.close)
			b.connections.Lock()
			for _, item := range b.connections.items {
				fmt.Printf("Closing connection to %s\n", item.p.Name)
				b.cm.CancelPeripheralConnection(item.p.p)
			}
			b.connections.items = b.connections.items[:0]
			b.connections.Unlock()
			b.ready = false
		}
	}
	b.setState(st)
	b.events <- UpdateStateEvent{State: stringState(st)}
}

func discoverPeripheral(c *ns.CBCentralManager, p *ns.CBPeripheral, d *ns.NSDictionary, rssi *ns.NSNumber) {
	b := cdLookup[c.Ptr()]
	peripheral := newPeripheral(p)
	peripheral.RSSI = (int)(rssi.IntValue())
	_discoverPeripheral(b, peripheral)
}

func _discoverPeripheral(b *BLE, peripheral Peripheral) {
	if peripheral.Name == "" {
		return
	}
	if ok := b.peripherals.Add(peripheral); ok {
		pdLookup[peripheral.p.Ptr()] = b
		b.events <- DiscoverPeripheralEvent{Peripheral: peripheral}
	}
}

func connectPeripheral(c *ns.CBCentralManager, p *ns.CBPeripheral) {
	fmt.Printf("Did connect peripheral\n")
	b := cdLookup[c.Ptr()]

	// set ourselves up as a peripheral delegate
	p.SetDelegate(b.cd)

	uuidstring := p.Identifier().UUIDString().String()
	peripheral := newPeripheral(p)
	found := false

	b.peripherals.Lock()
	for _, item := range b.peripherals.items {
		if item.p.Identifier == uuidstring {
			peripheral = item.p
			found = true
			break
		}
	}
	b.peripherals.Unlock()

	if !found {
		peripheral.Name = peripheralName(p)
		if ok := b.peripherals.Add(peripheral); ok {
			pdLookup[p.Ptr()] = b
		}
	}

	b.connections.UpdateState(peripheral, "connected")
	b.events <- ConnectEvent{peripheral}
	fmt.Printf("Go: connectPeripheral returning\n")
}

func (x Peripheral) DiscoverServices() {
	fmt.Printf("Discovering services on %s\n", x.Name)
	p := x.p

	// discover all services on this device

	p.DiscoverServices(nil)
}

func discoverServices(p *ns.CBPeripheral, e *ns.NSError) {
	b := pdLookup[p.Ptr()]
	fmt.Printf("Did discover services\n")
	p.Services().ObjectEnumerator().ForIn(func(o *ns.Id) bool {
		serv := o.CBService()
		uuid := serv.UUID().UUIDString().String()
		b.events <-DiscoverServiceEvent{
			Peripheral: newPeripheral(p),
			Gatt: gatt.Service{uuid},
			Service: serv,
		}
		return true
	})
	fmt.Printf("Go: discoverServices returning\n")
}

func hr(d *ns.NSData) int {
	if l := int(d.Length()); l < 4 {
		return 0
	}
	x := C.GoBytes(d.Bytes(), 4)
	flags := x[0]
	if flags&0x80 != 0 { // uint16 format
		return int(binary.BigEndian.Uint16(x[1:2]))
	} else {
		return int(x[1])
	}
}

func (p Peripheral) DiscoverCharacteristics(serv *ns.CBService) {
	p.p.DiscoverCharacteristics(nil, serv)
}

func discoverCharacteristics(p *ns.CBPeripheral, s *ns.CBService, e *ns.NSError) {
	b := pdLookup[p.Ptr()]
	fmt.Printf("Did discover characteristics\n")
	s.Characteristics().ObjectEnumerator().ForIn(func(o *ns.Id) bool {
		chr := o.CBCharacteristic()
		chuuid := chr.UUID()
		fmt.Printf("------%s\n", chuuid.UUIDString())
		b.events <-DiscoverCharacteristicEvent{
			Peripheral: newPeripheral(p),
			Service: s,
			Characteristic: chr,
			Gatt: gatt.Characteristic{chuuid.UUIDString().String()},
		}
		return true
	})
	fmt.Printf("Go: discoverCharacteristics returning\n")
}

func (p Peripheral) SetNotifyValue(c *ns.CBCharacteristic) {
	p.p.SetNotifyValue(1, c)
}

func updateValue(p *ns.CBPeripheral, chr *ns.CBCharacteristic, e *ns.NSError) {
	b := pdLookup[p.Ptr()]
	v := chr.Value()
	b.events <-UpdateValueEvent{
		Data: C.GoBytes(v.Bytes(), (C.int)(v.Length())),
	}
}

var (
	hrm_uuid  *ns.CBUUID
	hrv_uuid  *ns.CBUUID
	info_uuid *ns.CBUUID

	gble *BLE
)

func NewBLE() *BLE {
	ps := Peripherals{items: make([]PeripheralListItem, 0)}
	ble := &BLE{events: make(chan interface{}), peripherals: ps}
	gble = ble

	queue := ns.DispatchQueueCreate(ns.CharWithGoString("go_hrm_queue"), nil)

	cd := ns.CBDelegateAlloc()

	cd.CentralManagerDidUpdateStateCallback(updateState)
	cd.CentralManagerDidDiscoverPeripheralCallback(discoverPeripheral)
	cd.CentralManagerDidConnectPeripheralCallback(connectPeripheral)
	cd.PeripheralDidDiscoverServicesCallback(discoverServices)
	cd.PeripheralDidDiscoverCharacteristicsForServiceCallback(discoverCharacteristics)
	cd.PeripheralDidUpdateValueForCharacteristicCallback(updateValue)

	hrm_uuid = ns.CBUUIDWithGoString("180D")
	hrv_uuid = ns.CBUUIDWithGoString("2A37")
	info_uuid = ns.CBUUIDWithGoString("180A")

	ble.cd = cd
	if cdLookup == nil {
		cdLookup = make(map[unsafe.Pointer]*BLE, 0)
	}
	if pdLookup == nil {
		pdLookup = make(map[unsafe.Pointer]*BLE, 0)
	}

	// We defined our own queue because this won't work on the main queue.
	ble.cm = ns.CBCentralManagerAlloc().InitWithDelegateQueue(cd, queue)
	cdLookup[ble.cm.Ptr()] = ble

	// For debugging purposes, run GC every second to make sure things are
	// not over-released.
	go func() {
		for {
			runtime.GC()
			time.Sleep(time.Second * 30)
		}
	}()
	return ble
}