package concurrent

import (
	"fmt"
	"github.com/tursom/GoCollections/exceptions"
	"sync"
)

type ReentrantRWLock struct {
	lock      sync.Mutex
	rlock     sync.RWMutex
	cond      sync.Cond
	recursion int32
	host      int64
}

func NewReentrantRWLock() *ReentrantRWLock {
	res := &ReentrantRWLock{
		recursion: 0,
		host:      0,
	}
	res.cond = *sync.NewCond(&res.lock)
	return res
}

func (rt *ReentrantRWLock) Lock() {
	id := GetGoroutineID()
	rt.lock.Lock()
	defer rt.lock.Unlock()

	if rt.host == id {
		rt.recursion++
		return
	}

	for rt.recursion != 0 {
		rt.cond.Wait()
	}
	rt.host = id
	rt.recursion = 1
	rt.rlock.Lock()
}

func (rt *ReentrantRWLock) Unlock() {
	rt.lock.Lock()
	defer rt.lock.Unlock()

	if rt.recursion == 0 || rt.host != GetGoroutineID() {
		panic(exceptions.NewWrongCallHostException(fmt.Sprintf("the wrong call host: (%d); current_id: %d; recursion: %d", rt.host, GetGoroutineID(), rt.recursion)))
	}

	rt.recursion--
	if rt.recursion == 0 {
		rt.rlock.Unlock()
		rt.cond.Signal()
	}
}

func (rt *ReentrantRWLock) RLock() {
	if rt.host == GetGoroutineID() {
		return
	}
	rt.rlock.RLock()
}

func (rt *ReentrantRWLock) RUnlock() {
	if rt.host == GetGoroutineID() {
		return
	}
	rt.rlock.RUnlock()
}