package notify

import (
	"strings"
	"sync"
	"time"
)

const pendingWaitShardCount = 64

type pendingWaitShard struct {
	mu    sync.Mutex
	waits map[uint64]*WaitMsg
}

type pendingWaitPool struct {
	shards [pendingWaitShardCount]pendingWaitShard
}

func newPendingWaitPool() *pendingWaitPool {
	pool := &pendingWaitPool{}
	for i := range pool.shards {
		pool.shards[i].waits = make(map[uint64]*WaitMsg)
	}
	return pool
}

func (p *pendingWaitPool) createAndStore(msg TransferMsg) WaitMsg {
	return p.createAndStoreWithScope(msg, "")
}

func (p *pendingWaitPool) shard(id uint64) *pendingWaitShard {
	if p == nil {
		return nil
	}
	return &p.shards[id%pendingWaitShardCount]
}

func normalizePendingWaitScope(scope string) string {
	return strings.TrimSpace(scope)
}

func (p *pendingWaitPool) createAndStoreWithScope(msg TransferMsg, scope string) WaitMsg {
	wait := WaitMsg{
		TransferMsg: msg,
		Time:        time.Now(),
		Reply:       make(chan Message, 1),
		scope:       normalizePendingWaitScope(scope),
	}
	if shard := p.shard(wait.ID); shard != nil {
		shard.mu.Lock()
		shard.waits[wait.ID] = &wait
		shard.mu.Unlock()
	}
	return wait
}

func (p *pendingWaitPool) deliver(id uint64, message Message) bool {
	return p.deliverWithScopes(id, nil, message)
}

func (p *pendingWaitPool) deliverWithScopes(id uint64, scopes []string, message Message) bool {
	if p == nil {
		return false
	}
	shard := p.shard(id)
	if shard == nil {
		return false
	}
	shard.mu.Lock()
	wait := shard.waits[id]
	if wait == nil || !pendingWaitScopeMatches(wait.scope, scopes) {
		shard.mu.Unlock()
		return false
	}
	delete(shard.waits, id)
	shard.mu.Unlock()
	return safeSendWaitMessage(wait.Reply, message)
}

func pendingWaitScopeMatches(waitScope string, scopes []string) bool {
	waitScope = normalizePendingWaitScope(waitScope)
	if waitScope == "" {
		return true
	}
	for _, scope := range scopes {
		if waitScope == normalizePendingWaitScope(scope) {
			return true
		}
	}
	return false
}

func (p *pendingWaitPool) removeAndClose(id uint64) {
	if p == nil {
		return
	}
	shard := p.shard(id)
	if shard == nil {
		return
	}
	shard.mu.Lock()
	wait := shard.waits[id]
	if wait != nil {
		delete(shard.waits, id)
	}
	shard.mu.Unlock()
	if wait == nil {
		return
	}
	safeCloseWaitReply(wait.Reply)
}

func (p *pendingWaitPool) closeAll() {
	if p == nil {
		return
	}
	for i := range p.shards {
		shard := &p.shards[i]
		shard.mu.Lock()
		waits := make([]*WaitMsg, 0, len(shard.waits))
		for id, wait := range shard.waits {
			delete(shard.waits, id)
			if wait != nil {
				waits = append(waits, wait)
			}
		}
		shard.mu.Unlock()
		for _, wait := range waits {
			safeCloseWaitReply(wait.Reply)
		}
	}
}

func (p *pendingWaitPool) closeScope(scope string) {
	if p == nil {
		return
	}
	scope = normalizePendingWaitScope(scope)
	for i := range p.shards {
		shard := &p.shards[i]
		shard.mu.Lock()
		waits := make([]*WaitMsg, 0)
		for id, wait := range shard.waits {
			if wait != nil && wait.scope == scope {
				delete(shard.waits, id)
				waits = append(waits, wait)
			}
		}
		shard.mu.Unlock()
		for _, wait := range waits {
			safeCloseWaitReply(wait.Reply)
		}
	}
}

func (p *pendingWaitPool) closeServerScopeFamily(scope string) {
	if p == nil {
		return
	}
	base := normalizeFileScope(scope)
	for i := range p.shards {
		shard := &p.shards[i]
		shard.mu.Lock()
		waits := make([]*WaitMsg, 0)
		for id, wait := range shard.waits {
			if wait != nil && scopeBelongsToServerFileScope(wait.scope, base) {
				delete(shard.waits, id)
				waits = append(waits, wait)
			}
		}
		shard.mu.Unlock()
		for _, wait := range waits {
			safeCloseWaitReply(wait.Reply)
		}
	}
}

func (p *pendingWaitPool) cleanupExpired(maxKeepSeconds int64, now time.Time) {
	if p == nil || maxKeepSeconds <= 0 {
		return
	}
	maxKeep := time.Duration(maxKeepSeconds) * time.Second
	for i := range p.shards {
		shard := &p.shards[i]
		shard.mu.Lock()
		waits := make([]*WaitMsg, 0)
		for id, wait := range shard.waits {
			if wait != nil && wait.Time.Add(maxKeep).Before(now) {
				delete(shard.waits, id)
				waits = append(waits, wait)
			}
		}
		shard.mu.Unlock()
		for _, wait := range waits {
			safeCloseWaitReply(wait.Reply)
		}
	}
}

func safeSendWaitMessage(ch chan Message, message Message) (sent bool) {
	defer func() {
		if recover() != nil {
			sent = false
		}
	}()
	select {
	case ch <- message:
		return true
	default:
		return false
	}
}

func safeCloseWaitReply(ch chan Message) {
	defer func() {
		_ = recover()
	}()
	close(ch)
}

func pendingWaitClosedError(stopCh <-chan struct{}) error {
	return pendingWaitClosedErrorWith(stopCh, nil)
}

func pendingWaitClosedErrorWith(stopCh <-chan struct{}, detached error) error {
	if stopCh != nil {
		select {
		case <-stopCh:
			return errServiceShutdown
		default:
		}
	}
	if detached != nil {
		return detached
	}
	return errTransportDetached
}

func (c *ClientCommon) getPendingWaitPool() *pendingWaitPool {
	return c.getLogicalSessionState().pendingWaits
}

func (s *ServerCommon) getPendingWaitPool() *pendingWaitPool {
	return s.getLogicalSessionState().pendingWaits
}