package notify

import (
	"context"
	"fmt"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
)

type streamRuntime struct {
	rolePrefix string
	seq        atomic.Uint64
	dataSeq    atomic.Uint64

	mu      sync.RWMutex
	handler func(StreamAcceptInfo) error
	streams map[string]*streamHandle
	data    map[string]*streamHandle
	cfg     streamConfig
	flow    *streamFlowController
}

func newStreamRuntime(rolePrefix string) *streamRuntime {
	cfg := defaultStreamConfig()
	return &streamRuntime{
		rolePrefix: rolePrefix,
		streams:    make(map[string]*streamHandle),
		data:       make(map[string]*streamHandle),
		cfg:        cfg,
		flow:       newStreamFlowController(cfg),
	}
}

func (r *streamRuntime) nextID() string {
	if r == nil {
		return ""
	}
	return fmt.Sprintf("%s-%d", r.rolePrefix, r.seq.Add(1))
}

func (r *streamRuntime) nextDataID() uint64 {
	if r == nil {
		return 0
	}
	return r.dataSeq.Add(1)
}

func (r *streamRuntime) setHandler(fn func(StreamAcceptInfo) error) {
	if r == nil {
		return
	}
	r.mu.Lock()
	defer r.mu.Unlock()
	r.handler = fn
}

func (r *streamRuntime) handlerSnapshot() func(StreamAcceptInfo) error {
	if r == nil {
		return nil
	}
	r.mu.RLock()
	defer r.mu.RUnlock()
	return r.handler
}

func (r *streamRuntime) register(scope string, stream *streamHandle) error {
	if r == nil {
		return errStreamRuntimeNil
	}
	if stream == nil || stream.id == "" {
		return errStreamIDEmpty
	}
	key := streamRuntimeKey(scope, stream.id)
	dataKey := streamRuntimeDataKey(scope, stream.dataID)
	r.mu.Lock()
	defer r.mu.Unlock()
	if _, ok := r.streams[key]; ok {
		return errStreamAlreadyExists
	}
	if stream.dataID != 0 {
		if _, ok := r.data[dataKey]; ok {
			return errStreamAlreadyExists
		}
		r.data[dataKey] = stream
	}
	r.streams[key] = stream
	return nil
}

func (r *streamRuntime) lookup(scope string, streamID string) (*streamHandle, bool) {
	if r == nil || streamID == "" {
		return nil, false
	}
	key := streamRuntimeKey(scope, streamID)
	r.mu.RLock()
	defer r.mu.RUnlock()
	stream, ok := r.streams[key]
	return stream, ok
}

func (r *streamRuntime) lookupByDataID(scope string, dataID uint64) (*streamHandle, bool) {
	if r == nil || dataID == 0 {
		return nil, false
	}
	key := streamRuntimeDataKey(scope, dataID)
	r.mu.RLock()
	defer r.mu.RUnlock()
	stream, ok := r.data[key]
	return stream, ok
}

func (r *streamRuntime) remove(scope string, streamID string) {
	if r == nil || streamID == "" {
		return
	}
	key := streamRuntimeKey(scope, streamID)
	r.mu.Lock()
	defer r.mu.Unlock()
	if stream := r.streams[key]; stream != nil && stream.dataID != 0 {
		delete(r.data, streamRuntimeDataKey(scope, stream.dataID))
	}
	delete(r.streams, key)
}

func (r *streamRuntime) acquireOutbound(ctx context.Context, size int) (func(), error) {
	if r == nil || r.flow == nil {
		return func() {}, nil
	}
	return r.flow.acquire(ctx, size)
}

func (r *streamRuntime) snapshots() []StreamSnapshot {
	if r == nil {
		return nil
	}
	r.mu.RLock()
	snapshots := make([]StreamSnapshot, 0, len(r.streams))
	for _, stream := range r.streams {
		if stream == nil {
			continue
		}
		snapshots = append(snapshots, stream.snapshot())
	}
	r.mu.RUnlock()
	sortStreamSnapshots(snapshots)
	return snapshots
}

func (r *streamRuntime) closeAll(err error) {
	r.closeMatching(func(string) bool { return true }, err)
}

func (r *streamRuntime) closeScope(scope string, err error) {
	scope = normalizeFileScope(scope)
	r.closeMatching(func(key string) bool {
		return strings.HasPrefix(key, scope+"\x00")
	}, err)
}

func (r *streamRuntime) closeMatching(match func(string) bool, err error) {
	if r == nil || match == nil {
		return
	}
	resetErr := streamRuntimeCloseError(err)
	r.mu.RLock()
	streams := make([]*streamHandle, 0, len(r.streams))
	for key, stream := range r.streams {
		if stream == nil || !match(key) {
			continue
		}
		streams = append(streams, stream)
	}
	r.mu.RUnlock()
	for _, stream := range streams {
		stream.markReset(resetErr)
	}
}

func streamRuntimeKey(scope string, streamID string) string {
	return normalizeFileScope(scope) + "\x00" + streamID
}

func streamRuntimeDataKey(scope string, dataID uint64) string {
	return normalizeFileScope(scope) + "\x01" + strconv.FormatUint(dataID, 10)
}

func (c *ClientCommon) getStreamRuntime() *streamRuntime {
	if c == nil {
		return nil
	}
	return c.streamRuntime
}

func (s *ServerCommon) getStreamRuntime() *streamRuntime {
	if s == nil {
		return nil
	}
	return s.streamRuntime
}