package store

import (
	"sort"
	"strings"
	"time"

	"github.com/google/uuid"
)

func (m *Memory) ListPeerDiscoveries(tenantID, status string) ([]*BGPPeerDiscovery, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	status = strings.TrimSpace(strings.ToLower(status))
	var out []*BGPPeerDiscovery
	for _, d := range m.peerDiscoveries {
		if d == nil || d.TenantID != tenantID {
			continue
		}
		if status != "" && !strings.EqualFold(d.Status, status) {
			continue
		}
		out = append(out, copyPeerDiscovery(d))
	}
	sort.Slice(out, func(i, j int) bool {
		return out[i].LastSeenAt.After(out[j].LastSeenAt)
	})
	return out, nil
}

func (m *Memory) GetPeerDiscovery(tenantID, id string) (*BGPPeerDiscovery, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	d, ok := m.peerDiscoveries[id]
	if !ok || d.TenantID != tenantID {
		return nil, ErrNotFound
	}
	return copyPeerDiscovery(d), nil
}

func (m *Memory) UpsertPeerDiscovery(tenantID string, in *PeerDiscoveryUpsert) (*BGPPeerDiscovery, error) {
	if in == nil {
		return nil, ErrInvalidInput
	}
	neighbor, ok := NormalizePeerNeighborString(in.Neighbor)
	if !ok {
		return nil, ErrInvalidInput
	}
	neighborID := strings.TrimSpace(in.NeighborID)
	seenAt := in.SeenAt
	if seenAt.IsZero() {
		seenAt = time.Now().UTC()
	}

	m.mu.Lock()
	defer m.mu.Unlock()
	if _, ok := m.tenants[tenantID]; !ok {
		return nil, ErrTenantScope
	}

	existing := m.findPeerDiscoveryLocked(tenantID, neighborID, neighbor, in.RemoteASN)
	if existing != nil {
		if existing.Status == PeerDiscoveryRejected {
			return copyPeerDiscovery(existing), nil
		}
		if existing.Status == PeerDiscoveryApproved {
			existing.SessionState = strings.TrimSpace(in.SessionState)
			existing.ProtocolName = strings.TrimSpace(in.ProtocolName)
			existing.LastSeenAt = seenAt
			if sp := strings.TrimSpace(in.SpeakerID); sp != "" {
				existing.SpeakerID = sp
			}
			return copyPeerDiscovery(existing), nil
		}
		existing.Neighbor = neighbor
		existing.RemoteASN = in.RemoteASN
		if neighborID != "" {
			existing.NeighborID = neighborID
		}
		existing.ProtocolName = strings.TrimSpace(in.ProtocolName)
		existing.SessionState = strings.TrimSpace(in.SessionState)
		existing.LastSeenAt = seenAt
		if sp := strings.TrimSpace(in.SpeakerID); sp != "" {
			existing.SpeakerID = sp
		}
		return copyPeerDiscovery(existing), nil
	}

	id := uuid.NewString()
	d := &BGPPeerDiscovery{
		ID:           id,
		TenantID:     tenantID,
		SpeakerID:    strings.TrimSpace(in.SpeakerID),
		NeighborID:   neighborID,
		Neighbor:     neighbor,
		RemoteASN:    in.RemoteASN,
		ProtocolName: strings.TrimSpace(in.ProtocolName),
		SessionState: strings.TrimSpace(in.SessionState),
		Status:       PeerDiscoveryPending,
		FirstSeenAt:  seenAt,
		LastSeenAt:   seenAt,
	}
	m.peerDiscoveries[id] = d
	return copyPeerDiscovery(d), nil
}

func (m *Memory) ApprovePeerDiscovery(tenantID, id string, in *PeerDiscoveryApproveInput) (*BGPPeer, *BGPPeerDiscovery, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	d, ok := m.peerDiscoveries[id]
	if !ok || d.TenantID != tenantID {
		return nil, nil, ErrNotFound
	}
	if d.Status != PeerDiscoveryPending {
		return nil, nil, ErrInvalidInput
	}
	if d.RemoteASN == 0 {
		return nil, nil, ErrInvalidInput
	}
	neighbor, okN := NormalizePeerNeighborString(d.Neighbor)
	if !okN {
		return nil, nil, ErrInvalidInput
	}

	name := ""
	enabled := true
	var speakerID *string
	if in != nil {
		name = strings.TrimSpace(in.Name)
		if in.Enabled != nil {
			enabled = *in.Enabled
		}
		if in.SpeakerID != nil {
			v := strings.TrimSpace(*in.SpeakerID)
			if v != "" {
				speakerID = &v
			}
		}
	}
	if name == "" {
		if d.NeighborID != "" {
			name = "discovered-" + d.NeighborID
		} else {
			name = "discovered-" + neighbor
		}
	}
	if speakerID == nil && strings.TrimSpace(d.SpeakerID) != "" {
		sp := d.SpeakerID
		speakerID = &sp
	}

	peerID := uuid.NewString()
	peer := &BGPPeer{
		ID:           peerID,
		TenantID:     tenantID,
		SpeakerID:    speakerID,
		Name:         name,
		Neighbor:     neighbor,
		RemoteASN:    d.RemoteASN,
		Enabled:      enabled,
		SessionState: d.SessionState,
		PoliciesJSON: "{}",
	}
	m.peers[peerID] = peer

	d.Status = PeerDiscoveryApproved
	d.ApprovedPeerID = peerID
	d.LastSeenAt = time.Now().UTC()

	peerCopy := *peer
	return &peerCopy, copyPeerDiscovery(d), nil
}

func (m *Memory) RejectPeerDiscovery(tenantID, id string) (*BGPPeerDiscovery, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	d, ok := m.peerDiscoveries[id]
	if !ok || d.TenantID != tenantID {
		return nil, ErrNotFound
	}
	if d.Status == PeerDiscoveryApproved {
		return nil, ErrInvalidInput
	}
	d.Status = PeerDiscoveryRejected
	d.LastSeenAt = time.Now().UTC()
	return copyPeerDiscovery(d), nil
}

func (m *Memory) findPeerDiscoveryLocked(tenantID, neighborID, neighbor string, asn int64) *BGPPeerDiscovery {
	for _, d := range m.peerDiscoveries {
		if d == nil || d.TenantID != tenantID {
			continue
		}
		if neighborID != "" && d.NeighborID == neighborID {
			return d
		}
		if neighborID == "" && d.NeighborID == "" && d.Neighbor == neighbor && d.RemoteASN == asn {
			return d
		}
		if neighborID != "" && d.NeighborID == "" && d.Neighbor == neighbor && d.RemoteASN == asn {
			return d
		}
	}
	return nil
}

func copyPeerDiscovery(d *BGPPeerDiscovery) *BGPPeerDiscovery {
	if d == nil {
		return nil
	}
	cp := *d
	return &cp
}