package store

import (
	"context"
	"errors"
	"fmt"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/google/uuid"
)

var (
	ErrNotFound     = errors.New("store: not found")
	ErrTenantScope  = errors.New("store: tenant mismatch")
	ErrInvalidInput = errors.New("store: invalid input")
)

// Memory is a development-oriented in-memory backend for control-plane API handlers.
type Memory struct {
	mu sync.RWMutex

	tenants   map[string]*Tenant
	modules   map[string]*Module
	revisions map[string]*Revision
	speakers  map[string]*Speaker

	// speakerID -> latest published revision for evobgp-node pulls
	publishedRevision map[string]publishedInfo

	peers map[string]*BGPPeer

	peerDiscoveries map[string]*BGPPeerDiscovery

	dohProfiles            map[string]*DohProfile
	communities            map[string]*Community
	cdnSources             map[string]*CDNSource
	asEntries              map[string]*ASEntry
	domainEnt              map[string]*DomainEntry
	ipRanges               map[string]*IPRangeEntry
	settings               map[string]map[string]any // tenantID -> key -> JSON-compatible value
	revPrefixes            map[string][]PrefixRow
	moduleSnapshots        map[string]*moduleSnapshotRec
	snapshotLocks          sync.Map // key -> *sync.Mutex (per-module snapshot RMW)
	asnPrefixCache         map[int64]*ASNPrefixCacheEntry
	domainResolveCache     map[string]*DomainResolveCacheEntry
	apiKeys                map[string]*apiKeyRec
	firewallClients        map[string]*firewallClientRec
	firewallRules          map[string]*FirewallRule
	firewallHashIndex      map[string]string // hex hash -> client id
	maintenancePolicies    map[string]*MaintenancePolicy
	maintConfigAudit       []*MaintenancePolicyConfigAudit
	runtimeLogCleanupAudit []*RuntimeLogCleanupAudit
	auditLog               []*AuditEntry

	// DemoIDs valid after SeedDemo()
	demoTenantID   string
	demoModuleCDN  string
	demoModuleIP   string
	demoRevisionID string
	demoSpeakerID  string
}

type publishedInfo struct {
	RevisionID  string
	PublishedAt time.Time
}

type apiKeyRec struct {
	APIKey
	TokenHash []byte
}

type firewallClientRec struct {
	FirewallClient
	TokenHash []byte
}

type Tenant struct {
	ID   string
	Name string
	Slug string
}

type Module struct {
	ID                 string
	TenantID           string
	Type               string // AS_PREFIXES, CDN_CIDRS, DOMAINS, IP_RANGES
	Name               string
	Enabled            bool
	RefreshIntervalSec int    // 0 = unset
	CronExpr           string // optional cron for scheduler (display / future use)
	Priority           int
	DefaultCommunityID *string
	DohProfileID       *string // deprecated: first id in DohProfileIDs
	DohProfileIDs      []string
	DohResolverPolicy  string
	LastRefreshedAt    *time.Time
	DeletedAt          *time.Time
	CreatedByUserID    string // portal JWT sub; empty = system / API key
	InputHash          string // ingest fingerprint; empty = not yet computed
}

type Revision struct {
	ID               string
	TenantID         string
	ModuleID         string
	ContentHash      string
	ParentRevisionID *string
	CreatedAt        time.Time
	// MaterializedPrefixCount is the size of the prefix set for this revision (control-plane / render output).
	MaterializedPrefixCount int
	// PreviewFragments maps logical paths (e.g. bird.conf) to generated text.
	PreviewFragments map[string]string
}

// BGPPeer maps to bgp_peer (+ display fields in meta).
type BGPPeer struct {
	ID              string  `json:"id,omitempty"`
	TenantID        string  `json:"tenant_id,omitempty"`
	SpeakerID       *string `json:"bgp_speaker_id"`
	Name            string  `json:"name"`
	Neighbor        string  `json:"neighbor"`
	RemoteASN       int64   `json:"remote_asn"`
	Enabled         bool    `json:"enabled"`
	SessionState    string  `json:"session_state"`
	PoliciesJSON    string  `json:"policies_json"`
	CreatedByUserID string  `json:"created_by_user_id,omitempty"`
}

type Speaker struct {
	ID                    string  `json:"id,omitempty"`
	TenantID              string  `json:"tenant_id,omitempty"`
	Role                  string  `json:"role"`
	Endpoint              string  `json:"endpoint"`
	LastAppliedRevisionID *string `json:"last_applied_revision_id"`
	MetaJSON              string  `json:"meta_json"`
}

func NewMemory() *Memory {
	return &Memory{
		tenants:                make(map[string]*Tenant),
		modules:                make(map[string]*Module),
		revisions:              make(map[string]*Revision),
		speakers:               make(map[string]*Speaker),
		publishedRevision:      make(map[string]publishedInfo),
		peers:                  make(map[string]*BGPPeer),
		peerDiscoveries:        make(map[string]*BGPPeerDiscovery),
		dohProfiles:            make(map[string]*DohProfile),
		communities:            make(map[string]*Community),
		cdnSources:             make(map[string]*CDNSource),
		asEntries:              make(map[string]*ASEntry),
		domainEnt:              make(map[string]*DomainEntry),
		ipRanges:               make(map[string]*IPRangeEntry),
		settings:               make(map[string]map[string]any),
		revPrefixes:            make(map[string][]PrefixRow),
		moduleSnapshots:        make(map[string]*moduleSnapshotRec),
		asnPrefixCache:         make(map[int64]*ASNPrefixCacheEntry),
		domainResolveCache:     make(map[string]*DomainResolveCacheEntry),
		apiKeys:                make(map[string]*apiKeyRec),
		firewallClients:        make(map[string]*firewallClientRec),
		firewallRules:          make(map[string]*FirewallRule),
		firewallHashIndex:      make(map[string]string),
		maintenancePolicies:    make(map[string]*MaintenancePolicy),
		maintConfigAudit:       nil,
		runtimeLogCleanupAudit: nil,
	}
}

// SeedDemo installs a minimal tenant, modules, revision, and speaker for local testing.
func (m *Memory) SeedDemo() {
	m.mu.Lock()
	defer m.mu.Unlock()

	tid := uuid.NewString()
	m.tenants[tid] = &Tenant{ID: tid, Name: "Demo", Slug: "demo"}

	mCDN := uuid.NewString()
	m.modules[mCDN] = &Module{
		ID:                 mCDN,
		TenantID:           tid,
		Type:               "CDN_CIDRS",
		Name:               "demo-cdn",
		Enabled:            true,
		RefreshIntervalSec: 3600,
		CronExpr:           "",
		Priority:           10,
	}

	mIP := uuid.NewString()
	m.modules[mIP] = &Module{
		ID:                 mIP,
		TenantID:           tid,
		Type:               "IP_RANGES",
		Name:               "demo-static",
		Enabled:            true,
		RefreshIntervalSec: 0,
		CronExpr:           "",
		Priority:           20,
	}

	parent := uuid.NewString()
	m.revisions[parent] = &Revision{
		ID:                      parent,
		TenantID:                tid,
		ModuleID:                "",
		ContentHash:             "sha256:parent",
		ParentRevisionID:        nil,
		CreatedAt:               time.Now().UTC().Add(-time.Hour),
		MaterializedPrefixCount: 0,
		PreviewFragments:        map[string]string{"bird.conf": "# parent revision\n"},
	}

	rid := uuid.NewString()
	m.revisions[rid] = &Revision{
		ID:                      rid,
		TenantID:                tid,
		ModuleID:                "",
		ContentHash:             "sha256:demo-rev-1",
		ParentRevisionID:        &parent,
		CreatedAt:               time.Now().UTC(),
		MaterializedPrefixCount: 128,
		PreviewFragments: map[string]string{
			// Valid minimal BIRD 2 skeleton (see internal/birdfmt/testdata/scenarios/minimal/bird.conf).
			"bird.conf": `# EvoBGP demo bundle
router id 192.0.2.1;

protocol device {
}

protocol direct {
    ipv4;
    ipv6;
}
`,
			"bird.d/evobgp_demo.conf": "# static demo fragment\n",
		},
	}

	sid := uuid.NewString()
	m.speakers[sid] = &Speaker{
		ID:                    sid,
		TenantID:              tid,
		Role:                  "replica",
		Endpoint:              "10.0.0.2:179",
		LastAppliedRevisionID: nil,
	}
	m.publishedRevision[sid] = publishedInfo{RevisionID: rid, PublishedAt: time.Now().UTC()}

	p1 := uuid.NewString()
	m.peers[p1] = &BGPPeer{
		ID:           p1,
		TenantID:     tid,
		SpeakerID:    &sid,
		Name:         "demo-upstream-4",
		Neighbor:     "198.51.100.2",
		RemoteASN:    65001,
		Enabled:      true,
		SessionState: "Established",
	}
	p2 := uuid.NewString()
	m.peers[p2] = &BGPPeer{
		ID:           p2,
		TenantID:     tid,
		SpeakerID:    &sid,
		Name:         "demo-upstream-6",
		Neighbor:     "2001:db8::2",
		RemoteASN:    65002,
		Enabled:      true,
		SessionState: "Idle",
	}

	m.demoTenantID, m.demoModuleCDN, m.demoModuleIP, m.demoRevisionID, m.demoSpeakerID = tid, mCDN, mIP, rid, sid

	// Demo materialized prefixes for /revisions/{id}/prefixes
	cid := uuid.NewString()
	m.communities[cid] = &Community{ID: cid, TenantID: tid, Community: "demo-comm", Title: "Demo", ValueJSON: "{}"}
	m.revPrefixes[rid] = []PrefixRow{
		{Prefix: "203.0.113.0/24", CommunityID: &cid, Source: "demo"},
		{Prefix: "2001:db8::/32", CommunityID: &cid, Source: "demo"},
	}
}

// MaterializedPrefixStats returns max and sum of MaterializedPrefixCount across revisions.
func (m *Memory) MaterializedPrefixStats() (max int, sum int) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	for _, r := range m.revisions {
		sum += r.MaterializedPrefixCount
		if r.MaterializedPrefixCount > max {
			max = r.MaterializedPrefixCount
		}
	}
	return max, sum
}

// PeerCount returns the number of configured BGP peers.
func (m *Memory) PeerCount() int {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return len(m.peers)
}

// PeerSessionCountsByState returns peer counts grouped by SessionState.
func (m *Memory) PeerSessionCountsByState() map[string]int {
	m.mu.RLock()
	defer m.mu.RUnlock()
	out := make(map[string]int)
	for _, p := range m.peers {
		st := strings.TrimSpace(p.SessionState)
		if st == "" {
			st = "unknown"
		}
		out[st]++
	}
	return out
}

// DemoIDs returns IDs from SeedDemo; empty strings if SeedDemo was not called.
func (m *Memory) DemoIDs() (tenant, moduleCDN, moduleIP, revision, speaker string) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.demoTenantID, m.demoModuleCDN, m.demoModuleIP, m.demoRevisionID, m.demoSpeakerID
}

// Ping is a no-op for the in-memory backend.
func (m *Memory) Ping(ctx context.Context) error {
	_ = ctx
	return nil
}

// RunPeriodicMaintenance is a no-op for the in-memory backend.
func (m *Memory) RunPeriodicMaintenance(ctx context.Context) {
	_ = ctx
}

// ListTenantIDs returns tenant ids sorted lexicographically.
func (m *Memory) ListTenantIDs() ([]string, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	out := make([]string, 0, len(m.tenants))
	for id := range m.tenants {
		out = append(out, id)
	}
	sort.Strings(out)
	return out, nil
}

// CreateRenderRevision stores a new revision and its materialized prefixes.
func (m *Memory) CreateRenderRevision(revisionID, tenantID, moduleID string, parentRevisionID *string, contentHash string, previewFragments map[string]string, prefixes []PrefixRow) error {
	if strings.TrimSpace(revisionID) == "" || strings.TrimSpace(moduleID) == "" || strings.TrimSpace(contentHash) == "" {
		return ErrInvalidInput
	}
	m.mu.Lock()
	defer m.mu.Unlock()
	if _, exists := m.revisions[revisionID]; exists {
		return ErrInvalidInput
	}
	mod, ok := m.modules[moduleID]
	if !ok || mod.DeletedAt != nil || mod.TenantID != tenantID {
		return ErrNotFound
	}
	if parentRevisionID != nil && *parentRevisionID != "" {
		if pr, ok := m.revisions[*parentRevisionID]; !ok || pr.TenantID != tenantID {
			return ErrNotFound
		}
	}
	frag := make(map[string]string, len(previewFragments))
	for k, v := range previewFragments {
		frag[k] = v
	}
	parent := parentRevisionID
	createdAt := time.Now().UTC()
	for _, r := range m.revisions {
		if r == nil || r.TenantID != tenantID {
			continue
		}
		if !r.CreatedAt.Before(createdAt) {
			createdAt = r.CreatedAt.Add(time.Microsecond)
		}
	}
	m.revisions[revisionID] = &Revision{
		ID:                      revisionID,
		TenantID:                tenantID,
		ModuleID:                moduleID,
		ContentHash:             contentHash,
		ParentRevisionID:        parent,
		CreatedAt:               createdAt,
		MaterializedPrefixCount: len(prefixes),
		PreviewFragments:        frag,
	}
	if len(prefixes) > 0 {
		cp := make([]PrefixRow, len(prefixes))
		copy(cp, prefixes)
		m.revPrefixes[revisionID] = cp
	} else {
		m.revPrefixes[revisionID] = nil
	}
	return nil
}

// ListModules returns modules for a tenant (sorted by priority, then name).
func (m *Memory) ListModules(tenantID string) []*Module {
	m.mu.RLock()
	defer m.mu.RUnlock()
	var out []*Module
	for _, mod := range m.modules {
		if mod.TenantID == tenantID && mod.DeletedAt == nil {
			out = append(out, mod)
		}
	}
	sort.Slice(out, func(i, j int) bool {
		if out[i].Priority != out[j].Priority {
			return out[i].Priority < out[j].Priority
		}
		return out[i].Name < out[j].Name
	})
	for i := range out {
		out[i] = cloneModule(out[i])
	}
	return out
}

func (m *Memory) ListModulesPage(tenantID, cursor string, limit int) ([]*Module, string, bool) {
	all := m.ListModules(tenantID)
	return PaginateOffset(all, cursor, limit)
}

// ListPeers returns BGP peers for a tenant (sorted by name).
func (m *Memory) ListPeers(tenantID string) []*BGPPeer {
	m.mu.RLock()
	defer m.mu.RUnlock()
	var out []*BGPPeer
	for _, p := range m.peers {
		if p.TenantID == tenantID {
			out = append(out, p)
		}
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Name < out[j].Name })
	return out
}

func (m *Memory) GetModule(tenantID, moduleID string) (*Module, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	mod, ok := m.modules[moduleID]
	if !ok || mod.DeletedAt != nil {
		return nil, ErrNotFound
	}
	if mod.TenantID != tenantID {
		return nil, ErrTenantScope
	}
	return cloneModule(mod), nil
}

func (m *Memory) GetRevision(tenantID, revisionID string) (*Revision, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.getRevisionLocked(tenantID, revisionID)
}

func (m *Memory) GetRevisionSummary(tenantID, revisionID string) (*Revision, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	rev, err := m.getRevisionLocked(tenantID, revisionID)
	if err != nil {
		return nil, err
	}
	cp := *rev
	cp.PreviewFragments = nil
	return &cp, nil
}

func (m *Memory) GetSpeaker(tenantID, speakerID string) (*Speaker, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	sp, ok := m.speakers[speakerID]
	if !ok {
		return nil, ErrNotFound
	}
	if sp.TenantID != tenantID {
		return nil, ErrTenantScope
	}
	return sp, nil
}

// ListSpeakersForTenant returns speakers for a tenant (IDs sorted) for deploy-all and similar operations.
func (m *Memory) ListSpeakersForTenant(tenantID string) []*Speaker {
	m.mu.RLock()
	defer m.mu.RUnlock()
	var ids []string
	for id, sp := range m.speakers {
		if sp.TenantID == tenantID {
			ids = append(ids, id)
		}
	}
	sort.Strings(ids)
	out := make([]*Speaker, 0, len(ids))
	for _, id := range ids {
		out = append(out, m.speakers[id])
	}
	return out
}

// GetSpeakerAnyTenant resolves a speaker without tenant check (node API uses speaker id in path).
func (m *Memory) GetSpeakerAnyTenant(speakerID string) (*Speaker, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	sp, ok := m.speakers[speakerID]
	if !ok {
		return nil, ErrNotFound
	}
	return sp, nil
}

func (m *Memory) LatestPublishedRevision(speakerID string) (revisionID string, publishedAt time.Time, err error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	info, ok := m.publishedRevision[speakerID]
	if !ok {
		return "", time.Time{}, ErrNotFound
	}
	return info.RevisionID, info.PublishedAt, nil
}

// CreateRollbackRevision adds a new revision that reuses content from sourceRevisionID (same hash & preview copy).
func (m *Memory) CreateRollbackRevision(tenantID, sourceRevisionID string) (newID string, err error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	src, ok := m.revisions[sourceRevisionID]
	if !ok {
		return "", ErrNotFound
	}
	if src.TenantID != tenantID {
		return "", ErrTenantScope
	}
	newID = uuid.NewString()
	frag := make(map[string]string, len(src.PreviewFragments))
	for k, v := range src.PreviewFragments {
		frag[k] = v
	}
	parent := sourceRevisionID
	m.revisions[newID] = &Revision{
		ID:                      newID,
		TenantID:                tenantID,
		ModuleID:                src.ModuleID,
		ContentHash:             src.ContentHash + ":rollback",
		ParentRevisionID:        &parent,
		CreatedAt:               time.Now().UTC(),
		MaterializedPrefixCount: src.MaterializedPrefixCount,
		PreviewFragments:        frag,
	}
	if px, ok := m.revPrefixes[sourceRevisionID]; ok {
		cp := make([]PrefixRow, len(px))
		copy(cp, px)
		m.revPrefixes[newID] = cp
	}
	return newID, nil
}

// SetLastAppliedRevision updates speaker state after deploy job (demo).
func (m *Memory) SetLastAppliedRevision(tenantID, speakerID, revisionID string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	sp, ok := m.speakers[speakerID]
	if !ok {
		return ErrNotFound
	}
	if sp.TenantID != tenantID {
		return ErrTenantScope
	}
	if _, ok := m.revisions[revisionID]; !ok {
		return fmt.Errorf("%w: revision", ErrNotFound)
	}
	sp.LastAppliedRevisionID = &revisionID
	return nil
}

// PublishRevisionForSpeaker marks latest bundle pointer for a replica speaker.
func (m *Memory) PublishRevisionForSpeaker(speakerID, revisionID string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	if _, ok := m.speakers[speakerID]; !ok {
		return ErrNotFound
	}
	if _, ok := m.revisions[revisionID]; !ok {
		return fmt.Errorf("%w: revision", ErrNotFound)
	}
	m.publishedRevision[speakerID] = publishedInfo{RevisionID: revisionID, PublishedAt: time.Now().UTC()}
	return nil
}

// RevisionDiff returns prefix set diff from materialized snapshots when present.
func (m *Memory) RevisionDiff(tenantID, aID, bID string) (map[string]any, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	_, err := m.getRevisionLocked(tenantID, aID)
	if err != nil {
		return nil, err
	}
	_, err = m.getRevisionLocked(tenantID, bID)
	if err != nil {
		return nil, err
	}
	setA := make(map[string]struct{})
	setB := make(map[string]struct{})
	for _, p := range m.revPrefixes[aID] {
		setA[p.Prefix] = struct{}{}
	}
	for _, p := range m.revPrefixes[bID] {
		setB[p.Prefix] = struct{}{}
	}
	var added, removed []string
	unchanged := 0
	for p := range setB {
		if _, ok := setA[p]; !ok {
			added = append(added, p)
		} else {
			unchanged++
		}
	}
	for p := range setA {
		if _, ok := setB[p]; !ok {
			removed = append(removed, p)
		}
	}
	sort.Strings(added)
	sort.Strings(removed)
	return map[string]any{
		"revision_a": aID,
		"revision_b": bID,
		"prefixes": map[string]any{
			"added":           added,
			"removed":         removed,
			"unchanged_count": unchanged,
		},
	}, nil
}

func (m *Memory) getRevisionLocked(tenantID, revisionID string) (*Revision, error) {
	rev, ok := m.revisions[revisionID]
	if !ok {
		return nil, ErrNotFound
	}
	if rev.TenantID != tenantID {
		return nil, ErrTenantScope
	}
	return rev, nil
}

// ListRevisions returns recent revisions for tenant (newest first), cursor is opaque offset string.
func (m *Memory) ListRevisions(tenantID, moduleID string, cursor string, limit int) (items []*Revision, nextCursor string, hasMore bool) {
	if limit <= 0 {
		limit = 50
	}
	m.mu.RLock()
	defer m.mu.RUnlock()
	var all []*Revision
	for _, r := range m.revisions {
		if r.TenantID != tenantID {
			continue
		}
		if moduleID != "" && r.ModuleID != moduleID {
			continue
		}
		all = append(all, r)
	}
	sort.Slice(all, func(i, j int) bool {
		if all[i].CreatedAt.Equal(all[j].CreatedAt) {
			return all[i].ID > all[j].ID
		}
		return all[i].CreatedAt.After(all[j].CreatedAt)
	})
	off := 0
	if cursor != "" {
		if n, err := strconv.Atoi(cursor); err == nil && n >= 0 {
			off = n
		}
	}
	end := off + limit
	if end > len(all) {
		end = len(all)
	}
	page := all[off:end]
	if end < len(all) {
		nextCursor = fmt.Sprintf("%d", end)
		hasMore = true
	}
	return page, nextCursor, hasMore
}

func cloneStringPtr(s *string) *string {
	if s == nil {
		return nil
	}
	v := *s
	return &v
}

func (m *Memory) clearModuleInputHashLocked(moduleID string) {
	if mod, ok := m.modules[moduleID]; ok && mod != nil {
		mod.InputHash = ""
	}
}

func (m *Memory) clearTenantModuleHashesLocked(tenantID string) {
	for _, mod := range m.modules {
		if mod != nil && mod.TenantID == tenantID && mod.DeletedAt == nil {
			mod.InputHash = ""
		}
	}
}

func cloneModule(m *Module) *Module {
	if m == nil {
		return nil
	}
	cp := *m
	cp.DefaultCommunityID = cloneStringPtr(m.DefaultCommunityID)
	cp.DohProfileID = cloneStringPtr(m.DohProfileID)
	cp.DohProfileIDs = append([]string(nil), m.DohProfileIDs...)
	cp.LastRefreshedAt = cloneTime(m.LastRefreshedAt)
	cp.DeletedAt = cloneTime(m.DeletedAt)
	return &cp
}