package store

import (
	"context"
	"sort"
	"sync"
	"time"

	"github.com/google/uuid"
)

// Memory — in-process Store used when DATABASE_URL is empty. Convenient for
// local dev when you don't want to bring up Postgres + run migrations.
// Pre-seeded with the acme tenant.
type Memory struct {
	mu       sync.RWMutex
	tenants  map[string]*Tenant                   // id → tenant
	bySlug   map[string]string                    // slug → id
	products map[string]map[string]*TenantProduct // tenant_id → product → row
	apiKeys  map[string]*apiKeyWithHash           // id → key
	byPrefix map[string]string                    // prefix → id
	audit    []*AuditEvent
	auditID  int64
}

type apiKeyWithHash struct {
	APIKey
	Hash string
}

// NewMemory returns a fresh in-memory store with the seed acme tenant.
func NewMemory() *Memory {
	m := &Memory{
		tenants:  make(map[string]*Tenant),
		bySlug:   make(map[string]string),
		products: make(map[string]map[string]*TenantProduct),
		apiKeys:  make(map[string]*apiKeyWithHash),
		byPrefix: make(map[string]string),
	}
	now := time.Now().UTC()
	seed := &Tenant{
		ID:        "00000000-0000-0000-0000-000000000001",
		Slug:      "acme",
		Name:      "Acme Inc.",
		Status:    "active",
		Kind:      "customer",
		Plan:      "professional",
		CreatedAt: now,
		UpdatedAt: now,
	}
	m.tenants[seed.ID] = seed
	m.bySlug[seed.Slug] = seed.ID
	m.products[seed.ID] = map[string]*TenantProduct{
		"certifai":   {TenantID: seed.ID, Product: "certifai", Enabled: true, Config: map[string]interface{}{}, CreatedAt: now, UpdatedAt: now},
		"compliance": {TenantID: seed.ID, Product: "compliance", Enabled: true, Config: map[string]interface{}{}, CreatedAt: now, UpdatedAt: now},
	}
	return m
}

func (m *Memory) Close()                       {}
func (m *Memory) Ping(_ context.Context) error { return nil }

// ─── tenants ──────────────────────────────────────────────────────────────

func (m *Memory) CreateTenant(_ context.Context, in TenantCreate) (*Tenant, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	if _, taken := m.bySlug[in.Slug]; taken {
		return nil, ErrConflict
	}
	now := time.Now().UTC()
	kind := firstNonEmpty(in.Kind, "customer")
	status := "trial"
	var trialEnds *time.Time
	if kind == "demo" {
		status = "demo"
	} else {
		end := now.Add(14 * 24 * time.Hour)
		trialEnds = &end
	}
	t := &Tenant{
		ID:          uuid.NewString(),
		Slug:        in.Slug,
		Name:        in.Name,
		Status:      status,
		Kind:        kind,
		Plan:        firstNonEmpty(in.Plan, "starter"),
		SalesOwner:  in.SalesOwner,
		TrialEndsAt: trialEnds,
		CreatedAt:   now,
		UpdatedAt:   now,
	}
	m.tenants[t.ID] = t
	m.bySlug[t.Slug] = t.ID
	cp := *t
	return &cp, nil
}

func (m *Memory) GetTenant(_ context.Context, id string) (*Tenant, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	t, ok := m.tenants[id]
	if !ok {
		return nil, ErrNotFound
	}
	cp := *t
	return &cp, nil
}

func (m *Memory) GetTenantBySlug(_ context.Context, slug string) (*Tenant, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	id, ok := m.bySlug[slug]
	if !ok {
		return nil, ErrNotFound
	}
	t := m.tenants[id]
	cp := *t
	return &cp, nil
}

func (m *Memory) UpdateTenant(_ context.Context, id string, in TenantUpdate) (*Tenant, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	t, ok := m.tenants[id]
	if !ok {
		return nil, ErrNotFound
	}
	if in.Status != nil {
		t.Status = *in.Status
	}
	if in.Plan != nil {
		t.Plan = *in.Plan
	}
	if in.ErpCustomerID != nil {
		t.ErpCustomerID = *in.ErpCustomerID
	}
	if in.StripeCustID != nil {
		t.StripeCustID = *in.StripeCustID
	}
	if in.TrialEndsAt != nil {
		t.TrialEndsAt = in.TrialEndsAt
	}
	if in.ContractStart != nil {
		t.ContractStart = in.ContractStart
	}
	if in.ContractEnd != nil {
		t.ContractEnd = in.ContractEnd
	}
	if in.SalesOwner != nil {
		t.SalesOwner = *in.SalesOwner
	}
	t.UpdatedAt = time.Now().UTC()
	cp := *t
	return &cp, nil
}

// ─── entitlements ─────────────────────────────────────────────────────────

func (m *Memory) UpsertTenantProduct(_ context.Context, tp TenantProduct) (*TenantProduct, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	if _, ok := m.tenants[tp.TenantID]; !ok {
		return nil, ErrNotFound
	}
	if _, ok := m.products[tp.TenantID]; !ok {
		m.products[tp.TenantID] = map[string]*TenantProduct{}
	}
	now := time.Now().UTC()
	stored, exists := m.products[tp.TenantID][tp.Product]
	if !exists {
		stored = &TenantProduct{
			TenantID:  tp.TenantID,
			Product:   tp.Product,
			CreatedAt: now,
		}
		m.products[tp.TenantID][tp.Product] = stored
	}
	stored.Enabled = tp.Enabled
	stored.Config = tp.Config
	stored.ExpiresAt = tp.ExpiresAt
	stored.UpdatedAt = now
	cp := *stored
	return &cp, nil
}

func (m *Memory) ListTenantProducts(_ context.Context, tenantID string) ([]TenantProduct, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	if _, ok := m.tenants[tenantID]; !ok {
		return nil, ErrNotFound
	}
	out := make([]TenantProduct, 0, len(m.products[tenantID]))
	for _, p := range m.products[tenantID] {
		out = append(out, *p)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Product < out[j].Product })
	return out, nil
}

// ─── api keys ─────────────────────────────────────────────────────────────

func (m *Memory) CreateAPIKey(_ context.Context, in APIKeyCreate) (*APIKey, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	if _, ok := m.tenants[in.TenantID]; !ok {
		return nil, ErrNotFound
	}
	now := time.Now().UTC()
	k := &apiKeyWithHash{
		APIKey: APIKey{
			ID:        uuid.NewString(),
			TenantID:  in.TenantID,
			Product:   in.Product,
			Name:      in.Name,
			Scopes:    append([]string{}, in.Scopes...),
			Prefix:    in.Prefix,
			CreatedBy: in.CreatedBy,
			CreatedAt: now,
		},
		Hash: in.Hash,
	}
	m.apiKeys[k.ID] = k
	m.byPrefix[k.Prefix] = k.ID
	cp := k.APIKey
	return &cp, nil
}

func (m *Memory) FindAPIKeyByPrefix(_ context.Context, prefix string) (*APIKey, string, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	id, ok := m.byPrefix[prefix]
	if !ok {
		return nil, "", ErrNotFound
	}
	k := m.apiKeys[id]
	if k.RevokedAt != nil {
		return nil, "", ErrNotFound
	}
	cp := k.APIKey
	return &cp, k.Hash, nil
}

func (m *Memory) TouchAPIKeyUsed(_ context.Context, id string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	k, ok := m.apiKeys[id]
	if !ok {
		return ErrNotFound
	}
	now := time.Now().UTC()
	k.LastUsedAt = &now
	return nil
}

func (m *Memory) RevokeAPIKey(_ context.Context, id string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	k, ok := m.apiKeys[id]
	if !ok {
		return ErrNotFound
	}
	now := time.Now().UTC()
	k.RevokedAt = &now
	return nil
}

func (m *Memory) ListAPIKeys(_ context.Context, tenantID string) ([]APIKey, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	if _, ok := m.tenants[tenantID]; !ok {
		return nil, ErrNotFound
	}
	out := []APIKey{}
	for _, k := range m.apiKeys {
		if k.TenantID == tenantID {
			out = append(out, k.APIKey)
		}
	}
	sort.Slice(out, func(i, j int) bool { return out[i].CreatedAt.After(out[j].CreatedAt) })
	return out, nil
}

// ─── audit ────────────────────────────────────────────────────────────────

func (m *Memory) AppendAudit(_ context.Context, ev AuditEvent) (*AuditEvent, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.auditID++
	ev.ID = m.auditID
	ev.CreatedAt = time.Now().UTC()
	cp := ev
	m.audit = append(m.audit, &cp)
	out := ev
	return &out, nil
}

func (m *Memory) ListAudit(_ context.Context, f AuditFilter) ([]AuditEvent, int64, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	limit := f.Limit
	if limit <= 0 || limit > 500 {
		limit = 100
	}
	matches := []AuditEvent{}
	for _, ev := range m.audit {
		if ev.ID <= f.Cursor {
			continue
		}
		if f.TenantID != "" && ev.TenantID != f.TenantID {
			continue
		}
		if f.Product != "" && ev.Product != f.Product {
			continue
		}
		if f.ActorID != "" && ev.ActorID != f.ActorID {
			continue
		}
		if f.Action != "" && ev.Action != f.Action {
			continue
		}
		if f.Since != nil && ev.CreatedAt.Before(*f.Since) {
			continue
		}
		if f.Until != nil && ev.CreatedAt.After(*f.Until) {
			continue
		}
		matches = append(matches, *ev)
		if len(matches) >= limit {
			break
		}
	}
	var nextCursor int64
	if len(matches) == limit && len(matches) > 0 {
		nextCursor = matches[len(matches)-1].ID
	}
	return matches, nextCursor, nil
}

func firstNonEmpty(values ...string) string {
	for _, v := range values {
		if v != "" {
			return v
		}
	}
	return ""
}