package billing

import (
	"context"
	"encoding/json"
	"errors"
	"regexp"
	"strings"
	"time"

	"data-terminal-cloud/internal/audit"
	"data-terminal-cloud/internal/idempotency"
	"data-terminal-cloud/internal/identity"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

var (
	ErrInvalid         = errors.New("billing input is invalid")
	ErrAccessDenied    = errors.New("billing operations access denied")
	ErrNotFound        = errors.New("billing resource not found")
	ErrStateConflict   = errors.New("billing resource state conflict")
	ErrVersionConflict = errors.New("billing resource version conflict")
	ErrSelfApproval    = errors.New("billing price creator cannot publish own version")
)

var codePattern = regexp.MustCompile(`^[a-z][a-z0-9_.-]{1,79}$`)

type RateInput struct {
	UsageCategory   string `json:"usage_category"`
	MetricCode      string `json:"metric_code"`
	Unit            string `json:"unit"`
	UnitPriceMicros int64  `json:"unit_price_micros"`
}

type CreatePriceBookInput struct {
	TenantID      string      `json:"-"`
	Provider      string      `json:"provider"`
	Currency      string      `json:"currency"`
	SourceRef     string      `json:"source_ref"`
	ChangeSummary string      `json:"change_summary"`
	EffectiveFrom time.Time   `json:"effective_from"`
	Rates         []RateInput `json:"rates"`
}

type PriceRate struct {
	ID              string `json:"id"`
	UsageCategory   string `json:"usage_category"`
	MetricCode      string `json:"metric_code"`
	Unit            string `json:"unit"`
	UnitPriceMicros int64  `json:"unit_price_micros"`
}

type PriceBook struct {
	ID            string      `json:"id"`
	TenantID      string      `json:"tenant_id"`
	Provider      string      `json:"provider"`
	Currency      string      `json:"currency"`
	VersionNo     int         `json:"version_no"`
	Status        string      `json:"status"`
	SourceRef     string      `json:"source_ref"`
	ChangeSummary string      `json:"change_summary"`
	EffectiveFrom time.Time   `json:"effective_from"`
	CreatedBy     string      `json:"created_by"`
	PublishedBy   *string     `json:"published_by,omitempty"`
	PublishedAt   *time.Time  `json:"published_at,omitempty"`
	RetiredAt     *time.Time  `json:"retired_at,omitempty"`
	RowVersion    int64       `json:"row_version"`
	Rates         []PriceRate `json:"rates"`
	CreatedAt     time.Time   `json:"created_at"`
	UpdatedAt     time.Time   `json:"updated_at"`
}

type QuotaInput struct {
	ScopeType          string `json:"scope_type"`
	ScopeID            string `json:"scope_id,omitempty"`
	BillingTimezone    string `json:"billing_timezone"`
	Currency           string `json:"currency"`
	DailyLimitMicros   int64  `json:"daily_limit_micros"`
	MonthlyLimitMicros int64  `json:"monthly_limit_micros"`
	MaxConcurrentCalls int    `json:"max_concurrent_calls"`
	MaxCallDurationSec int    `json:"max_call_duration_sec"`
	InProgressAction   string `json:"in_progress_action"`
	ChangeSummary      string `json:"change_summary"`
}

type QuotaPolicy struct {
	ID                 string     `json:"id"`
	TenantID           string     `json:"tenant_id"`
	ScopeType          string     `json:"scope_type"`
	ScopeID            *string    `json:"scope_id,omitempty"`
	VersionNo          int        `json:"version_no"`
	Status             string     `json:"status"`
	BillingTimezone    string     `json:"billing_timezone"`
	Currency           string     `json:"currency"`
	DailyLimitMicros   int64      `json:"daily_limit_micros"`
	MonthlyLimitMicros int64      `json:"monthly_limit_micros"`
	MaxConcurrentCalls int        `json:"max_concurrent_calls"`
	MaxCallDurationSec int        `json:"max_call_duration_sec"`
	InProgressAction   string     `json:"in_progress_action"`
	ChangeSummary      string     `json:"change_summary"`
	CreatedBy          string     `json:"created_by"`
	RetiredAt          *time.Time `json:"retired_at,omitempty"`
	RowVersion         int64      `json:"row_version"`
	CreatedAt          time.Time  `json:"created_at"`
	UpdatedAt          time.Time  `json:"updated_at"`
}

type actor struct {
	tenantID, tenantPublicID, userID, userPublicID, role string
}

type Service struct {
	pool  *pgxpool.Pool
	audit *audit.Repository
	idem  *idempotency.Executor
}

func NewService(pool *pgxpool.Pool, auditRepository *audit.Repository) (*Service, error) {
	if pool == nil || auditRepository == nil {
		return nil, errors.New("billing service dependencies are required")
	}
	return &Service{pool: pool, audit: auditRepository, idem: idempotency.NewExecutor(pool)}, nil
}

func (s *Service) CreatePriceBook(ctx context.Context, principal identity.Principal, key, requestID string, input CreatePriceBookInput) (PriceBook, bool, error) {
	normalizePriceInput(&input)
	if err := validatePriceInput(input); err != nil {
		return PriceBook{}, false, err
	}
	currentActor, err := s.resolveActor(ctx, principal, input.TenantID, "ops_operator", "ops_approver", "ops_admin")
	if err != nil {
		return PriceBook{}, false, err
	}
	requestBody, _ := json.Marshal(input)
	result, err := s.idem.Execute(ctx, idempotency.Request{TenantID: &currentActor.tenantID, ActorKey: "ops:" + currentActor.userPublicID, Scope: "POST /api/v1/ops/price-books", Key: key, RequestHash: idempotency.Hash(requestBody), ExpiresAfter: 24 * time.Hour}, func(operationContext context.Context, tx pgx.Tx) (idempotency.Result, error) {
		if _, queryErr := tx.Exec(operationContext, `SELECT pg_advisory_xact_lock(hashtextextended($1,0))`, currentActor.tenantID+":"+input.Provider); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		var versionNo int
		if queryErr := tx.QueryRow(operationContext, `SELECT COALESCE(MAX(version_no),0)+1 FROM billing_price_book WHERE tenant_id=$1::uuid AND provider=$2`, currentActor.tenantID, input.Provider).Scan(&versionNo); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		publicID := uuid.NewString()
		var internalID string
		if queryErr := tx.QueryRow(operationContext, `INSERT INTO billing_price_book(public_id,tenant_id,provider,currency,version_no,source_ref,change_summary,effective_from,created_by) VALUES($1::uuid,$2::uuid,$3,$4,$5,$6,$7,$8,$9::uuid) RETURNING id::text`, publicID, currentActor.tenantID, input.Provider, input.Currency, versionNo, input.SourceRef, input.ChangeSummary, input.EffectiveFrom.UTC(), currentActor.userID).Scan(&internalID); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		for _, rate := range input.Rates {
			if _, queryErr := tx.Exec(operationContext, `INSERT INTO billing_price_rate(price_book_id,usage_category,metric_code,unit,unit_price_micros) VALUES($1::uuid,$2,$3,$4,$5)`, internalID, rate.UsageCategory, rate.MetricCode, rate.Unit, rate.UnitPriceMicros); queryErr != nil {
				return idempotency.Result{}, queryErr
			}
		}
		if queryErr := s.audit.Record(operationContext, tx, audit.Event{TenantID: &currentActor.tenantID, ActorType: "user", ActorPublicID: &currentActor.userPublicID, Action: "billing.price_book.create", ResourceType: "billing_price_book", ResourceID: &internalID, RequestID: requestID, Purpose: input.ChangeSummary, Result: "success", Detail: map[string]any{"provider": input.Provider, "currency": input.Currency, "version_no": versionNo, "rate_count": len(input.Rates)}}); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		item, queryErr := getPriceBookTx(operationContext, tx, currentActor.tenantID, publicID)
		if queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		body, _ := json.Marshal(item)
		return idempotency.Result{StatusCode: 201, Body: body, ResourceID: &internalID}, nil
	})
	if err != nil {
		return PriceBook{}, false, err
	}
	var item PriceBook
	if err = json.Unmarshal(result.Body, &item); err != nil {
		return PriceBook{}, false, err
	}
	return item, !result.Replayed, nil
}

func (s *Service) PublishPriceBook(ctx context.Context, principal identity.Principal, tenantPublicID, publicID, requestID, reason string, expectedVersion int64) (PriceBook, error) {
	reason = strings.TrimSpace(reason)
	if reason == "" || len([]rune(reason)) > 500 {
		return PriceBook{}, ErrInvalid
	}
	currentActor, err := s.resolveActor(ctx, principal, tenantPublicID, "ops_approver", "ops_admin")
	if err != nil {
		return PriceBook{}, err
	}
	tx, err := s.pool.BeginTx(ctx, pgx.TxOptions{})
	if err != nil {
		return PriceBook{}, err
	}
	defer func() { _ = tx.Rollback(context.Background()) }()
	var internalID, status, creatorID, provider, currency string
	var rowVersion int64
	var effectiveFrom time.Time
	err = tx.QueryRow(ctx, `SELECT id::text,status,created_by::text,provider,currency,row_version,effective_from FROM billing_price_book WHERE tenant_id=$1::uuid AND public_id=$2::uuid FOR UPDATE`, currentActor.tenantID, publicID).Scan(&internalID, &status, &creatorID, &provider, &currency, &rowVersion, &effectiveFrom)
	if errors.Is(err, pgx.ErrNoRows) {
		return PriceBook{}, ErrNotFound
	}
	if err != nil {
		return PriceBook{}, err
	}
	if rowVersion != expectedVersion {
		return PriceBook{}, ErrVersionConflict
	}
	if status != "DRAFT" {
		return PriceBook{}, ErrStateConflict
	}
	if creatorID == currentActor.userID {
		return PriceBook{}, ErrSelfApproval
	}
	if effectiveFrom.After(time.Now().UTC().Add(5 * time.Minute)) {
		return PriceBook{}, ErrStateConflict
	}
	var incompatibleCurrency bool
	if err = tx.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM billing_price_book WHERE tenant_id=$1::uuid AND provider<>$2 AND status='PUBLISHED' AND currency<>$3) OR EXISTS(SELECT 1 FROM usage_quota_policy WHERE tenant_id=$1::uuid AND status='ACTIVE' AND currency<>$3)`, currentActor.tenantID, provider, currency).Scan(&incompatibleCurrency); err != nil {
		return PriceBook{}, err
	}
	if incompatibleCurrency {
		return PriceBook{}, ErrStateConflict
	}
	if _, err = tx.Exec(ctx, `SELECT pg_advisory_xact_lock(hashtextextended($1,0))`, currentActor.tenantID+":"+provider); err != nil {
		return PriceBook{}, err
	}
	if _, err = tx.Exec(ctx, `UPDATE billing_price_book SET status='RETIRED',retired_at=now(),row_version=row_version+1,updated_at=now() WHERE tenant_id=$1::uuid AND provider=$2 AND status='PUBLISHED'`, currentActor.tenantID, provider); err != nil {
		return PriceBook{}, err
	}
	if _, err = tx.Exec(ctx, `UPDATE billing_price_book SET status='PUBLISHED',published_by=$2::uuid,published_at=now(),row_version=row_version+1,updated_at=now() WHERE id=$1::uuid`, internalID, currentActor.userID); err != nil {
		return PriceBook{}, err
	}
	if err = s.audit.Record(ctx, tx, audit.Event{TenantID: &currentActor.tenantID, ActorType: "user", ActorPublicID: &currentActor.userPublicID, Action: "billing.price_book.publish", ResourceType: "billing_price_book", ResourceID: &internalID, RequestID: requestID, Purpose: reason, Result: "success", Detail: map[string]any{"provider": provider, "currency": currency}}); err != nil {
		return PriceBook{}, err
	}
	item, err := getPriceBookTx(ctx, tx, currentActor.tenantID, publicID)
	if err == nil {
		err = tx.Commit(ctx)
	}
	return item, err
}

func (s *Service) ListPriceBooks(ctx context.Context, principal identity.Principal, tenantPublicID string) ([]PriceBook, error) {
	currentActor, err := s.resolveActor(ctx, principal, tenantPublicID, "ops_viewer", "ops_operator", "ops_approver", "ops_admin")
	if err != nil {
		return nil, err
	}
	rows, err := s.pool.Query(ctx, `SELECT public_id::text FROM billing_price_book WHERE tenant_id=$1::uuid ORDER BY provider,currency,version_no DESC LIMIT 500`, currentActor.tenantID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	ids := []string{}
	for rows.Next() {
		var id string
		if err = rows.Scan(&id); err != nil {
			return nil, err
		}
		ids = append(ids, id)
	}
	if err = rows.Err(); err != nil {
		return nil, err
	}
	items := make([]PriceBook, 0, len(ids))
	for _, id := range ids {
		item, queryErr := getPriceBookPool(ctx, s.pool, currentActor.tenantID, id)
		if queryErr != nil {
			return nil, queryErr
		}
		items = append(items, item)
	}
	return items, nil
}

func (s *Service) CreateQuotaPolicy(ctx context.Context, principal identity.Principal, tenantPublicID, key, requestID string, input QuotaInput) (QuotaPolicy, bool, error) {
	normalizeQuotaInput(&input)
	if err := validateQuotaInput(input); err != nil {
		return QuotaPolicy{}, false, err
	}
	currentActor, err := s.resolveActor(ctx, principal, tenantPublicID, "ops_approver", "ops_admin")
	if err != nil {
		return QuotaPolicy{}, false, err
	}
	requestBody, _ := json.Marshal(input)
	result, err := s.idem.Execute(ctx, idempotency.Request{TenantID: &currentActor.tenantID, ActorKey: "ops:" + currentActor.userPublicID, Scope: "POST /api/v1/ops/quota-policies", Key: key, RequestHash: idempotency.Hash(requestBody), ExpiresAfter: 24 * time.Hour}, func(operationContext context.Context, tx pgx.Tx) (idempotency.Result, error) {
		var incompatiblePriceCurrency bool
		if queryErr := tx.QueryRow(operationContext, `SELECT EXISTS(SELECT 1 FROM billing_price_book WHERE tenant_id=$1::uuid AND status='PUBLISHED' AND currency<>$2)`, currentActor.tenantID, input.Currency).Scan(&incompatiblePriceCurrency); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		if incompatiblePriceCurrency {
			return idempotency.Result{}, ErrInvalid
		}
		var deviceID *string
		if input.ScopeType == "DEVICE" {
			var id string
			queryErr := tx.QueryRow(operationContext, `SELECT id::text FROM device WHERE tenant_id=$1::uuid AND public_id=$2::uuid AND status='registered'`, currentActor.tenantID, input.ScopeID).Scan(&id)
			if errors.Is(queryErr, pgx.ErrNoRows) {
				return idempotency.Result{}, ErrAccessDenied
			}
			if queryErr != nil {
				return idempotency.Result{}, queryErr
			}
			deviceID = &id
			var tenantTimezone, tenantCurrency string
			queryErr = tx.QueryRow(operationContext, `SELECT billing_timezone,currency FROM usage_quota_policy WHERE tenant_id=$1::uuid AND scope_type='TENANT' AND status='ACTIVE'`, currentActor.tenantID).Scan(&tenantTimezone, &tenantCurrency)
			if queryErr != nil && !errors.Is(queryErr, pgx.ErrNoRows) {
				return idempotency.Result{}, queryErr
			}
			if queryErr == nil && (tenantTimezone != input.BillingTimezone || tenantCurrency != input.Currency) {
				return idempotency.Result{}, ErrInvalid
			}
		} else {
			var incompatibleDevicePolicy bool
			queryErr := tx.QueryRow(operationContext, `SELECT EXISTS(SELECT 1 FROM usage_quota_policy WHERE tenant_id=$1::uuid AND scope_type='DEVICE' AND status='ACTIVE' AND (billing_timezone<>$2 OR currency<>$3))`, currentActor.tenantID, input.BillingTimezone, input.Currency).Scan(&incompatibleDevicePolicy)
			if queryErr != nil {
				return idempotency.Result{}, queryErr
			}
			if incompatibleDevicePolicy {
				return idempotency.Result{}, ErrInvalid
			}
		}
		lockKey := currentActor.tenantID + ":quota:" + input.ScopeType + ":" + input.ScopeID
		if _, queryErr := tx.Exec(operationContext, `SELECT pg_advisory_xact_lock(hashtextextended($1,0))`, lockKey); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		var versionNo int
		if queryErr := tx.QueryRow(operationContext, `SELECT COALESCE(MAX(version_no),0)+1 FROM usage_quota_policy WHERE tenant_id=$1::uuid AND scope_type=$2 AND (($2='TENANT') OR device_id=$3::uuid)`, currentActor.tenantID, input.ScopeType, deviceID).Scan(&versionNo); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		if _, queryErr := tx.Exec(operationContext, `UPDATE usage_quota_policy SET status='RETIRED',retired_at=now(),row_version=row_version+1,updated_at=now() WHERE tenant_id=$1::uuid AND scope_type=$2 AND status='ACTIVE' AND (($2='TENANT') OR device_id=$3::uuid)`, currentActor.tenantID, input.ScopeType, deviceID); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		publicID := uuid.NewString()
		var internalID string
		if queryErr := tx.QueryRow(operationContext, `INSERT INTO usage_quota_policy(public_id,tenant_id,scope_type,device_id,version_no,billing_timezone,currency,daily_limit_micros,monthly_limit_micros,max_concurrent_calls,max_call_duration_sec,in_progress_action,change_summary,created_by) VALUES($1::uuid,$2::uuid,$3,$4::uuid,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14::uuid) RETURNING id::text`, publicID, currentActor.tenantID, input.ScopeType, deviceID, versionNo, input.BillingTimezone, input.Currency, input.DailyLimitMicros, input.MonthlyLimitMicros, input.MaxConcurrentCalls, input.MaxCallDurationSec, input.InProgressAction, input.ChangeSummary, currentActor.userID).Scan(&internalID); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		if queryErr := s.audit.Record(operationContext, tx, audit.Event{TenantID: &currentActor.tenantID, ActorType: "user", ActorPublicID: &currentActor.userPublicID, Action: "billing.quota_policy.activate", ResourceType: "usage_quota_policy", ResourceID: &internalID, RequestID: requestID, Purpose: input.ChangeSummary, Result: "success", Detail: map[string]any{"scope_type": input.ScopeType, "scope_id": input.ScopeID, "version_no": versionNo}}); queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		item, queryErr := getQuotaTx(operationContext, tx, currentActor.tenantID, publicID)
		if queryErr != nil {
			return idempotency.Result{}, queryErr
		}
		body, _ := json.Marshal(item)
		return idempotency.Result{StatusCode: 201, Body: body, ResourceID: &internalID}, nil
	})
	if err != nil {
		return QuotaPolicy{}, false, err
	}
	var item QuotaPolicy
	if err = json.Unmarshal(result.Body, &item); err != nil {
		return QuotaPolicy{}, false, err
	}
	return item, !result.Replayed, nil
}

func (s *Service) ListQuotaPolicies(ctx context.Context, principal identity.Principal, tenantPublicID string) ([]QuotaPolicy, error) {
	currentActor, err := s.resolveActor(ctx, principal, tenantPublicID, "ops_viewer", "ops_operator", "ops_approver", "ops_admin")
	if err != nil {
		return nil, err
	}
	rows, err := s.pool.Query(ctx, quotaSelect+` WHERE qp.tenant_id=$1::uuid ORDER BY CASE qp.status WHEN 'ACTIVE' THEN 1 ELSE 2 END,qp.scope_type,qp.version_no DESC LIMIT 1000`, currentActor.tenantID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	items := []QuotaPolicy{}
	for rows.Next() {
		item, scanErr := scanQuota(rows)
		if scanErr != nil {
			return nil, scanErr
		}
		items = append(items, item)
	}
	return items, rows.Err()
}

func (s *Service) resolveActor(ctx context.Context, principal identity.Principal, tenantPublicID string, roles ...string) (actor, error) {
	if _, err := uuid.Parse(tenantPublicID); err != nil {
		return actor{}, ErrInvalid
	}
	var result actor
	err := s.pool.QueryRow(ctx, `SELECT t.id::text,t.public_id::text,ua.id::text,ua.public_id::text,ua.platform_role FROM user_account ua JOIN tenant t ON t.id=ua.tenant_id AND t.status='active' WHERE t.public_id=$1::uuid AND ua.oidc_issuer=$2 AND ua.oidc_subject=$3 AND ua.status='active'`, tenantPublicID, principal.Issuer, principal.Subject).Scan(&result.tenantID, &result.tenantPublicID, &result.userID, &result.userPublicID, &result.role)
	if errors.Is(err, pgx.ErrNoRows) {
		return actor{}, ErrAccessDenied
	}
	if err != nil {
		return actor{}, err
	}
	for _, role := range roles {
		if result.role == role {
			return result, nil
		}
	}
	return actor{}, ErrAccessDenied
}

func normalizePriceInput(input *CreatePriceBookInput) {
	input.Provider = strings.ToLower(strings.TrimSpace(input.Provider))
	input.Currency = strings.ToUpper(strings.TrimSpace(input.Currency))
	input.SourceRef = strings.TrimSpace(input.SourceRef)
	input.ChangeSummary = strings.TrimSpace(input.ChangeSummary)
	for index := range input.Rates {
		input.Rates[index].UsageCategory = strings.ToUpper(strings.TrimSpace(input.Rates[index].UsageCategory))
		input.Rates[index].MetricCode = strings.ToLower(strings.TrimSpace(input.Rates[index].MetricCode))
		input.Rates[index].Unit = strings.ToLower(strings.TrimSpace(input.Rates[index].Unit))
	}
}

func validatePriceInput(input CreatePriceBookInput) error {
	if _, err := uuid.Parse(input.TenantID); err != nil {
		return ErrInvalid
	}
	if !regexp.MustCompile(`^[a-z][a-z0-9_.-]{1,39}$`).MatchString(input.Provider) || !regexp.MustCompile(`^[A-Z]{3}$`).MatchString(input.Currency) || input.SourceRef == "" || len([]rune(input.SourceRef)) > 300 || input.ChangeSummary == "" || len([]rune(input.ChangeSummary)) > 500 || input.EffectiveFrom.IsZero() || len(input.Rates) == 0 || len(input.Rates) > 100 {
		return ErrInvalid
	}
	seen := map[string]struct{}{}
	for _, rate := range input.Rates {
		if !validCategory(rate.UsageCategory) || !codePattern.MatchString(rate.MetricCode) || !regexp.MustCompile(`^[a-z][a-z0-9_.-]{1,39}$`).MatchString(rate.Unit) || rate.UnitPriceMicros < 0 {
			return ErrInvalid
		}
		key := rate.UsageCategory + ":" + rate.MetricCode + ":" + rate.Unit
		if _, exists := seen[key]; exists {
			return ErrInvalid
		}
		seen[key] = struct{}{}
	}
	return nil
}

func normalizeQuotaInput(input *QuotaInput) {
	input.ScopeType = strings.ToUpper(strings.TrimSpace(input.ScopeType))
	input.BillingTimezone = strings.TrimSpace(input.BillingTimezone)
	input.Currency = strings.ToUpper(strings.TrimSpace(input.Currency))
	input.InProgressAction = strings.ToUpper(strings.TrimSpace(input.InProgressAction))
	input.ChangeSummary = strings.TrimSpace(input.ChangeSummary)
}

func validateQuotaInput(input QuotaInput) error {
	if input.ScopeType != "TENANT" && input.ScopeType != "DEVICE" {
		return ErrInvalid
	}
	if input.ScopeType == "TENANT" && strings.TrimSpace(input.ScopeID) != "" {
		return ErrInvalid
	}
	if input.ScopeType == "DEVICE" {
		if _, err := uuid.Parse(input.ScopeID); err != nil {
			return ErrInvalid
		}
	}
	if _, err := time.LoadLocation(input.BillingTimezone); err != nil {
		return ErrInvalid
	}
	if !regexp.MustCompile(`^[A-Z]{3}$`).MatchString(input.Currency) || input.DailyLimitMicros <= 0 || input.MonthlyLimitMicros < input.DailyLimitMicros || input.MaxConcurrentCalls < 1 || input.MaxConcurrentCalls > 100000 || input.MaxCallDurationSec < 60 || input.MaxCallDurationSec > 86400 || (input.InProgressAction != "STOP_IMMEDIATELY" && input.InProgressAction != "COMPLETE_CURRENT_TURN") || input.ChangeSummary == "" || len([]rune(input.ChangeSummary)) > 500 {
		return ErrInvalid
	}
	return nil
}

func validCategory(value string) bool {
	switch value {
	case "RTC", "END_TO_END_VOICE", "ASR", "LLM", "TTS", "STORAGE", "POST_PROCESSING":
		return true
	}
	return false
}

type rowScanner interface{ Scan(...any) error }

const priceBookSelect = `SELECT pb.public_id::text,t.public_id::text,pb.provider,pb.currency,pb.version_no,pb.status,pb.source_ref,pb.change_summary,pb.effective_from,creator.public_id::text,publisher.public_id::text,pb.published_at,pb.retired_at,pb.row_version,pb.created_at,pb.updated_at FROM billing_price_book pb JOIN tenant t ON t.id=pb.tenant_id JOIN user_account creator ON creator.id=pb.created_by LEFT JOIN user_account publisher ON publisher.id=pb.published_by`

func scanPriceBook(row rowScanner) (PriceBook, error) {
	var item PriceBook
	err := row.Scan(&item.ID, &item.TenantID, &item.Provider, &item.Currency, &item.VersionNo, &item.Status, &item.SourceRef, &item.ChangeSummary, &item.EffectiveFrom, &item.CreatedBy, &item.PublishedBy, &item.PublishedAt, &item.RetiredAt, &item.RowVersion, &item.CreatedAt, &item.UpdatedAt)
	return item, err
}

func getPriceBookTx(ctx context.Context, tx pgx.Tx, tenantID, publicID string) (PriceBook, error) {
	item, err := scanPriceBook(tx.QueryRow(ctx, priceBookSelect+` WHERE pb.tenant_id=$1::uuid AND pb.public_id=$2::uuid`, tenantID, publicID))
	if err != nil {
		return PriceBook{}, err
	}
	rows, err := tx.Query(ctx, `SELECT id::text,usage_category,metric_code,unit,unit_price_micros FROM billing_price_rate WHERE price_book_id=(SELECT id FROM billing_price_book WHERE tenant_id=$1::uuid AND public_id=$2::uuid) ORDER BY usage_category,metric_code,unit`, tenantID, publicID)
	if err != nil {
		return PriceBook{}, err
	}
	defer rows.Close()
	item.Rates = []PriceRate{}
	for rows.Next() {
		var rate PriceRate
		if err = rows.Scan(&rate.ID, &rate.UsageCategory, &rate.MetricCode, &rate.Unit, &rate.UnitPriceMicros); err != nil {
			return PriceBook{}, err
		}
		item.Rates = append(item.Rates, rate)
	}
	return item, rows.Err()
}

func getPriceBookPool(ctx context.Context, pool *pgxpool.Pool, tenantID, publicID string) (PriceBook, error) {
	item, err := scanPriceBook(pool.QueryRow(ctx, priceBookSelect+` WHERE pb.tenant_id=$1::uuid AND pb.public_id=$2::uuid`, tenantID, publicID))
	if err != nil {
		return PriceBook{}, err
	}
	rows, err := pool.Query(ctx, `SELECT id::text,usage_category,metric_code,unit,unit_price_micros FROM billing_price_rate WHERE price_book_id=(SELECT id FROM billing_price_book WHERE tenant_id=$1::uuid AND public_id=$2::uuid) ORDER BY usage_category,metric_code,unit`, tenantID, publicID)
	if err != nil {
		return PriceBook{}, err
	}
	defer rows.Close()
	item.Rates = []PriceRate{}
	for rows.Next() {
		var rate PriceRate
		if err = rows.Scan(&rate.ID, &rate.UsageCategory, &rate.MetricCode, &rate.Unit, &rate.UnitPriceMicros); err != nil {
			return PriceBook{}, err
		}
		item.Rates = append(item.Rates, rate)
	}
	return item, rows.Err()
}

const quotaSelect = `SELECT qp.public_id::text,t.public_id::text,qp.scope_type,d.public_id::text,qp.version_no,qp.status,qp.billing_timezone,qp.currency,qp.daily_limit_micros,qp.monthly_limit_micros,qp.max_concurrent_calls,qp.max_call_duration_sec,qp.in_progress_action,qp.change_summary,ua.public_id::text,qp.retired_at,qp.row_version,qp.created_at,qp.updated_at FROM usage_quota_policy qp JOIN tenant t ON t.id=qp.tenant_id JOIN user_account ua ON ua.id=qp.created_by LEFT JOIN device d ON d.id=qp.device_id`

func scanQuota(row rowScanner) (QuotaPolicy, error) {
	var item QuotaPolicy
	err := row.Scan(&item.ID, &item.TenantID, &item.ScopeType, &item.ScopeID, &item.VersionNo, &item.Status, &item.BillingTimezone, &item.Currency, &item.DailyLimitMicros, &item.MonthlyLimitMicros, &item.MaxConcurrentCalls, &item.MaxCallDurationSec, &item.InProgressAction, &item.ChangeSummary, &item.CreatedBy, &item.RetiredAt, &item.RowVersion, &item.CreatedAt, &item.UpdatedAt)
	return item, err
}
func getQuotaTx(ctx context.Context, tx pgx.Tx, tenantID, publicID string) (QuotaPolicy, error) {
	item, err := scanQuota(tx.QueryRow(ctx, quotaSelect+` WHERE qp.tenant_id=$1::uuid AND qp.public_id=$2::uuid`, tenantID, publicID))
	return item, err
}