package repository

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"time"

	"github.com/google/uuid"
	"gorm.io/gorm"

	"apskel-pos-be/internal/entities"
)

// ErrAuditTxRequired is returned when an audit row is written outside a transaction:
// the row must commit or roll back together with the change it records.
var ErrAuditTxRequired = errors.New("audit: write must run inside a transaction")

// AuditLogRepository stores audit_logs (docs/rfc-enakgame.md §5.9).
type AuditLogRepository interface {
	// Insert writes a row in the caller's transaction, or returns ErrAuditTxRequired.
	Insert(ctx context.Context, entry *entities.AuditLog) error
	// ListByEntity returns an entity's rows in an organization, newest first.
	ListByEntity(ctx context.Context, organizationID uuid.UUID, entityType string, entityID uuid.UUID, limit int) ([]entities.AuditLog, error)
}

type auditLogRepository struct {
	db *gorm.DB
}

func NewAuditLogRepository(db *gorm.DB) AuditLogRepository {
	return &auditLogRepository{db: db}
}

func (r *auditLogRepository) Insert(ctx context.Context, entry *entities.AuditLog) error {
	tx, ok := ctx.Value(txKey).(*gorm.DB)
	if !ok || tx == nil {
		return ErrAuditTxRequired
	}
	if entry.ID == uuid.Nil {
		entry.ID = uuid.New()
	}
	var rows []struct{ CreatedAt time.Time }
	err := tx.WithContext(ctx).Raw(`
		INSERT INTO audit_logs (id, organization_id, actor_type, actor_id, entity_type, entity_id,
			action, before, after, reason, source)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?::jsonb, ?::jsonb, ?, ?)
		RETURNING created_at`,
		entry.ID, entry.OrganizationID, entry.ActorType, entry.ActorID, entry.EntityType, entry.EntityID,
		entry.Action, jsonOrNull(entry.Before), jsonOrNull(entry.After), entry.Reason, entry.Source).
		Scan(&rows).Error
	if err != nil {
		return fmt.Errorf("failed to write audit log: %w", err)
	}
	if len(rows) == 1 {
		entry.CreatedAt = rows[0].CreatedAt
	}
	return nil
}

func (r *auditLogRepository) ListByEntity(ctx context.Context, organizationID uuid.UUID, entityType string, entityID uuid.UUID, limit int) ([]entities.AuditLog, error) {
	var rows []struct {
		ID             string
		OrganizationID string
		ActorType      string
		ActorID        *string
		EntityType     string
		EntityID       string
		Action         string
		Before         *string
		After          *string
		Reason         *string
		Source         string
		CreatedAt      time.Time
	}
	err := DBFromContext(ctx, r.db).WithContext(ctx).Raw(`
		SELECT id::text AS id, organization_id::text AS organization_id, actor_type, actor_id::text AS actor_id,
			entity_type, entity_id::text AS entity_id, action, before::text AS before, after::text AS after,
			reason, source, created_at
		FROM audit_logs
		WHERE organization_id = ? AND entity_type = ? AND entity_id = ?
		ORDER BY created_at DESC, id
		LIMIT ?`, organizationID, entityType, entityID, limit).Scan(&rows).Error
	if err != nil {
		return nil, fmt.Errorf("failed to read audit logs: %w", err)
	}
	out := make([]entities.AuditLog, 0, len(rows))
	for _, row := range rows {
		entry := entities.AuditLog{
			ActorType:  row.ActorType,
			EntityType: row.EntityType,
			Action:     row.Action,
			Reason:     row.Reason,
			Source:     row.Source,
			CreatedAt:  row.CreatedAt,
		}
		entry.ID, _ = uuid.Parse(row.ID)
		entry.OrganizationID, _ = uuid.Parse(row.OrganizationID)
		entry.EntityID, _ = uuid.Parse(row.EntityID)
		if row.ActorID != nil {
			if id, err := uuid.Parse(*row.ActorID); err == nil {
				entry.ActorID = &id
			}
		}
		if row.Before != nil {
			entry.Before = json.RawMessage(*row.Before)
		}
		if row.After != nil {
			entry.After = json.RawMessage(*row.After)
		}
		out = append(out, entry)
	}
	return out, nil
}

// jsonOrNull passes a JSON document as text, or NULL when there is none.
func jsonOrNull(doc json.RawMessage) *string {
	if len(doc) == 0 {
		return nil
	}
	s := string(doc)
	return &s
}