package hardwareprovision

import (
	"context"
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/hex"
	"errors"
	"fmt"
	"io"
	"regexp"
	"strings"
	"time"

	"data-terminal-cloud/internal/audit"
	"data-terminal-cloud/internal/deviceactivation"
	"data-terminal-cloud/internal/deviceauth"
	"data-terminal-cloud/internal/devicebinding"

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

var (
	ErrUnavailable      = errors.New("hardware provider provisioning is unavailable")
	ErrInvalid          = errors.New("invalid hardware provider provisioning input")
	ErrBindingMissing   = errors.New("hardware agent binding is missing")
	ErrBindingMismatch  = errors.New("hardware agent product binding does not match platform provisioning configuration")
	ErrHardwareMismatch = errors.New("hardware identity does not match the provisioned credential")
	ErrActivationState  = errors.New("device activation state does not allow provider provisioning")
)

var hardwareIDPattern = regexp.MustCompile(`^[a-zA-Z0-9_\-.:@]{1,200}$`)

type Options struct {
	Enabled             bool
	InstanceID          string
	ProductKey          string
	BotID               string
	Transport           string
	MinimumSDKVersion   string
	ProductSecret       string
	CredentialMasterKey string
	RegisterURL         string
	RegisterTimeout     time.Duration
	DeviceNamePrefix    string
	Registrar           Registrar
}

type ProvisionInput struct {
	HardwareID string `json:"hardware_id"`
}

type ProvisionResponse struct {
	InstanceID        string    `json:"instance_id"`
	ProductKey        string    `json:"product_key"`
	DeviceName        string    `json:"device_name"`
	HardwareID        string    `json:"hardware_id"`
	DeviceSecret      string    `json:"device_secret"`
	CredentialRef     string    `json:"credential_ref"`
	CredentialVersion int64     `json:"credential_version"`
	CredentialSource  string    `json:"credential_source"`
	IssuedAt          time.Time `json:"issued_at"`
}

type Service struct {
	enabled          bool
	pool             *pgxpool.Pool
	audit            *audit.Repository
	registrar        Registrar
	aead             cipher.AEAD
	instanceID       string
	productKey       string
	botID            string
	transport        string
	minimumSDK       string
	deviceNamePrefix string
}

func NewService(pool *pgxpool.Pool, auditRepository *audit.Repository, options Options) (*Service, error) {
	service := &Service{enabled: options.Enabled}
	if !options.Enabled {
		return service, nil
	}
	if pool == nil || auditRepository == nil {
		return nil, errors.New("hardware provider provisioning requires database and audit repository")
	}
	service.instanceID = strings.TrimSpace(options.InstanceID)
	service.productKey = strings.TrimSpace(options.ProductKey)
	service.botID = strings.TrimSpace(options.BotID)
	service.transport = strings.TrimSpace(options.Transport)
	service.minimumSDK = strings.TrimSpace(options.MinimumSDKVersion)
	service.deviceNamePrefix = strings.TrimSpace(options.DeviceNamePrefix)
	if service.deviceNamePrefix == "" {
		service.deviceNamePrefix = "dt-"
	}
	if service.instanceID == "" || len(service.instanceID) > 200 || service.productKey == "" || len(service.productKey) > 200 ||
		service.botID == "" || len(service.botID) > 200 || (service.transport != "high_quality" && service.transport != "low_load") ||
		service.minimumSDK == "" || len(service.minimumSDK) > 80 ||
		!regexp.MustCompile(`^[a-zA-Z0-9_\-.:@]{1,32}$`).MatchString(service.deviceNamePrefix) {
		return nil, errors.New("hardware provider instance, product defaults and device-name prefix are invalid")
	}
	key, err := hex.DecodeString(strings.TrimSpace(options.CredentialMasterKey))
	if err != nil || len(key) != 32 {
		return nil, errors.New("VOLC_HARDWARE_DEVICE_CREDENTIAL_MASTER_KEY must be 32 bytes encoded as 64 hexadecimal characters")
	}
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, fmt.Errorf("create hardware provider credential cipher: %w", err)
	}
	service.aead, err = cipher.NewGCM(block)
	if err != nil {
		return nil, fmt.Errorf("create hardware provider credential AEAD: %w", err)
	}
	service.registrar = options.Registrar
	if service.registrar == nil {
		service.registrar, err = NewHTTPRegistrar(options.RegisterURL, options.ProductSecret, options.RegisterTimeout)
		if err != nil {
			return nil, err
		}
	}
	service.pool = pool
	service.audit = auditRepository
	return service, nil
}

func (s *Service) Provision(ctx context.Context, identity deviceauth.Identity, requestID string, input ProvisionInput) (ProvisionResponse, error) {
	if !s.enabled {
		return ProvisionResponse{}, ErrUnavailable
	}
	hardwareID := strings.TrimSpace(input.HardwareID)
	if !hardwareIDPattern.MatchString(hardwareID) {
		return ProvisionResponse{}, ErrInvalid
	}
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return ProvisionResponse{}, fmt.Errorf("begin hardware provider provisioning: %w", err)
	}
	defer tx.Rollback(ctx)
	if _, err := tx.Exec(ctx, `SELECT pg_advisory_xact_lock(hashtextextended($1, 0))`, identity.ID); err != nil {
		return ProvisionResponse{}, fmt.Errorf("lock hardware provider provisioning: %w", err)
	}
	if err := devicebinding.RequireLegacy(ctx, tx, identity.ID); err != nil {
		return ProvisionResponse{}, err
	}
	activationState, err := s.prepareActivation(ctx, tx, identity, requestID)
	if err != nil {
		return ProvisionResponse{}, err
	}
	if err := s.ensureProductBinding(ctx, tx, identity); err != nil {
		return ProvisionResponse{}, err
	}
	existing, found, err := s.readExisting(ctx, tx, identity.ID)
	if err != nil {
		return ProvisionResponse{}, err
	}
	if found {
		if existing.HardwareID != hardwareID {
			return ProvisionResponse{}, ErrHardwareMismatch
		}
		if existing.InstanceID != s.instanceID || existing.ProductKey != s.productKey {
			return ProvisionResponse{}, ErrBindingMismatch
		}
		secret, err := s.aead.Open(nil, existing.Nonce, existing.EncryptedSecret, credentialAAD(existing.CredentialRef, existing.KeyVersion, existing.InstanceID, existing.ProductKey, existing.DeviceName))
		if err != nil {
			return ProvisionResponse{}, errors.New("decrypt hardware provider device credential")
		}
		response := ProvisionResponse{InstanceID: existing.InstanceID, ProductKey: existing.ProductKey, DeviceName: existing.DeviceName,
			HardwareID: existing.HardwareID, DeviceSecret: string(secret), CredentialRef: existing.CredentialRef,
			CredentialVersion: existing.KeyVersion, CredentialSource: "platform_stored", IssuedAt: existing.IssuedAt}
		if existing.Status == "SUSPENDED" {
			if _, err := tx.Exec(ctx, `UPDATE hardware_agent_provider_credential SET status='ACTIVE',revoked_at=NULL,updated_at=now() WHERE device_id=$1::uuid AND status='SUSPENDED'`, identity.ID); err != nil {
				return ProvisionResponse{}, fmt.Errorf("reactivate hardware provider credential: %w", err)
			}
		}
		if activationState == deviceactivation.Provisioning {
			if _, err := deviceactivation.Apply(ctx, tx, deviceactivation.Input{DeviceID: identity.ID, TenantID: identity.TenantID,
				Target: deviceactivation.Active, Reason: "火山运行凭据已就绪", Source: "provider-provisioning", ActorType: "device",
				ActorPublicID: &identity.PublicID, RequestID: requestID}); err != nil {
				return ProvisionResponse{}, fmt.Errorf("complete provider activation: %w", err)
			}
		}
		if err := s.recordAudit(ctx, tx, identity, requestID, "hardware_agent.provider_credential.resolve", response, true); err != nil {
			return ProvisionResponse{}, err
		}
		if err := tx.Commit(ctx); err != nil {
			return ProvisionResponse{}, fmt.Errorf("commit hardware provider credential resolution: %w", err)
		}
		return response, nil
	}

	var configuredProduct, configuredDeviceName string
	err = tx.QueryRow(ctx, `
		SELECT COALESCE(product_key,''),COALESCE(provider_device_ref,'')
		FROM hardware_agent_device_binding
		WHERE device_id=$1::uuid AND tenant_id=$2::uuid AND provider='volcengine' AND status='ACTIVE'
		FOR UPDATE`, identity.ID, identity.TenantID).Scan(&configuredProduct, &configuredDeviceName)
	if errors.Is(err, pgx.ErrNoRows) {
		return ProvisionResponse{}, ErrBindingMissing
	}
	if err != nil {
		return ProvisionResponse{}, fmt.Errorf("read hardware agent provider binding: %w", err)
	}
	if configuredProduct != "" && configuredProduct != s.productKey {
		return ProvisionResponse{}, ErrBindingMismatch
	}
	deviceName := strings.TrimSpace(configuredDeviceName)
	if deviceName == "" {
		deviceName = s.deviceNamePrefix + strings.ReplaceAll(identity.PublicID, "-", "")
	}
	if len(deviceName) > 128 || !regexp.MustCompile(`^[a-zA-Z0-9_\-.:@]{1,128}$`).MatchString(deviceName) {
		return ProvisionResponse{}, ErrInvalid
	}
	registered, err := s.registrar.Register(ctx, RegisterInput{InstanceID: s.instanceID, ProductKey: s.productKey, DeviceName: deviceName})
	if err != nil {
		return ProvisionResponse{}, fmt.Errorf("register hardware provider device: %w", err)
	}
	secret := []byte(strings.TrimSpace(registered.DeviceSecret))
	if len(secret) < 16 || len(secret) > 4096 {
		return ProvisionResponse{}, errors.New("hardware provider returned an invalid device credential")
	}
	credentialRef := "volc-device-secret://" + identity.PublicID
	const keyVersion int64 = 1
	nonce := make([]byte, s.aead.NonceSize())
	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
		return ProvisionResponse{}, fmt.Errorf("generate hardware provider credential nonce: %w", err)
	}
	encrypted := s.aead.Seal(nil, nonce, secret, credentialAAD(credentialRef, keyVersion, s.instanceID, s.productKey, deviceName))
	issuedAt := time.Now().UTC()
	_, err = tx.Exec(ctx, `
		INSERT INTO hardware_agent_provider_credential(
			tenant_id,device_id,credential_ref,instance_id,product_key,provider_device_name,hardware_id,
			key_version,encrypted_secret,nonce,status,issued_at
		) VALUES($1::uuid,$2::uuid,$3,$4,$5,$6,$7,$8,$9,$10,'ACTIVE',$11)`,
		identity.TenantID, identity.ID, credentialRef, s.instanceID, s.productKey, deviceName, hardwareID,
		keyVersion, encrypted, nonce, issuedAt)
	if err != nil {
		return ProvisionResponse{}, fmt.Errorf("store hardware provider device credential: %w", err)
	}
	_, err = tx.Exec(ctx, `
		UPDATE hardware_agent_device_binding
		SET product_key=$2,provider_device_ref=$3,credential_ref=$4,updated_at=now()
		WHERE device_id=$1::uuid`, identity.ID, s.productKey, deviceName, credentialRef)
	if err != nil {
		return ProvisionResponse{}, fmt.Errorf("update hardware agent provider binding: %w", err)
	}
	response := ProvisionResponse{InstanceID: s.instanceID, ProductKey: s.productKey, DeviceName: deviceName, HardwareID: hardwareID,
		DeviceSecret: string(secret), CredentialRef: credentialRef, CredentialVersion: keyVersion,
		CredentialSource: "platform_dynamic_registration", IssuedAt: issuedAt}
	if activationState == deviceactivation.Provisioning {
		if _, err := deviceactivation.Apply(ctx, tx, deviceactivation.Input{DeviceID: identity.ID, TenantID: identity.TenantID,
			Target: deviceactivation.Active, Reason: "火山动态注册与运行凭据已就绪", Source: "provider-provisioning", ActorType: "device",
			ActorPublicID: &identity.PublicID, RequestID: requestID}); err != nil {
			return ProvisionResponse{}, fmt.Errorf("complete provider activation: %w", err)
		}
	}
	if err := s.recordAudit(ctx, tx, identity, requestID, "hardware_agent.provider_credential.provision", response, false); err != nil {
		return ProvisionResponse{}, err
	}
	if err := tx.Commit(ctx); err != nil {
		return ProvisionResponse{}, fmt.Errorf("commit hardware provider provisioning: %w", err)
	}
	return response, nil
}

// ensureProductBinding resolves the device runtime from the platform-owned
// product defaults. DynamicRegister only creates the provider device identity;
// it does not return a Bot ID, so devices must never supply or persist that
// routing choice themselves.
func (s *Service) ensureProductBinding(ctx context.Context, tx pgx.Tx, identity deviceauth.Identity) error {
	var runtime string
	if err := tx.QueryRow(ctx, `SELECT COALESCE(desired_config->>'voice_runtime','legacy_voicechat') FROM device_twin WHERE device_id=$1::uuid AND tenant_id=$2::uuid FOR UPDATE`, identity.ID, identity.TenantID).Scan(&runtime); errors.Is(err, pgx.ErrNoRows) {
		return ErrBindingMissing
	} else if err != nil {
		return fmt.Errorf("read hardware agent runtime: %w", err)
	}
	if runtime != "volc_hardware_agent" {
		return ErrBindingMissing
	}
	_, err := tx.Exec(ctx, `
		INSERT INTO hardware_agent_device_binding(
			tenant_id,device_id,provider,product_key,bot_id,transport,minimum_sdk_version,status
		) VALUES($1::uuid,$2::uuid,'volcengine',$3,$4,$5,$6,'ACTIVE')
		ON CONFLICT(device_id) DO UPDATE SET
			product_key=EXCLUDED.product_key,bot_id=EXCLUDED.bot_id,transport=EXCLUDED.transport,
			minimum_sdk_version=EXCLUDED.minimum_sdk_version,status='ACTIVE',updated_at=now()`,
		identity.TenantID, identity.ID, s.productKey, s.botID, s.transport, s.minimumSDK)
	if err != nil {
		return fmt.Errorf("bind hardware agent product defaults: %w", err)
	}
	_, err = tx.Exec(ctx, `
		UPDATE device_twin SET desired_revision=desired_revision+1,
			desired_config=desired_config||jsonb_build_object(
				'voice_runtime','volc_hardware_agent','hardware_agent_transport',$2::text,'minimum_sdk_version',$3::text
			),updated_at=now()
		WHERE device_id=$1::uuid AND (
			COALESCE(desired_config->>'hardware_agent_transport','')<>$2 OR
			COALESCE(desired_config->>'minimum_sdk_version','')<>$3
		)`, identity.ID, s.transport, s.minimumSDK)
	if err != nil {
		return fmt.Errorf("publish hardware agent product defaults: %w", err)
	}
	return nil
}

type storedCredential struct {
	Status          string
	CredentialRef   string
	InstanceID      string
	ProductKey      string
	DeviceName      string
	HardwareID      string
	KeyVersion      int64
	EncryptedSecret []byte
	Nonce           []byte
	IssuedAt        time.Time
}

func (s *Service) readExisting(ctx context.Context, tx pgx.Tx, deviceID string) (storedCredential, bool, error) {
	var item storedCredential
	err := tx.QueryRow(ctx, `
		SELECT status,credential_ref,instance_id,product_key,provider_device_name,hardware_id,key_version,encrypted_secret,nonce,issued_at
		FROM hardware_agent_provider_credential
		WHERE device_id=$1::uuid AND provider='volcengine' AND status IN ('ACTIVE','SUSPENDED')
		FOR UPDATE`, deviceID).Scan(&item.Status, &item.CredentialRef, &item.InstanceID, &item.ProductKey, &item.DeviceName, &item.HardwareID,
		&item.KeyVersion, &item.EncryptedSecret, &item.Nonce, &item.IssuedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return storedCredential{}, false, nil
	}
	if err != nil {
		return storedCredential{}, false, fmt.Errorf("read hardware provider device credential: %w", err)
	}
	return item, true, nil
}

func (s *Service) prepareActivation(ctx context.Context, tx pgx.Tx, identity deviceauth.Identity, requestID string) (deviceactivation.State, error) {
	var stateText string
	if err := tx.QueryRow(ctx, `SELECT activation_state FROM device WHERE id=$1::uuid AND tenant_id=$2::uuid FOR UPDATE`, identity.ID, identity.TenantID).Scan(&stateText); err != nil {
		return "", fmt.Errorf("read device activation for provisioning: %w", err)
	}
	state, err := deviceactivation.Parse(stateText)
	if err != nil {
		return "", ErrActivationState
	}
	if state == deviceactivation.Bound {
		result, err := deviceactivation.Apply(ctx, tx, deviceactivation.Input{DeviceID: identity.ID, TenantID: identity.TenantID,
			Target: deviceactivation.Provisioning, Reason: "设备请求火山运行凭据", Source: "provider-provisioning", ActorType: "device",
			ActorPublicID: &identity.PublicID, RequestID: requestID})
		if err != nil {
			return "", fmt.Errorf("start provider activation: %w", err)
		}
		return result.To, nil
	}
	if state != deviceactivation.Provisioning && state != deviceactivation.Active {
		return "", ErrActivationState
	}
	return state, nil
}

func (s *Service) recordAudit(ctx context.Context, tx pgx.Tx, identity deviceauth.Identity, requestID, action string, response ProvisionResponse, reused bool) error {
	return s.audit.Record(ctx, tx, audit.Event{TenantID: &identity.TenantID, ActorType: "device", ActorPublicID: &identity.PublicID,
		Action: action, ResourceType: "device", ResourceID: &identity.PublicID, RequestID: requestID, Result: "success",
		Detail: map[string]any{"provider": "volcengine", "product_key": response.ProductKey, "provider_device_name": response.DeviceName,
			"credential_version": response.CredentialVersion, "reused": reused}})
}

func credentialAAD(reference string, version int64, instanceID, productKey, deviceName string) []byte {
	return []byte(fmt.Sprintf("hardware-provider-credential-v1\n%s\n%d\n%s\n%s\n%s", reference, version, instanceID, productKey, deviceName))
}