package service

import (
	"bytes"
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"net"
	"net/http"
	"regexp"
	"strings"
	"sync"
	"time"

	"github.com/1024XEngineer/xinfra/server/internal/config"
	"github.com/1024XEngineer/xinfra/server/internal/model"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

var dnsLabelPattern = regexp.MustCompile(`^[a-z0-9](?:[-a-z0-9]*[a-z0-9])?$`)

type MySQLDeliveryInput struct {
	BusinessLineID            uint64  `json:"business_line_id" binding:"required"`
	TargetID                  uint64  `json:"target_id" binding:"required"`
	Namespace                 string  `json:"namespace" binding:"required"`
	InstanceName              string  `json:"instance_name" binding:"required"`
	MySQLVersion              string  `json:"mysql_version"`
	Topology                  string  `json:"topology"`
	MySQLPort                 int     `json:"mysql_port"`
	DataDisk                  string  `json:"data_disk"`
	CPUCores                  int64   `json:"cpu_cores" binding:"required"`
	MemoryGB                  int64   `json:"memory_gb" binding:"required"`
	StorageGB                 int64   `json:"storage_gb" binding:"required"`
	ParamTemplate             string  `json:"param_template"`
	TimeZone                  string  `json:"timezone"`
	LowerCaseTableNames       int     `json:"lower_case_table_names"`
	CharacterSet              string  `json:"character_set"`
	Collation                 string  `json:"collation"`
	MaxConnections            string  `json:"max_connections"`
	InnoDBRedoLogCapacity     string  `json:"innodb_redo_log_capacity"`
	InnoDBFlushLogAtTrxCommit int     `json:"innodb_flush_log_at_trx_commit"`
	SyncBinlog                int     `json:"sync_binlog"`
	InnoDBIOCapacity          int     `json:"innodb_io_capacity"`
	LongQueryTime             float64 `json:"long_query_time"`
	BinlogExpireLogsSeconds   int64   `json:"binlog_expire_logs_seconds"`
	MaxBinlogSize             string  `json:"max_binlog_size"`
	CPUMilli                  int64   `json:"-"`
	MemoryMi                  int64   `json:"-"`
	StorageGi                 int64   `json:"-"`
}

type deliveryPayload struct {
	MySQLDeliveryInput
	TargetType string `json:"target_type"`
}

type DeliveryTarget struct {
	ID             uint64 `json:"id"`
	Name           string `json:"name"`
	TargetType     string `json:"target_type"`
	AWXInventoryID uint64 `json:"awx_inventory_id"`
	AWXTemplateID  uint64 `json:"awx_template_id"`
	Enabled        bool   `json:"enabled"`
	Metadata       string `json:"metadata"`
}

type DeliveryStageEventInput struct {
	Stage    string `json:"stage" binding:"required"`
	Status   string `json:"status" binding:"required"`
	Message  string `json:"message"`
	AWXJobID string `json:"awx_job_id"`
}

type AWXJobNotificationInput struct {
	ID        uint64 `json:"id"`
	Status    string `json:"status"`
	Name      string `json:"name"`
	URL       string `json:"url"`
	Traceback string `json:"traceback"`
	ExtraVars any    `json:"extra_vars"`
}

type DeliveryTaskListFilter struct {
	BusinessLineID uint64
	Component      string
	ActiveOnly     bool
}

// targetMetadata describes the native VM候选节点池以及部署形态，由 AWX inventory hosts 动态组装。
type targetMetadata struct {
	Topology  string       `json:"topology"`
	MySQLPort int          `json:"mysql_port"`
	Hosts     []targetHost `json:"hosts"`
}

type targetHost struct {
	Name string `json:"name"`
	IP   string `json:"ip"`
}

func parseTargetMetadata(raw string) targetMetadata {
	meta := targetMetadata{}
	if strings.TrimSpace(raw) != "" {
		_ = json.Unmarshal([]byte(raw), &meta)
	}
	if meta.Topology == "" {
		meta.Topology = "standalone"
	}
	if meta.MySQLPort == 0 {
		meta.MySQLPort = 13306
	}
	return meta
}

// firstFreeHost 返回候选池中第一个未被占用的节点。
func firstFreeHost(hosts []targetHost, occupied []string) *targetHost {
	taken := make(map[string]bool, len(occupied))
	for _, h := range occupied {
		taken[h] = true
	}
	for i := range hosts {
		if !taken[hosts[i].Name] {
			return &hosts[i]
		}
	}
	return nil
}

func firstFreePort(occupied []int) int {
	taken := make(map[int]bool, len(occupied))
	for _, port := range occupied {
		taken[port] = true
	}
	for port := 13306; port <= 13999; port++ {
		if !taken[port] {
			return port
		}
	}
	return 0
}

type DeliveryService struct {
	db          *gorm.DB
	cfg         config.Config
	awx         *AWXClient
	audit       *AuditService
	executionMu sync.Mutex
}

func (s *DeliveryService) DB() *gorm.DB { return s.db }

func NewDeliveryService(cfg config.Config, db *gorm.DB, audit *AuditService) *DeliveryService {
	return &DeliveryService{db: db, cfg: cfg, awx: NewAWXClient(cfg.AWXBaseURL, cfg.AWXToken, cfg.AWXUsername, cfg.AWXPassword), audit: audit}
}

func (s *DeliveryService) ListTargets(ctx context.Context, component string) ([]DeliveryTarget, error) {
	templates, err := s.awx.ListJobTemplates(ctx)
	if err != nil {
		return nil, err
	}
	component = strings.ToLower(strings.TrimSpace(component))
	var targets []DeliveryTarget
	for _, template := range templates {
		if template.Inventory == 0 {
			continue
		}
		if component != "" && component != "all" {
			text := strings.ToLower(template.Name + " " + template.Description)
			if !strings.Contains(text, component) {
				continue
			}
		}
		target, err := s.awxDeliveryTarget(ctx, template)
		if err != nil {
			continue
		}
		targets = append(targets, target)
	}
	return targets, nil
}

func (s *DeliveryService) getTarget(ctx context.Context, templateID uint64) (DeliveryTarget, error) {
	template, err := s.awx.GetJobTemplate(ctx, templateID)
	if err != nil {
		return DeliveryTarget{}, fmt.Errorf("deployment target is unavailable: %w", err)
	}
	return s.awxDeliveryTarget(ctx, *template)
}

func (s *DeliveryService) awxDeliveryTarget(ctx context.Context, template AWXJobTemplate) (DeliveryTarget, error) {
	if !template.AskVariablesOnLaunch || !template.AskLimitOnLaunch {
		return DeliveryTarget{}, fmt.Errorf("AWX job template %d must enable Prompt on launch for Variables and Limit", template.ID)
	}
	hosts, err := s.awx.ListInventoryHosts(ctx, template.Inventory)
	if err != nil {
		return DeliveryTarget{}, err
	}
	meta := targetMetadata{Topology: "standalone", MySQLPort: 13306}
	for _, host := range hosts {
		if !host.Enabled {
			continue
		}
		meta.Hosts = append(meta.Hosts, targetHost{Name: host.Name, IP: AWXHostIP(host)})
	}
	raw, err := json.Marshal(meta)
	if err != nil {
		return DeliveryTarget{}, err
	}
	return DeliveryTarget{
		ID:             template.ID,
		Name:           template.Name,
		TargetType:     "k8s",
		AWXInventoryID: template.Inventory,
		AWXTemplateID:  template.ID,
		Enabled:        true,
		Metadata:       string(raw),
	}, nil
}

func (s *DeliveryService) CreateTask(ctx context.Context, userID uint64, isAdmin bool, idempotencyKey string, input MySQLDeliveryInput) (*model.DeliveryTask, bool, error) {
	idempotencyKey = strings.TrimSpace(idempotencyKey)
	if idempotencyKey == "" || len(idempotencyKey) > 128 {
		return nil, false, fmt.Errorf("Idempotency-Key header is required and must not exceed 128 characters")
	}
	normalizeMySQLDeliveryInput(&input)
	if err := validateDeliveryInput(input); err != nil {
		return nil, false, err
	}

	var existing model.DeliveryTask
	if err := s.db.WithContext(ctx).Where("idempotency_key = ?", idempotencyKey).First(&existing).Error; err == nil {
		if existing.RequestedBy != userID {
			return nil, false, fmt.Errorf("idempotency key is already in use by another user")
		}
		return &existing, true, nil
	} else if !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, false, err
	}

	target, err := s.getTarget(ctx, input.TargetID)
	if err != nil {
		return nil, false, err
	}
	if target.TargetType != "k8s" {
		return nil, false, fmt.Errorf("target type %q is not supported in the MVP", target.TargetType)
	}
	if !isAdmin {
		var count int64
		if err := s.db.WithContext(ctx).Model(&model.BusinessLineUser{}).
			Where("business_line_id = ? AND user_id = ?", input.BusinessLineID, userID).Count(&count).Error; err != nil {
			return nil, false, err
		}
		if count == 0 {
			return nil, false, fmt.Errorf("user is not authorized for this business line")
		}
	}
	payload := deliveryPayload{MySQLDeliveryInput: input, TargetType: target.TargetType}
	raw, err := json.Marshal(payload)
	if err != nil {
		return nil, false, err
	}
	digest := sha256.Sum256(raw)
	task := model.DeliveryTask{
		ID:               randomUUID(),
		BusinessLineID:   input.BusinessLineID,
		RequestedBy:      userID,
		Component:        "mysql",
		TargetType:       target.TargetType,
		TargetID:         target.ID,
		Namespace:        input.Namespace,
		InstanceName:     input.InstanceName,
		Status:           model.TaskPending,
		ImmutablePayload: string(raw),
		PayloadHash:      hex.EncodeToString(digest[:]),
		IdempotencyKey:   idempotencyKey,
	}
	if err := s.db.WithContext(ctx).Create(&task).Error; err != nil {
		if lookupErr := s.db.WithContext(ctx).Where("idempotency_key = ?", idempotencyKey).First(&existing).Error; lookupErr == nil {
			return &existing, true, nil
		}
		return nil, false, err
	}
	_ = s.db.WithContext(ctx).Create(&model.TaskEvent{TaskID: task.ID, ToState: model.TaskPending, Message: "delivery task created"}).Error
	return &task, false, nil
}

var supportedMySQLVersions = map[string]bool{"8.0": true}
var supportedMySQLTopologies = map[string]bool{"standalone": true}
var supportedDataDisks = map[string]bool{"/data": true, "/disk1": true, "/mnt/vol-1": true}
var supportedParamTemplates = map[string]bool{"default": true, "high_performance": true, "high_safety": true}
var supportedCharacterSets = map[string]bool{"utf8mb4": true, "utf8": true, "gbk": true, "latin1": true}
var supportedCollations = map[string]bool{
	"utf8mb4_general_ci": true, "utf8mb4_unicode_ci": true, "utf8mb4_0900_ai_ci": true,
	"utf8_general_ci": true, "gbk_chinese_ci": true, "latin1_swedish_ci": true,
}
var supportedRedoLogCapacity = map[string]bool{"auto": true, "128M": true, "256M": true, "512M": true, "1G": true}
var supportedMaxBinlogSize = map[string]bool{"128M": true, "256M": true, "512M": true, "1G": true}

func normalizeMySQLDeliveryInput(input *MySQLDeliveryInput) {
	if input.MySQLVersion == "" {
		input.MySQLVersion = "8.0"
	}
	if input.Topology == "" {
		input.Topology = "standalone"
	}
	if input.DataDisk == "" {
		input.DataDisk = "/data"
	}
	if input.ParamTemplate == "" {
		input.ParamTemplate = "default"
	}
	if input.TimeZone == "" {
		input.TimeZone = "+08:00"
	}
	if input.CharacterSet == "" {
		input.CharacterSet = "utf8mb4"
	}
	if input.Collation == "" {
		input.Collation = defaultCollation(input.CharacterSet)
	}
	if input.MaxConnections == "" {
		input.MaxConnections = "auto"
	}
	if input.InnoDBRedoLogCapacity == "" {
		input.InnoDBRedoLogCapacity = "auto"
	}
	if input.InnoDBFlushLogAtTrxCommit == 0 {
		input.InnoDBFlushLogAtTrxCommit = 1
	}
	if input.SyncBinlog == 0 {
		input.SyncBinlog = 1
	}
	if input.InnoDBIOCapacity == 0 {
		input.InnoDBIOCapacity = 2000
	}
	if input.LongQueryTime == 0 {
		input.LongQueryTime = 1
	}
	if input.BinlogExpireLogsSeconds == 0 {
		input.BinlogExpireLogsSeconds = 604800
	}
	if input.MaxBinlogSize == "" {
		input.MaxBinlogSize = "256M"
	}
	input.CPUMilli = input.CPUCores * 1000
	input.MemoryMi = input.MemoryGB * 1024
	input.StorageGi = input.StorageGB
}

func defaultCollation(characterSet string) string {
	switch characterSet {
	case "utf8":
		return "utf8_general_ci"
	case "gbk":
		return "gbk_chinese_ci"
	case "latin1":
		return "latin1_swedish_ci"
	default:
		return "utf8mb4_general_ci"
	}
}

func validateDeliveryInput(input MySQLDeliveryInput) error {
	if len(input.Namespace) > 63 || !dnsLabelPattern.MatchString(input.Namespace) {
		return fmt.Errorf("namespace must be a valid Kubernetes DNS label")
	}
	if len(input.InstanceName) > 63 || !dnsLabelPattern.MatchString(input.InstanceName) {
		return fmt.Errorf("instance_name must be a valid Kubernetes DNS label")
	}
	if !oneOfInt64(input.CPUCores, []int64{1, 2, 4, 8, 16}) {
		return fmt.Errorf("cpu_cores must be one of 1, 2, 4, 8, 16")
	}
	if !oneOfInt64(input.MemoryGB, []int64{2, 4, 8, 16, 32, 64}) {
		return fmt.Errorf("memory_gb must be one of 2, 4, 8, 16, 32, 64")
	}
	if input.StorageGB < 20 || input.StorageGB > 2000 {
		return fmt.Errorf("storage_gb must be between 20 and 2000")
	}
	if input.MySQLVersion != "" && !supportedMySQLVersions[input.MySQLVersion] {
		return fmt.Errorf("unsupported mysql_version %q, supported: 8.0", input.MySQLVersion)
	}
	if input.Topology != "" && !supportedMySQLTopologies[input.Topology] {
		return fmt.Errorf("unsupported topology %q, supported: standalone", input.Topology)
	}
	if input.MySQLPort != 0 && (input.MySQLPort < 13306 || input.MySQLPort > 13999) {
		return fmt.Errorf("mysql_port must be empty for auto assignment or between 13306 and 13999")
	}
	if !supportedDataDisks[input.DataDisk] {
		return fmt.Errorf("unsupported data_disk %q", input.DataDisk)
	}
	if !supportedParamTemplates[input.ParamTemplate] {
		return fmt.Errorf("unsupported param_template %q", input.ParamTemplate)
	}
	if !validTimeZone(input.TimeZone) {
		return fmt.Errorf("unsupported timezone %q", input.TimeZone)
	}
	if input.LowerCaseTableNames != 0 && input.LowerCaseTableNames != 1 {
		return fmt.Errorf("lower_case_table_names must be 0 or 1")
	}
	if !supportedCharacterSets[input.CharacterSet] {
		return fmt.Errorf("unsupported character_set %q", input.CharacterSet)
	}
	if !supportedCollations[input.Collation] || !strings.HasPrefix(input.Collation, input.CharacterSet+"_") {
		return fmt.Errorf("collation %q is not valid for character_set %q", input.Collation, input.CharacterSet)
	}
	if !validMaxConnections(input.MaxConnections) {
		return fmt.Errorf("max_connections must be auto or one of 200, 500, 1000, 2000, 4000, 8000, 16000")
	}
	if !supportedRedoLogCapacity[input.InnoDBRedoLogCapacity] {
		return fmt.Errorf("unsupported innodb_redo_log_capacity %q", input.InnoDBRedoLogCapacity)
	}
	if !oneOfInt(input.InnoDBFlushLogAtTrxCommit, []int{0, 1, 2}) {
		return fmt.Errorf("innodb_flush_log_at_trx_commit must be one of 0, 1, 2")
	}
	if input.SyncBinlog != 0 && input.SyncBinlog != 1 {
		return fmt.Errorf("sync_binlog must be 0 or 1")
	}
	if !oneOfInt(input.InnoDBIOCapacity, []int{200, 2000, 5000}) {
		return fmt.Errorf("innodb_io_capacity must be one of 200, 2000, 5000")
	}
	if !oneOfFloat(input.LongQueryTime, []float64{0.5, 1, 2, 5, 10}) {
		return fmt.Errorf("long_query_time must be one of 0.5, 1, 2, 5, 10")
	}
	if !oneOfInt64(input.BinlogExpireLogsSeconds, []int64{86400, 259200, 604800, 1209600}) {
		return fmt.Errorf("binlog_expire_logs_seconds must be one of 86400, 259200, 604800, 1209600")
	}
	if !supportedMaxBinlogSize[input.MaxBinlogSize] {
		return fmt.Errorf("unsupported max_binlog_size %q", input.MaxBinlogSize)
	}
	return nil
}

func oneOfInt(value int, allowed []int) bool {
	for _, item := range allowed {
		if value == item {
			return true
		}
	}
	return false
}

func oneOfInt64(value int64, allowed []int64) bool {
	for _, item := range allowed {
		if value == item {
			return true
		}
	}
	return false
}

func oneOfFloat(value float64, allowed []float64) bool {
	for _, item := range allowed {
		if value == item {
			return true
		}
	}
	return false
}

func validTimeZone(value string) bool {
	return value == "SYSTEM" || value == "+08:00" || value == "+00:00" || value == "Asia/Shanghai"
}

func validMaxConnections(value string) bool {
	if value == "auto" {
		return true
	}
	switch value {
	case "200", "500", "1000", "2000", "4000", "8000", "16000":
		return true
	default:
		return false
	}
}

func (s *DeliveryService) ListTasks(ctx context.Context, userID uint64, isAdmin bool, filter DeliveryTaskListFilter) ([]model.DeliveryTask, error) {
	query := s.db.WithContext(ctx).Order("created_at DESC")
	if filter.BusinessLineID != 0 {
		query = query.Where("business_line_id = ?", filter.BusinessLineID)
	}
	if filter.Component != "" {
		query = query.Where("component = ?", strings.ToLower(strings.TrimSpace(filter.Component)))
	}
	if filter.ActiveOnly {
		query = query.Where("status NOT IN ?", terminalTaskStatuses())
	}
	if !isAdmin {
		query = query.Where("business_line_id IN (?)", s.db.Model(&model.BusinessLineUser{}).Select("business_line_id").Where("user_id = ?", userID))
	}
	var tasks []model.DeliveryTask
	return tasks, query.Find(&tasks).Error
}

func (s *DeliveryService) GetTask(ctx context.Context, taskID string, userID uint64, isAdmin bool) (*model.DeliveryTask, []model.TaskEvent, error) {
	query := s.db.WithContext(ctx).Where("id = ?", taskID)
	if !isAdmin {
		query = query.Where("business_line_id IN (?)", s.db.Model(&model.BusinessLineUser{}).Select("business_line_id").Where("user_id = ?", userID))
	}
	var task model.DeliveryTask
	if err := query.First(&task).Error; err != nil {
		return nil, nil, err
	}
	var events []model.TaskEvent
	if err := s.db.WithContext(ctx).Where("task_id = ?", taskID).Order("id ASC").Find(&events).Error; err != nil {
		return nil, nil, err
	}
	return &task, events, nil
}

func (s *DeliveryService) AWXJobStdout(ctx context.Context, jobID string) (string, error) {
	return s.awx.JobStdout(ctx, jobID)
}

func (s *DeliveryService) Cancel(ctx context.Context, taskID string, userID uint64, isAdmin bool) error {
	task, _, err := s.GetTask(ctx, taskID, userID, isAdmin)
	if err != nil {
		return err
	}
	if task.Status == model.TaskPending {
		return s.transition(ctx, task, model.TaskCanceled, "canceled before dispatch", "")
	}
	if task.Status != model.TaskRunning && task.Status != model.TaskDispatching {
		return fmt.Errorf("task in state %q cannot be canceled", task.Status)
	}
	var job model.ExecutionJob
	if err := s.db.WithContext(ctx).Where("task_id = ?", task.ID).First(&job).Error; err != nil {
		return err
	}
	if err := s.awx.Cancel(ctx, job.ExecutorJobID); err != nil {
		return err
	}
	return s.transition(ctx, task, model.TaskCanceling, "cancel requested in AWX", "")
}

func (s *DeliveryService) claimAndReserve(ctx context.Context) (*model.DeliveryTask, error) {
	var task model.DeliveryTask
	var payload deliveryPayload
	var target DeliveryTarget
	dispatchable := false
	err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE", Options: "SKIP LOCKED"}).Where("status = ?", model.TaskPending).Order("created_at DESC").First(&task).Error; err != nil {
			return err
		}
		var targetErr error
		target, targetErr = s.getTarget(ctx, task.TargetID)
		if targetErr != nil {
			return s.failInTransaction(tx, &task, model.TaskValidationFailed, targetErr.Error())
		}
		if err := json.Unmarshal([]byte(task.ImmutablePayload), &payload); err != nil {
			return s.failInTransaction(tx, &task, model.TaskValidationFailed, "stored deployment payload is invalid")
		}
		normalizeMySQLDeliveryInput(&payload.MySQLDeliveryInput)
		activeStates := []string{model.TaskValidating, model.TaskDispatching, model.TaskRunning, model.TaskCanceling}
		checks := []struct {
			query   string
			args    []any
			limit   int
			message string
		}{
			{"status IN ?", []any{activeStates}, s.cfg.DeliveryGlobalLimit, "global concurrency limit reached"},
			{"status IN ? AND target_id = ?", []any{activeStates, task.TargetID}, s.cfg.DeliveryTargetLimit, "target concurrency limit reached"},
		}
		for _, check := range checks {
			var count int64
			if check.limit > 0 {
				if err := tx.Model(&model.DeliveryTask{}).Where(check.query, check.args...).Count(&count).Error; err != nil {
					return err
				}
				if count >= int64(check.limit) {
					return fmt.Errorf("defer: %s", check.message)
				}
			}
		}
		quotaOK, err := checkResourceQuota(tx, task.BusinessLineID, task.TargetID, payload)
		if err != nil {
			return err
		}
		if !quotaOK {
			return s.failInTransaction(tx, &task, model.TaskValidationFailed, "resource quota is insufficient")
		}
		meta := parseTargetMetadata(target.Metadata)
		if len(meta.Hosts) == 0 {
			return s.failInTransaction(tx, &task, model.TaskValidationFailed, "deployment target has no candidate hosts")
		}
		var occupied []string
		occupiedExclude := []string{model.TaskExecutionFailed, model.TaskValidationFailed, model.TaskCanceled}
		if err := tx.Model(&model.DeliveryTask{}).Where("target_id = ? AND target_host <> ? AND status NOT IN ?", task.TargetID, "", occupiedExclude).Pluck("target_host", &occupied).Error; err != nil {
			return err
		}
		host := firstFreeHost(meta.Hosts, occupied)
		if host == nil {
			return fmt.Errorf("defer: no free host available on target")
		}
		mysqlPort := payload.MySQLPort
		if mysqlPort == 0 {
			var occupiedPorts []int
			if err := tx.Model(&model.DeliveryTask{}).Where("target_id = ? AND target_host = ? AND mysql_port <> ? AND status NOT IN ?", task.TargetID, host.Name, 0, occupiedExclude).Pluck("mysql_port", &occupiedPorts).Error; err != nil {
				return err
			}
			mysqlPort = firstFreePort(occupiedPorts)
			if mysqlPort == 0 {
				return fmt.Errorf("defer: no free MySQL port available on target host")
			}
		}
		reservation := model.ResourceReservation{TaskID: task.ID, BusinessLineID: task.BusinessLineID, TargetID: task.TargetID, CPUMilli: payload.CPUMilli, MemoryMi: payload.MemoryMi, StorageGi: payload.StorageGi, InstanceCount: 1, Status: "reserved", ExpiresAt: time.Now().Add(time.Duration(s.cfg.ReservationTTLMinutes) * time.Minute)}
		if err := tx.Create(&reservation).Error; err != nil {
			return err
		}
		if err := tx.Model(&model.DeliveryTask{}).Where("id = ?", task.ID).Updates(map[string]any{"target_host": host.Name, "target_host_ip": host.IP, "mysql_port": mysqlPort}).Error; err != nil {
			return err
		}
		task.TargetHost = host.Name
		task.TargetHostIP = host.IP
		task.MySQLPort = mysqlPort
		if err := s.transitionTx(tx, &task, model.TaskDispatching, "resources reserved", ""); err != nil {
			return err
		}
		dispatchable = true
		return nil
	})
	if err == nil && !dispatchable {
		err = gorm.ErrRecordNotFound
	}
	return &task, err
}

func checkResourceQuota(tx *gorm.DB, businessLineID, targetID uint64, payload deliveryPayload) (bool, error) {
	var quota model.ResourceQuota
	if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Where("business_line_id = ? AND target_id = ?", businessLineID, targetID).First(&quota).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return true, nil
		}
		return false, err
	}
	type totals struct{ CPU, Memory, Storage, Instances int64 }
	var used, reserved totals
	if err := tx.Model(&model.ResourceUsage{}).Select("COALESCE(SUM(cpu_milli),0) cpu, COALESCE(SUM(memory_mi),0) memory, COALESCE(SUM(storage_gi),0) storage, COALESCE(SUM(instance_count),0) instances").Where("business_line_id = ? AND target_id = ? AND status = ?", businessLineID, targetID, "active").Scan(&used).Error; err != nil {
		return false, err
	}
	if err := tx.Model(&model.ResourceReservation{}).Select("COALESCE(SUM(cpu_milli),0) cpu, COALESCE(SUM(memory_mi),0) memory, COALESCE(SUM(storage_gi),0) storage, COALESCE(SUM(instance_count),0) instances").Where("business_line_id = ? AND target_id = ? AND status = ? AND expires_at > ?", businessLineID, targetID, "reserved", time.Now()).Scan(&reserved).Error; err != nil {
		return false, err
	}
	return used.CPU+reserved.CPU+payload.CPUMilli <= quota.CPUMilli &&
		used.Memory+reserved.Memory+payload.MemoryMi <= quota.MemoryMi &&
		used.Storage+reserved.Storage+payload.StorageGi <= quota.StorageGi &&
		used.Instances+reserved.Instances+1 <= quota.InstanceLimit, nil
}

func (s *DeliveryService) failInTransaction(tx *gorm.DB, task *model.DeliveryTask, status, message string) error {
	if err := s.transitionTx(tx, task, status, message, message); err != nil {
		return err
	}
	return nil
}

func (s *DeliveryService) transition(ctx context.Context, task *model.DeliveryTask, status, message, errorMessage string) error {
	return s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error { return s.transitionTx(tx, task, status, message, errorMessage) })
}

func (s *DeliveryService) transitionTx(tx *gorm.DB, task *model.DeliveryTask, status, message, errorMessage string) error {
	from := task.Status
	updates := map[string]any{"status": status, "error_message": errorMessage}
	now := time.Now()
	if status == model.TaskRunning {
		updates["started_at"] = now
	}
	if status == model.TaskFinished || status == model.TaskExecutionFailed || status == model.TaskValidationFailed || status == model.TaskCanceled || status == model.TaskRegisterFailed {
		updates["finished_at"] = now
	}
	result := tx.Model(&model.DeliveryTask{}).Where("id = ? AND status = ?", task.ID, from).Updates(updates)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected != 1 {
		return fmt.Errorf("task %s changed concurrently", task.ID)
	}
	task.Status = status
	task.ErrorMessage = errorMessage
	return tx.Create(&model.TaskEvent{TaskID: task.ID, FromState: from, ToState: status, Message: message}).Error
}

func (s *DeliveryService) releaseReservation(tx *gorm.DB, taskID string) error {
	return tx.Model(&model.ResourceReservation{}).Where("task_id = ? AND status = ?", taskID, "reserved").Update("status", "released").Error
}

func randomUUID() string {
	b := make([]byte, 16)
	if _, err := rand.Read(b); err != nil {
		panic(err)
	}
	b[6] = (b[6] & 0x0f) | 0x40
	b[8] = (b[8] & 0x3f) | 0x80
	return fmt.Sprintf("%08x-%04x-%04x-%04x-%012x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:16])
}

func mysqlReady(ctx context.Context, address string) error {
	dialer := net.Dialer{Timeout: 5 * time.Second}
	conn, err := dialer.DialContext(ctx, "tcp", address)
	if err != nil {
		return err
	}
	return conn.Close()
}

func (s *DeliveryService) DispatchOnce(ctx context.Context) error {
	task, err := s.claimAndReserve(ctx)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) || strings.HasPrefix(err.Error(), "defer:") {
			return nil
		}
		return err
	}
	_, _, err = s.CreateExecution(ctx, task.ID, task.PayloadHash, task.IdempotencyKey)
	if err != nil {
		return s.failTask(ctx, task, model.TaskExecutionFailed, err.Error())
	}
	return nil
}

func (s *DeliveryService) CreateExecution(ctx context.Context, taskID, payloadHash, idempotencyKey string) (*model.ExecutionJob, bool, error) {
	s.executionMu.Lock()
	defer s.executionMu.Unlock()
	var existing model.ExecutionJob
	if err := s.db.WithContext(ctx).Where("task_id = ? OR idempotency_key = ?", taskID, idempotencyKey).First(&existing).Error; err == nil {
		if existing.TaskID != taskID || existing.IdempotencyKey != idempotencyKey {
			return nil, false, fmt.Errorf("idempotency key is already bound to another task")
		}
		return &existing, true, nil
	} else if !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, false, err
	}
	var task model.DeliveryTask
	if err := s.db.WithContext(ctx).First(&task, "id = ?", taskID).Error; err != nil {
		return nil, false, err
	}
	if task.PayloadHash != payloadHash || task.IdempotencyKey != idempotencyKey {
		return nil, false, fmt.Errorf("execution request does not match the immutable task payload")
	}
	if task.Status != model.TaskDispatching {
		return nil, false, fmt.Errorf("task in state %q is not ready for execution", task.Status)
	}
	target, err := s.getTarget(ctx, task.TargetID)
	if err != nil {
		return nil, false, err
	}
	var payload deliveryPayload
	if err := json.Unmarshal([]byte(task.ImmutablePayload), &payload); err != nil {
		return nil, false, err
	}
	normalizeMySQLDeliveryInput(&payload.MySQLDeliveryInput)
	meta := parseTargetMetadata(target.Metadata)
	topology := payload.Topology
	if topology == "" {
		topology = meta.Topology
	}
	// Persist execution record BEFORE launching AWX to ensure crash recovery.
	now := time.Now()
	execution := model.ExecutionJob{TaskID: task.ID, IdempotencyKey: task.IdempotencyKey, ExecutorJobID: pendingExecutorJobID(task.ID), Status: "launching", StartedAt: &now}
	if err := s.db.WithContext(ctx).Create(&execution).Error; err != nil {
		return nil, false, err
	}
	job, err := s.awx.Launch(ctx, target.AWXTemplateID, AWXLaunchRequest{InventoryID: target.AWXInventoryID, Limit: task.TargetHost, ExtraVars: map[string]any{
		"task_id": task.ID, "payload_hash": task.PayloadHash,
		"target_hosts": task.TargetHost, "topology": topology,
		"instance_name": payload.InstanceName, "mysql_port": task.MySQLPort,
		"data_disk": payload.DataDisk, "cpu_cores": payload.CPUCores,
		"memory_gb": payload.MemoryGB, "storage_gb": payload.StorageGB,
		"mysql_version": payload.MySQLVersion, "param_template": payload.ParamTemplate,
		"timezone": payload.TimeZone, "lower_case_table_names": payload.LowerCaseTableNames,
		"character_set": payload.CharacterSet, "collation": payload.Collation,
		"max_connections": payload.MaxConnections, "innodb_redo_log_capacity": payload.InnoDBRedoLogCapacity,
		"innodb_flush_log_at_trx_commit": payload.InnoDBFlushLogAtTrxCommit, "sync_binlog": payload.SyncBinlog,
		"innodb_io_capacity": payload.InnoDBIOCapacity, "long_query_time": payload.LongQueryTime,
		"binlog_expire_logs_seconds": payload.BinlogExpireLogsSeconds, "max_binlog_size": payload.MaxBinlogSize,
		"delivery_callback_url": s.deliveryCallbackURL(task.ID), "delivery_callback_token": s.cfg.AWXWebhookToken,
	}})
	if err != nil {
		_ = s.db.WithContext(ctx).Model(&execution).Updates(map[string]any{"status": "failed", "finished_at": time.Now()})
		return nil, false, err
	}
	if err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := tx.Model(&execution).Updates(map[string]any{"executor_job_id": fmt.Sprint(job.ID), "status": "running"}).Error; err != nil {
			return err
		}
		return s.transitionTx(tx, &task, model.TaskRunning, "AWX job started", "")
	}); err != nil {
		return nil, false, err
	}
	return &execution, false, nil
}

func (s *DeliveryService) deliveryCallbackURL(taskID string) string {
	base := strings.TrimRight(strings.TrimSpace(s.cfg.DeliveryCallbackBaseURL), "/")
	if base == "" {
		return ""
	}
	return base + "/auth/internal/delivery/tasks/" + taskID + "/events"
}

func (s *DeliveryService) HandleStageEvent(ctx context.Context, taskID string, input DeliveryStageEventInput) error {
	stage := strings.ToLower(strings.TrimSpace(input.Stage))
	status := strings.ToLower(strings.TrimSpace(input.Status))
	if !validDeliveryStage(stage) {
		return fmt.Errorf("invalid delivery stage %q", input.Stage)
	}
	if !validDeliveryStageStatus(status) {
		return fmt.Errorf("invalid delivery stage status %q", input.Status)
	}
	message := strings.TrimSpace(input.Message)
	if message == "" {
		message = stage + " " + status
	}
	eventState := "stage_" + stage + "_" + status

	return s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var task model.DeliveryTask
		if err := tx.First(&task, "id = ?", taskID).Error; err != nil {
			return err
		}
		if input.AWXJobID != "" {
			var execution model.ExecutionJob
			if err := tx.Where("task_id = ?", task.ID).First(&execution).Error; err != nil {
				return err
			}
			if execution.ExecutorJobID != strings.TrimSpace(input.AWXJobID) {
				return fmt.Errorf("AWX job %s does not match task %s", input.AWXJobID, task.ID)
			}
		}
		if isTerminalTaskStatus(task.Status) {
			return nil
		}
		if err := tx.Create(&model.TaskEvent{
			TaskID:      task.ID,
			FromState:   task.Status,
			ToState:     eventState,
			Stage:       stage,
			EventStatus: status,
			Message:     message,
		}).Error; err != nil {
			return err
		}
		if status == "failed" {
			now := time.Now()
			if err := tx.Model(&model.ExecutionJob{}).Where("task_id = ?", task.ID).Updates(map[string]any{"status": "failed", "finished_at": now}).Error; err != nil {
				return err
			}
			if err := s.transitionTx(tx, &task, model.TaskExecutionFailed, message, message); err != nil {
				return err
			}
			return s.releaseReservation(tx, task.ID)
		}
		return nil
	})
}

func (s *DeliveryService) HandleAWXJobNotification(ctx context.Context, input AWXJobNotificationInput) error {
	status := strings.ToLower(strings.TrimSpace(input.Status))
	if status == "" && input.ID == 0 && awxNotificationTaskID(input.ExtraVars) == "" {
		return nil
	}
	if status == "" {
		return fmt.Errorf("missing AWX job status")
	}
	execution, err := s.findExecutionForAWXNotification(ctx, input)
	if err != nil {
		return err
	}
	message := awxNotificationMessage(input)
	switch status {
	case "pending", "waiting", "running", "new":
		return s.recordAWXEvent(ctx, execution.TaskID, status, message)
	case "successful":
		s.finishExecution(ctx, execution, "successful")
		if err := s.completeTask(ctx, execution.TaskID); err != nil {
			_ = s.failTask(ctx, &model.DeliveryTask{ID: execution.TaskID, Status: model.TaskRunning}, model.TaskValidationFailed, err.Error())
			return err
		}
		return nil
	case "canceled", "cancelled":
		s.finishExecution(ctx, execution, "canceled")
		return s.failTask(ctx, &model.DeliveryTask{ID: execution.TaskID, Status: model.TaskRunning}, model.TaskCanceled, message)
	case "failed", "error":
		s.finishExecution(ctx, execution, "failed")
		return s.failTask(ctx, &model.DeliveryTask{ID: execution.TaskID, Status: model.TaskRunning}, model.TaskExecutionFailed, message)
	default:
		s.finishExecution(ctx, execution, "failed")
		return s.failTask(ctx, &model.DeliveryTask{ID: execution.TaskID, Status: model.TaskRunning}, model.TaskExecutionFailed, "AWX job finished with status "+status)
	}
}

func (s *DeliveryService) findExecutionForAWXNotification(ctx context.Context, input AWXJobNotificationInput) (*model.ExecutionJob, error) {
	var execution model.ExecutionJob
	if input.ID != 0 {
		if err := s.db.WithContext(ctx).Where("executor_job_id = ?", fmt.Sprint(input.ID)).First(&execution).Error; err == nil {
			return &execution, nil
		} else if !errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, err
		}
	}
	taskID := awxNotificationTaskID(input.ExtraVars)
	if taskID == "" {
		return nil, fmt.Errorf("AWX notification did not include a known job id or task_id")
	}
	if err := s.db.WithContext(ctx).Where("task_id = ?", taskID).First(&execution).Error; err != nil {
		return nil, err
	}
	return &execution, nil
}

func (s *DeliveryService) recordAWXEvent(ctx context.Context, taskID, status, message string) error {
	var task model.DeliveryTask
	if err := s.db.WithContext(ctx).First(&task, "id = ?", taskID).Error; err != nil {
		return err
	}
	if isTerminalTaskStatus(task.Status) {
		return nil
	}
	return s.db.WithContext(ctx).Create(&model.TaskEvent{
		TaskID:      task.ID,
		FromState:   task.Status,
		ToState:     "awx_" + status,
		Stage:       "awx",
		EventStatus: status,
		Message:     message,
	}).Error
}

func validDeliveryStage(stage string) bool {
	switch stage {
	case "precheck", "install", "configure", "healthcheck", "register":
		return true
	default:
		return false
	}
}

func validDeliveryStageStatus(status string) bool {
	switch status {
	case "running", "success", "failed":
		return true
	default:
		return false
	}
}

func isTerminalTaskStatus(status string) bool {
	for _, item := range terminalTaskStatuses() {
		if status == item {
			return true
		}
	}
	return false
}

func terminalTaskStatuses() []string {
	return []string{model.TaskFinished, model.TaskExecutionFailed, model.TaskValidationFailed, model.TaskRegisterFailed, model.TaskCanceled}
}

func awxNotificationMessage(input AWXJobNotificationInput) string {
	status := strings.TrimSpace(input.Status)
	name := strings.TrimSpace(input.Name)
	if strings.TrimSpace(input.Traceback) != "" {
		return strings.TrimSpace(input.Traceback)
	}
	if name == "" {
		return "AWX job " + status
	}
	return "AWX job " + name + " " + status
}

func awxNotificationTaskID(extraVars any) string {
	var values map[string]any
	switch v := extraVars.(type) {
	case map[string]any:
		values = v
	case string:
		if strings.TrimSpace(v) == "" {
			return ""
		}
		_ = json.Unmarshal([]byte(v), &values)
	default:
		raw, err := json.Marshal(v)
		if err != nil {
			return ""
		}
		_ = json.Unmarshal(raw, &values)
	}
	if values == nil {
		return ""
	}
	if taskID, ok := values["task_id"].(string); ok {
		return strings.TrimSpace(taskID)
	}
	return ""
}

func (s *DeliveryService) finishExecution(ctx context.Context, execution *model.ExecutionJob, status string) {
	now := time.Now()
	_ = s.db.WithContext(ctx).Model(execution).Updates(map[string]any{"status": status, "finished_at": now})
}

func (s *DeliveryService) completeTask(ctx context.Context, taskID string) error {
	var task model.DeliveryTask
	if err := s.db.WithContext(ctx).First(&task, "id = ?", taskID).Error; err != nil {
		return err
	}
	if isTerminalTaskStatus(task.Status) {
		return nil
	}
	var payload deliveryPayload
	if err := json.Unmarshal([]byte(task.ImmutablePayload), &payload); err != nil {
		return err
	}
	normalizeMySQLDeliveryInput(&payload.MySQLDeliveryInput)
	addr := fmt.Sprintf("%s:%d", task.TargetHostIP, task.MySQLPort)
	if err := mysqlReady(ctx, addr); err != nil {
		return fmt.Errorf("MySQL health check failed: %w", err)
	}
	now := time.Now()
	if err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := s.transitionTx(tx, &task, model.TaskRegistering, "AWX succeeded and MySQL health check passed", ""); err != nil {
			return err
		}
		instance := model.MySQLInstance{TaskID: task.ID, BusinessLineID: task.BusinessLineID, TargetID: task.TargetID, Namespace: payload.Namespace, Name: payload.InstanceName, NodeName: task.TargetHost, Host: task.TargetHostIP, Port: task.MySQLPort, Version: payload.MySQLVersion, Status: "active"}
		if err := tx.Create(&instance).Error; err != nil {
			return err
		}
		if err := tx.Create(&model.ResourceUsage{TaskID: task.ID, InstanceID: instance.ID, BusinessLineID: task.BusinessLineID, TargetID: task.TargetID, CPUMilli: payload.CPUMilli, MemoryMi: payload.MemoryMi, StorageGi: payload.StorageGi, InstanceCount: 1, Status: "active"}).Error; err != nil {
			return err
		}
		if err := tx.Model(&model.ResourceReservation{}).Where("task_id = ? AND status = ?", task.ID, "reserved").Update("status", "consumed").Error; err != nil {
			return err
		}
		if err := tx.Model(&model.ExecutionJob{}).Where("task_id = ?", task.ID).Updates(map[string]any{"status": "successful", "finished_at": now}).Error; err != nil {
			return err
		}
		return nil
	}); err != nil {
		return err
	}
	if err := s.RegisterCloudDM(ctx, task.ID); err != nil {
		return s.transition(ctx, &task, model.TaskRegisterFailed, "CloudDM registration failed", err.Error())
	}
	return s.transition(ctx, &task, model.TaskFinished, "MySQL delivery completed", "")
}

func (s *DeliveryService) RegisterCloudDM(ctx context.Context, taskID string) error {
	if s.cfg.CloudDMRegisterURL == "" {
		return nil
	}
	var instance model.MySQLInstance
	if err := s.db.WithContext(ctx).Where("task_id = ?", taskID).First(&instance).Error; err != nil {
		return err
	}
	body := map[string]any{"name": instance.Name, "host": instance.Host, "port": instance.Port, "username": "root", "database_type": "mysql"}
	raw, _ := json.Marshal(body)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, s.cfg.CloudDMRegisterURL, bytes.NewReader(raw))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	if s.cfg.CloudDMAPIToken != "" {
		req.Header.Set("Authorization", "Bearer "+s.cfg.CloudDMAPIToken)
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("CloudDM returned %s", resp.Status)
	}
	return nil
}

func (s *DeliveryService) failTask(ctx context.Context, task *model.DeliveryTask, status, message string) error {
	return s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var current model.DeliveryTask
		if err := tx.First(&current, "id = ?", task.ID).Error; err != nil {
			return err
		}
		if current.Status != model.TaskPending && current.Status != model.TaskDispatching && current.Status != model.TaskRunning && current.Status != model.TaskRegistering && current.Status != model.TaskCanceling {
			return nil
		}
		if err := s.transitionTx(tx, &current, status, message, message); err != nil {
			return err
		}
		if status == model.TaskExecutionFailed || status == model.TaskValidationFailed || status == model.TaskCanceled {
			return s.releaseReservation(tx, current.ID)
		}
		return nil
	})
}

func (s *DeliveryService) Run(ctx context.Context) {
	interval := time.Duration(s.cfg.DeliveryDispatchSeconds) * time.Second
	if interval < time.Second {
		interval = time.Second
	}
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	if err := s.DispatchOnce(ctx); err != nil {
		log.Printf("[delivery] dispatch pending task failed: %v", err)
	}
	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			if err := s.DispatchOnce(ctx); err != nil {
				log.Printf("[delivery] dispatch pending task failed: %v", err)
			}
		}
	}
}

func pendingExecutorJobID(taskID string) string {
	return "pending:" + taskID
}