// Package audit 提供统一审计事件的只读调查查询。
package audit

import (
	"context"
	"time"

	"github.com/bytedance/sonic"
	"gorm.io/datatypes"
	"gorm.io/gorm"

	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
	"github.com/break/junhong_cmp_fiber/pkg/middleware"
)

// EventFilter 定义平台全局事件列表的受控组合筛选。
type EventFilter struct {
	CreatedFrom   *time.Time
	CreatedTo     *time.Time
	Action        string
	Category      string
	ActorKind     string
	ActorID       string
	Source        string
	Result        string
	Risk          string
	ScopeType     string
	ScopeID       string
	ResourceType  string
	ResourceID    string
	ResourceKey   string
	RequestID     string
	CorrelationID string
	Page          int
	PageSize      int
}

// EventPage 是平台全局事件稳定分页结果。
type EventPage struct {
	Total    int64       `json:"total"`
	Page     int         `json:"page"`
	PageSize int         `json:"page_size"`
	Items    []EventView `json:"items"`
}

// EventView 是不暴露 GORM Model 的审计事件投影。
type EventView struct {
	EventID             string            `json:"event_id"`
	OccurredAt          time.Time         `json:"occurred_at"`
	Category            string            `json:"category"`
	ActionCode          string            `json:"action_code"`
	ActionName          string            `json:"action_name"`
	Summary             string            `json:"summary"`
	ActorKind           string            `json:"actor_kind"`
	ActorID             string            `json:"actor_id"`
	ActorName           string            `json:"actor_name"`
	ActorShopID         *uint             `json:"actor_shop_id,omitempty"`
	ActorShopName       string            `json:"actor_shop_name"`
	ActorEnterpriseID   *uint             `json:"actor_enterprise_id,omitempty"`
	ActorEnterpriseName string            `json:"actor_enterprise_name"`
	Source              string            `json:"source"`
	RequestPath         string            `json:"request_path"`
	RequestMethod       string            `json:"request_method"`
	IPAddress           string            `json:"ip_address"`
	UserAgent           string            `json:"user_agent"`
	ScopeType           string            `json:"scope_type"`
	ScopeID             string            `json:"scope_id"`
	ScopeName           string            `json:"scope_name"`
	Result              string            `json:"result"`
	RiskLevel           string            `json:"risk_level"`
	ErrorCode           string            `json:"error_code"`
	ErrorSummary        string            `json:"error_summary"`
	RequestID           string            `json:"request_id"`
	CorrelationID       string            `json:"correlation_id"`
	ParentEventID       string            `json:"parent_event_id"`
	BatchTotal          int               `json:"batch_total"`
	SuccessCount        int               `json:"success_count"`
	FailCount           int               `json:"fail_count"`
	Metadata            map[string]any    `json:"metadata"`
	ContentHash         string            `json:"content_hash"`
	CreatedAt           time.Time         `json:"created_at"`
	Resources           []ResourceView    `json:"resources"`
	InvestigationRefs   InvestigationRefs `json:"investigation_refs"`
}

// InvestigationRefs 是平台调查视角间唯一允许使用的稳定跳转引用。
type InvestigationRefs struct {
	EventID         *string                    `json:"event_id"`
	ActorRef        *ActorRef                  `json:"actor_ref"`
	ResourceRefs    []InvestigationResourceRef `json:"resource_refs"`
	RequestID       *string                    `json:"request_id"`
	CorrelationID   *string                    `json:"correlation_id"`
	IntegrationRefs []IntegrationRef           `json:"integration_refs"`
}

// ActorRef 是操作者时间线的稳定引用。
type ActorRef struct {
	Kind string `json:"kind"`
	ID   string `json:"id"`
}

// InvestigationResourceRef 是通用资源时间线的稳定引用。
type InvestigationResourceRef struct {
	ResourceType string  `json:"resource_type"`
	ResourceID   *string `json:"resource_id"`
	ResourceKey  string  `json:"resource_key"`
	DisplayName  string  `json:"display_name"`
}

// IntegrationRef 是 Integration 详情的稳定引用。
type IntegrationRef struct {
	IntegrationID string `json:"integration_id"`
}

// ResourceView 是事件发生时独立资源身份与变化的只读投影。
type ResourceView struct {
	ResourceType      string         `json:"resource_type"`
	ResourceID        *string        `json:"resource_id,omitempty"`
	ResourceKey       string         `json:"resource_key"`
	DisplayName       string         `json:"display_name"`
	Relation          string         `json:"relation"`
	Role              string         `json:"role"`
	IdentitySnapshot  map[string]any `json:"identity_snapshot"`
	BeforeData        map[string]any `json:"before_data"`
	AfterData         map[string]any `json:"after_data"`
	SubjectVisibility string         `json:"subject_visibility"`
	SubjectSummary    string         `json:"subject_summary"`
	SubjectData       map[string]any `json:"subject_data"`
	SortOrder         int            `json:"sort_order"`
	CreatedAt         time.Time      `json:"created_at"`
}

// Query 提供平台统一审计事件列表与详情读取。
type Query struct {
	db *gorm.DB
}

// New 创建统一审计事件 Query。
func New(db *gorm.DB) *Query {
	return &Query{db: db}
}

// List 查询平台范围的全局审计事件。
func (q *Query) List(ctx context.Context, filter EventFilter) (*EventPage, error) {
	if err := q.authorize(ctx); err != nil {
		return nil, err
	}
	if !validEventFilter(filter) {
		return nil, errors.New(errors.CodeInvalidParam)
	}
	filter.Page, filter.PageSize = normalizePage(filter.Page, filter.PageSize)
	query := q.applyFilters(q.db.WithContext(ctx).Model(&model.AuditEvent{}), filter)
	var total int64
	if err := query.Count(&total).Error; err != nil {
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "统计审计事件失败")
	}
	rows := make([]model.AuditEvent, 0, filter.PageSize)
	if err := query.Order("occurred_at DESC, id DESC").
		Offset((filter.Page - 1) * filter.PageSize).Limit(filter.PageSize).Find(&rows).Error; err != nil {
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询审计事件失败")
	}
	items, err := q.project(ctx, rows)
	if err != nil {
		return nil, err
	}
	return &EventPage{Total: total, Page: filter.Page, PageSize: filter.PageSize, Items: items}, nil
}

func validEventFilter(filter EventFilter) bool {
	return validOptionalValue(filter.Result, constants.AuditResultSuccess, constants.AuditResultFailed,
		constants.AuditResultDenied, constants.AuditResultPartial, constants.AuditResultUnknown) &&
		validOptionalValue(filter.Risk, constants.AuditRiskLow, constants.AuditRiskNormal,
			constants.AuditRiskHigh, constants.AuditRiskCritical) &&
		validOptionalValue(filter.Source, constants.AuditSourceAdminAPI, constants.AuditSourcePersonalAPI,
			constants.AuditSourceOpenAPI, constants.AuditSourceWorker, constants.AuditSourceScheduler, constants.AuditSourceCallback) &&
		(filter.ActorKind == "" || validActorKind(filter.ActorKind)) &&
		filter.Page >= 0 && filter.PageSize >= 0 && filter.PageSize <= constants.MaxPageSize
}

func validOptionalValue(value string, allowed ...string) bool {
	if value == "" {
		return true
	}
	for _, candidate := range allowed {
		if value == candidate {
			return true
		}
	}
	return false
}

// Get 查询平台范围的单个稳定审计事件详情。
func (q *Query) Get(ctx context.Context, eventID string) (*EventView, error) {
	if err := q.authorize(ctx); err != nil {
		return nil, err
	}
	if eventID == "" {
		return nil, errors.New(errors.CodeInvalidParam)
	}
	var row model.AuditEvent
	if err := q.db.WithContext(ctx).Where("event_id = ?", eventID).First(&row).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, errors.New(errors.CodeNotFound, "审计事件不存在")
		}
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询审计事件详情失败")
	}
	items, err := q.project(ctx, []model.AuditEvent{row})
	if err != nil {
		return nil, err
	}
	return &items[0], nil
}

func (q *Query) authorize(ctx context.Context) error {
	if q == nil || q.db == nil {
		return errors.New(errors.CodeServiceUnavailable, "审计查询能力未配置")
	}
	userType := middleware.GetUserTypeFromContext(ctx)
	if userType != constants.UserTypeSuperAdmin && userType != constants.UserTypePlatform {
		return errors.New(errors.CodeForbidden, "无权限操作该资源或资源不存在")
	}
	return nil
}

func (q *Query) applyFilters(query *gorm.DB, filter EventFilter) *gorm.DB {
	if filter.CreatedFrom != nil {
		query = query.Where("occurred_at >= ?", filter.CreatedFrom.UTC())
	}
	if filter.CreatedTo != nil {
		query = query.Where("occurred_at < ?", filter.CreatedTo.UTC())
	}
	for column, value := range map[string]string{
		"action_code": filter.Action, "category": filter.Category,
		"actor_kind": filter.ActorKind, "actor_id": filter.ActorID,
		"source": filter.Source, "result": filter.Result, "risk_level": filter.Risk,
		"scope_type": filter.ScopeType, "scope_id": filter.ScopeID,
		"request_id": filter.RequestID, "correlation_id": filter.CorrelationID,
	} {
		if value != "" {
			query = query.Where(column+" = ?", value)
		}
	}
	if filter.ResourceType != "" || filter.ResourceID != "" || filter.ResourceKey != "" {
		resource := q.db.Table("tb_audit_event_resource AS aer").Select("1").
			Where("aer.audit_event_id = tb_audit_event.id")
		if filter.ResourceType != "" {
			resource = resource.Where("aer.resource_type = ?", filter.ResourceType)
		}
		if filter.ResourceID != "" {
			resource = resource.Where("aer.resource_id = ?", filter.ResourceID)
		}
		if filter.ResourceKey != "" {
			resource = resource.Where("aer.resource_key = ?", filter.ResourceKey)
		}
		query = query.Where("EXISTS (?)", resource)
	}
	return query
}

func (q *Query) project(ctx context.Context, rows []model.AuditEvent) ([]EventView, error) {
	items := make([]EventView, len(rows))
	if len(rows) == 0 {
		return items, nil
	}
	ids := make([]uint, 0, len(rows))
	for _, row := range rows {
		ids = append(ids, row.ID)
	}
	var resources []model.AuditEventResource
	if err := q.db.WithContext(ctx).Where("audit_event_id IN ?", ids).
		Order("audit_event_id ASC, sort_order ASC, id ASC").Find(&resources).Error; err != nil {
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "批量查询审计事件资源失败")
	}
	resourcesByEvent := make(map[uint][]ResourceView, len(rows))
	for _, resource := range resources {
		view, err := projectResource(resource)
		if err != nil {
			return nil, err
		}
		resourcesByEvent[resource.AuditEventID] = append(resourcesByEvent[resource.AuditEventID], view)
	}
	for index, row := range rows {
		metadata, err := decodeObject(row.Metadata)
		if err != nil {
			return nil, err
		}
		items[index] = EventView{
			EventID: row.EventID, OccurredAt: row.OccurredAt, Category: row.Category,
			ActionCode: row.ActionCode, ActionName: row.ActionName, Summary: row.Summary,
			ActorKind: row.ActorKind, ActorID: row.ActorID, ActorName: row.ActorName,
			ActorShopID: row.ActorShopID, ActorShopName: row.ActorShopName,
			ActorEnterpriseID: row.ActorEnterpriseID, ActorEnterpriseName: row.ActorEnterpriseName,
			Source: row.Source, RequestPath: row.RequestPath, RequestMethod: row.RequestMethod,
			IPAddress: row.IPAddress, UserAgent: row.UserAgent,
			ScopeType: row.ScopeType, ScopeID: row.ScopeID, ScopeName: row.ScopeName,
			Result: row.Result, RiskLevel: row.RiskLevel, ErrorCode: row.ErrorCode, ErrorSummary: row.ErrorSummary,
			RequestID: row.RequestID, CorrelationID: row.CorrelationID, ParentEventID: row.ParentEventID,
			BatchTotal: row.BatchTotal, SuccessCount: row.SuccessCount, FailCount: row.FailCount,
			Metadata: metadata, ContentHash: row.ContentHash, CreatedAt: row.CreatedAt,
			Resources: resourcesByEvent[row.ID],
		}
		if items[index].Resources == nil {
			items[index].Resources = []ResourceView{}
		}
		items[index].InvestigationRefs = investigationRefs(row, items[index].Resources)
	}
	return items, nil
}

func investigationRefs(event model.AuditEvent, resources []ResourceView) InvestigationRefs {
	refs := InvestigationRefs{
		EventID: stringPointer(event.EventID), ActorRef: investigationActorRef(event.ActorKind, event.ActorID),
		ResourceRefs: make([]InvestigationResourceRef, 0, len(resources)),
		RequestID:    stringPointer(event.RequestID), CorrelationID: stringPointer(event.CorrelationID),
		IntegrationRefs: []IntegrationRef{},
	}
	for _, resource := range resources {
		refs.ResourceRefs = append(refs.ResourceRefs, InvestigationResourceRef{
			ResourceType: resource.ResourceType, ResourceID: resource.ResourceID,
			ResourceKey: resource.ResourceKey, DisplayName: resource.DisplayName,
		})
	}
	return refs
}

func investigationActorRef(kind, id string) *ActorRef {
	if id == "" {
		return nil
	}
	switch kind {
	case constants.AuditActorAccount, constants.AuditActorOpenAPI, constants.AuditActorSystemTask,
		constants.AuditActorScheduledJob, constants.AuditActorExternalSystem:
		return &ActorRef{Kind: kind, ID: id}
	default:
		return nil
	}
}

func stringPointer(value string) *string {
	if value == "" {
		return nil
	}
	return &value
}

func projectResource(row model.AuditEventResource) (ResourceView, error) {
	identity, err := decodeObject(row.IdentitySnapshot)
	if err != nil {
		return ResourceView{}, err
	}
	before, err := decodeObject(row.BeforeData)
	if err != nil {
		return ResourceView{}, err
	}
	after, err := decodeObject(row.AfterData)
	if err != nil {
		return ResourceView{}, err
	}
	subject, err := decodeObject(row.SubjectData)
	if err != nil {
		return ResourceView{}, err
	}
	return ResourceView{
		ResourceType: row.ResourceType, ResourceID: row.ResourceID, ResourceKey: row.ResourceKey,
		DisplayName: row.DisplayName, Relation: row.Relation, Role: row.Role,
		IdentitySnapshot: identity, BeforeData: before, AfterData: after,
		SubjectVisibility: row.SubjectVisibility, SubjectSummary: row.SubjectSummary, SubjectData: subject,
		SortOrder: row.SortOrder, CreatedAt: row.CreatedAt,
	}, nil
}

func decodeObject(value datatypes.JSON) (map[string]any, error) {
	result := map[string]any{}
	if len(value) == 0 {
		return result, nil
	}
	if err := sonic.Unmarshal(value, &result); err != nil {
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "解析审计结构化字段失败")
	}
	return result, nil
}

func normalizePage(page, pageSize int) (int, int) {
	if page < 1 {
		page = 1
	}
	if pageSize < 1 {
		pageSize = constants.DefaultPageSize
	}
	if pageSize > constants.MaxPageSize {
		pageSize = constants.MaxPageSize
	}
	return page, pageSize
}