package rest

import (
	"context"
	"fmt"
	"git.nspix.com/golang/rest/v3/cache"
	loggerpkg "git.nspix.com/golang/rest/v3/logger"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	"gorm.io/gorm/logger"
	"strings"
	"time"
)

const (
	DefaultNamespace = "default"

	NamespaceVariable  = "namespace"
	UserVariable       = "@uid"
	DepartmentVariable = "@department"

	NamespaceField   = "namespace"
	CreatedByField   = "CreatedBy"
	CreatedDeptField = "CreatedDept"
	UpdatedByField   = "UpdatedBy"
	UpdatedDeptField = "UpdatedDept"
)

const (
	TypeModule = "module"
	TypeTable  = "table"
)

type (
	CRUD struct {
		api         *Api
		db          *gorm.DB
		modules     []*Restful
		delegate    *delegate
		enableCache bool
	}

	treeValue struct {
		Label    string       `json:"label"`
		Value    string       `json:"value"`
		Type     string       `json:"type"`
		Children []*treeValue `json:"children,omitempty"`
	}
)

func (t *treeValue) Append(v *treeValue) {
	if t.Children == nil {
		t.Children = make([]*treeValue, 0)
	}
	t.Children = append(t.Children, v)
}

//createStatement 创建一个声明
func (r *CRUD) createStatement(db *gorm.DB) *gorm.Statement {
	return &gorm.Statement{
		DB:       db,
		ConnPool: db.Statement.ConnPool,
		Context:  db.Statement.Context,
		Clauses:  map[string]clause.Clause{},
	}
}

func (r *CRUD) DB() *gorm.DB {
	return r.db
}

//DisableCache 禁用缓存
func (r *CRUD) DisableCache() *CRUD {
	r.enableCache = false
	return r
}

//WithCache 启用缓存
func (r *CRUD) WithCache() *CRUD {
	r.enableCache = true
	return r
}

//WithDebug 开启调试
func (r *CRUD) WithDebug() *CRUD {
	r.db.Logger = r.db.Logger.LogMode(logger.Info)
	return r
}

//RegisterDelegate 注册一个旁观者
func (r *CRUD) RegisterDelegate(d Delegate) {
	r.delegate.Register(d)
}

//Attach 注册一个模型
func (r *CRUD) Attach(ctx context.Context, model Model, cbs ...Option) (err error) {
	var (
		ok           bool
		opts         *Options
		dynamicModel *Dynamic
	)
	opts = newOptions()
	for _, cb := range cbs {
		cb(opts)
	}
	if opts.DB == nil {
		opts.DB = r.db
	}
	if dynamicModel, ok = model.(*Dynamic); ok {
		sess := r.db.Session(&gorm.Session{NewDB: true})
		sess.Dialector = newDynamicDialector(model.TableName(), r.db.Dialector)
		if err = sess.AutoMigrate(dynamicModel.Interface()); err != nil {
			return
		}
	} else {
		if err = r.db.AutoMigrate(model); err != nil {
			return
		}
		//不启用schema
		if opts.Schema {
			if err = r.migrateSchema(ctx, DefaultNamespace, model); err != nil {
				return
			}
		}
	}
	opts.Delegate = r.delegate
	opts.LookupFunc = r.VisibleSchemas
	rt := newRestful(model, opts)
	r.modules = append(r.modules, rt)
	if r.api != nil {
		r.api.Attach(rt)
	}
	return
}

//migrateSchema 合并表的结构数据
func (r *CRUD) migrateSchema(ctx context.Context, namespace string, model Model) (err error) {
	var (
		pos            int
		columnLabel    string
		columnName     string
		columnIsExists bool
		stmt           *gorm.Statement
		schemas        []*Schema
		schemaModels   []*Schema
	)

	schemas, err = r.GetSchemas(ctx, namespace, model.ModuleName(), model.TableName())
	stmt = r.createStatement(r.db)
	if err = stmt.Parse(model); err != nil {
		return
	}
	if len(schemas) > 0 {
		pos = len(schemas)
	}
	for index, field := range stmt.Schema.Fields {
		columnName = field.DBName
		if columnName == "-" {
			continue
		}
		if columnName == "" {
			columnName = field.Name
		}
		columnIsExists = false
		for _, sm := range schemas {
			if sm.Column == columnName {
				columnIsExists = true
				break
			}
		}
		if columnIsExists {
			continue
		}
		columnLabel = field.Tag.Get("comment")
		if columnLabel == "" {
			columnLabel = generateFieldName(field.DBName)
		}
		isPrimaryKey := uint8(0)
		if field.PrimaryKey {
			isPrimaryKey = 1
		}
		schemaModel := &Schema{
			Namespace:    namespace,
			ModuleName:   model.ModuleName(),
			TableName:    model.TableName(),
			Enable:       1,
			Column:       columnName,
			Label:        columnLabel,
			Type:         strings.ToLower(dataTypeOf(field)),
			Format:       strings.ToLower(dataFormatOf(field)),
			Native:       1,
			IsPrimaryKey: isPrimaryKey,
			Scenarios:    generateFieldScenario(index, field),
			Rule:         generateFieldRule(field),
			Attribute:    generateFieldAttribute(field),
			Position:     pos,
		}
		schemaModels = append(schemaModels, schemaModel)
		pos++
	}
	if len(schemaModels) > 0 {
		err = r.db.Create(schemaModels).Error
	}
	return
}

//GetSchemas 获取表的结构数据
func (r *CRUD) GetSchemas(ctx context.Context, namespace, moduleName, tableName string) (schemas []*Schema, err error) {
	cacheKey := fmt.Sprintf("schema:%s:%s:%s", namespace, moduleName, tableName)
	if r.enableCache {
		if v, ok := cache.Get(cacheKey); ok {
			return v.([]*Schema), nil
		}
	}
	schemas = make([]*Schema, 0)
	if len(namespace) == 0 {
		namespace = DefaultNamespace
	}
	sess := r.db.Session(&gorm.Session{NewDB: true, Context: ctx})
	if err = sess.Where("`namespace`=? AND `module_name`=? AND `table_name`=?", namespace, moduleName, tableName).Order("position,id ASC").Find(&schemas).Error; err == nil {
		if r.enableCache {
			cache.SetEx(cacheKey, schemas, time.Minute*30)
		}
	}
	return
}

//VisibleSchemas 获取指定场景表的数据
func (r *CRUD) VisibleSchemas(ctx context.Context, ns, moduleName, tableName, scene string) (result []*Schema) {
	var (
		err     error
		schemas []*Schema
	)
	if schemas, err = r.GetSchemas(ctx, ns, moduleName, tableName); err == nil {
		result = make([]*Schema, 0, len(schemas))
		for _, s := range schemas {
			if s.Scenarios.Has(scene) || s.Attribute.PrimaryKey {
				result = append(result, s)
			}
		}
	}
	return
}

//New  create new restful
func New(dialer gorm.Dialector) (r *CRUD, err error) {
	r = &CRUD{
		delegate:    &delegate{},
		enableCache: true,
	}
	if r.db, err = gorm.Open(dialer); err != nil {
		return
	}
	r.api = &Api{crud: r}
	r.db.Logger = loggerpkg.New()
	err = r.db.AutoMigrate(&Schema{})
	return
}