package plugins

import (
	"context"
	"fmt"
	"git.nspix.com/golang/rest/v3"
	errpkg "git.nspix.com/golang/rest/v3/error"
	"git.nspix.com/golang/rest/v3/utils"
	validator "github.com/go-playground/validator/v10"
	"gorm.io/gorm"
	"gorm.io/gorm/schema"
	"reflect"
	"regexp"
	"strconv"
	"strings"
)

const (
	SkipValidations = "validations:skip_validations"
)

type (
	validateRule struct {
		Rule  string
		Value string
		Valid bool
	}

	validateScope struct{}

	validScope struct {
		DB     *gorm.DB
		Column string
		Model  interface{}
	}

	validation struct {
		crud *rest.CRUD
	}
)

var (
	validate         = validator.New()
	validateScopeKey = validateScope{}

	telephoneRegex = regexp.MustCompile("^\\d{5,20}$")
)

func init() {

	_ = validate.RegisterValidationCtx("telephone", func(ctx context.Context, fl validator.FieldLevel) bool {
		val := fmt.Sprint(fl.Field().Interface())
		return telephoneRegex.MatchString(val)
	})

	_ = validate.RegisterValidationCtx("db_unique", func(ctx context.Context, fl validator.FieldLevel) bool {
		var (
			scope           *validScope
			ok              bool
			count           int64
			field           *schema.Field
			primaryKeyValue reflect.Value
		)
		val := fl.Field().Interface()
		if scope, ok = ctx.Value(validateScopeKey).(*validScope); !ok {
			return true
		}
		if len(scope.DB.Statement.Schema.PrimaryFields) > 0 {
			field = scope.DB.Statement.Schema.PrimaryFields[0]
			primaryKeyValue = reflect.Indirect(reflect.ValueOf(scope.Model))
			for _, n := range field.BindNames {
				primaryKeyValue = primaryKeyValue.FieldByName(n)
			}
		}
		sess := scope.DB.Session(&gorm.Session{NewDB: true})
		if primaryKeyValue.IsValid() && !primaryKeyValue.IsZero() && field != nil {
			sess.Model(scope.Model).Where(scope.Column+"=? AND "+field.Name+" != ?", val, primaryKeyValue.Interface()).Count(&count)
		} else {
			sess.Model(scope.Model).Where(scope.Column+"=?", val).Count(&count)
		}
		if count > 0 {
			return false
		}
		return true
	})
}

func newRule(ss ...string) *validateRule {
	v := &validateRule{
		Valid: true,
	}
	if len(ss) == 1 {
		v.Rule = ss[0]
	} else if len(ss) >= 2 {
		v.Rule = ss[0]
		v.Value = ss[1]
	}
	return v
}

func generateRules(scm *rest.Schema, scenario string, rule rest.Rule) []*validateRule {
	rules := make([]*validateRule, 0, 5)
	if rule.Min != 0 {
		rules = append(rules, newRule("min", strconv.Itoa(rule.Min)))
	}
	if rule.Max != 0 {
		rules = append(rules, newRule("max", strconv.Itoa(rule.Max)))
	}
	//主键不做唯一判断
	if rule.Unique && !scm.Attribute.PrimaryKey {
		rules = append(rules, newRule("db_unique"))
	}
	if rule.Type != "" {
		rules = append(rules, newRule(rule.Type))
	}
	if rule.Required != nil && len(rule.Required) > 0 {
		for _, v := range rule.Required {
			if v == scenario {
				rules = append(rules, newRule("required"))
				break
			}
		}
	}
	return rules
}

func buildRules(rs []*validateRule) string {
	var sb strings.Builder
	for _, r := range rs {
		if !r.Valid {
			continue
		}
		if sb.Len() > 0 {
			sb.WriteString(",")
		}
		if r.Value == "" {
			sb.WriteString(r.Rule)
		} else {
			sb.WriteString(r.Rule + "=" + r.Value)
		}
	}
	return sb.String()
}

func getRule(name string, rules []*validateRule) *validateRule {
	for _, r := range rules {
		if r.Rule == name {
			return r
		}
	}
	return nil
}

func formatError(rule rest.Rule, scm *rest.Schema, tag string) string {
	var s string
	switch tag {
	case "db_unique":
		s = scm.Label + "值已经存在."
		break
	case "required":
		s = scm.Label + "值不能为空."
	case "max":
		if scm.Type == "string" {
			s = scm.Label + "长度不能大于" + strconv.Itoa(rule.Max)
		} else {
			s = scm.Label + "值不能大于" + strconv.Itoa(rule.Max)
		}
	case "min":
		if scm.Type == "string" {
			s = scm.Label + "长度不能小于" + strconv.Itoa(rule.Max)
		} else {
			s = scm.Label + "值不能小于" + strconv.Itoa(rule.Max)
		}
	}
	return s
}

func (vv *validation) validation(db *gorm.DB) {
	if result, ok := db.Get(SkipValidations); ok && result.(bool) {
		return
	}
	var (
		ok           bool
		err          error
		rules        []*validateRule
		stmt         *gorm.Statement
		model        rest.Model
		scenario     string
		skipValidate bool
		value        reflect.Value
		schemas      []*rest.Schema
	)
	stmt = db.Statement
	if stmt.Model == nil {
		return
	}
	if model, ok = stmt.Model.(rest.Model); !ok {
		return
	}
	scenario = rest.ScenarioUpdate
	for _, pk := range stmt.Schema.PrimaryFields {
		if utils.IsEmpty(stmt.ReflectValue.FieldByName(pk.Name).Interface()) {
			scenario = rest.ScenarioCreate
			break
		}
	}
	schemas = vv.crud.VisibleSchemas(context.Background(), stmt.ReflectValue.FieldByName("Namespace").String(), model.ModuleName(), model.TableName(), scenario)
	for _, scm := range schemas {
		if rules = generateRules(scm, scenario, scm.Rule); len(rules) <= 0 {
			continue
		}
		value = stmt.ReflectValue.FieldByName(stmt.Schema.LookUpField(scm.Column).Name)
		if !value.IsValid() {
			continue
		}
		skipValidate = false
		if r := getRule("required", rules); r != nil {
			if value.Interface() != nil {
				vType := reflect.ValueOf(value.Interface())
				switch vType.Kind() {
				case reflect.Bool:
					skipValidate = true
				case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
					skipValidate = true
				case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
					skipValidate = true
				case reflect.Float32, reflect.Float64:
					skipValidate = true
				}
			}
			if skipValidate {
				r.Valid = false
			}
		} else {
			if utils.IsEmpty(value.Interface()) {
				continue
			}
		}
		ctx := context.WithValue(context.Background(), validateScopeKey, &validScope{
			DB:     db,
			Column: scm.Column,
			Model:  stmt.Model,
		})
		if err = validate.VarCtx(ctx, value.Interface(), buildRules(rules)); err != nil {
			if errs, ok := err.(validator.ValidationErrors); ok {
				for _, e := range errs {
					_ = db.AddError(&errpkg.StructError{
						Tag:     e.Tag(),
						Column:  scm.Column,
						Message: formatError(scm.Rule, scm, e.Tag()),
					})
				}
			} else {
				_ = db.AddError(err)
			}
			break
		}
	}
}

func RegisterValidationCallback(db *gorm.DB, crud *rest.CRUD) (err error) {
	callback := db.Callback()
	vv := &validation{crud: crud}
	if callback.Create().Get("validations:validate") == nil {
		err = callback.Create().Before("gorm:before_create").Register("validations:validate", vv.validation)
	}
	if callback.Update().Get("validations:validate") == nil {
		err = callback.Update().Before("gorm:before_update").Register("validations:validate", vv.validation)
	}
	return
}