package orm

import (
	"context"
	"fmt"
	"reflect"
	"time"

	"github.com/fatih/structtag"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

// Model - "base" struct for all queryable models
type Model struct {
	// Created time. updated/added automatically.
	Created time.Time `bson:"createdAt" json:"createdAt"`
	// Modified time. updated/added automatically.
	Modified time.Time `bson:"updatedAt" json:"updatedAt"`
	typeName string    `bson:"-"`
	self     any       `bson:"-"`
	exists   bool      `bson:"-"`
}

func (m *Model) getCreated() time.Time {
	return m.Created
}

func (m *Model) setCreated(Created time.Time) {
	m.Created = Created
}

func (m *Model) getModified() time.Time {
	return m.Modified
}

func (m *Model) setModified(Modified time.Time) {
	m.Modified = Modified
}

// HasID is a simple interface that you must implement
// in your models, using a pointer receiver.
// This allows for more flexibility in cases where
// your ID isn't an ObjectID (e.g., int, uint, string...).
//
// and yes, those darn ugly ObjectIDs are supported :)
type HasID interface {
	Id() any
	SetId(id any)
}

type HasIDSlice []HasID

type IModel interface {
	Append(field string, a ...interface{}) error
	Find(query interface{}, opts ...*options.FindOptions) (*mongo.Cursor, error)
	FindAll(query interface{}, opts ...*options.FindOptions) (*Query, error)
	FindByID(id interface{}) (*Query, error)
	FindOne(query interface{}, options ...*options.FindOneOptions) (*Query, error)
	FindPaged(query interface{}, page int64, perPage int64, options ...*options.FindOptions) (*Query, error)
	getColl() *mongo.Collection
	getIdxs() []*mongo.IndexModel
	getParsedIdxs() map[string][]InternalIndex
	Save() error
	serializeToStore() any
	setTypeName(str string)
	getExists() bool
	setExists(n bool)
	setModified(Modified time.Time)
	setCreated(Modified time.Time)
	getModified() time.Time
	getCreated() time.Time
	setSelf(arg interface{})
}

func (m *Model) setTypeName(str string) {
	m.typeName = str
}

func (m *Model) setSelf(arg interface{}) {
	m.self = arg
}

func (m *Model) getExists() bool {
	return m.exists
}
func (m *Model) setExists(n bool) {
	m.exists = n
}

func (m *Model) getColl() *mongo.Collection {
	_, ri, ok := ModelRegistry.HasByName(m.typeName)
	if !ok {
		panic(fmt.Sprintf("the model '%s' has not been registered", m.typeName))
	}
	return DB.Collection(ri.Collection)
}

func (m *Model) getIdxs() []*mongo.IndexModel {
	mi := make([]*mongo.IndexModel, 0)
	if mpi := m.getParsedIdxs(); mpi != nil {
		for _, v := range mpi {
			for _, i := range v {
				mi = append(mi, buildIndex(i))
			}
		}
		return mi
	}
	return nil
}

func (m *Model) getParsedIdxs() map[string][]InternalIndex {
	_, ri, ok := ModelRegistry.HasByName(m.typeName)
	if !ok {
		panic(fmt.Sprintf("model '%s' not registered", m.typeName))
	}
	return ri.Indexes
}

func (m *Model) Find(query interface{}, opts ...*options.FindOptions) (*mongo.Cursor, error) {
	coll := m.getColl()
	cursor, err := coll.Find(context.TODO(), query, opts...)
	return cursor, err
}

func (m *Model) FindAll(query interface{}, opts ...*options.FindOptions) (*Query, error) {
	qqn := ModelRegistry.new_(m.typeName)
	qqv := reflect.New(reflect.SliceOf(reflect.TypeOf(qqn).Elem()))
	qqv.Elem().Set(reflect.Zero(qqv.Elem().Type()))
	qq := &Query{
		Model:      *m,
		Collection: m.getColl(),
		doc:        qqv.Interface(),
		Op:         OP_FIND_ALL,
	}
	q, err := m.Find(query, opts...)

	if err == nil {
		rawRes := bson.A{}
		err = q.All(context.TODO(), &rawRes)
		if err == nil {
			m.exists = true
		}
		qq.rawDoc = rawRes
		err = q.All(context.TODO(), &qq.doc)
		if err != nil {
			qq.reOrganize()
			err = nil
		}
	}

	return qq, err
}

func (m *Model) FindPaged(query interface{}, page int64, perPage int64, opts ...*options.FindOptions) (*Query, error) {
	skipAmt := perPage * (page - 1)
	if skipAmt < 0 {
		skipAmt = 0
	}
	if len(opts) > 0 {
		opts[0].SetSkip(skipAmt).SetLimit(perPage)
	} else {
		opts = append(opts, options.Find().SetSkip(skipAmt).SetLimit(perPage))
	}
	q, err := m.FindAll(query, opts...)
	q.Op = OP_FIND_PAGED
	return q, err
}

func (m *Model) FindByID(id interface{}) (*Query, error) {
	return m.FindOne(bson.D{{"_id", id}})
}

func (m *Model) FindOne(query interface{}, options ...*options.FindOneOptions) (*Query, error) {
	coll := m.getColl()
	rip := coll.FindOne(context.TODO(), query, options...)
	raw := bson.M{}
	err := rip.Decode(&raw)
	panik(err)
	m.exists = true
	qq := &Query{
		Collection: m.getColl(),
		rawDoc:     raw,
		doc:        ModelRegistry.new_(m.typeName),
		Op:         OP_FIND_ONE,
		Model:      *m,
	}
	qq.rawDoc = raw
	err = rip.Decode(qq.doc)
	if err != nil {
		qq.reOrganize()
		err = nil
	}
	m.self = qq.doc
	return qq, err
}
func doDelete(m *Model, arg interface{}) error {
	self, ok := arg.(HasID)

	if !ok {
		return fmt.Errorf("Object '%s' does not implement HasID", nameOf(arg))
	}
	c := m.getColl()
	_, err := c.DeleteOne(context.TODO(), bson.M{"_id": self.Id()})
	if err == nil {
		m.exists = false
	}
	return err
}
func (m *Model) Delete() error {
	var err error
	val := valueOf(m.self)
	if val.Kind() == reflect.Slice {
		for i := 0; i < val.Len(); i++ {
			cur := val.Index(i)
			if err = doDelete(m, cur.Interface()); err != nil {
				return err
			}
		}
		return nil
	} else {
		return doDelete(m, m.self)
	}
}

func incrementTagged(item interface{}) interface{} {
	rv := reflect.ValueOf(item)
	rt := reflect.TypeOf(item)
	if rv.Kind() != reflect.Pointer {
		rv = makeSettable(rv, item)
	}
	if rt.Kind() == reflect.Pointer {
		rt = rt.Elem()
	}
	if rt.Kind() != reflect.Struct {
		if rt.Kind() == reflect.Slice {
			for i := 0; i < rv.Elem().Len(); i++ {
				incrementTagged(rv.Elem().Index(i).Addr().Interface())
			}
		} else {
			return item
		}
	}
	for i := 0; i < rt.NumField(); i++ {
		structField := rt.Field(i)
		cur := rv.Elem().Field(i)
		tags, err := structtag.Parse(string(structField.Tag))
		if err != nil {
			continue
		}
		incTag, err := tags.Get("autoinc")
		if err != nil {
			continue
		}

		nid := getLastInColl(incTag.Name, cur.Interface())
		if cur.IsZero() {
			coerced := coerceInt(reflect.ValueOf(incrementInterface(nid)), cur)
			if coerced != nil {
				cur.Set(reflect.ValueOf(coerced))
			} else {
				cur.Set(reflect.ValueOf(incrementInterface(nid)))
			}
		}
		counterColl := DB.Collection(COUNTER_COL)
		counterColl.UpdateOne(context.TODO(), bson.M{"collection": incTag.Name}, bson.M{"$set": bson.M{"collection": incTag.Name, "current": cur.Interface()}}, options.Update().SetUpsert(true))

	}
	return rv.Elem().Interface()
}

func incrementAll(item interface{}) {
	if item == nil {
		return
	}
	vp := reflect.ValueOf(item)
	el := vp
	if vp.Kind() == reflect.Pointer {
		el = vp.Elem()
	}
	if vp.Kind() == reflect.Pointer && vp.IsNil() {
		return
	}
	vt := el.Type()
	switch el.Kind() {
	case reflect.Struct:
		incrementTagged(item)
		for i := 0; i < el.NumField(); i++ {
			fv := el.Field(i)
			fst := vt.Field(i)
			if !fst.IsExported() {
				continue
			}
			incrementAll(fv.Interface())
		}
	case reflect.Slice:
		for i := 0; i < el.Len(); i++ {
			incd := incrementTagged(el.Index(i).Addr().Interface())
			if reflect.ValueOf(incd).Kind() == reflect.Pointer {
				el.Index(i).Set(reflect.ValueOf(incd).Elem())
			} else {
				el.Index(i).Set(reflect.ValueOf(incd))
			}
		}
	}
}

func checkStruct(ref reflect.Value) error {
	if ref.Kind() == reflect.Slice {
		return fmt.Errorf("Cannot append to multiple documents!")
	}
	if ref.Kind() != reflect.Struct {
		return fmt.Errorf("Current object is not a struct!")
	}
	return nil
}

// Append appends one or more items to `field`.
// will error if this Model contains a reference
// to multiple documents, or if `field` is not a
// slice.
func (m *Model) Append(field string, a ...interface{}) error {
	rv := reflect.ValueOf(m.self)
	selfRef := rv
	rt := reflect.TypeOf(m.self)
	if selfRef.Kind() == reflect.Pointer {
		selfRef = selfRef.Elem()
		rt = rt.Elem()
	}
	if err := checkStruct(selfRef); err != nil {
		return err
	}
	_, origV, err := getNested(field, selfRef)
	if err != nil {
		return err
	}

	origRef := makeSettable(*origV, (*origV).Interface())
	fv := origRef
	if fv.Kind() == reflect.Pointer {
		fv = fv.Elem()
	}
	if fv.Kind() != reflect.Slice {
		return fmt.Errorf("Current object is not a slice!")
	}
	for _, b := range a {
		val := reflect.ValueOf(incrementTagged(b))
		fv.Set(reflect.Append(fv, val))
	}
	return nil
}

func (m *Model) Pull(field string, a ...any) error {
	rv := reflect.ValueOf(m.self)
	selfRef := rv
	rt := reflect.TypeOf(m.self)
	if selfRef.Kind() == reflect.Pointer {
		selfRef = selfRef.Elem()
		rt = rt.Elem()
	}
	if err := checkStruct(selfRef); err != nil {
		return err
	}
	_, origV, err := getNested(field, selfRef)
	if err != nil {
		return err
	}

	origRef := makeSettable(*origV, (*origV).Interface())
	fv := origRef
	if fv.Kind() == reflect.Pointer {
		fv = fv.Elem()
	}
	if fv.Kind() != reflect.Slice {
		return fmt.Errorf("Current object is not a slice!")
	}
outer:
	for _, b := range a {
		for i := 0; i < fv.Len(); i++ {
			if reflect.DeepEqual(b, fv.Index(i).Interface()) {
				fv.Set(pull(fv, i, fv.Index(i).Type()))
				break outer
			}
		}
	}
	return nil
}

func doSave(c *mongo.Collection, isNew bool, arg interface{}) error {
	var err error
	m, ok := arg.(IModel)
	if !ok {
		return fmt.Errorf("type '%s' is not a model", nameOf(arg))
	}
	m.setSelf(m)
	now := time.Now()
	selfo := reflect.ValueOf(m)
	vp := selfo
	if vp.Kind() != reflect.Ptr {
		vp = reflect.New(selfo.Type())
		vp.Elem().Set(selfo)
	}
	var asHasId = vp.Interface().(HasID)
	if isNew {
		m.setCreated(now)
	}
	m.setModified(now)
	idxs := m.getIdxs()
	for _, i := range idxs {
		_, err = c.Indexes().CreateOne(context.TODO(), *i)
		if err != nil {
			return err
		}
	}
	if isNew {
		nid := getLastInColl(c.Name(), asHasId.Id())
		pnid := incrementInterface(nid)
		if reflect.ValueOf(asHasId.Id()).IsZero() {
			(asHasId).SetId(pnid)
		}
		incrementAll(asHasId)

		_, err = c.InsertOne(context.TODO(), m.serializeToStore())
		if err == nil {
			m.setExists(true)
		}
	} else {
		_, err = c.ReplaceOne(context.TODO(), bson.D{{Key: "_id", Value: m.(HasID).Id()}}, m.serializeToStore())
	}
	return err
}

func (m *Model) Save() error {
	val := valueOf(m.self)
	if val.Kind() == reflect.Slice {
		for i := 0; i < val.Len(); i++ {
			cur := val.Index(i)
			if err := doSave(m.getColl(), !m.exists, cur.Interface()); err != nil {
				return err
			}
		}
		return nil
	} else {
		return doSave(m.getColl(), !m.exists, m.self)
	}
}

func (m *Model) serializeToStore() any {
	return serializeIDs((m).self)
}

func serializeIDs(input interface{}) interface{} {

	vp := reflect.ValueOf(input)
	mt := reflect.TypeOf(input)
	var ret interface{}
	if vp.Kind() != reflect.Ptr {
		if vp.CanAddr() {
			vp = vp.Addr()
		} else {
			vp = makeSettable(vp, input)
		}
	}

	if mt.Kind() == reflect.Pointer {
		mt = mt.Elem()
	}
	getID := func(bbb interface{}) interface{} {
		mptr := reflect.ValueOf(bbb)
		if mptr.Kind() != reflect.Pointer {
			mptr = makeSettable(mptr, bbb)
		}
		ifc, ok := mptr.Interface().(HasID)
		if ok {
			return ifc.Id()
		} else {
			return nil
		}
	}
	/*var itagged interface{}
	if reflect.ValueOf(itagged).Kind() != reflect.Pointer {
		itagged = incrementTagged(&input)
	} else {
		itagged = incrementTagged(input)
	}
	taggedVal := reflect.ValueOf(reflect.ValueOf(itagged).Interface()).Elem()
	if vp.Kind() == reflect.Ptr {
		tmp := reflect.ValueOf(taggedVal.Interface())
		if tmp.Kind() == reflect.Pointer {
			vp.Elem().Set(tmp.Elem())
		} else {
			vp.Elem().Set(tmp)
		}
	}*/
	switch vp.Elem().Kind() {
	case reflect.Struct:
		ret0 := bson.M{}
		for i := 0; i < vp.Elem().NumField(); i++ {
			fv := vp.Elem().Field(i)
			ft := mt.Field(i)
			tag, err := structtag.Parse(string(ft.Tag))
			panik(err)
			bbson, err := tag.Get("bson")
			if err != nil || bbson.Name == "-" {
				continue
			}
			if bbson.Name == "" {
				marsh, _ := bson.Marshal(fv.Interface())
				unmarsh := bson.M{}
				bson.Unmarshal(marsh, &unmarsh)
				for k, v := range unmarsh {
					ret0[k] = v
					/*if t, ok := v.(primitive.DateTime); ok {
						ret0
					} else {
					}*/
				}
			} else {
				_, terr := tag.Get("ref")
				if reflect.ValueOf(fv.Interface()).Type().Kind() != reflect.Pointer {
					vp1 := reflect.New(fv.Type())
					vp1.Elem().Set(reflect.ValueOf(fv.Interface()))
					fv.Set(vp1.Elem())
				}
				if terr == nil {
					ifc, ok := fv.Interface().(HasID)
					if fv.Kind() == reflect.Slice {
						rarr := bson.A{}
						for j := 0; j < fv.Len(); j++ {
							rarr = append(rarr, getID(fv.Index(j).Interface()))
						}
						ret0[bbson.Name] = rarr
						/*ret0[bbson.Name] = serializeIDs(fv.Interface())
						break*/
					} else if !ok {
						panic(fmt.Sprintf("referenced model slice at '%s.%s' does not implement HasID", nameOf(input), ft.Name))
					} else {
						if reflect.ValueOf(ifc).IsNil() {
							ret0[bbson.Name] = nil
						} else {
							ret0[bbson.Name] = ifc.Id()
						}
					}

				} else {
					ret0[bbson.Name] = serializeIDs(fv.Interface())
				}
			}

			ret = ret0
		}
	case reflect.Slice:
		ret0 := bson.A{}
		for i := 0; i < vp.Elem().Len(); i++ {

			ret0 = append(ret0, serializeIDs(vp.Elem().Index(i).Addr().Interface()))
		}
		ret = ret0
	default:
		ret = vp.Elem().Interface()
	}
	return ret
}

// Create creates a new instance of a given model
// and returns a pointer to it.
func Create(d any) any {
	var n string
	var ri *InternalModel
	var ok bool

	n, ri, ok = ModelRegistry.HasByName(nameOf(d))

	if !ok {
		ModelRegistry.Model(d)
		n, ri, _ = ModelRegistry.Has(d)
	}
	t := ri.Type
	v := valueOf(d)
	i := ModelRegistry.Index(n)

	r := reflect.New(t)

	r.Elem().Set(v)

	df := r.Elem().Field(i)
	dm := df.Interface().(Model)
	if reflect.ValueOf(d).Kind() == reflect.Pointer {
		r.Elem().Set(reflect.ValueOf(d).Elem())
	} else {
		r.Elem().Set(reflect.ValueOf(d))
	}
	dm.typeName = n
	what := r.Interface()
	dm.self = what
	df.Set(reflect.ValueOf(dm))
	return what
}

func (m *Model) PrintMe() {
	fmt.Printf("My name is %s !\n", nameOf(m))
}