package server

import (
	"encoding/json"
	"errors"
	"io"
	"local/dndex/storage/entity"
	"local/dndex/storage/operator"
	"net/http"
	"path"
	"strings"

	"github.com/google/uuid"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"gopkg.in/mgo.v2/bson"
)

type shortEntity struct {
	Name string
	ID   string
}

func (rest *REST) entities(w http.ResponseWriter, r *http.Request) {
	scope, err := rest.entityScope(r)
	if err != nil {
		rest.respNotFound(w)
		return
	}
	if r.Method == http.MethodGet {
	} else if r.Method == http.MethodPost && len(scope) != 0 {
		rest.respNotFound(w)
		return
	} else if len(scope) > 1 {
		if r.Method == http.MethodDelete {
			q := r.URL.Query()
			q.Set("delete", "")
			r.URL.RawQuery = q.Encode()
		}
		r.Method = http.MethodPatch
	}
	if r.Method == http.MethodPatch && len(scope) == 1 {
		r.Method = http.MethodPut
	}
	if r.Method == http.MethodPatch && len(scope) == 0 {
		rest.respNotFound(w)
		return
	}
	switch r.Method {
	case http.MethodPut:
		rest.entitiesReplace(w, r)
	case http.MethodPatch:
		rest.entitiesUpdate(w, r)
	case http.MethodPost:
		rest.entitiesCreate(w, r)
	case http.MethodGet:
		rest.entitiesGet(w, r)
	case http.MethodDelete:
		rest.entitiesDelete(w, r)
	default:
		rest.respNotFound(w)
	}
}

func (rest *REST) entitiesCreate(w http.ResponseWriter, r *http.Request) {
	scope := rest.scope(r)
	one, err := rest.entityParse(r.Body)
	if err != nil {
		rest.respBadRequest(w, err.Error())
		return
	}
	one.ID = uuid.New().String()
	if err := rest.g.Insert(r.Context(), scope.Namespace, one); err != nil {
		rest.respError(w, err)
		return
	}
	r.URL.Path += "/" + one.ID
	rest.entitiesGet(w, r)
}

func (rest *REST) entitiesDelete(w http.ResponseWriter, r *http.Request) {
	scope := rest.scope(r)
	if err := rest.g.Delete(r.Context(), scope.Namespace, bson.M{entity.ID: scope.EntityID}); err != nil {
		rest.respError(w, err)
		return
	}
	rest.respOK(w)
}

func (rest *REST) entitiesGet(w http.ResponseWriter, r *http.Request) {
	entityScope, _ := rest.entityScope(r)
	switch len(entityScope) {
	case 0:
		rest.entitiesGetN(w, r)
	case 1:
		rest.entitiesGetOne(w, r)
	default:
		rest.entitiesGetOneSub(w, r)
	}
}

func (rest *REST) entitiesGetOne(w http.ResponseWriter, r *http.Request) {
	scope := rest.scope(r)
	entityScope, _ := rest.entityScope(r)
	one, err := rest.g.Get(r.Context(), scope.Namespace, entityScope[0])
	if err != nil {
		rest.respNotFound(w)
		return
	}
	resp := one.Generic()
	if _, ok := r.URL.Query()["light"]; !ok {
		m := bson.M{}
		for id := range one.Connections {
			one2, err := rest.g.Get(r.Context(), scope.Namespace, id)
			if err == nil {
				m2 := one2.Generic()
				m2[entity.Relationship] = one.Connections[id].Relationship
				m[id] = m2
			}
		}
		resp[entity.Connections] = m
	}
	rest.respMap(w, entityScope[0], resp)
}

func (rest *REST) entitiesGetOneSub(w http.ResponseWriter, r *http.Request) {
	entityScope, _ := rest.entityScope(r)
	scope := rest.scope(r)
	one, err := rest.g.Get(r.Context(), scope.Namespace, scope.EntityID)
	if err != nil {
		rest.respNotFound(w)
		return
	}
	b, err := bson.Marshal(one)
	if err != nil {
		rest.respError(w, err)
		return
	}
	var m bson.M
	err = bson.Unmarshal(b, &m)
	if err != nil {
		rest.respError(w, err)
		return
	}
	entityScope = entityScope[1:]
	for len(entityScope) > 1 {
		k := entityScope[0]
		entityScope = entityScope[1:]
		subm, ok := m[k]
		if !ok {
			m = nil
			break
		}
		mm, ok := subm.(bson.M)
		if !ok {
			m = nil
			break
		}
		m = mm
	}
	rest.respMap(w, scope.EntityID, m[entityScope[0]])
}

func (rest *REST) entitiesGetN(w http.ResponseWriter, r *http.Request) {
	scope := rest.scope(r)
	entities, err := rest.g.List(r.Context(), scope.Namespace)
	if err != nil {
		rest.respError(w, err)
		return
	}
	short := make([]shortEntity, len(entities))
	for i := range entities {
		short[i] = shortEntity{Name: entities[i].Name, ID: entities[i].ID}
	}
	rest.respMap(w, scope.Namespace, short)
}

func (rest *REST) entitiesReplace(w http.ResponseWriter, r *http.Request) {
	scope := rest.scope(r)
	one, err := rest.entityParse(r.Body)
	if err != nil {
		rest.respBadRequest(w, err.Error())
		return
	}
	if one.ID != scope.EntityID && one.ID != "" {
		rest.respBadRequest(w, "cannot change primary key")
		return
	}
	one.ID = scope.EntityID
	err = rest.g.Update(r.Context(), scope.Namespace, bson.M{entity.ID: scope.EntityID}, operator.SetMany{Value: one})
	if err != nil {
		rest.respError(w, err)
		return
	}
	rest.entitiesGet(w, r)
}

func (rest *REST) entitiesUpdate(w http.ResponseWriter, r *http.Request) {
	entityScope, _ := rest.entityScope(r)
	scope := rest.scope(r)

	_, del := r.URL.Query()["delete"]

	var m interface{}
	if !del {
		err := json.NewDecoder(r.Body).Decode(&m)
		if err != nil {
			rest.respBadRequest(w, err.Error())
			return
		}
		if mm, ok := m.(primitive.M); ok {
			delete(mm, entity.ID)
			m = mm
		}
	}

	key := strings.Join(entityScope[1:], ".")
	var operation interface{}
	operation = operator.Set{Key: key, Value: m}
	if del {
		operation = operator.Unset(key)
	}

	err := rest.g.Update(
		r.Context(),
		scope.Namespace,
		bson.M{entity.ID: scope.EntityID},
		operation,
	)
	if err != nil {
		rest.respError(w, err)
		return
	}

	r.URL.Path = path.Join("/", scope.EntityID)
	rest.entitiesGet(w, r)
}

func (rest *REST) entityParse(r io.Reader) (entity.One, error) {
	var one entity.One
	err := json.NewDecoder(r).Decode(&one)
	return one, err
}

func (rest *REST) entityScope(r *http.Request) ([]string, error) {
	p := r.URL.Path
	if path.Dir(p) == path.Base(p) {
		if r.Method == http.MethodGet || r.Method == http.MethodPost {
			return []string{}, nil
		}
		return nil, errors.New("nothing specified")
	}
	ps := strings.Split(p, "/")
	ps2 := []string{}
	for i := range ps {
		if ps[i] != "" {
			ps2 = append(ps2, ps[i])
		}
	}
	return ps2, nil
}