/*
Real-time Online/Offline Charging System (OCS) for Telecom & ISP environments
Copyright (C) ITsysCOM GmbH

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOev.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>
*/

package engine

import (
	"encoding/xml"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/cgrates/cgrates/config"
	"github.com/cgrates/cgrates/utils"
)

// CGRReplier is the interface supported by replies convertible to CGRReply
type NavigableMapper interface {
	AsNavigableMap([]*config.CfgCdrField) (*NavigableMap, error)
}

// NewNavigableMap constructs a NavigableMap
func NewNavigableMap(data map[string]interface{}) *NavigableMap {
	if data == nil {
		data = make(map[string]interface{})
	}
	return &NavigableMap{data: data}
}

// NMItem is an item in the NavigableMap
type NMItem struct {
	Path   []string            // path in map
	Data   interface{}         // value of the element
	Config *config.CfgCdrField // so we can store additional configuration
}

// NavigableMap is a map who's values can be navigated via path
// data can be retrieved as ordered
// NavigableMap is not thread safe due to performance demands, could come back if needed
type NavigableMap struct {
	data  map[string]interface{} // layered map
	order [][]string             // order of field paths
}

// Add will add items into NavigableMap populating also order
func (nM *NavigableMap) Set(path []string, data interface{}, ordered bool) {
	if ordered {
		nM.order = append(nM.order, path)
	}
	mp := nM.data
	for i, spath := range path {
		if i == len(path)-1 { // last path
			mp[spath] = data
			return
		}
		if _, has := mp[spath]; !has {
			mp[spath] = make(map[string]interface{})
		}
		mp = mp[spath].(map[string]interface{}) // so we can check further down
	}
}

// FieldAsInterface returns the field value as interface{} for the path specified
// implements DataProvider
func (nM *NavigableMap) FieldAsInterface(fldPath []string) (fldVal interface{}, err error) {
	lenPath := len(fldPath)
	if lenPath == 0 {
		return nil, errors.New("empty field path")
	}
	lastMp := nM.data // last map when layered
	var canCast bool
	for i, spath := range fldPath {
		if i == lenPath-1 { // lastElement
			var has bool
			fldVal, has = lastMp[spath]
			if !has {
				return nil, utils.ErrNotFound
			}
			return
		}
		elmnt, has := lastMp[spath]
		if !has {
			return nil, utils.ErrNotFound
		}
		lastMp, canCast = elmnt.(map[string]interface{})
		if !canCast {
			lastMpNM, canCast := elmnt.(*NavigableMap) // attempt to cast into NavigableMap
			if !canCast {
				err = fmt.Errorf("cannot cast field: <%+v> type: %T with path: <%s> to map[string]interface{}",
					elmnt, elmnt, spath)
				return
			}
			lastMp = lastMpNM.data
		}
	}
	err = errors.New("end of function")
	return
}

// FieldAsString returns the field value as string for the path specified
// implements DataProvider
func (nM *NavigableMap) FieldAsString(fldPath []string) (fldVal string, err error) {
	var valIface interface{}
	valIface, err = nM.FieldAsInterface(fldPath)
	if err != nil {
		return
	}
	var canCast bool
	if fldVal, canCast = utils.CastFieldIfToString(valIface); !canCast {
		return "", fmt.Errorf("cannot cast field: %s to string", utils.ToJSON(valIface))
	}
	return
}

func (nM *NavigableMap) String() string {
	return utils.ToJSON(nM.data)
}

// indexMapElements will recursively go through map and index the element paths into elmns
func indexMapElements(mp map[string]interface{}, path []string, vals *[]interface{}) {
	for k, v := range mp {
		vPath := append(path, k)
		if mpIface, isMap := v.(map[string]interface{}); isMap {
			indexMapElements(mpIface, vPath, vals)
			continue
		}
		valsOut := append(*vals, v)
		*vals = valsOut
	}
}

// Values returns the values in map, ordered by order information
func (nM *NavigableMap) Values() (vals []interface{}) {
	if len(nM.data) == 0 {
		return
	}
	if len(nM.order) == 0 {
		indexMapElements(nM.data, []string{}, &vals)
		return
	}
	vals = make([]interface{}, len(nM.order))
	for i, path := range nM.order {
		val, _ := nM.FieldAsInterface(path)
		vals[i] = val
	}
	return
}

// AsNavigableMap implements both NavigableMapper as well as DataProvider interfaces
func (nM *NavigableMap) AsNavigableMap(
	tpl []*config.CfgCdrField) (oNM *NavigableMap, err error) {
	return nil, utils.ErrNotImplemented
}

// Merge will update nM with values from a second one
func (nM *NavigableMap) Merge(nM2 *NavigableMap) {
	if nM2 == nil {
		return
	}
	for k, v := range nM2.data {
		nM.data[k] = v
	}
	if len(nM2.order) != 0 {
		nM.order = append(nM.order, nM2.order...)
	}
}

// indexMapPaths parses map returning the parsed branchPath, useful when not having order for NavigableMap
func indexMapPaths(mp map[string]interface{}, branchPath []string, parsedPaths *[][]string) {
	for k, v := range mp {
		if mpIface, isMap := v.(map[string]interface{}); isMap {
			indexMapPaths(mpIface, append(branchPath, k), parsedPaths)
			continue
		}
		tmpPaths := append(*parsedPaths, append(branchPath, k))
		*parsedPaths = tmpPaths
	}
}

// AsCGREvent builds a CGREvent considering Time as time.Now()
// and Event as linear map[string]interface{} with joined paths
// treats particular case when the value of map is []*NMItem - used in agents/AgentRequest
func (nM *NavigableMap) AsCGREvent(tnt string, pathSep string) (cgrEv *utils.CGREvent) {
	if nM == nil || len(nM.data) == 0 {
		return
	}
	cgrEv = &utils.CGREvent{
		Tenant: tnt,
		ID:     utils.UUIDSha1Prefix(),
		Time:   utils.TimePointer(time.Now()),
		Event:  make(map[string]interface{})}
	if len(nM.order) == 0 {
		indexMapPaths(nM.data, nil, &nM.order)
	}
	for _, branchPath := range nM.order {
		val, _ := nM.FieldAsInterface(branchPath)
		if nmItms, isNMItems := val.([]*NMItem); isNMItems { // special case when we have added multiple items inside a key, used in agents
			for _, nmItm := range nmItms {
				if nmItm.Config == nil ||
					nmItm.Config.AttributeID == "" {
					val = nmItm.Data // first item which is not an attribute will become the value
					break
				}
			}
		}
		cgrEv.Event[strings.Join(branchPath, pathSep)] = val
	}
	return
}

// XMLElement is specially crafted to be automatically marshalled by encoding/xml
type XMLElement struct {
	XMLName    xml.Name
	Value      string        `xml:",chardata"`
	Attributes []*xml.Attr   `xml:",attr"`
	Elements   []*XMLElement `xml:"omitempty"`
}

// AsXMLElements returns the values as []*XMLElement which can be later marshaled
// considers each value returned by .Values() in the form of []*NMItem, otherwise errors
func (nM *NavigableMap) AsXMLElements() (ents []*XMLElement, err error) {
	pathIdx := make(map[string]*XMLElement) // Keep the index of elements based on path
	for _, val := range nM.Values() {
		nmItms, isNMItems := val.([]*NMItem)
		if !isNMItems {
			return nil, fmt.Errorf("value: %+v is not []*NMItem", val)
		}
		for _, nmItm := range nmItms {
			if nmItm.Config != nil && nmItm.Config.NewBranch {
				pathIdx = make(map[string]*XMLElement) // reset cache so we can start having other elements with same path
			}
			val, canCast := utils.CastFieldIfToString(nmItm.Data)
			if !canCast {
				return nil,
					fmt.Errorf("cannot cast value: <%s> to string", utils.ToJSON(nmItm.Data))
			}
			var pathCached bool
			for i := len(nmItm.Path); i > 0; i-- {
				var cachedElm *XMLElement
				if cachedElm, pathCached = pathIdx[strings.Join(nmItm.Path[:i], "")]; !pathCached {
					continue
				}
				if i == len(nmItm.Path) { // lastElmnt, overwrite value or add attribute
					if nmItm.Config != nil &&
						nmItm.Config.AttributeID != "" {
						cachedElm.Attributes = append(cachedElm.Attributes,
							&xml.Attr{xml.Name{Local: nmItm.Config.AttributeID}, val})
					} else {
						cachedElm.Value = val
					}
					break
				}
				// create elements in reverse order so we can append already created
				var newElm *XMLElement
				for j := len(nmItm.Path); j > i; j-- {
					elm := &XMLElement{XMLName: xml.Name{Local: nmItm.Path[j-1]}}
					pathIdx[strings.Join(nmItm.Path[:j], "")] = elm
					if newElm == nil {
						if nmItm.Config != nil &&
							nmItm.Config.AttributeID != "" {
							elm.Attributes = append(elm.Attributes,
								&xml.Attr{xml.Name{Local: nmItm.Config.AttributeID}, val})
						} else {
							elm.Value = val
						}
						newElm = elm // last element
					} else {
						elm.Elements = append(elm.Elements, newElm)
						newElm = elm
					}
				}
				cachedElm.Elements = append(cachedElm.Elements, newElm)
			}
			if !pathCached { // not an update but new element to be created
				var newElm *XMLElement
				for i := len(nmItm.Path); i > 0; i-- {
					elm := &XMLElement{XMLName: xml.Name{Local: nmItm.Path[i-1]}}
					pathIdx[strings.Join(nmItm.Path[:i], "")] = elm
					if newElm == nil { // last element, create data inside
						if nmItm.Config != nil &&
							nmItm.Config.AttributeID != "" {
							elm.Attributes = append(elm.Attributes,
								&xml.Attr{xml.Name{Local: nmItm.Config.AttributeID}, val})
						} else {
							elm.Value = val
						}
						newElm = elm // last element
					} else {
						elm.Elements = append(elm.Elements, newElm)
						newElm = elm
					}
				}
				ents = append(ents, newElm)
			}
		}
	}
	return
}