package webutility

  
  import (

  	"database/sql"

  	"encoding/json"

  	"fmt"

  	"io"

  	"net/http"

  	"sync"

  	"time"

  	"git.to-net.rs/marko.tikvic/gologger"

  )

  var (

  	mu        = &sync.Mutex{}
  	metadata  = make(map[string]Payload)
  	updateQue = make(map[string][]byte)

  	metadataDB    *sql.DB

  	activeProject string
  
  	inited bool
  )

  var logger *gologger.Logger
  
  func init() {
  	var err error

  	logger, err = gologger.New("metadata", gologger.MaxLogSize100KB)

  	if err != nil {
  		fmt.Printf("webutility: %s
  ", err.Error())
  	}
  }

  type LangMap map[string]map[string]string
  
  type Field struct {

  	Parameter string `json:"param"`
  	Type      string `json:"type"`
  	Visible   bool   `json:"visible"`
  	Editable  bool   `json:"editable"`

  }

  type CorrelationField struct {
  	Result   string   `json:"result"`
  	Elements []string `json:"elements"`
  	Type     string   `json:"type"`
  }
  
  type Translation struct {

  	Language     string            `json:"language"`

  	FieldsLabels map[string]string `json:"fieldsLabels"`

  }

  type Payload struct {

  	Method       string             `json:"method"`
  	Params       map[string]string  `json:"params"`
  	Lang         []Translation      `json:"lang"`
  	Fields       []Field            `json:"fields"`

  	Correlations []CorrelationField `json:"correlationFields"`
  	IdField      string             `json:"idField"`

  	// Data holds JSON payload. It can't be used for itteration.

  	Data interface{} `json:"data"`

  }

  // NewPayload returs a payload sceleton for entity described with etype.
  func NewPayload(r *http.Request, etype string) Payload {
  	pload := metadata[etype]
  	pload.Method = r.Method + " " + r.RequestURI
  	return pload
  }
  
  // DecodeJSON decodes JSON data from r to v.
  // Returns an error if it fails.
  func DecodeJSON(r io.Reader, v interface{}) error {
  	return json.NewDecoder(r).Decode(v)
  }

  // LoadPayloadsdetaData loads all payloads' information into 'metadata' variable.

  func LoadPayloadsMetadata(db *sql.DB, project string) error {

  	metadataDB = db
  	activeProject = project

  	mu.Lock()
  	defer mu.Unlock()
  	err := initMetadata(project)

  	if err != nil {
  		return err
  	}

  	inited = true
  
  	return nil
  }

  func EnableHotloading(interval int) {
  	if interval > 0 {
  		go hotload(interval)
  	}
  }

  func GetMetadataForAllEntities() map[string]Payload {
  	return metadata
  }
  
  func GetMetadataForEntity(t string) (Payload, bool) {
  	p, ok := metadata[t]
  	return p, ok
  }
  
  func QueEntityModelUpdate(entityType string, v interface{}) {
  	updateQue[entityType], _ = json.Marshal(v)
  }

  func initMetadata(project string) error {
  	rows, err := metadataDB.Query(`select
  		entity_type,
  		metadata
  		from entities
  		where projekat = ` + fmt.Sprintf("'%s'", project))
  	if err != nil {
  		return err
  	}
  	defer rows.Close()
  
  	count := 0
  	success := 0
  	if len(metadata) > 0 {
  		metadata = nil
  	}
  	metadata = make(map[string]Payload)
  	for rows.Next() {
  		var name, load string
  		rows.Scan(&name, &load)
  
  		p := Payload{}
  		err := json.Unmarshal([]byte(load), &p)
  		if err != nil {
  			logger.Log("couldn't init: '%s' metadata: %s
  %s
  ", name, err.Error(), load)
  		} else {
  			success++
  			metadata[name] = p
  		}
  		count++
  	}
  	perc := float32(success/count) * 100.0
  	logger.Log("loaded %d/%d (%.1f%%) entities
  ", success, count, perc)
  
  	return nil
  }
  
  func hotload(n int) {
  	entityScan := make(map[string]int64)
  	firstCheck := true
  	for {
  		time.Sleep(time.Duration(n) * time.Second)
  		rows, err := metadataDB.Query(`select
  			ora_rowscn,
  			entity_type
  			from entities where projekat = ` + fmt.Sprintf("'%s'", activeProject))
  		if err != nil {
  			logger.Log("hotload failed: %v
  ", err)
  			time.Sleep(time.Duration(n) * time.Second)
  			continue
  		}
  
  		var toRefresh []string
  		for rows.Next() {
  			var scanID int64
  			var entity string
  			rows.Scan(&scanID, &entity)
  			oldID, ok := entityScan[entity]
  			if !ok || oldID != scanID {
  				entityScan[entity] = scanID
  				toRefresh = append(toRefresh, entity)
  			}
  		}
  		rows.Close()
  
  		if rows.Err() != nil {
  			logger.Log("hotload rset error: %v
  ", rows.Err())
  			time.Sleep(time.Duration(n) * time.Second)
  			continue
  		}
  
  		if len(toRefresh) > 0 && !firstCheck {
  			mu.Lock()
  			refreshMetadata(toRefresh)
  			mu.Unlock()
  		}
  		if firstCheck {
  			firstCheck = false
  		}
  	}
  }
  
  func refreshMetadata(entities []string) {
  	for _, e := range entities {
  		fmt.Printf("refreshing %s
  ", e)
  		rows, err := metadataDB.Query(`select
  			metadata
  			from entities
  			where projekat = ` + fmt.Sprintf("'%s'", activeProject) +
  			` and entity_type = ` + fmt.Sprintf("'%s'", e))
  
  		if err != nil {
  			logger.Log("webutility: refresh: prep: %v
  ", err)
  			rows.Close()
  			continue
  		}
  
  		for rows.Next() {
  			var load string
  			rows.Scan(&load)
  			p := Payload{}
  			err := json.Unmarshal([]byte(load), &p)
  			if err != nil {
  				logger.Log("couldn't refresh: '%s' metadata: %s
  %s
  ", e, err.Error(), load)
  			} else {
  				metadata[e] = p
  			}
  		}
  		rows.Close()
  	}
  }
  
  /*

  func UpdateEntityModels(command string) (total, upd, add int, err error) {
  	if command != "force" && command != "missing" {
  		return total, 0, 0, errors.New("uknown command: " + command)
  	}

  	if !inited {

  		return 0, 0, 0, errors.New("webutil: metadata not initialized but update was tried.")

  	}

  	total = len(updateQue)

  	forUpdate := make([]string, 0)

  	forAdd := make([]string, 0)

  	for k, _ := range updateQue {

  		if _, exists := metadata[k]; exists {

  			if command == "force" {

  				forUpdate = append(forUpdate, k)
  			}

  		} else {

  			forAdd = append(forAdd, k)

  		}
  	}
  
  	for _, k := range forUpdate {

  		_, err := metadataDB.PrepAndExe(`update entities set

  			entity_model = :1
  			where entity_type = :2`,
  			string(updateQue[k]),

  			k)
  
  		if err != nil {

  			logger.Log("webutility: update metadata: prep and exe: %v
  ", err)

  			continue
  		}
  		upd++

  		logger.Log("webutility: updated %s payload model
  ", k)

  	}

  	blankPayload, _ := json.Marshal(Payload{})
  	for _, k := range forAdd {

  		_, err := metadataDB.PrepAndExe(`insert into entities
  			(projekat, metadata, entity_type, entity_model)
  			values(:1, :2, :3, :4)`,
  			activeProject,
  			string(blankPayload),
  			k,
  			string(updateQue[k]))
  
  		if err != nil {

  			logger.Log("webutility: add metadata: prep and exe: %v
  ", err)

  			continue
  		}
  		metadata[k] = Payload{}

  		add++

  		logger.Log("webutility: added %s to the payload models
  ", k)

  	}

  	return total, upd, add, nil

  }

  func ModifyMetadataForEntity(entityType string, p *Payload) error {
  	md, err := json.Marshal(*p)

  	if err != nil {
  		return err
  	}

  	mu.Lock()
  	defer mu.Unlock()

  	_, err = metadataDB.PrepAndExe(`update entities set
  		metadata = :1
  		where projekat = :2
  		and entity_type = :3`,
  		string(md),
  		activeProject,
  		entityType)
  	if err != nil {
  		return err

  	}
  	return nil
  }

  func DeleteEntityModel(entityType string) error {
  	_, err := metadataDB.PrepAndExe("delete from entities where entity_type = :1", entityType)
  	if err == nil {
  		mu.Lock()
  		delete(metadata, entityType)
  		mu.Unlock()
  	}
  	return err

  }

  */