const _ = require("lodash")
const {Index, Document, Worker} = require("flexsearch")
const settings = require("../settings")
const fs = require("node:fs")

/////////////////////////////////////////////////////////////////////////

// Message index
const options = {
   // tokenize: "full",
   tokenize: "forward",
   split: true,
}

const idxUser = new Index(options)

// Tag index
const optionsTag = {
   tokenize: "forward", // nur vorwärts indexieren bei den tags
   split: true, // ein Tag ist immer nur ein Wort
   // split: true, // doc
   encode: function (it) {
      // return it
      return it.split(" ")
      // return [it]
   },
   // encode: it => function (it) {
   //    return it.split(" ")
   // },
   // encode: "default",
   stemmer: false,
   matcher: false,
   context: false,
}
const idxTags = new Index(optionsTag)
// const idxTags = new Document({
//    document: {
//       id: "_id",
//       index: [
//          {
//             field: "tags",
//             tokenize: "forward",
//             // encode: it => it, // encode sorgt dafür, dass die Suche nach "+" funktioniert, aber auch dass komische Ergebnisse erscheinen
//          }
//       ],
//    },
// })

/////////////////////////////////////////////////////////////////////////

module.exports = {
   // idxMessage: idxUser,
   // idxTags,

   doIndex,
   search,

   // searchUsers,
   // searchTags,

   // addMessage: addUser,
   // updateMessage: updateUser,
   // deleteMessage: removeUser,

   // addTags,
   // removeTags,
}

// run()
// .then(console.log)
// .catch(console.error)

async function run () {
   await doIndex()
   console.log(search("latu"))
}

/////////////////////////////////////////////////////////////////////////

let indexed = false
async function doIndex () {
   const start = Date.now()
   console.log("++ START indexing Users...")
   const {readFromFile, file} = settings.search
   clearIndex(idxUser)

   let users
   if (readFromFile) {
      users = fs.readFileSync(file, "utf8")
      users = JSON.parse(users)
   }
   else {
      console.log("~~~ reading users from DB ... ~~~")
      const db = require("./db")
      const {data} = await db.getUsers(0, 100000)
      console.log(`loaded ${data.length} users from DB...`)
      users = data
   }

   for (const user of users) {
      addUser(user)
      // addTags(user)
   }
   indexed = true
   console.log(`++ END indexing Users in ${Date.now() - start}ms`)
}

async function search (query) {
   // when called from a cli program the search index is not initalized
   if(!indexed) await doIndex()
   const searchLimit = 10000
   return idxUser.search(query, searchLimit)
}

function searchUsers (query, user) {
   // query = query.split(" ").join(" OR ") // ohne das "OR" scheint immer nur "AND" zu sein | die search option {bool:"or"} wird ignoriert
   // console.log(`searching messages for "${query}"`)
   return idxUser.search(`${user} ${query}`, {suggest: true})
}

function searchTags (query, user) {
   const limit = 100000 // todo das mit dem Limit anders lösen // count? nein siehe https://github.com/nextapps-de/flexsearch?tab=readme-ov-file#limit--offset
   const results = idxTags.search(`${user} ${query}`, limit)
   return results
   // format is now [{field,result:[_id]}] because using document index
   // return results.length ? results[0].result : []
}

/////// idxMessage FNS ////////////////////////////////////////////////////////////////

function getUserString (user) {
   const {usr_id, firstname, lastname, login, institution, department} = user
   // if(firstname.trim()==="Adolfo") console.log(user)
   return `${login} ${firstname} ${lastname} ${institution} ${department}`.trim()
   // return `${usr_id} ${login} ${firstname} ${lastname} ${institution} ${department}`.trim() // KEINE usr_id
   // return `${usr_id} ${firstname} ${lastname}`.trim()
}

function addUser (user) {
   add(idxUser, user.usr_id, getUserString(user))
}

function updateUser ({_id, title, tags, user}) {
   update(idxUser, user.usr_id, getUserString(user))
}

function removeUser (usr_id) {
   remove(idxUser, usr_id)
}

function clearIndex(index) {
   index.clear()
}


/////// idxTags FNS ////////////////////////////////////////////////////////////////

/**
 * add Tags from a message
 * @param _id
 * @param tags
 */
function addTags (msg) {
   let {_id, tags, user} = msg
   if (!tags) throw new Error("tags must be an array")
   if (_.isString(tags)) tags = [tags]
   add(idxTags, _id.toString(), `${user} ${tags.join(" ")}`) // muss erst gejoined werden, dann später in encode wird noch mal gesplittet - anders rum geht es nicht!
}

function removeTags (_id) {
   remove(idxTags, _id.toString())
}

/////// FNS ////////////////////////////////////////////////////////////////

function add (index, key, value) {
   index.add(key, value)
}

function update (index, key, value) {
   index.update(key, value)
}

function remove (index, key) {
   index.remove(key)
}