const mysql = require("mysql2/promise")

const {host, port, user, database, password} = require("./../settings").db

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

let poolP = initPool()

async function initPool () {
   return mysql.createPool({
      host,
      port,
      database,
      user,
      password,
   })
}

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

module.exports = {
   getUsers,
   getUserCount,
   getUserByLogin,
   getUserByUserId,
   getUserDefinedFields,
   getUserDefinedField,
   getUserTeilnahmen,

   getObjIdFromRefId,
   getRefIdFromObjId,

   getKurse,
   getKurs,
   getKursItems,
   // getKursByObjId,
   // getKursByRefId,
   getKursTeilnehmer,
   getKursTeilnehmerCount,

}

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

async function getUsers (offset = 0, limit = 10) {
   limit = Number(limit) || 10
   offset = Number(offset) || 0
   const sel = `usr_id, login, firstname, lastname, gender, email, institution, street, city, zipcode, country, department, active`
   // TODO user defined fields
   // TODO check args for SQL Injection

   const pool = await poolP
   const [results, fields] = await pool.query(
      `SELECT ${sel}
       FROM ${database}.usr_data AS ud
       WHERE login REGEXP '^[0-9]+$'
       LIMIT ${limit}
       OFFSET ${offset}
      `
   )
   const count = await getUserCount()
   return {
      total: count,
      offset, limit,
      data: results,
   }
}

async function getUserCount () {
   const pool = await poolP
   const [results, fields] = await pool.query(
      `SELECT COUNT(*)
       FROM ${database}.usr_data AS ud
       WHERE login REGEXP '^[0-9]+$'`
   )
   return results[0]["COUNT(*)"]
}

async function getUserByLogin (login) {
   const sel = `usr_id, login, firstname, lastname, gender, email, institution, street, city, zipcode, country, department, active`
   // TODO user defined fields
   // TODO check args for SQL Injection

   const pool = await poolP
   const [results, fields] = await pool.query(
      `SELECT ${sel}
       FROM ${database}.usr_data AS ud
       WHERE login = '${login}'`
   )
   console.log(results)
   return joinUDF(results[0])
}

async function getUserByUserId (userId) {
   const sel = `usr_id, login, firstname, lastname, gender, email, institution, street, city, zipcode, country, department, active`
   // TODO user defined fields
   // TODO check args for SQL Injection

   const pool = await poolP
   const [results, fields] = await pool.query(
      `SELECT ${sel}
       FROM ${database}.usr_data AS ud
       WHERE usr_id = '${userId}'`
   )
   return joinUDF(results[0])
}

async function getUserDefinedFields () {
   const pool = await poolP
   const [results] = await pool.query(
      `SELECT ut.usr_id, ud.field_name, ut.value
       FROM ${database}.udf_definition ud
                JOIN ${database}.udf_text ut ON ut.field_id = ud.field_id`
   )
   return results
}

async function getUserDefinedField (usr_id) {
   const pool = await poolP
   const [results] = await pool.query(
      `SELECT ut.usr_id, ud.field_name, ut.value
       FROM ${database}.udf_definition ud
                JOIN ${database}.udf_text ut ON ut.field_id = ud.field_id
       WHERE ut.usr_id = '${usr_id}'
      `
   )
   return results
}

/////// obj_id / ref_id ////////////////////////////////////////////////////////////////

async function getObjIdFromRefId (refId) {
   const pool = await poolP
   const [results] = await pool.query(
      `SELECT ref_id, obj_id
       FROM ${database}.object_reference as obr
       WHERE obr.ref_id = ${refId}
      `
   )
   return results.length ? results[0] : undefined
}

async function getRefIdFromObjId (objId) {
   const pool = await poolP
   const [results] = await pool.query(
      `SELECT ref_id, obj_id
       FROM ${database}.object_reference as obr
       WHERE obr.obj_id = ${objId}
      `
   )
   return results.length ? results[0] : undefined
}

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

async function promiseDelay (ms) {
   return new Promise(resolve => setTimeout(resolve, ms))
}

async function joinUDF (user) {
   if (!user) return user
   const fields = await getUserDefinedField(user.usr_id)
   for (const field of fields) {
      user[field.field_name] = field.value
   }
   return user
}

/////// Kurs ////////////////////////////////////////////////////////////////

async function getKurse () {
   const pool = await poolP
   const q = `SELECT or2.ref_id, or2.obj_id, od.title, od.description, od.type
              FROM ${database}.object_reference or2
                       INNER JOIN ${database}.object_data od ON od.obj_id = or2.obj_id
              WHERE od.type = 'crs'
                AND or2.deleted IS NULL
   `
   const [results] = await pool.query(q)
   return results
}

// async function getKursByRefId (refId) {
//    const {ref_id, obj_id} = await getObjIdFromRefId(refId)
//    return getKursByObjId(obj_id)
// }

async function getKurs (ref_id) {
   const pool = await poolP
   const q = `SELECT or2.ref_id, or2.obj_id, od.title, od.description, od.type
              FROM ${database}.object_reference or2
                       INNER JOIN ${database}.object_data od ON od.obj_id = or2.obj_id
              WHERE or2.ref_id = '${ref_id}'
   `
   let [results] = await pool.query(q)
   results = results.length ? results[0] : undefined
   return results
}

async function getKursItems (ref_id) {
   const pool = await poolP
   // const q = `SELECT or2.ref_id, or2.obj_id, od.title, od.description, od.type
   //            FROM ${database}.object_reference or2
   //            INNER JOIN ${database}.object_data od ON od.obj_id = or2.obj_id
   //            WHERE or2.obj_id = '${obj_id}'
   // `
   const q = `SELECT ci.parent_id, or2.ref_id, or2.obj_id, od.title, od.type
              FROM ${database}.crs_items ci
                       INNER JOIN ${database}.object_reference or2 ON or2.ref_id = ci.obj_id
                       INNER JOIN ${database}.object_data od ON od.obj_id = or2.obj_id
              WHERE or2.ref_id = ${ref_id}
                 OR parent_id = ${ref_id}
                  AND or2.deleted is NULL
   `
   const [results] = await pool.query(q)
   return results
}

async function getKursTeilnehmer (ref_id) {
   const pool = await poolP
   const q = `SELECT ci.parent_id,
                     or2.ref_id,
                     or2.obj_id,
                     od.title,
                     od.type,
                     om.usr_id,
                     ud.login,
                     ud.firstname,
                     ud.lastname,
                     ud.active,
                     om.passed,
                     ulm.status,
                     ulm.status_changed
              FROM ${database}.crs_items ci
                       INNER JOIN ${database}.object_reference or2 ON or2.ref_id = ci.obj_id
                       INNER JOIN ${database}.object_data od ON od.obj_id = or2.obj_id
                       INNER JOIN ${database}.obj_members om ON om.obj_id = or2.obj_id AND om.member = 1
                       INNER JOIN ${database}.usr_data ud ON ud.usr_id = om.usr_id
                       LEFT JOIN ${database}.ut_lp_marks ulm ON ulm.obj_id = or2.obj_id AND ud.usr_id = ulm.usr_id
              WHERE (or2.ref_id = ${ref_id} OR parent_id = ${ref_id})
              ORDER BY usr_id
   `
   const [results] = await pool.query(q)
   return results
}

async function getKursTeilnehmerCount (ref_id) {
   const pool = await poolP
   const q = `SELECT COUNT(*) as count
              FROM ${database}.crs_items ci
                  INNER JOIN ${database}.object_reference or2
              ON or2.ref_id = ci.obj_id
                  INNER JOIN ${database}.object_data od ON od.obj_id = or2.obj_id
                  INNER JOIN ${database}.obj_members om ON om.obj_id = or2.obj_id AND om.member = 1
                  INNER JOIN ${database}.usr_data ud ON ud.usr_id = om.usr_id
                  LEFT JOIN ${database}.ut_lp_marks ulm ON ulm.obj_id = or2.obj_id AND ud.usr_id = ulm.usr_id
              WHERE (or2.ref_id = ${ref_id}
                 OR parent_id = ${ref_id})
              ORDER BY usr_id
   `
   let [results] = await pool.query(q)
   results = results.length ? results[0] : undefined
   return {ref_id, count: results.count}
}

async function getUserTeilnahmen (usr_id) {
   const pool = await poolP
   const q = `SELECT om.obj_id, or2.ref_id , om.usr_id, od.title , ulm.status, om.passed, ulm.status_changed
              FROM ${database}.obj_members om
                       INNER JOIN ${database}.object_reference or2 ON or2.obj_id = om.obj_id
                       INNER JOIN ${database}.usr_data ud ON ud.usr_id = om.usr_id
                       INNER JOIN ${database}.object_data od ON od.obj_id = om.obj_id
                       LEFT JOIN ${database}.ut_lp_marks ulm
                                 ON ulm.usr_id = om.usr_id AND ulm.obj_id = om.obj_id
              WHERE om.usr_id = ${usr_id}
                AND om.member = 1
   `
   console.log(q)
   const [results] = await pool.query(q)
   return results
}