package main

import (
  "fmt"
  "sync"
  "strconv"
  _ "github.com/lib/pq"
  "database/sql"
  "time"
  "math/rand"
  "sort"
)

//Create a struct that will be written to and then passed into a channel of that struct type
//query results with result.Value and place them into db.QueryRow function to update database
//then implement a simple method for creating purposeful errors with the database
//test simple KNN impute algorithm against the database, as a seperate application
//create the presentation around this

func printLn(query string, count int, results chan<- string) {
  result := query + "_" + strconv.Itoa(count)
  // fmt.Println(result)
  results <- result
}

func main () {
  results := make(chan string)
  var waitGroup sync.WaitGroup
  query := "friend_ID_"
  for i := 1; i < 101; i++ {
    waitGroup.Add(1)
    go func (query string, i int) {
      printLn(query, i, results)
      waitGroup.Done()
    }(query, i)
  }

  go func() {
    // Wait for everything to be processed.
    waitGroup.Wait()

    // Close the channel to signal to the Display
    // function that we can exit the program.
    close(results)
  }()
  // Display our final results
  writeDB(results)
}

func writeDB (results chan string) {
  count := 0
  const (
      DB_USER     = "postgres"
      DB_PASSWORD = "postgres"
      DB_NAME     = "orangemvp"
  )
  dbinfo := fmt.Sprintf("user=%s password=%s dbname=%s sslmode=disable",
      DB_USER, DB_PASSWORD, DB_NAME)
  db, err := sql.Open("postgres", dbinfo)
  if err != nil {
    fmt.Println(fmt.Sprint(err))
  }
  defer db.Close()
  for result := range results {
    count++
    var friendSlice []float64
    if (count % 1000 == 0) {
      fmt.Println(result + ": " + strconv.Itoa(count))
    }
    for i := 0; i < 7; i++ {
      friendSlice = append(friendSlice, randNum())
    }
    sort.Float64s(friendSlice)
    //This can be used to simulate randomly missing values within our database
    if (count % 25000 == 0) {
      friendSlice[random(0, 6)] = 0.0
    }
    // fmt.Println(friendSlice)
    // fmt.Println(result)
    db.QueryRow("INSERT INTO friendlistrelation(friend_id, friend_1, friend_2, friend_3, friend_4, friend_5, friend_6, friend_7, created) VALUES($1, $2, $3, $4, $5, $6, $7, $8, $9)", result, friendSlice[6], friendSlice[5], friendSlice[4], friendSlice[3], friendSlice[2], friendSlice[1], friendSlice[0], time.Now().Local()).Scan()
  }

  return
}

func randNum() (randFloat float64) {
  return rand.Float64()
}

func random(min, max int) int {
    rand.Seed(time.Now().Unix())
    return rand.Intn(max - min) + min
}