library(conflicted)
library(yaml)
library(RPostgreSQL)
library(tidyverse)
conflicts_prefer(
  dplyr::filter,
  dplyr::lag
)
library(magrittr)

# read the password from file
credentials <- yaml.load_file("../rapids/credentials.yaml")
pw <- credentials$PSQL_STRAW$password

# load the PostgreSQL driver
drv <- RPostgres::Postgres()

# creates a connection to the postgres database
# note that "con" will be used later in each connection to the database
con <- RPostgres::dbConnect(drv,
  dbname = "staw",
  host = "eol.ijs.si", port = 5432,
  user = "staw_db", password = pw
)

rm(pw, credentials) # removes the password

# check for the bluetooth table, an example
dbExistsTable(con, "app_categories")

df_app_categories <- tbl(con, "app_categories") %>%
  collect()

head(df_app_categories)
table(df_app_categories$play_store_genre)

# Correct some mistakes
df_app_categories %<>%
  mutate(
    play_store_genre = {
      function(x) {
        case_when(
          x == "Education,Education" ~ "Education",
          x == "EducationEducation" ~ "Education",
          x == "not_found" ~ "System",
          .default = x
        )
      }
    }(play_store_genre)
  ) %>%
  select(-package_name) %>% 
  rename(
    genre = play_store_genre,
    package_name = package_hash)

table(df_app_categories$genre)

df_app_categories %>% 
  group_by(genre) %>% 
  count() %>% 
  arrange(desc(n)) %>%
  write_csv("play_store_categories_count.csv")

write_csv(
  x = select(df_app_categories, c(package_name, genre)),
  file = "play_store_application_genre_catalogue.csv"
)

dbDisconnect(con)