SA_census2011

## specify the require packages
packages = c(
  "dplyr",
  "sf",
  "ghql",
  "jsonlite"
)

## Now load or install & load all
package.check <- lapply(
  packages,
  FUN = function(x){
    if(!require(x, character.only = TRUE)){
      install.packages(x, dependencies = TRUE)
      library(x, character.only = TRUE)
    }
  }
)

# EXTRACT DATA VIA GRAPHQL ====

# create a link
`
x = 'https://census-api.frith.dev/graphql'
con = ghql::GraphqlClient$new(url = x)

# Loading the census api data schema into the R graphql client
query = 'query($type: String!){
  subplacebyName: places(type: $type){
    code
    name
    type {name descrip }
    province { code name }
    population
    area
    geom
  }
}'

# Making a request and parsing in the query (schema)
qry <- ghql::Query$new()
qry$query('x', query)
qry$queries$x

# query the variable pine from the request sent.
variables <- list(
  type = 'subplace'
)

# execute the query and variables %>% convert from json
result <- con$exec(qry$queries$x, variables = variables) %>% 
  jsonlite::fromJSON(flatten = T)


# WRANGLE DATA ====
sub_place <- result$data$subplacebyName %>%
  # convert coordinates to a list of points
  mutate(geom.coordinates = lapply(geom.coordinates, function(x) list(list(matrix(x,ncol=2,byrow=FALSE))))) %>%
  mutate(geometry = mapply(
    function(type, points) {
      # don't know if this is a valid assumption
      #  but get st_* function based on type column
      get(paste0("st_",tolower(type)))(points)
    },
    geom.type,
    geom.coordinates,
    SIMPLIFY = FALSE
  )) %>%
  mutate(geometry = geometry) %>%
  st_sf(crs = "WGS84") %>% 
  select(-geom.coordinates)

sub_place <- json$data$subplacebyName %>%
  mutate(geometry = mapply(
    function(type, points, i) {
      # don't know if this is a valid assumption
      #  but get st_* function based on type column
      if(inherits(points,"array")) {
        points <- list(#lapply(
          # points,
          # function(poly) {
            unlist(
              apply(points,2,function(x){list(matrix(x,ncol=2,byrow=FALSE))}),
              recursive=FALSE
            )
          # }
        )#)
      }
      if(inherits(points,"list") && any(sapply(points,function(x)inherits(x,"array")))) {
        points <- lapply(points,function(x){
          if(inherits(x,"array")) {
            list(matrix(x,ncol=2,byrow=FALSE))
          } else {
            x
          }
        })
      }
      geo <- st_multipolygon()
      tryCatch(
        assign("geo", get(paste0("st_",tolower(type)))(points)),
        error = function(e) print(i)
      )
      return(geo)
    },
    geom.type,
    geom.coordinates,
    seq_len(length(geom.coordinates)),
    SIMPLIFY = FALSE
  )) %>%
  st_sf(crs = "WGS84") %>% 
  select(-starts_with("geom."))