library(dplyr)
library(purrr)
library(tidyr)
library(stringr)
library(readr)
library(forcats)
library(gganimate)

DATA_DIR <- "data-raw"

fs::dir_create(here::here(DATA_DIR))

DOWNLOAD_DATA <- if (!exists(DOWNLOAD_DATA)) TRUE else DOWNLOAD_DATA

download_file <- function(filename, url, basedir) {
  filename <- gsub(" ", "_", filename)
  filename <- gsub("/", "-", filename)
  fs::dir_create(basedir)
  download.file(url, destfile = fs::path(basedir, filename))
}

if (DOWNLOAD_DATA) {
  ## ----download-popest-tables-1900-1980, eval=FALSE------------------------
  x <- xml2::read_html("https://www2.census.gov/programs-surveys/popest/tables/1900-1980/national/asrh/")

  xx <-
    data_frame(
      filename = rvest::html_nodes(x, "a") %>% rvest::html_text(),
      url = rvest::html_nodes(x, "a") %>% rvest::html_attr("href")
    ) %>%
    filter(str_detect(url, "\\.csv")) %>%
    mutate(url = str_c(
      "https://www2.census.gov/programs-surveys/popest/tables/1900-1980/national/asrh/",
      url
    ))

  pwalk(xx, download_file, basedir = here::here(DATA_DIR, "1900-1980"))

  ## ----download-popest-tables-1980-1990, eval=FALSE------------------------
  xml2::read_html("https://www.census.gov/data/datasets/time-series/demo/popest/1980s-national.html") %>%
    rvest::html_nodes(".list.section .uscb-text-link") %>%
    rvest::html_attrs() %>%
    purrr::transpose() %>%
    as_tibble() %>%
    unnest() %>%
    filter(str_detect(href, "rqi\\.zip")) %>%
    select(filename = name, url = href) %>%
    mutate(
      url = paste0("https:", url),
      filename = basename(url)
    ) %>%
    pwalk(download_file, basedir = here::here(DATA_DIR, "1980-1990"))

  withr::with_dir(here::here(DATA_DIR, "1980-1990"), {
    fs::dir_ls(regexp = "zip") %>%
      purrr::walk(unzip)
  })

  ## ----download-popest-tables-1990-2000, eval=FALSE------------------------
  xml2::read_html("https://www.census.gov/data/datasets/time-series/demo/popest/intercensal-1990-2000-national.html") %>%
    rvest::html_nodes("#listArticlesContainer_list_0 .uscb-text-link") %>%
    rvest::html_attrs() %>%
    purrr::transpose() %>%
    as_tibble() %>%
    unnest() %>%
    select(filename = name, url = href) %>%
    mutate(url = paste0("https:", url),
           filename = paste0(filename, ".csv")) %>%
    pwalk(download_file, basedir = here::here(DATA_DIR, "1990-2000"))

  ## ----download-popest-tables-2000-2010----
  ## "2000-2010/us-est00int-01.xls"
  download_file(
    "us-est00int-alldata-5yr.csv",
    "https://www2.census.gov/programs-surveys/popest/datasets/2000-2010/intercensal/national/us-est00int-alldata-5yr.csv",
    here::here(DATA_DIR, "2000-2010")
  )


  ## ----download-popest-tables-2010----
  ## "2010-2017/PEP_2017_PEPSYASEXN_with_ann.csv"
  ## Download manually from https://factfinder.census.gov/bkmk/table/1.0/en/PEP/2017/PEPSYASEXN/0100000US
  fs::dir_create(here::here(DATA_DIR, "2010-2017"))
  if (!fs::file_exists(here::here(DATA_DIR, "2010-2017", "PEP_2017_PEPSYASEXN_with_ann.csv"))) {
    rlang::abort(paste(
      "Download the Annual Estimates of Resident Population by Single Year of Age from:\n",
      "https://factfinder.census.gov/bkmk/table/1.0/en/PEP/2017/PEPSYASEXN/0100000US\n",
      "and extract `PEP_2017_PEPSYASEXN_with_ann.csv` into:", here::here(DATA_DIR, "2010-2017")
    ))
  }

  ## ----download-popest-projections
  ## "np2017_d1.csv"
  download_file(
    "np2017_d1.csv",
    "https://www2.census.gov/programs-surveys/popproj/datasets/2017/2017-popproj/np2017_d1.csv",
    here::here(DATA_DIR)
  )
}