Crawl Reservoir 2

library(data.table)
library(stringi)
library(lubridate)
library(foreach)
library(httr)
library(xml2)
library(rvest)
library(pipeR)

# windows才需要先把locale改成C，並用stringi::stri_conv轉成big5
backupLocale <- Sys.getlocale("LC_COLLATE")
Sys.setlocale("LC_ALL", 'C')

timeVec <- seq(ymd_hms("2017/06/09 00:00:00"), ymd_hms("2017/06/11 00:00:00")-1, 600)
reservoirUrl <- "http://fhy.wra.gov.tw/ReservoirPage_2011/Statistics.aspx" # 10 min data


# for (time in timeVec) {
time = timeVec[1]

getRes <- GET(reservoirUrl) %>>% content

POSTParas1 <- getRes %>>% {
  list("__VIEWSTATE" = xml_find_all(., "//input[@name='__VIEWSTATE']"),
       "__VIEWSTATEGENERATOR" = xml_find_all(., "//input[@name='__VIEWSTATEGENERATOR']"),
       "__EVENTVALIDATION" = xml_find_all(., "//input[@name='__EVENTVALIDATION']")) %>>%
    lapply(xml_attr, attr = "value")
}

ctl00_ctl02_HiddenField <- getRes %>>% xml_find_all("//script") %>>% xml_attr("src") %>>%
  `[`(grepl("AjaxControlToolkit", .)) %>>%
  (sub("/ReservoirPage_2011/Statistics.aspx\\?_TSM_HiddenField_=", "", .))

POSTParas2 <- lapply(c(year, month, day, hour, minute), function(f) f(time)) %>>%
  `names<-`(paste0("ctl00$cphMain$ucDate$cbo",
                   c("Year", "Month", "Day", "Hour", "Minute")))
postBody <- c(list("ctl00$cphMain$cboSearch" = "全部", "__EVENTTARGET" = "ctl00$cphMain$btnQuery",
                   ctl00_ctl02_HiddenField = ctl00_ctl02_HiddenField,
                   "ctl00$ctl02" = "ctl00$cphMain$ctl00|ctl00$cphMain$btnQuery"), POSTParas1, POSTParas2)

outTbl <- POST(reservoirUrl, body = postBody) %>>% content %>>%
  xml_find_first("//table[@id='ctl00_cphMain_gvList']") %>>%
  html_table(fill = TRUE) %>>% setDT %>>%
  `[`(j = lapply(.SD, stri_conv, from = "UTF-8", to = "Big5"))
setnames(outTbl, stri_conv(names(outTbl), "UTF-8", "Big5"))

# }

Sys.setlocale(locale = backupLocale)