# -------------------------------------------------------------------
# Creation of a defined CRAN snapshot to be made available on 
# https://cran.intiquan.com 
#
# Run script from its location on the server!
#
# Snapshots are currently copied from MRAN (https://cran.microsoft.com/). 
#
# This will continue as long as MRAN is up-to-date and continues its
# service. If at any point in time the MRAN service becomes unavailable,
# snapshots will be taken from CRAN whenever these are needed.
# -------------------------------------------------------------------

scriptPath <- setwd(IQRtools::aux_fileparts(rstudioapi::getActiveDocumentContext()$path)$pathname)
setwd(scriptPath)

# ----------------------------------
# Define the (MRAN) snapshot to be copied
# ----------------------------------
SNAPSHOT <- "snapshot/2020-12-21/src/contrib/"

# ----------------------------------
# Just run
# ----------------------------------

if (file.exists(SNAPSHOT)) stop("Snapshot already present")

# Define the MRAN URL to copy it from
MRAN_REPO <- paste0("https://cran.microsoft.com/",SNAPSHOT)

# Create folder to download all packages
IQRtools::aux_mkdir(SNAPSHOT)

# Get names of all source package files 
download.file(url = MRAN_REPO,destfile = "content.txt",method = "libcurl")
content <- IQRtools::aux_fileread("content.txt",collapserows = FALSE)
content <- content[grepl(".tar.gz",content)]
unlink("content.txt")
m <- gregexpr('">(.*?)</a>',content)
matches <- unlist(regmatches(content,m))
matches <- gsub('">|</a>',"",matches)

# Download all source packages
parallel::mclapply(seq_along(matches), function (k) {
  download.file(url = paste0(MRAN_REPO,matches[k]),destfile = paste0(SNAPSHOT,matches[k]),quiet = TRUE,method = "libcurl")
},mc.cores = ifelse(.Platform$OS.type=="windows",1,64),mc.preschedule = FALSE)

# Write the PACKAGES files
setwd(SNAPSHOT)
tools::write_PACKAGES(".",type = "source")

# Change folder back
setwd(scriptPath)

# Final message
message("Copying CRAN snapshot completed!")