library(git2r)

r <- repository()

current_branches <- branches(r)

vars <- expand.grid(list(language = "r",
    sudo = c("required", "false"),
    dist = c("precise", "trusty"),
    r = c("3.1", "3.2", "devel"),
    r_binary_packages = c(NA_character_, "withr"),
    use_bioc = c(NA_character_, "true")),
  stringsAsFactors = FALSE)


# add rows for r-devel for devel builds
devel_bioc <- subset(vars, r == 'devel' & use_bioc == 'true')
devel_bioc$use_bioc_devel = "true"
vars <- plyr::rbind.fill(vars, devel_bioc)

# Add a Bioconductor package to the DESCRIPTION if use_bioc is true
desc_txt <- readLines("DESCRIPTION")
desc_txt[grepl("^Suggests:", desc_txt)] <- "Suggests: knitr, BiocParallel"
use_bioc <- !is.na(vars$use_bioc) & vars$use_bioc == 'true'
vars$extra_content <- list(list())
vars$extra_content[use_bioc] <- list(list(DESCRIPTION = desc_txt))
vars[is.na(vars)] <- NA_character_

content <- function(data) {
  paste0(names(data), ": ", data, collapse = "\n")
}

name <- function(data) {
  paste0(names(data), "_", data, collapse = "-")
}

commit_msg <- function(data) {
  paste0(names(data), ": ", data, collapse = ", ")
}

write_branch <- function(data) {
  data <- Filter(Negate(is.na), data)

  extra_content <- data$extra_content[[1]]
  data$extra_content <- NULL

  con <- content(data)

  nme <- name(data)

  if (!nme %in% names(branches(r))) {
    branch_create(commits(r)[[1]], nme)
  } else {
    checkout(r, nme)
  }

  writeLines(con, ".travis.yml")
  add(r, ".travis.yml")

  for (i in seq_along(extra_content)) {
    path <- names(extra_content)[i]
    txt <- extra_content[[i]]
    writeLines(txt, path)
    add(r, path)
  }
  commit <- commit(r, commit_msg(data))
}

for (i in seq_len(NROW(vars))) {
   write_branch(vars[i, ])
}
checkout(r, "master")