#  File src/library/tools/R/writePACKAGES.R
#  Part of the R package, http://www.R-project.org
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  A copy of the GNU General Public License is available at
#  http://www.r-project.org/Licenses/

write_PACKAGES <-
function(dir = ".", fields = NULL,
         type = c("source", "mac.binary", "win.binary"),
         verbose = FALSE, unpacked = FALSE, subdirs = FALSE,
         latestOnly = TRUE, addFiles = FALSE)
{
    if(missing(type) && .Platform$OS.type == "windows")
        type <- "win.binary"
    type <- match.arg(type)
    nfields <- 0
    out <- file(file.path(dir, "PACKAGES"), "wt")
    outgz <- gzfile(file.path(dir, "PACKAGES.gz"), "wt")

    paths <- ""
    if(is.logical(subdirs) && subdirs) {
        owd <- setwd(dir)
        paths <- unique(dirname(list.files(".", recursive=TRUE)))
        setwd(owd)
        paths <- c("", paths[paths != "."])
    } else if(is.character(subdirs)) paths <- c("", subdirs)

    for(path in paths) {
        this <- if(nzchar(path)) file.path(dir, path) else dir
        desc <- .build_repository_package_db(this, fields, type, verbose,
                                             unpacked)

        if(length(desc)) {
            Files <- names(desc)
            fields <- names(desc[[1L]])
            desc <- matrix(unlist(desc), ncol = length(fields), byrow = TRUE)
            colnames(desc) <- fields
            if(addFiles) desc <- cbind(desc, File = Files)
            if(latestOnly) desc <- .remove_stale_dups(desc)

            ## Standardize licenses or replace by NA.
            license_info <- analyze_licenses(desc[, "License"])
            desc[, "License"] <-
                ifelse(license_info$is_standardizable,
                       license_info$standardization,
                       NA)

            ## Writing PACKAGES file from matrix desc linewise in order to
            ## omit NA entries appropriately:
            for(i in seq_len(nrow(desc))){
                desci <- desc[i, !(is.na(desc[i, ]) | (desc[i, ] == "")),
                              drop = FALSE]
                write.dcf(desci, file = out)
                if(nzchar(path)) cat("Path: ", path, "\n", sep="", file = out)
                cat("\n", file = out)
                write.dcf(desci, file = outgz)
                if(nzchar(path)) cat("Path: ", path, "\n", sep="", file = outgz)
                cat("\n", file = outgz)
            }
            nfields <- nfields + nrow(desc)
        }
    }

    close(out)
    close(outgz)
    invisible(nfields)
}

## this is OK provided all the 'fields' are ASCII -- so be careful
## what you add.
.build_repository_package_db <-
function(dir, fields = NULL,
         type = c("source", "mac.binary", "win.binary"),
         verbose = getOption("verbose"),
         unpacked = FALSE)
{
    if(unpacked)
        return(.build_repository_package_db_from_source_dirs(dir,
                                                             fields,
                                                             verbose))

    type <- match.arg(type)

    ## FIXME: might the source pattern be more general?
    ## was .tar.gz prior to 2.10.0
    package_pattern <- switch(type,
                              "source" = "_.*\\.tar\\..*$",
                              "mac.binary" = "_.*\\.tgz$",
                              "win.binary" = "_.*\\.zip$")
    files <- list.files(dir, pattern = package_pattern)

    if(!length(files))
        return(list())

    ## Add the standard set of fields required to build a repository's
    ## PACKAGES file:
    fields <- unique(c(.get_standard_repository_db_fields(), fields))
    packages <- sapply(strsplit(files, "_", fixed = TRUE), "[", 1L)
    db <- vector(length(files), mode = "list")
    names(db) <- files
    ## Many (roughly length(files)) warnings are *expected*, hence
    ## suppressed.
    op <- options(warn = -1)
    on.exit(options(op))
    if(verbose) message("Processing packages:")
    if(type == "win.binary") {
        files <- file.path(dir, files)
        for(i in seq_along(files)) {
            if(verbose) message(paste(" ", files[i]))
            con <- unz(files[i], file.path(packages[i], "DESCRIPTION"))
            temp <- tryCatch(read.dcf(con, fields = fields)[1L, ],
                             error = identity)
            if(inherits(temp, "error")) {
                close(con)
                next
            }
            db[[i]] <- temp
            close(con)
        }
    } else {
        dir <- file_path_as_absolute(dir)
        files <- file.path(dir, files)
        cwd <- getwd()
        if (is.null(cwd))
            stop("current working directory cannot be ascertained")
        td <- tempfile("PACKAGES")
        if(!dir.create(td)) stop("unable to create ", td)
        on.exit(unlink(td, recursive = TRUE), add = TRUE)
        setwd(td)
        for(i in seq_along(files)) {
            if(verbose) message(paste(" ", files[i]))
            p <- file.path(packages[i], "DESCRIPTION")
            ## temp <- try(system(paste("tar zxf", files[i], p)))
            temp <- try(utils::untar(files[i], files = p))
            if(!inherits(temp, "try-error")) {
                temp <- tryCatch(read.dcf(p, fields = fields)[1L, ],
                                 error = identity)
                if(!inherits(temp, "error"))
                    db[[i]] <- temp
            }
            unlink(packages[i], recursive = TRUE)
        }
        setwd(cwd)
    }
    if(verbose) message("done")

    db
}

.build_repository_package_db_from_source_dirs <-
function(dir, fields = NULL, verbose = getOption("verbose"))
{
    dir <- file_path_as_absolute(dir)
    fields <- unique(c(.get_standard_repository_db_fields(), fields))
    paths <- list.files(dir, full.names = TRUE)
    paths <- paths[file_test("-d", paths) &
                   file_test("-f", file.path(paths, "DESCRIPTION"))]
    db <- vector(length(paths), mode = "list")
    if(verbose) message("Processing packages:")
    for(i in seq_along(paths)) {
        if(verbose) message(paste(" ", basename(paths[i])))
        temp <- tryCatch(read.dcf(file.path(paths[i], "DESCRIPTION"),
                                  fields = fields)[1L, ],
                         error = identity)
        if(!inherits(temp, "error"))
            db[[i]] <- temp
    }
    if(verbose) message("done")
    names(db) <- basename(paths)
    db
}

dependsOnPkgs <-
function(pkgs,
         dependencies = c("Depends", "Imports", "LinkingTo"),
         recursive = TRUE,
         lib.loc = NULL,
         installed = installed.packages(lib.loc, fields = "Enhances"))
{
    need <- apply(installed[, dependencies, drop = FALSE], 1L,
                  function(x)
                  any(pkgs %in% utils:::.clean_up_dependencies(x)) )
    uses <- rownames(installed)[need]
    if(recursive) {
        p <- pkgs
        repeat {
            p <- unique(c(p, uses))
            need <- apply(installed[, dependencies, drop = FALSE], 1L,
                          function(x)
                          any(p %in% utils:::.clean_up_dependencies(x)) )
            uses <- unique(c(p, rownames(installed)[need]))
            if(length(uses) <= length(p)) break
        }
    }
    setdiff(uses, pkgs)
}

.remove_stale_dups <-
function(ap)
{
    ## Given a matrix from available.packages, return a copy
    ## with no duplicate packages, being sure to keep the packages
    ## with highest version number.
    ## (Also works for data frame package repository dbs.)
    pkgs <- ap[ , "Package"]
    dup_pkgs <- pkgs[duplicated(pkgs)]
    stale_dups <- integer(length(dup_pkgs))
    i <- 1L
    for (dp in dup_pkgs) {
        wh <- which(dp == pkgs)
        vers <- package_version(ap[wh, "Version"])
        keep_ver <- max(vers)
        keep_idx = which(vers == keep_ver)[1L] # they might all be max
        wh <- wh[-keep_idx]
        end_i <- i + length(wh) - 1L
        stale_dups[i:end_i] <- wh
        i <- end_i + 1L
    }
    ## Possible to have only one package in a repository
    if(length(stale_dups)) ap[-stale_dups, , drop = FALSE] else ap
}

.package_dependencies <-
function(packages = NULL, db,
         which = c("Depends", "Imports", "LinkingTo"),
         recursive = FALSE, reverse = FALSE)
{
    ## <FIXME>
    ## What about duplicated entries?
    ## </FIXME>

    ## For given packages which are not found in the db, return "list
    ## NAs" (i.e., NULL entries), as opposed to character() entries
    ## which indicate no dependencies.

    ## For forward non-recursive depends, we can simplify matters by
    ## subscripting the db right away---modulo boundary cases.

    out_of_db_packages <- character()
    if(!recursive && !reverse) {
        if(!is.null(packages)) {
            ind <- match(packages, db[, "Package"], nomatch = 0L)
            db <- db[ind, , drop = FALSE]
            out_of_db_packages <- packages[ind == 0L]
        }
    }

    depends <-
        do.call(Map,
                c(list("c"),
                  ## Try to make this work for dbs which are character
                  ## matrices as from available.packages(), or data
                  ## frame variants thereof.
                  lapply(which,
                         function(f) {
                             if(is.list(d <- db[, f])) d
                             else lapply(d,
                                         .extract_dependency_package_names)
                         }),
                  list(USE.NAMES = FALSE)))

    if(!recursive && !reverse) {
        names(depends) <- db[, "Package"]
        if(length(out_of_db_packages)) {
            depends <-
                c(depends,
                  structure(vector("list", length(out_of_db_packages)),
                            names = out_of_db_packages))
        }
        return(depends)
    }

    all_packages <- sort(unique(c(db[, "Package"], unlist(depends))))

    if(!recursive) {
        ## Need to invert.
        depends <-
            split(rep.int(db[, "Package"], sapply(depends, length)),
                  factor(unlist(depends), levels = all_packages))
        if(!is.null(packages)) {
            depends <- depends[match(packages, names(depends))]
            names(depends) <- packages
        }
        return(depends)
    }

    ## Recursive dependencies.
    ## We need to compute the transitive closure of the dependency
    ## relation, but e.g. Warshall's algorithm (O(n^3)) is
    ## computationally infeasible.
    ## Hence, in principle, we do the following.
    ## Take the current list of pairs (i,j) in the relation.
    ## Iterate over all j and whenever i R j and j R k add (i,k).
    ## Repeat this until no new pairs get added.
    ## To do this in R, we use a 2-column matrix of (i,j) rows.
    ## We then create two lists which for all j contain the i and k
    ## with i R j and j R k, respectively, and combine these.
    ## This works reasonably well, but of course more efficient
    ## implementations should be possible.
    tab <- if(reverse)
        split(match(rep.int(db[, "Package"],
                            sapply(depends, length)),
                    all_packages),
              factor(match(unlist(depends), all_packages),
                     levels = seq_along(all_packages)))
    else
        split(match(unlist(depends), all_packages),
              factor(match(rep.int(db[, "Package"],
                                   sapply(depends, length)),
                           all_packages),
                     levels = seq_along(all_packages)))
    if(is.null(packages)) {
        if(reverse) {
            packages <- all_packages
            p_L <- seq_along(all_packages)
        } else {
            packages <- db[, "Package"]
            p_L <- match(packages, all_packages)
        }
    } else {
        p_L <- match(packages, all_packages, nomatch = 0L)
        if(any(ind <- (p_L == 0L))) {
            out_of_db_packages <- packages[ind]
            packages <- packages[!ind]
            p_L <- p_L[!ind]
        }
    }
    p_R <- tab[p_L]
    pos <- cbind(rep.int(p_L, sapply(p_R, length)), unlist(p_R))
    ctr <- 1L
    verbose <- getOption("verbose")
    repeat {
        if(verbose) cat("Cycle:", ctr)
        p_L <- split(pos[, 1L], pos[, 2L])
        new <- do.call(rbind,
                       Map(function(i, k)
                           cbind(rep.int(i, length(k)),
                                     rep(k, each = length(i))),
                           p_L, tab[as.integer(names(p_L))]))
        npos <- unique(rbind(pos, new))
        nnew <- nrow(npos) - nrow(pos)
        if(verbose) cat(" NNew:", nnew, "\n")
        if(!nnew) break
        pos <- npos
        ctr <- ctr + 1L
    }
    depends <-
        split(all_packages[pos[, 2L]],
              factor(all_packages[pos[, 1L]], levels = packages))
    if(length(out_of_db_packages)) {
        depends <-
            c(depends,
              structure(vector("list", length(out_of_db_packages)),
                        names = out_of_db_packages))
    }
    depends
}

.extract_dependency_package_names <-
function(x) {
    ## Assume a character *string*.
    if(is.na(x)) return(character())
    x <- unlist(strsplit(x, ",[[:space:]]*"))
    x <- sub("[[:space:]]*([[:alnum:].]+).*", "\\1", x)
    x[nzchar(x) & (x != "R")]
}
