## git2r, R bindings to the libgit2 library.
## Copyright (C) 2013-2019 The git2r contributors
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License, version 2,
## as published by the Free Software Foundation.
##
## git2r 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.
##
## You should have received a copy of the GNU General Public License along
## with this program; if not, write to the Free Software Foundation, Inc.,
## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

##' Ahead Behind
##'
##' Count the number of unique commits between two commit objects.
##' @param local a git_commit object. Can also be a tag or a branch,
##'     and in that case the commit will be the target of the tag or
##'     branch.
##' @param upstream a git_commit object. Can also be a tag or a
##'     branch, and in that case the commit will be the target of the
##'     tag or branch.
##' @return An integer vector of length 2 with number of commits that
##'     the upstream commit is ahead and behind the local commit
##' @export
##' @examples \dontrun{
##' ## Create a directory in tempdir
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##'
##' ## Initialize a repository
##' repo <- init(path)
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##'
##' ## Create a file, add and commit
##' lines <- "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do"
##' writeLines(lines, file.path(path, "test.txt"))
##' add(repo, "test.txt")
##' commit_1 <- commit(repo, "Commit message 1")
##' tag_1 <- tag(repo, "Tagname1", "Tag message 1")
##'
##' # Change file and commit
##' lines <- c(
##'   "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do",
##'   "eiusmod tempor incididunt ut labore et dolore magna aliqua.")
##' writeLines(lines, file.path(path, "test.txt"))
##' add(repo, "test.txt")
##' commit_2 <- commit(repo, "Commit message 2")
##' tag_2 <- tag(repo, "Tagname2", "Tag message 2")
##'
##' ahead_behind(commit_1, commit_2)
##' ahead_behind(tag_1, tag_2)
##' }
ahead_behind <- function(local = NULL, upstream = NULL) {
    .Call(git2r_graph_ahead_behind,
          lookup_commit(local),
          lookup_commit(upstream))
}

##' Add sessionInfo to message
##'
##' @param message The message.
##' @return message with appended sessionInfo
##' @importFrom utils capture.output
##' @importFrom utils sessionInfo
##' @noRd
add_session_info <- function(message) {
    paste0(message, "\n\nsessionInfo:\n",
           paste0(utils::capture.output(utils::sessionInfo()),
                  collapse = "\n"))
}

##' Commit
##'
##' @template repo-param
##' @param message The commit message.
##' @param all Stage modified and deleted files. Files not added to
##'     Git are not affected.
##' @param session Add sessionInfo to commit message. Default is
##'     FALSE.
##' @param author Signature with author and author time of commit.
##' @param committer Signature with committer and commit time of
##'     commit.
##' @return A list of class \code{git_commit} with entries:
##' \describe{
##'   \item{sha}{
##'     The 40 character hexadecimal string of the SHA-1
##'   }
##'   \item{author}{
##'     An author signature
##'   }
##'   \item{committer}{
##'     The committer signature
##'   }
##'   \item{summary}{
##'     The short "summary" of a git commit message, comprising the first
##'     paragraph of the message with whitespace trimmed and squashed.
##'   }
##'   \item{message}{
##'     The message of a commit
##'   }
##'   \item{repo}{
##'     The \code{git_repository} object that contains the commit
##'   }
##' }
##' @export
##' @examples
##' \dontrun{
##' ## Initialize a repository
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##' repo <- init(path)
##'
##' ## Config user
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##'
##' ## Write to a file and commit
##' lines <- "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do"
##' writeLines(lines, file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit(repo, "First commit message")
##' }
commit <- function(repo      = ".",
                   message   = NULL,
                   all       = FALSE,
                   session   = FALSE,
                   author    = NULL,
                   committer = NULL) {
    repo <- lookup_repository(repo)
    if (is.null(author))
        author <- default_signature(repo)
    if (is.null(committer))
        committer <- default_signature(repo)

    stopifnot(is.character(message), identical(length(message), 1L))
    if (!nchar(message[1]))
        stop("Aborting commit due to empty commit message.")

    if (isTRUE(all)) {
        s <- status(repo,
                    unstaged  = TRUE,
                    staged    = FALSE,
                    untracked = FALSE,
                    ignored   = FALSE)

        ## Convert list of lists to character vector
        unstaged <- unlist(s$unstaged)
        for (i in seq_along(unstaged)) {
            if (names(unstaged)[i] == "modified") {
                ## Stage modified files
                add(repo, unstaged[i])
            } else if (names(unstaged)[i] == "deleted") {
                ## Stage deleted files
                .Call(git2r_index_remove_bypath, repo, unstaged[i])
            }
        }

    }

    if (isTRUE(session))
        message <- add_session_info(message)

    .Call(git2r_commit, repo, message, author, committer)
}

##' Check limit in number of commits
##' @noRd
get_upper_limit_of_commits <- function(n) {
    if (is.null(n)) {
        n <- -1L
    } else if (is.numeric(n)) {
        if (!identical(length(n), 1L))
            stop("'n' must be integer")
        if (abs(n - round(n)) >= .Machine$double.eps^0.5)
            stop("'n' must be integer")
        n <- as.integer(n)
    } else {
        stop("'n' must be integer")
    }

    n
}

shallow_commits <- function(repo, sha, n) {
    ## List to hold result
    result <- list()

    ## Get latest commit
    x <- lookup(repo, sha)

    ## Repeat until no more parent commits
    repeat {
        if (n == 0) {
            break
        } else if (n > 0) {
            n <- n - 1
        }

        if (is.null(x))
            break
        result[[length(result) + 1]] <- x

        ## Get parent to commit
        x <- tryCatch(parents(x)[[1]], error = function(e) NULL)
    }

    result
}

##' Commits
##'
##' @template repo-param
##' @param topological Sort the commits in topological order (parents
##'     before children); can be combined with time sorting. Default
##'     is TRUE.
##' @param time Sort the commits by commit time; Can be combined with
##'     topological sorting. Default is TRUE.
##' @param reverse Sort the commits in reverse order; can be combined
##'     with topological and/or time sorting. Default is FALSE.
##' @param n The upper limit of the number of commits to output. The
##'     default is NULL for unlimited number of commits.
##' @param ref The name of a reference to list commits from e.g. a tag
##'     or a branch. The default is NULL for the current branch.
##' @param path The path to a file. If not NULL, only commits modifying
##'     this file will be returned. Note that modifying commits that
##'     occurred before the file was given its present name are not
##'     returned; that is, the output of \code{git log} with
##'     \code{--no-follow} is reproduced.
##' @return list of commits in repository
##' @export
##' @examples
##' \dontrun{
##' ## Initialize a repository
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##' repo <- init(path)
##'
##' ## Config user
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##'
##' ## Write to a file and commit
##' lines <- "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do"
##' writeLines(lines, file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit(repo, "First commit message")
##'
##' ## Change file and commit
##' lines <- c(
##'   "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do",
##'   "eiusmod tempor incididunt ut labore et dolore magna aliqua.")
##' writeLines(lines, file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit(repo, "Second commit message")
##'
##' ## Create a tag
##' tag(repo, "Tagname", "Tag message")
##'
##' ## Change file again and commit
##' lines <- c(
##'   "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do",
##'   "eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad",
##'   "minim veniam, quis nostrud exercitation ullamco laboris nisi ut")
##' writeLines(lines, file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit(repo, "Third commit message")
##'
##' ## Create a new file containing R code, and commit.
##' writeLines(c("x <- seq(1,100)",
##'              "print(mean(x))"),
##'            file.path(path, "mean.R"))
##' add(repo, "mean.R")
##' commit(repo, "Fourth commit message")
##'
##' ## List the commits in the repository
##' commits(repo)
##'
##' ## List the commits starting from the tag
##' commits(repo, ref = "Tagname")
##'
##' ## List the commits modifying example.txt and mean.R.
##' commits(repo, path = "example.txt")
##' commits(repo, path = "mean.R")
##'
##' ## Create and checkout 'dev' branch in the repo
##' checkout(repo, "dev", create = TRUE)
##'
##' ## Add changes to the 'dev' branch
##' lines <- c(
##'   "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do",
##'   "eiusmod tempor incididunt ut labore et dolore magna aliqua.")
##' writeLines(lines, file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit(repo, "Commit message in dev branch")
##'
##' ## Checkout the 'master' branch again and list the commits
##' ## starting from the 'dev' branch.
##' checkout(repo, "master")
##' commits(repo, ref = "dev")
##' }
commits <- function(repo        = ".",
                    topological = TRUE,
                    time        = TRUE,
                    reverse     = FALSE,
                    n           = NULL,
                    ref         = NULL,
                    path        = NULL) {
    ## Check limit in number of commits
    n <- get_upper_limit_of_commits(n)

    if (!is.null(path)) {
        if (!(is.character(path) && length(path) == 1)) {
            stop("path must be a single file")
        }
    }

    repo <- lookup_repository(repo)
    if (is_empty(repo))
        return(list())

    if (is.null(ref)) {
        sha <- sha(repository_head(repo))
    } else {
        sha <- sha(lookup_commit(.Call(git2r_reference_dwim, repo, ref)))
    }

    if (is_shallow(repo)) {
        ## FIXME: Remove this if-statement when libgit2 supports
        ## shallow clones, see #219.  Note: This workaround does not
        ## use the 'topological', 'time' and 'reverse' flags.
        return(shallow_commits(repo, sha, n))
    }

    if (!is.null(path)) {
        repo_wd <- normalizePath(workdir(repo), winslash = "/")
        path <- sanitize_path(path, repo_wd)
        path_revwalk <- .Call(git2r_revwalk_list2, repo, sha, topological,
                              time, reverse, n, path)
        return(path_revwalk[!vapply(path_revwalk, is.null, logical(1))])
    }

    .Call(git2r_revwalk_list, repo, sha, topological, time, reverse, n)
}

##' Last commit
##'
##' Get last commit in the current branch.
##' @template repo-param
##' @export
##' @examples
##' \dontrun{
##' ## Initialize a repository
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##' repo <- init(path)
##'
##' ## Config user
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##'
##' ## Write to a file and commit
##' lines <- "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do"
##' writeLines(lines, file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit(repo, "First commit message")
##'
##' ## Get last commit
##' last_commit(repo)
##' last_commit(path)
##'
##' ## Coerce the last commit to a data.frame
##' as.data.frame(last_commit(path), "data.frame")
##'
##' ## Summary of last commit in repository
##' summary(last_commit(repo))
##' }
last_commit <- function(repo = ".") {
    commits(lookup_repository(repo), n = 1)[[1]]
}

##' Descendant
##'
##' Determine if a commit is the descendant of another commit
##' @param commit a git_commit object. Can also be a tag or a branch,
##'     and in that case the commit will be the target of the tag or
##'     branch.
##' @param ancestor a git_commit object to check if ancestor to
##'     \code{commit}. Can also be a tag or a branch, and in that case
##'     the commit will be the target of the tag or branch.
##' @return TRUE if \code{commit} is descendant of \code{ancestor},
##'     else FALSE
##' @export
##' @examples
##' \dontrun{
##' ## Create a directory in tempdir
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##'
##' ## Initialize a repository
##' repo <- init(path)
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##'
##' ## Create a file, add and commit
##' lines <- "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do"
##' writeLines(lines, file.path(path, "test.txt"))
##' add(repo, "test.txt")
##' commit_1 <- commit(repo, "Commit message 1")
##' tag_1 <- tag(repo, "Tagname1", "Tag message 1")
##'
##' # Change file and commit
##' lines <- c(
##'   "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do",
##'   "eiusmod tempor incididunt ut labore et dolore magna aliqua.")
##' writeLines(lines, file.path(path, "test.txt"))
##' add(repo, "test.txt")
##' commit_2 <- commit(repo, "Commit message 2")
##' tag_2 <- tag(repo, "Tagname2", "Tag message 2")
##'
##' descendant_of(commit_1, commit_2)
##' descendant_of(commit_2, commit_1)
##' descendant_of(tag_1, tag_2)
##' descendant_of(tag_2, tag_1)
##' }
descendant_of <- function(commit = NULL, ancestor = NULL) {
    .Call(git2r_graph_descendant_of,
          lookup_commit(commit),
          lookup_commit(ancestor))
}

##' Check if object is a git_commit object
##'
##' @param object Check if object is a git_commit object
##' @return TRUE if object is a git_commit, else FALSE
##' @export
##' @examples
##' \dontrun{
##' ## Initialize a temporary repository
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##' repo <- init(path)
##'
##' ## Create a user
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##'
##' ## Commit a text file
##' writeLines("Hello world!", file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit_1 <- commit(repo, "First commit message")
##'
##' ## Check if commit
##' is_commit(commit_1)
##' }
is_commit <- function(object) {
    inherits(object, "git_commit")
}

##' Is merge
##'
##' Determine if a commit is a merge commit, i.e. has more than one
##' parent.
##' @param commit a git_commit object.
##' @return TRUE if commit has more than one parent, else FALSE
##' @export
##' @examples
##' \dontrun{
##' ## Initialize a temporary repository
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##' repo <- init(path)
##'
##' ## Create a user and commit a file
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##' writeLines(c("First line in file 1.", "Second line in file 1."),
##'            file.path(path, "example-1.txt"))
##' add(repo, "example-1.txt")
##' commit(repo, "First commit message")
##'
##' ## Create and add one more file
##' writeLines(c("First line in file 2.", "Second line in file 2."),
##'            file.path(path, "example-2.txt"))
##' add(repo, "example-2.txt")
##' commit(repo, "Second commit message")
##'
##' ## Create a new branch 'fix'
##' checkout(repo, "fix", create = TRUE)
##'
##' ## Update 'example-1.txt' (swap words in first line) and commit
##' writeLines(c("line First in file 1.", "Second line in file 1."),
##'            file.path(path, "example-1.txt"))
##' add(repo, "example-1.txt")
##' commit(repo, "Third commit message")
##'
##' checkout(repo, "master")
##'
##' ## Update 'example-2.txt' (swap words in second line) and commit
##' writeLines(c("First line in file 2.", "line Second in file 2."),
##'            file.path(path, "example-2.txt"))
##' add(repo, "example-2.txt")
##' commit(repo, "Fourth commit message")
##'
##' ## Merge 'fix'
##' merge(repo, "fix")
##'
##' ## Display parents of last commit
##' parents(lookup(repo, branch_target(repository_head(repo))))
##'
##' ## Check that last commit is a merge
##' is_merge(lookup(repo, branch_target(repository_head(repo))))
##' }
is_merge <- function(commit = NULL) {
    length(parents(commit)) > 1
}

##' Parents
##'
##' Get parents of a commit.
##' @param object a git_commit object.
##' @return list of git_commit objects
##' @export
##' @examples
##' \dontrun{
##' ## Initialize a temporary repository
##' path <- tempfile(pattern="git2r-")
##' dir.create(path)
##' repo <- init(path)
##'
##' ## Create a user and commit a file
##' config(repo, user.name = "Alice", user.email = "alice@@example.org")
##' writeLines("First line.",
##'            file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit_1 <- commit(repo, "First commit message")
##'
##' ## commit_1 has no parents
##' parents(commit_1)
##'
##' ## Update 'example.txt' and commit
##' writeLines(c("First line.", "Second line."),
##'            file.path(path, "example.txt"))
##' add(repo, "example.txt")
##' commit_2 <- commit(repo, "Second commit message")
##'
##' ## commit_2 has commit_1 as parent
##' parents(commit_2)
##' }
parents <- function(object = NULL) {
    .Call(git2r_commit_parent_list, object)
}

##' @export
format.git_commit <- function(x, ...) {
    sprintf("[%s] %s: %s",
            substring(x$sha, 1, 7),
            substring(as.character(x$author$when), 1, 10),
            x$summary)
}

##' @export
print.git_commit <- function(x, ...) {
    cat(format(x, ...), "\n", sep = "")
    invisible(x)
}

##' @export
summary.git_commit <- function(object, ...) {
    is_merge_commit <- is_merge(object)
    po <- parents(object)

    cat(sprintf("Commit:  %s\n", object$sha))

    if (is_merge_commit) {
        sha <- vapply(po, "[[", character(1), "sha")
        cat(sprintf("Merge:   %s\n", sha[1]))
        cat(paste0("         ", sha[-1]), sep = "\n")
    }

    cat(sprintf(paste0("Author:  %s <%s>\n",
                       "When:    %s\n\n"),
                object$author$name,
                object$author$email,
                as.character(object$author$when)))

    msg <- paste0("    ", readLines(textConnection(object$message)))
    cat("", sprintf("%s\n", msg))

    if (is_merge_commit) {
        cat("\n")
        lapply(po, function(parent) {
            cat("Commit message: ", parent$sha, "\n")
            msg <- paste0("    ",
                          readLines(textConnection(parent$message)))
            cat("", sprintf("%s\n", msg), "\n")
        })
    }

    if (identical(length(po), 1L)) {
        df <- diff(tree(po[[1]]), tree(object))
        if (length(df) > 0) {
            if (length(df) > 1) {
                cat(sprintf("%i files changed, ", length(df)))
            } else {
                cat("1 file changed, ")
            }

            cat(sprintf(
                "%i insertions, %i deletions\n",
                sum(vapply(lines_per_file(df), "[[", numeric(1), "add")),
                sum(vapply(lines_per_file(df), "[[", numeric(1), "del"))))

            plpf <- print_lines_per_file(df)
            hpf <- hunks_per_file(df)
            hunk_txt <- ifelse(hpf > 1, " hunks",
                        ifelse(hpf > 0, " hunk",
                               " hunk (binary file)"))
            phpf <- paste0("  in ", format(hpf), hunk_txt)
            cat(paste0(plpf, phpf), sep = "\n")
        }

        cat("\n")
    }

    invisible(NULL)
}

##' @export
as.data.frame.git_commit <- function(x, ...) {
    data.frame(sha              = x$sha,
               summary          = x$summary,
               message          = x$message,
               author           = x$author$name,
               email            = x$author$email,
               when             = as.POSIXct(x$author$when),
               stringsAsFactors = FALSE)
}