%  Copyright (C) 2003-2004 David Roundy
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\darcsCommand{tag}
\begin{code}
module Darcs.Commands.Tag ( tag ) where
import Control.Monad ( when )

import Darcs.Commands ( DarcsCommand(DarcsCommand, command_name, command_help,
                        command_description, command_extra_args,
                        command_extra_arg_help, command_command, command_prereq,
                        command_get_arg_possibilities, command_argdefaults,
                        command_advanced_options, command_basic_options),
                        nodefaults )
import Darcs.Arguments ( nocompress, umask_option, patchname_option, author,
                         checkpoint, pipe_interactive, ask_long_comment,
                         working_repo_dir, get_author )
import Darcs.Hopefully ( n2pia )
import Darcs.Repository ( amInRepository, withRepoLock, ($-), read_repo,
                    tentativelyAddPatch, finalizeRepositoryChanges, 
                  )
import Darcs.Repository.Checkpoint ( write_recorded_checkpoint )
import Darcs.Patch ( infopatch, identity, adddeps )
import Darcs.Patch.Info ( patchinfo )
import Darcs.Patch.Depends ( get_tags_right )
import Darcs.Commands.Record ( get_date, get_log )
import Darcs.Ordered ( FL(..) )
import Darcs.Lock ( world_readable_temp )
import Darcs.Flags ( DarcsFlag(..) )
import System.IO ( hPutStr, stderr )

tag_description :: String
tag_description = "Name the current repository state for future reference."

tag_help :: String
tag_help =
 "The `darcs tag' command names the current repository state, so that it\n" ++
 "can easily be referred to later.  Every `important' state should be\n" ++
 "tagged; in particular it is good practice to tag each stable release\n" ++
 "with a number or codename.  Advice on release numbering can be found\n" ++
 "at http://producingoss.com/en/development-cycle.html.\n" ++
 "\n" ++
 "To reproduce the state of a repository `R' as at tag `t', use the\n" ++
 "command `darcs get --tag t R'.  The command `darcs show tags' lists\n" ++
 "all tags in the current repository.\n" ++
 "\n" ++
 "Tagging also provides significant performance benefits: when Darcs\n" ++
 "reaches a shared tag that depends on all antecedent patches, it can\n" ++
 "simply stop processing.\n" ++
 "\n" ++
 "Like normal patches, a tag has a name, an author, a timestamp and an\n" ++
 "optional long description, but it does not change the working tree.\n" ++
 "A tag can have any name, but it is generally best to pick a naming\n" ++
 "scheme and stick to it.\n" ++
 "\n" ++
 "The `darcs tag' command accepts the --pipe and --checkpoint options,\n" ++
 "which behave as described in `darcs record' and `darcs optimize'\n" ++
 "respectively.\n"

tag :: DarcsCommand
tag = DarcsCommand {command_name = "tag",
                    command_help = tag_help,
                    command_description = tag_description,
                    command_extra_args = -1,
                    command_extra_arg_help = ["[TAGNAME]"],
                    command_command = tag_cmd,
                    command_prereq = amInRepository,
                    command_get_arg_possibilities = return [],
                    command_argdefaults = nodefaults,
                    command_advanced_options = [nocompress,umask_option],
                    command_basic_options = [patchname_option, author,
                                            checkpoint,
                                            pipe_interactive,
                                            ask_long_comment,
                                            working_repo_dir]}

tag_cmd :: [DarcsFlag] -> [String] -> IO ()
tag_cmd opts args = withRepoLock opts $- \repository -> do
    date <- get_date opts
    the_author <- get_author opts
    deps <- get_tags_right `fmap` read_repo repository
    (name, long_comment)  <- get_name_log opts args
    myinfo <- patchinfo date name the_author long_comment
    let mypatch = infopatch myinfo identity
    tentativelyAddPatch repository opts $ n2pia $ adddeps mypatch deps
    finalizeRepositoryChanges repository
    when (CheckPoint `elem` opts) $ write_recorded_checkpoint repository myinfo
    putStrLn $ "Finished tagging patch '"++name++"'"
  where  get_name_log :: [DarcsFlag] -> [String] -> IO (String, [String])
         get_name_log o a = do let o2 = if null a then o else (add_patch_name o (unwords a))
                               (name, comment, _) <- get_log o2 Nothing (world_readable_temp "darcs-tag") NilFL
                               when (length name < 2) $ hPutStr stderr $
                                 "Do you really want to tag '"
                                 ++name++"'? If not type: darcs obliterate --last=1\n"
                               return ("TAG " ++ name, comment)
         add_patch_name :: [DarcsFlag] -> String -> [DarcsFlag]
         add_patch_name o a| has_patch_name o = o
                           | otherwise = [PatchName a] ++ o
         has_patch_name (PatchName _:_) = True
         has_patch_name (_:fs) = has_patch_name fs
         has_patch_name [] = False

-- This may be useful for developers, but users don't care about
-- internals:
--
-- A tagged version automatically depends on all patches in the
-- repository.  This allows you to later reproduce precisely that
-- version.  The tag does this by depending on all patches in the
-- repository, except for those which are depended upon by other tags
-- already in the repository.  In the common case of a sequential
-- series of tags, this means that the tag depends on all patches
-- since the last tag, plus that tag itself.
\end{code}