/* vim: set sw=4 sts=4 et foldmethod=syntax : */

/*
 * Copyright (c) 2010, 2011 Ciaran McCreesh
 *
 * This file is part of the Paludis package manager. Paludis 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.
 *
 * Paludis 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., 59 Temple
 * Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <paludis/merger.hh>
#include <paludis/util/stringify.hh>
#include <paludis/util/exception.hh>
#include <paludis/util/log.hh>
#include <paludis/util/pimp-impl.hh>
#include <paludis/util/timestamp.hh>
#include <paludis/util/make_null_shared_ptr.hh>
#include <paludis/util/fs_iterator.hh>
#include <paludis/util/fs_stat.hh>
#include <paludis/selinux/security_context.hh>
#include <paludis/environment.hh>
#include <paludis/hook.hh>
#include <set>
#include <istream>
#include <ostream>

using namespace paludis;

MergerError::MergerError(const std::string & m) throw () :
    Exception(m)
{
}

namespace paludis
{
    template <>
    struct Imp<Merger>
    {
        MergerParams params;
        bool result;
        bool skip_dir;

        std::set<FSPath, FSPathComparator> fixed_entries;

        Imp(const MergerParams & p) :
            params(p),
            result(true),
            skip_dir(false)
        {
        }
    };
}

#include <paludis/merger-se.cc>

Merger::Merger(const MergerParams & p) :
    _imp(p)
{
}

Merger::~Merger() = default;

Hook
Merger::extend_hook(const Hook & h)
{
    return h;
}

bool
Merger::check()
{
    Context context("When checking merge from '" + stringify(_imp->params.image()) + "' to '"
            + stringify(_imp->params.root()) + "':");

    if (0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_pre")
                         ("INSTALL_SOURCE", stringify(_imp->params.image()))
                         ("INSTALL_DESTINATION", stringify(_imp->params.root()))),
                _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();

    do_dir_recursive(true, _imp->params.image(), _imp->params.root() / _imp->params.install_under());

    if (0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_post")
                         ("INSTALL_SOURCE", stringify(_imp->params.image()))
                         ("INSTALL_DESTINATION", stringify(_imp->params.root()))),
                _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();

    return _imp->result;
}

void
Merger::merge()
{
    Context context("When performing merge from '" + stringify(_imp->params.image()) + "' to '"
            + stringify(_imp->params.root()) + "':");

    if (0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_install_pre")
                         ("INSTALL_SOURCE", stringify(_imp->params.image()))
                         ("INSTALL_DESTINATION", stringify(_imp->params.root()))),
                _imp->params.maybe_output_manager()).max_exit_status())
        Log::get_instance()->message("merger.pre_hooks.failure", ll_warning, lc_context) <<
            "Merge of '" << _imp->params.image() << "' to '" << _imp->params.root() << "' pre hooks returned non-zero";

    prepare_install_under();

    if (! _imp->params.no_chown())
        do_ownership_fixes_recursive(_imp->params.image());

    do_dir_recursive(false, _imp->params.image(), canonicalise_root_path(_imp->params.root() / _imp->params.install_under()));
    on_done_merge();

    if (0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_install_post")
                         ("INSTALL_SOURCE", stringify(_imp->params.image()))
                         ("INSTALL_DESTINATION", stringify(_imp->params.root()))),
                _imp->params.maybe_output_manager()).max_exit_status())
        Log::get_instance()->message("merger.post_hooks.failure", ll_warning, lc_context) <<
            "Merge of '" << _imp->params.image() << "' to '" << _imp->params.root() << "' post hooks returned non-zero";
}


void
Merger::make_check_fail()
{
    _imp->result = false;
}

void
Merger::do_dir_recursive(bool is_check, const FSPath & src, const FSPath & dst)
{
    Context context("When " + stringify(is_check ? "checking" : "performing") + " merge from '" +
            stringify(src) + "' to '" + stringify(dst) + "':");

    if (! src.stat().is_directory())
        throw MergerError("Source directory '" + stringify(src) + "' is not a directory");

    on_enter_dir(is_check, src);

    FSIterator d(src, { fsio_include_dotfiles, fsio_inode_sort }), d_end;

    if (is_check)
    {
        if (d == d_end && dst != _imp->params.root().realpath())
        {
            if (_imp->params.options()[mo_allow_empty_dirs])
                Log::get_instance()->message("merger.empty_directory", ll_warning, lc_context) << "Installing empty directory '"
                    << stringify(dst) << "'";
            else
                on_error(is_check, "Attempted to install empty directory '" + stringify(dst) + "'");
        }

        if (! _imp->params.permit_destination()(dst.strip_leading(_imp->params.root().realpath())))
            on_error(is_check, "Not allowed to merge '" + stringify(src) + "' to '" + stringify(dst) + "'");
    }

    for ( ; d != d_end ; ++d)
    {
        EntryType m(entry_type(*d));
        switch (m)
        {
            case et_sym:
                on_sym(is_check, *d, dst);
                continue;

            case et_file:
                on_file(is_check, *d, dst);
                continue;

            case et_dir:
                on_dir(is_check, *d, dst);
                if (_imp->result)
                {
                    if (! _imp->skip_dir)
                        do_dir_recursive(is_check, *d,
                                is_check ? (dst / d->basename()) : canonicalise_root_path(dst / d->basename()));
                    else
                        _imp->skip_dir = false;
                }
                continue;

            case et_misc:
                on_misc(is_check, *d, dst);
                continue;

            case et_nothing:
            case last_et:
                ;
        }

        throw InternalError(PALUDIS_HERE, "Unexpected entry_type '" + stringify(m) + "'");
    }

    on_leave_dir(is_check, src);
}

void
Merger::on_enter_dir(bool, const FSPath)
{
}

void
Merger::on_leave_dir(bool, const FSPath)
{
}

EntryType
Merger::entry_type(const FSPath & f)
{
    Context context("When checking type of '" + stringify(f) + "':");

    FSStat f_stat(f);

    if (! f_stat.exists())
        return et_nothing;

    if (f_stat.is_symlink())
        return et_sym;

    if (f_stat.is_regular_file())
        return et_file;

    if (f_stat.is_directory())
        return et_dir;

    return et_misc;
}

void
Merger::on_file(bool is_check, const FSPath & src, const FSPath & dst)
{
    Context context("When handling file '" + stringify(src) + "' to '" + stringify(dst) + "':");

    if (is_check &&
        0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_file_pre")
                         ("INSTALL_SOURCE", stringify(src))
                         ("INSTALL_DESTINATION", stringify(dst / src.basename()))),
            _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();

    if (! is_check)
    {
        HookResult hr(_imp->params.environment()->perform_hook(extend_hook(
                        Hook("merger_install_file_override")
                        ("INSTALL_SOURCE", stringify(src))
                        ("INSTALL_DESTINATION", stringify(dst / src.basename()))
                        .grab_output(Hook::AllowedOutputValues()("skip"))),
                    _imp->params.maybe_output_manager()));

        if (hr.max_exit_status() != 0)
            Log::get_instance()->message("merger.file.skip_hooks.failure", ll_warning, lc_context) << "Merge of '"
                << stringify(src) << "' to '" << stringify(dst) << "' skip hooks returned non-zero";
        else if (hr.output() == "skip")
        {
            std::string tidy(stringify((dst / src.basename()).strip_leading(_imp->params.root().realpath())));
            display_override("--- [skp] " + tidy);
            return;
        }
    }

    FSStat src_stat(src);
    if (is_check && src_stat.mtim() < _imp->params.fix_mtimes_before())
        src.utime(_imp->params.fix_mtimes_before());

    on_file_main(is_check, FSPath(stringify(src)), dst);

    if (is_check &&
        0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_file_post")
                         ("INSTALL_SOURCE", stringify(src))
                         ("INSTALL_DESTINATION", stringify(dst / src.basename()))),
            _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();
}

void
Merger::on_dir(bool is_check, const FSPath & src, const FSPath & dst)
{
    Context context("When handling dir '" + stringify(src) + "' to '" + stringify(dst) + "':");

    if (is_check &&
        0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_dir_pre")
                         ("INSTALL_SOURCE", stringify(src))
                         ("INSTALL_DESTINATION", stringify(dst / src.basename()))),
            _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();

    if (! is_check)
    {
        HookResult hr(_imp->params.environment()->perform_hook(extend_hook(
                        Hook("merger_install_dir_override")
                        ("INSTALL_SOURCE", stringify(src))
                        ("INSTALL_DESTINATION", stringify(dst / src.basename()))
                        .grab_output(Hook::AllowedOutputValues()("skip"))),
                    _imp->params.maybe_output_manager()));

        if (hr.max_exit_status() != 0)
            Log::get_instance()->message("merger.dir.skip_hooks.failure", ll_warning, lc_context) << "Merge of '"
                << stringify(src) << "' to '" << stringify(dst) << "' skip hooks returned non-zero";
        else if (hr.output() == "skip")
        {
            std::string tidy(stringify((dst / src.basename()).strip_leading(_imp->params.root().realpath())));
            display_override("--- [skp] " + tidy);
            _imp->skip_dir = true;
            return;
        }
    }

    on_dir_main(is_check, src, dst);

    if (is_check &&
        0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_dir_post")
                         ("INSTALL_SOURCE", stringify(src))
                         ("INSTALL_DESTINATION", stringify(dst / src.basename()))),
            _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();
}

void
Merger::on_sym(bool is_check, const FSPath & src, const FSPath & dst)
{
    Context context("When handling sym '" + stringify(src) + "' to '" + stringify(dst) + "':");

    if (is_check &&
        0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_sym_pre")
                         ("INSTALL_SOURCE", stringify(src))
                         ("INSTALL_DESTINATION", stringify(dst / src.basename()))),
            _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();

    if (! is_check)
    {
        HookResult hr(_imp->params.environment()->perform_hook(extend_hook(
                        Hook("merger_install_sym_override")
                        ("INSTALL_SOURCE", stringify(src))
                        ("INSTALL_DESTINATION", stringify(dst / src.basename()))
                        .grab_output(Hook::AllowedOutputValues()("skip"))),
                    _imp->params.maybe_output_manager()));

        if (hr.max_exit_status() != 0)
            Log::get_instance()->message("merger.sym.skip_hooks.failure", ll_warning, lc_context) << "Merge of '"
                << stringify(src) << "' to '" << stringify(dst) << "' skip hooks returned non-zero";
        else if (hr.output() == "skip")
        {
            std::string tidy(stringify((dst / src.basename()).strip_leading(_imp->params.root().realpath())));
            display_override("--- [skp] " + tidy);
            return;
        }

    }

    if (symlink_needs_rewriting(src))
    {
        if (! _imp->params.options()[mo_rewrite_symlinks])
            on_error(is_check, "Symlink to image detected at: " + stringify(src) + " (" + src.readlink() + ")");
        else if (is_check)
            rewrite_symlink_as_needed(src, dst);
    }

    on_sym_main(is_check, FSPath(stringify(src)), dst);

    if (is_check &&
        0 != _imp->params.environment()->perform_hook(extend_hook(
                         Hook("merger_check_sym_post")
                         ("INSTALL_SOURCE", stringify(src))
                         ("INSTALL_DESTINATION", stringify(dst / src.basename()))),
            _imp->params.maybe_output_manager()).max_exit_status())
        make_check_fail();
}

void
Merger::on_misc(bool is_check, const FSPath & src, const FSPath & dst)
{
    Context context("When handling misc '" + stringify(src) + "' to '" + stringify(dst) + "':");

    on_error(is_check, "Cannot write '" + stringify(src) + "' to '" + stringify(dst) +
            "' because it is not a recognised file type");
}

bool
Merger::symlink_needs_rewriting(const FSPath & sym)
{
    std::string target(sym.readlink());
    std::string real_image(stringify(_imp->params.image().realpath()));

    return (0 == target.compare(0, real_image.length(), real_image));
}

void
Merger::set_skipped_dir(const bool value)
{
    _imp->skip_dir = value;
}

void
Merger::do_ownership_fixes_recursive(const FSPath & dir)
{
    for (FSIterator d(dir, { fsio_include_dotfiles, fsio_inode_sort }), d_end ; d != d_end ; ++d)
    {
        std::pair<uid_t, gid_t> new_ids(_imp->params.get_new_ids_or_minus_one()(*d));
        if (uid_t(-1) != new_ids.first || gid_t(-1) != new_ids.second)
        {
            FSPath f(*d);
            FSStat f_stat(f);
            f.lchown(new_ids.first, new_ids.second);

            if (et_sym != entry_type(*d))
            {
                mode_t mode(f_stat.permissions());

                if (et_dir == entry_type(*d))
                {
                    if (uid_t(-1) != new_ids.first)
                        mode &= ~S_ISUID;
                    if (gid_t(-1) != new_ids.second)
                        mode &= ~S_ISGID;
                }

                f.chmod(mode); /* set*id */
            }

            _imp->fixed_entries.insert(f);
        }

        EntryType m(entry_type(*d));
        switch (m)
        {
            case et_sym:
            case et_file:
                continue;

            case et_dir:
                do_ownership_fixes_recursive(*d);
                continue;

            case et_misc:
                throw MergerError("Unexpected 'et_misc' entry found at: " + stringify(*d));
                continue;

            case et_nothing:
            case last_et:
                ;
        }

        throw InternalError(PALUDIS_HERE, "Unexpected entry_type '" + stringify(m) + "'");
    }
}

bool
Merger::fixed_ownership_for(const FSPath & f)
{
    return _imp->fixed_entries.end() != _imp->fixed_entries.find(f);
}

void
Merger::on_done_merge()
{
}

void
Merger::rewrite_symlink_as_needed(const FSPath & src, const FSPath & dst_dir)
{
    if (! symlink_needs_rewriting(src))
        return;

    FSCreateCon createcon(MatchPathCon::get_instance()->match(stringify(dst_dir / src.basename()), S_IFLNK));

    FSPath real_image(_imp->params.image().realpath());
    FSPath dst(src.readlink());
    std::string fixed_dst(stringify(dst.strip_leading(real_image)));

    Log::get_instance()->message("merger.rewriting_symlink", ll_qa, lc_context) << "Rewriting bad symlink: "
            << src << " -> " << dst << " to " << fixed_dst;

    FSPath s(src);
    s.unlink();
    s.symlink(fixed_dst);
}