#include "buffer_utils.hh"

#include "buffer_manager.hh"
#include "coord.hh"
#include "event_manager.hh"
#include "file.hh"
#include "selection.hh"
#include "changes.hh"

#include <unistd.h>

#if defined(__APPLE__)
#define st_mtim st_mtimespec
#endif


namespace Kakoune
{

void replace(Buffer& buffer, ArrayView<BufferRange> ranges, ConstArrayView<String> strings)
{
    ForwardChangesTracker changes_tracker;
    size_t timestamp  = buffer.timestamp();
    for (size_t index = 0; index < ranges.size(); ++index)
    {
        auto& range = ranges[index];
        range.begin = changes_tracker.get_new_coord_tolerant(range.begin);
        range.end = changes_tracker.get_new_coord_tolerant(range.end);
        kak_assert(buffer.is_valid(range.begin) and buffer.is_valid(range.end));

        range = buffer.replace(range.begin, range.end, strings.empty() ? StringView{} : strings[std::min(index, strings.size()-1)]);
        kak_assert(buffer.is_valid(range.begin) and buffer.is_valid(range.end));
        changes_tracker.update(buffer, timestamp);
    }

    buffer.check_invariant();
}

ColumnCount get_column(const Buffer& buffer,
                       ColumnCount tabstop, BufferCoord coord)
{
    auto line = buffer[coord.line];
    auto col = 0_col;
    for (auto it = line.begin();
         it != line.end() and coord.column > (int)(it - line.begin()); )
    {
        if (*it == '\t')
        {
            col = (col / tabstop + 1) * tabstop;
            ++it;
        }
        else
            col += codepoint_width(utf8::read_codepoint(it, line.end()));
    }
    return col;
}

ColumnCount column_length(const Buffer& buffer, ColumnCount tabstop, LineCount line)
{
    return get_column(buffer, tabstop, BufferCoord{line, ByteCount{INT_MAX}});
}

ByteCount get_byte_to_column(const Buffer& buffer, ColumnCount tabstop, DisplayCoord coord)
{
    auto line = buffer[coord.line];
    auto col = 0_col;
    auto it = line.begin();
    while (it != line.end() and coord.column > col)
    {
        if (*it == '\t')
        {
            col = (col / tabstop + 1) * tabstop;
            if (col > coord.column) // the target column was in the tab
                break;
            ++it;
        }
        else
        {
            auto next = it;
            col += codepoint_width(utf8::read_codepoint(next, line.end()));
            if (col > coord.column) // the target column was in the char
                break;
            it = next;
        }
    }
    return (int)(it - line.begin());
}

static BufferLines parse_lines(const char* pos, const char* end, EolFormat eolformat)
{
    BufferLines lines;
    while (pos < end)
    {
        if (lines.size() >= std::numeric_limits<int>::max())
            throw runtime_error("too many lines");

        const char* eol = std::find(pos, end, '\n');
        if ((eol - pos) >= std::numeric_limits<int>::max())
            throw runtime_error("line is too long");

        lines.emplace_back(StringData::create(StringView{pos, eol - (eolformat == EolFormat::Crlf and eol != end ? 1 : 0)}, "\n"));
        pos = eol + 1;
    }

    if (lines.empty())
        lines.emplace_back(StringData::create("\n"));

    return lines;
}

Buffer* create_buffer_from_string(String name, Buffer::Flags flags, StringView data)
{
    return BufferManager::instance().create_buffer(
        std::move(name), flags,
        parse_lines(data.begin(), data.end(), EolFormat::Lf),
        ByteOrderMark::None, EolFormat::Lf,
        FsStatus{InvalidTime, {}, {}});
}

template<typename Func>
decltype(auto) parse_file(StringView filename, Func&& func)
{
    MappedFile file{parse_filename(filename)};

    const char* pos = file.data;
    const char* end = pos + file.st.st_size;

    auto bom = ByteOrderMark::None;
    if (file.st.st_size >= 3 && StringView{pos, 3_byte} == "\xEF\xBB\xBF")
    {
        bom = ByteOrderMark::Utf8;
        pos += 3;
    }

    bool has_crlf = false, has_lf = false;
    for (auto it = std::find(pos, end, '\n'); it != end; it = std::find(it+1, end, '\n'))
        ((it != pos and *(it-1) == '\r') ? has_crlf : has_lf) = true;
    auto eolformat = (has_crlf and not has_lf) ? EolFormat::Crlf : EolFormat::Lf;

    FsStatus fs_status{file.st.st_mtim, file.st.st_size, murmur3(file.data, file.st.st_size)};
    return func(parse_lines(pos, end, eolformat), bom, eolformat, fs_status);
}

Buffer* open_file_buffer(StringView filename, Buffer::Flags flags)
{
    return parse_file(filename, [&](BufferLines&& lines, ByteOrderMark bom, EolFormat eolformat, FsStatus fs_status)  {
        return BufferManager::instance().create_buffer(filename.str(), Buffer::Flags::File | flags,
                                                       std::move(lines), bom, eolformat, fs_status);
    });
}

Buffer* open_or_create_file_buffer(StringView filename, Buffer::Flags flags)
{
    auto path = parse_filename(filename);
    if (file_exists(path))
        return open_file_buffer(filename.str(), Buffer::Flags::File | flags);
    return create_buffer_from_string(filename.str(), Buffer::Flags::File | Buffer::Flags::New, StringView{});
}

void reload_file_buffer(Buffer& buffer)
{
    kak_assert(buffer.flags() & Buffer::Flags::File);
    parse_file(buffer.name(), [&](auto&&... params) {
        buffer.reload(std::forward<decltype(params)>(params)...);
    });
    buffer.flags() &= ~Buffer::Flags::New;
}

void write_buffer_to_fd(Buffer& buffer, int fd)
{
    auto eolformat = buffer.options()["eolformat"].get<EolFormat>();
    StringView eoldata;
    if (eolformat == EolFormat::Crlf)
        eoldata = "\r\n";
    else
        eoldata = "\n";


    BufferedWriter<false> writer{fd};
    if (buffer.options()["BOM"].get<ByteOrderMark>() == ByteOrderMark::Utf8)
        writer.write("\xEF\xBB\xBF");

    for (LineCount i = 0; i < buffer.line_count(); ++i)
    {
        // end of lines are written according to eolformat but always
        // stored as \n
        StringView linedata = buffer[i];
        writer.write(linedata.substr(0, linedata.length()-1));
        writer.write(eoldata);
    }
}

void write_buffer_to_file(Buffer& buffer, StringView filename,
                          WriteMethod method, WriteFlags flags)
{
    auto zfilename = filename.zstr();
    struct stat st;

    bool replace = method == WriteMethod::Replace;
    bool force = flags & WriteFlags::Force;

    if ((replace or force) and (::stat(zfilename, &st) != 0 or
                                (st.st_mode & S_IFMT) != S_IFREG))
    {
        force = false;
        replace = false;
    }

    if (force and ::chmod(zfilename, st.st_mode | S_IWUSR) < 0)
        throw runtime_error(format("unable to change file permissions: {}", strerror(errno)));

    char temp_filename[PATH_MAX];
    const int fd = replace ? open_temp_file(filename, temp_filename)
                           : create_file(zfilename);
    if (fd == -1)
    {
        auto saved_errno = errno;
        if (force)
            ::chmod(zfilename, st.st_mode);
        throw file_access_error(filename, strerror(saved_errno));
    }

    {
        auto close_fd = OnScopeEnd([fd]{ close(fd); });
        write_buffer_to_fd(buffer, fd);
        if (flags & WriteFlags::Sync)
            ::fsync(fd);
    }

    if (replace and geteuid() == 0 and ::chown(temp_filename, st.st_uid, st.st_gid) < 0)
        throw runtime_error(format("unable to set replacement file ownership: {}", strerror(errno)));
    if (replace and ::chmod(temp_filename, st.st_mode) < 0)
        throw runtime_error(format("unable to set replacement file permissions: {}", strerror(errno)));
    if (force and not replace and ::chmod(zfilename, st.st_mode) < 0)
        throw runtime_error(format("unable to restore file permissions: {}", strerror(errno)));

    if (replace and rename(temp_filename, zfilename) != 0)
    {
        if (force)
            ::chmod(zfilename, st.st_mode);
        throw runtime_error("replacing file failed");
    }

    if ((buffer.flags() & Buffer::Flags::File) and
        real_path(filename) == real_path(buffer.name()))
        buffer.notify_saved(get_fs_status(real_path(filename)));
}

void write_buffer_to_backup_file(Buffer& buffer)
{
    const int fd = open_temp_file(buffer.name());
    if (fd >= 0)
    {
        write_buffer_to_fd(buffer, fd);
        close(fd);
    }
}

Buffer* create_fifo_buffer(String name, int fd, Buffer::Flags flags, AutoScroll scroll)
{
    static ValueId fifo_watcher_id = get_free_value_id();

    auto& buffer_manager = BufferManager::instance();
    Buffer* buffer = buffer_manager.get_buffer_ifp(name);
    if (buffer)
    {
        buffer->flags() |= Buffer::Flags::NoUndo | flags;
        buffer->values().clear();
        buffer->reload({StringData::create("\n")}, ByteOrderMark::None, EolFormat::Lf, {InvalidTime, {}, {}});
        buffer_manager.make_latest(*buffer);
    }
    else
        buffer = buffer_manager.create_buffer(
            std::move(name), flags | Buffer::Flags::Fifo | Buffer::Flags::NoUndo,
            {StringData::create("\n")}, ByteOrderMark::None, EolFormat::Lf, {InvalidTime, {}, {}});

    struct FifoWatcher : FDWatcher
    {
        FifoWatcher(int fd, Buffer& buffer, AutoScroll scroll)
            : FDWatcher(fd, FdEvents::Read, EventMode::Normal,
                        [](FDWatcher& watcher, FdEvents, EventMode mode) {
                            if (mode == EventMode::Normal)
                                static_cast<FifoWatcher&>(watcher).read_fifo();
                        }),
              m_buffer(buffer), m_scroll(scroll)
        {}

        ~FifoWatcher()
        {
            kak_assert(m_buffer.flags() & Buffer::Flags::Fifo);
            close_fd();
            m_buffer.run_hook_in_own_context(Hook::BufCloseFifo, "");
            if (not m_buffer.values().contains(fifo_watcher_id))
                m_buffer.flags() &= ~(Buffer::Flags::Fifo | Buffer::Flags::NoUndo);
        }

        void read_fifo()
        {
            kak_assert(m_buffer.flags() & Buffer::Flags::Fifo);

            constexpr size_t buffer_size = 2048;
            // if we read data slower than it arrives in the fifo, limiting the
            // iteration number allows us to go back go back to the event loop and
            // handle other events sources (such as input)
            constexpr size_t max_loop = 1024;
            bool closed = false;
            size_t loop = 0;
            char data[buffer_size];
            Optional<BufferCoord> insert_begin;
            const int fifo = fd();

            {
                auto restore_flags = OnScopeEnd([this, flags=m_buffer.flags()] { m_buffer.flags() = flags; });
                m_buffer.flags() &= ~Buffer::Flags::ReadOnly;
                do
                {

                    const ssize_t count = ::read(fifo, data, buffer_size);
                    if (count <= 0)
                    {
                        closed = true;
                        break;
                    }

                    auto pos = m_buffer.back_coord();
                    const bool is_first = pos == BufferCoord{0,0};
                    if ((m_scroll == AutoScroll::No and (is_first or m_had_trailing_newline))
                        or (m_scroll == AutoScroll::NotInitially and is_first))
                        pos = m_buffer.next(pos);

                    auto inserted_range = m_buffer.insert(pos, StringView(data, data+count));
                    if (not insert_begin)
                        insert_begin = inserted_range.begin;
                    pos = inserted_range.end;

                    bool have_trailing_newline = (data[count-1] == '\n');
                    if (m_scroll != AutoScroll::Yes)
                    {
                        if (is_first)
                        {
                            m_buffer.erase({0,0}, m_buffer.next({0,0}));
                            --insert_begin->line;
                            if (m_scroll == AutoScroll::NotInitially and have_trailing_newline)
                                m_buffer.insert(m_buffer.end_coord(), "\n");
                        }
                        else if (m_scroll == AutoScroll::No and
                                 not m_had_trailing_newline and have_trailing_newline)
                            m_buffer.erase(m_buffer.prev(pos), pos);
                    }
                    m_had_trailing_newline = have_trailing_newline;
                }
                while (++loop < max_loop  and fd_readable(fifo));
            }

            if (insert_begin)
            {
                auto insert_back = (m_had_trailing_newline and m_scroll == AutoScroll::No)
                                 ? m_buffer.back_coord() : m_buffer.prev(m_buffer.back_coord());
                m_buffer.run_hook_in_own_context(
                    Hook::BufReadFifo,
                    selection_to_string(ColumnType::Byte, m_buffer, {*insert_begin, insert_back}));
            }

            if (closed)
                m_buffer.values().erase(fifo_watcher_id); // will delete this
        }

        Buffer& m_buffer;
        AutoScroll m_scroll;
        bool m_had_trailing_newline = false;
    };

    buffer->values()[fifo_watcher_id] = Value(Meta::Type<FifoWatcher>{}, fd, *buffer, scroll);
    buffer->flags() = flags | Buffer::Flags::Fifo | Buffer::Flags::NoUndo;
    buffer->run_hook_in_own_context(Hook::BufOpenFifo, buffer->name());

    return buffer;
}

auto to_string(Buffer::HistoryId id)
{
    using Result = decltype(to_string(size_t{}));
    if (id == Buffer::HistoryId::Invalid)
        return Result{1, "-"};
    return to_string(static_cast<size_t>(id));
}

static String modification_as_string(const Buffer::Modification& modification)
{
    return format("{}{}.{}|{}",
                  modification.type == Buffer::Modification::Type::Insert ? '+' : '-',
                  modification.coord.line, modification.coord.column,
                  modification.content->strview());
}

Vector<String> history_as_strings(ConstArrayView<Buffer::HistoryNode> history)
{
    Vector<String> res;
    for (auto& node : history)
    {
        auto seconds = std::chrono::duration_cast<std::chrono::seconds>(node.committed.time_since_epoch());
        res.push_back(to_string(node.parent));
        res.push_back(to_string(seconds.count()));
        res.push_back(to_string(node.redo_child));
        for (auto& modification : node.undo_group)
            res.push_back(modification_as_string(modification));
    };
    return res;
}

Vector<String> undo_group_as_strings(const Buffer::UndoGroup& undo_group)
{
    Vector<String> res;
    for (auto& modification : undo_group)
        res.push_back(modification_as_string(modification));
    return res;
}

String generate_buffer_name(StringView pattern)
{
    auto& buffer_manager = BufferManager::instance();
    for (int i = 0; true; ++i)
    {
        String name = format(pattern, i);
        if (buffer_manager.get_buffer_ifp(name) == nullptr)
            return name;
    }
}

}