-- tree view of the file system like the "tree" unix utility

-- John Belmonte <jvb@prairienet.org>

local posix = require 'posix'

local leaf_indent = '|   '

local tail_leaf_indent = '    '

local leaf_prefix = '|-- '

local tail_leaf_prefix = '`-- '

local link_prefix = ' -> '

local function printf(...)

  io.write(string.format(...))

end

local function do_directory(directory, level, prefix)

    local num_dirs = 0

    local num_files = 0

    local files = posix.dir(directory)

    local last_file_index = #files

    table.sort(files)

    for i, name in ipairs(files) do

        if name ~= '.' and name ~= '..' then

            local full_name = string.format('%s/%s', directory, name)

            local info = assert(posix.stat(full_name))

            local is_tail = (i==last_file_index)

            local prefix2 = is_tail and tail_leaf_prefix or leaf_prefix

            local link = ''

            if info.type == 'link' then

                linked_name = assert(posix.readlink(full_name))

                link = string.format('%s%s', link_prefix, linked_name)

            end

            printf('%s%s%s%s\n', prefix, prefix2, name, link)

            if info.type == 'directory' then

                local indent = is_tail and tail_leaf_indent or leaf_indent

                -- TODO: cache string concatination

                sub_dirs, sub_files = do_directory(full_name, level+1,

                    prefix .. indent)

                num_dirs = num_dirs + sub_dirs + 1

                num_files = num_files + sub_files

            else

                num_files = num_files + 1

            end

        end

    end

    return num_dirs, num_files

end

local function fore(directory)

    print(directory)

    num_dirs, num_files = do_directory(directory, 0, '')

    printf('\n%d directories, %d files\n', num_dirs, num_files)

end

directory = (arg and #arg > 0) and arg[1] or '.'

fore(directory)