#!/usr/bin/env lua
-- openwisp-config configuration updater

local os = require('os')
local lfs = require('lfs')
local uci = require('uci')
local utils = require('openwisp.utils')
local arg = {...}

-- parse arguments
local MERGE = true
local TEST = false
local conf = nil

for _, value in pairs(arg) do
    if utils.starts_with(value, '--conf=') then
        conf = string.sub(value, 8)
    end
    if value == '--merge=0' then MERGE = false; end
    -- test argument
    if value == '--test=1' then TEST = true; end
end

local working_dir = lfs.currentdir()
local tmp_dir = not TEST and '/tmp/openwisp' or working_dir
local check_dir = tmp_dir .. '/check'
local check_config_dir = check_dir..'/etc/config'
local downloaded_conf = conf or (tmp_dir .. '/configuration.tar.gz')
local openwisp_dir = not TEST and '/etc/openwisp' or working_dir .. '/openwisp'
local standard_config_dir = not TEST and '/etc/config' or working_dir .. '/update-test/etc/config'
local test_root_dir = working_dir .. '/update-test'
local remote_dir = openwisp_dir .. '/remote'
local remote_config_dir = remote_dir .. '/etc/config'
local stored_dir = openwisp_dir .. '/stored'
local added_file = openwisp_dir .. '/added.list'
local modified_file = openwisp_dir .. '/modified.list'
local get_standard = function() return uci.cursor(standard_config_dir) end
local get_remote = function() return uci.cursor(remote_config_dir, '/tmp/openwisp/.uci') end
local get_check = function() return uci.cursor(check_config_dir, '/tmp/openwisp/.uci') end

-- uci cursors
local standard = get_standard()
local remote = get_remote()

-- check downloaded UCI files before proceeding
os.execute('mkdir -p '..check_dir)
os.execute('tar -zxf '..downloaded_conf..' -C '..check_dir)
local check = get_check()

if lfs.attributes(check_config_dir, 'mode') == 'directory' then
    for file in lfs.dir(check_config_dir) do
        local path = check_config_dir..'/'..file
        if lfs.attributes(path, 'mode') == 'file' then
            if check:get_all(file) == nil then
                print('ERROR: invalid UCI configuration file: '..file)
                os.execute('rm -rf '..check_dir)
                if TEST then
                  return
                else
                  os.exit(2)
                end
            end
        end
    end
end

-- update UCI configuration
-- (overwrite or merge)

-- remove config items added via openwisp-config
if lfs.attributes(remote_config_dir, 'mode') == 'directory' then
    for file in lfs.dir(remote_config_dir) do
        local standard_path = standard_config_dir .. '/' .. file
        if lfs.attributes(standard_path, 'mode') == 'file' then
            for _, section in pairs(remote:get_all(file)) do
                -- search section in the downloaded configuration
                local section_check = check:get(file, section['.name'])
                -- remove section from current configuration if not in downloaded configuration
                if section_check == nil then
                    utils.remove_uci_options(standard, file, section)
                else
                    -- compare each option in current and downloaded configuration
                    for option, value in pairs(section) do
                        if not utils.starts_with_dot(option) then
                            -- remove option from current configuration if not in downloaded configuration
                            if check:get(file, section['.name'], option) == nil then
                                standard:delete(file, section['.name'], option)
                            end
                        end
                    end
                    -- remove entire section if empty
                    local result = standard:get_all(file, section['.name'])
                    if result and utils.is_uci_empty(result) then
                        standard:delete(file, section['.name'])
                    end
                end
            end
            standard:commit(file)
            -- remove uci file if empty
            local uci_file = standard:get_all(file)
            if uci_file and utils.is_table_empty(uci_file) then
                os.remove(standard_path)
            end
        end
    end
end
os.execute('rm -rf '..check_dir)

-- persist remote config in /etc/openwisp/remote
os.execute('rm -rf '..remote_dir)
os.execute('mkdir -p '..remote_dir)
os.execute('tar -zxf '..downloaded_conf..' -C '..remote_dir)
-- reload uci cursors
standard = get_standard()
remote = get_remote()

if lfs.attributes(remote_config_dir, 'mode') == 'directory' then
    -- loop over each file in new remote uci config
    for file in lfs.dir(remote_config_dir) do
        local standard_path = standard_config_dir .. '/' .. file
        local remote_path = remote_config_dir .. '/' .. file
        -- ensure we are acting on a file
        if lfs.attributes(remote_path, 'mode') == 'file' then
            -- MERGE mode
            if MERGE then
                -- avoid "file does not exist" error
                os.execute('touch ' .. standard_path)
                for _, section in pairs(remote:get_all(file)) do
                    utils.write_uci_section(standard, file, section)
                end
                standard:commit(file)
            -- OVERWRITE mode
            else
                os.execute('cp '..remote_config_dir..'/* '..standard_config_dir)
            end
        end
    end
end

-- ensure list files exist
os.execute('touch ' .. added_file)
os.execute('touch ' .. modified_file)
-- convert lists to lua sets
local added = utils.file_to_set(added_file)
local modified = utils.file_to_set(modified_file)
local added_changed = false
local modified_changed = false

-- loop each file except directories and standard UCI config files
local ignored_path = remote_config_dir .. '/'
local function is_ignored(path)
    return utils.starts_with(path, ignored_path)
end

for path, attr in utils.dirtree(remote_dir) do
    if attr.mode == 'file' and not is_ignored(path) then
        -- calculates destination dir
        local dest_path = path:sub(#(remote_dir .. '/'))
        local dest_dir = utils.dirname(dest_path)
        -- like dest_path but used during automated tests
        local check_path = not TEST and dest_path or test_root_dir .. dest_path
        local is_added = added[dest_path] == true
        local is_modified = modified[dest_path] == true
        -- if file is neither in added.list nor modified.list
        if is_added == false and is_modified == false then
            -- if file exists
            if utils.file_exists(check_path) then
                -- add file path to modified set
                modified[dest_path] = true
                modified_changed = true
                -- store original in /etc/openwisp/stored/<path>
                os.execute('mkdir -p '..stored_dir..dest_dir)
                os.execute('cp '..check_path..' '..stored_dir..dest_path)
            else
                -- add file path added set
                added[dest_path] = true
                added_changed = true
            end
        end
        if TEST then
          dest_path = test_root_dir .. dest_path
          dest_dir = test_root_dir .. dest_dir
        end
        -- add file to filesystem
        os.execute('mkdir -p '..dest_dir)
        os.execute('cp '..path..' '..dest_path)
    end
end

-- remove files that have been added via openwisp
-- which are not present anymore
for file, bool in pairs(added) do
    local remote_path = remote_dir .. file
    local dest_path = not TEST and file or test_root_dir .. file
    -- if file is not in /etc/openwisp/remote anymore
    if not utils.file_exists(remote_path) then
        -- remove file
        os.remove(dest_path)
        -- remove entry from added set
        added[file] = nil
        added_changed = true
    end
end

-- restore pre-existing files that were changed via openwisp
-- which are not present anymore
for file, bool in pairs(modified) do
    local remote_path = remote_dir .. file
    local stored_path = stored_dir .. file
    local dest_path = not TEST and file or test_root_dir .. file
    -- if file is not in /etc/openwisp/remote anymore
    if not utils.file_exists(remote_path) then
        -- restore original file
        os.execute('mv '..stored_path..' '..dest_path)
        -- remove stored dir if empty
        lfs.rmdir(utils.dirname(stored_path))
        -- remove entry from modified set
        modified[file] = nil
        modified_changed = true
    end
end

-- persist changes to file lists
if added_changed then utils.set_to_file(added, added_file) end
if modified_changed then utils.set_to_file(modified, modified_file) end