local uuid      = require "resty.jit-uuid"
local cjson     = require "cjson"

local json_string = nil

---- Automatic seeding with os.time(), LuaSocket, or ngx.time()
uuid.seed()
uuid()

-- Get post json argv
local arg = ngx.req.get_post_args()
for k,v in pairs(arg) do
    ngx.log(ngx.INFO , "Image append [POST] key:", k .." | ".." v:", v)
    json_string = v
end

-- Decode json string
local json = cjson.decode(json_string)
ngx.say("Image append input filename number is :" , table.getn(json.data))
local image_append_input_files_number = table.getn(json.data)
for i = 1, image_append_input_files_number do
    ngx.log(ngx.INFO , "Image append input filename is :" , json.data[i])
end

-- Image append
---- Upload file save path config in nginx.conf
local save_upload_file_path = ngx.var.store_dir
local append_image_table = {}
local output_image_uuid = uuid.generate_v4();

-- Add path to input image filename
for i = 1, image_append_input_files_number do
    append_image_table[i] = save_upload_file_path .. json.data[i] .. " "
    ngx.log(ngx.INFO, "Insert append image table "..i.." with "..append_image_table[i])
end

-- Concat input image to a command string
local append_input_images = table.concat(append_image_table)
ngx.log(ngx.INFO , "Input images list  : " , append_input_images)

-- Add path to output image filename
local append_output_image = save_upload_file_path .. output_image_uuid..".jpg ";
ngx.log(ngx.INFO , "Output image is : "..append_output_image)

-- Debug
ngx.log(ngx.INFO , '/usr/local/ImageMagick/bin/magick convert -append '..append_input_images..' '..append_output_image)

local call_imagemagick_cmd = io.popen('/usr/local/ImageMagick/bin/magick convert -append '..append_input_images..' '..append_output_image)
local imagemagick_cmd_replay = call_imagemagick_cmd:read("*all")
ngx.log(ngx.INFO , imagemagick_cmd_replay)