-- Require lua modules
local upload    = require "resty/upload"
local uuid      = require "resty.jit-uuid"
local redis     = require "resty.redis"
local cjson     = require "cjson"
---------------------------------------------------------------------------------------

-- Functions : String split
string.split = function(s, p)
    local rt= {}
    string.gsub(s, '[^'..p..']+', function(w) table.insert(rt, w) end )
    return rt
end

-- Functions : Get file trim
string.trim = function(s)
    return (s:gsub("^%s*(.-)%s*$", "%1"))
end
---------------------------------------------------------------------------------------

-- Init
---- Upload init
local chunk_size = 5 -- should be set to 4096 or 8192
-- for real-world settings

local form, error = upload:new(chunk_size)

if not form then
    ngx.log(ngx.ERR, "Fail to create new form: ", error)
    ngx.exit(500)
end

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

---- Redis init
------ Connect to redis
local redis_task_database = redis:new()

redis_task_database:set_timeouts(1000, 1000, 1000)

local ok, error = redis_task_database:connect("127.0.0.1", 6379)
if not ok then
    ngx.log(ngx.ERR, "Fail to connect redis: ", error)
    ngx.exit(500)
end
---------------------------------------------------------------------------------------

-- Save upload images
---- Upload file save path config in nginx.conf
local save_upload_file_path = ngx.var.store_dir
local file_to_save
local ret_save = false
local upload_image_filename
local save_image_filename
local upload_image_table = {}
local data_table = {}
local upload_image_index = 1

form:set_timeout(1000) -- 1 sec

---- Read image file from http packet and save it
while true do

    local http_type, result, error = form:read()

    if not http_type then
        ngx.log(ngx.ERR, "Failed to read form: ", error)
        ngx.exit(500)
    end

    if http_type == "header" then
        -- Start to read http header

        local key   = result[1]
        local value = result[2]

        if key == "Content-Disposition" then

            -- Analyze this time upload image filename , use ; as interval
            -- Like: form-data; name="testFileName"; filename="testfile.txt"
            local key_value_list = string.split(value, ';')

            for _, key_value in ipairs(key_value_list) do

                local segment = string.trim(key_value)

                if segment:find("filename") then

                    local key_value_file    = string.split(segment, "=")
                    upload_image_filename   = string.sub(key_value_file[2], 2, -2)

                    ngx.log(ngx.INFO, "Upload origin filename: ", upload_image_filename)

                    -- Save upload file
                    if upload_image_filename then
                        -- Save file name with generate uuid
                        save_image_filename = uuid:generate_v4() -- Generate save filename uuid
                        save_image_filename = save_image_filename .. '.' .. upload_image_filename:match(".+%.(%w+)$")
                        file_to_save = io.open(save_upload_file_path .. save_image_filename, "w+")

                        if not file_to_save then
                            ngx.log(ngx.ERR , "Fail open file: ", save_image_filename)
                            ngx.exit(500)
                        else
                            ngx.log(ngx.INFO, "Success open file: ", save_image_filename)

                            -- Save all upload files as a table
                            data_table[upload_image_index] = save_image_filename
                            upload_image_table[upload_image_index] = save_upload_file_path .. save_image_filename .. " "
                            ngx.log(ngx.INFO, "Insert upload image table "..upload_image_index.." with "..upload_image_table[upload_image_index])

                            upload_image_index = upload_image_index + 1
                        end
                        break
                    end
                end
            end
        end

    elseif http_type == "body" then

        -- Start to read http body
        if file_to_save then
            file_to_save:write(result)
        end

    elseif http_type == "part_end" then

        -- Write to save file finish
        if file_to_save then
            file_to_save:close()
            file_to_save = nil
        end

        ret_save = true

    elseif http_type == "eof" then
        -- Read file end
        break
    else
        ngx.log(ngx.INFO, "Maybe do other things")
    end
end
---------------------------------------------------------------------------------------

-- Show all input and may output files
if ret_save then
    ngx.log(ngx.INFO, "Show all upload save files\n")

    ---- Show all upload save files
    upload_image_index = upload_image_index -1
    for i = 1, upload_image_index do
        ngx.log(ngx.INFO, "Save upload file is : " .. upload_image_table[i])
    end
    ---------------------------------------------------------------------------------------

    -- Communicate with front end
    ---- Generate task uuid
    local task_uuid = uuid.generate_v4();
    ---------------------------------------------------------------------------------------

    -- Construct {key: task_id | value: [images] } in json
    -- Example:
    -- {"task_id":"488a8e6c556a-4271-adec--071e843c9856","data:"[\"2109aac0-556a-4271-adec-9eac494f622f.jpg\",\"488a8e6c-01e6-4cb3-af88-a1d90e04e6b8.jpg\",\"c3f76317-592f-4117-ab0d-071e843c9856.jpg\"]"}
    local task_table = {}
    task_table["task_id"] = task_uuid
    task_table["data"] = data_table

    local task_jason = cjson.encode(task_table)
    ngx.log(ngx.INFO , task_jason) -- Response to front end
    ---------------------------------------------------------------------------------------

    -- Redis control
    ---- Set json to redis
    ok, error = redis_task_database:set(task_uuid, task_jason)
    if not ok then
        ngx.log(ngx.ERR , "Failed to set task json: ", error)
        ngx.exit(500)
    end
    ngx.log(ngx.INFO , "Set redis task json result: ", ok)

    ---- Get data from redis
    local result, error = redis_task_database:get(task_uuid)
    if not result then
        ngx.log(ngx.ERR , "Failed to get task json: ", error)
        ngx.exit(500)
    end

    if result == ngx.null then
        ngx.log(ngx.ERR , "Not found task id")
        ngx.exit(500)
    end

    ngx.log(ngx.INFO, "Get redis task id: " .. task_uuid .. " | value :" .. result)
    ---------------------------------------------------------------------------------------

    -- Create task
    local result = ngx.location.capture(
            '/mock_task_server',
            {
                method = ngx.HTTP_POST,
                body = ngx.encode_args({task = task_jason})
            }
    )
    ngx.say(result.body)

    -- Response task ID to front end
    ngx.say(task_uuid)

    -- Mock a image append request from task from task server
    local result = ngx.location.capture(
            '/image_append',
            {
                method = ngx.HTTP_POST,
                body = ngx.encode_args({task = task_jason})
            }
    )
    ngx.say(result.body)


end