-----------------------------------------------------------------------------
-- modified by Michael Palmer from:

-- JSONRPC4Lua: JSON RPC client calls over http for the Lua language.
-- json.rpc Module.
-- Author: Craig Mason-Jones
-- Homepage: http://json.luaforge.net/
-- Version: 0.9.40
-- This module is released under the MIT License (MIT).
--
-- REQUIREMENTS:
--    Lua socket 2.0 (http://www.cs.princeton.edu/~diego/professional/luasocket/)
--    mol2chemfig_dkjson.lua
--    compat-5.1 if using Lua 5.0.
-----------------------------------------------------------------------------

-----------------------------------------------------------------------------
-- Imports and dependencies
-----------------------------------------------------------------------------
local json = require("mol2chemfig_dkjson")
local http = require("socket.http")
local assert = assert
local require = require
local string = string
local table = table
local setmetatable = setmetatable
local unpack = unpack

local base = _G

module("mol2chemfig_jsonrpc")


-----------------------------------------------------------------------------
-- PUBLIC functions
-----------------------------------------------------------------------------

function proxy(url)
    local serverProxy = {}
    local proxyMeta = {
        __index = function(t, key)
            return function(...)
                return call(url, key, unpack(arg))
            end
        end
    }
    setmetatable(serverProxy, proxyMeta)
    return serverProxy
end


function call(url, method, ...)
    assert(method,'method param is nil to call')
    local JSONRequestArray = {
        id = "httpRequest",
        method = method,
        params = arg
    }
    local httpResponse, result, code
    local jsonRequest = json.encode(JSONRequestArray)
    local ltn12 = require('ltn12')
    local resultChunks = {}
    httpResponse, code = http.request(
        {   url = url,
            sink = ltn12.sink.table(resultChunks),
            method = 'POST',
            headers = {
                ['content-type']='text/plain',
                ['content-length']=string.len(jsonRequest)
            },
            source = ltn12.source.string(jsonRequest)
        }
    )
    httpResponse = table.concat(resultChunks)
    -- Check the http response code
    if (code~=200) then
        return nil, "HTTP ERROR: " .. code
    end
    -- And decode the httpResponse and check the JSON RPC result code
    result = json.decode( httpResponse )
    if result.result then
        return result.result, nil
    else
        return nil, result.error
    end
end