/lib/downloader.lua

local fs = require("filesystem")
local internet = require("internet")
local serialization = require("serialization")

local function GetPastebinID(url_or_id)
    local id = url_or_id:match("https://pastebin%.com/(.+)")
    if not id then
        id = url_or_id:match("https://pastebin%.com/raw/(.+)")
    end

    return id
end

local function HttpFetch(url)
    local handle, response = internet.request(url, nil, {
        ["User-Agent"] = "OpenComputers"
    }), ""

    for chunk in handle do
        response = response .. chunk
    end

    return response
end

local function GetGithubBlob(user, repo, branch, path)
    return string.format("https://github.com/%s/%s/blob/%s/%s", user, repo, branch, path)
end

local download = {}

function download.download(path, url, alive_time)
    alive_time = alive_time or 86400

    if not fs.exists(path) then
        os.execute("wget ".. url .." ".. path)
    elseif (fs.lastModified(path) / 1000 + alive_time) < (os.time() / 100) then
        os.execute("rm ".. path)
        os.execute("wget ".. url .." ".. path)
    end
end

function download.require(path, url, alive_time)
    download.download(path, url, alive_time)
    return require(path)
end

function download.load(path, url, alive_time)
    download.download(path, url, alive_time)

    local f = io.open(path, "r")
    if not f then return "" end
    local data = f:read("*a")
    io.close(f)
    return data
end

download.pastebin = {}

function download.pastebin.require(path, url_or_id, alive_time)
    local id = GetPastebinID(url_or_id) or url_or_id
    return download.require(path, "https://pastebin.com/raw/".. id, alive_time)
end

function download.pastebin.load(path, url_or_id, alive_time)
    local id = GetPastebinID(url_or_id) or url_or_id
    return download.load(path, "https://pastebin.com/raw/".. id, alive_time)
end

download.github = {}

local is_file, is_dir = {blob = true}, {tree = true}

function download.github.listrepo(user, repo, branch, cback)
    local url = string.format("https://api.github.com/repos/%s/%s/git/trees/%s?recursive=1", user, repo, branch)
    local json = HttpFetch(url)
    local tree = serialization.unserialize(json)

    local function recursive(tree)
        for i, data in ipairs(tree) do
            if is_file[data.type] then
                cback(data.path, data.url)
            elseif is_dir[data.type] then
                recursive(data)
            end
        end
    end

    recursive(tree)
end

function download.github.reqirerepo(dir_path, init_file, user, repo, branch, alive_time)
    branch = branch or "master"

    download.github.listrepo(user, repo, branch, function(fpath, url)
        download.download(dir_path .."/".. fpath, url, alive_time)
    end)

    return require(dir_path .."/".. init_file)
end

function download.github.reqire(path, user, repo, branch, fpath, alive_time)
    local url = GetGithubBlob(user, repo, branch, fpath)
    return download.require(path, url, alive_time)
end

function download.github.load(path, user, repo, branch, fpath, alive_time)
    local url = GetGithubBlob(user, repo, branch, fpath)
    return download.load(path, url, alive_time)
end

return download