local ffi = require "ffi"
local openssl = require "openssl"

local utils = {}

utils.errors = {
    [400] = "bad_request",
    [401] = "unauthorized",
    [403] = "forbidden",
    [404] = "not_found",
    [405] = "method_not_allowed",
    [408] = "request_timeout",
    [409] = "conflict",
    [410] = "gone",
    [411] = "length_required",
    [413] = "payload_too_large",
    [414] = "uri_too_long",
    [415] = "unsupported_media_type",
    [418] = "im_a_teapot",
    [429] = "too_many_requests",
    [500] = "internal_server_error",
    [501] = "not_implemented",
    [502] = "bad_gateway",
    [503] = "service_unavailable",
    [504] = "gateway_timeout",
    [505] = "http_version_not_supported"
}

-- TODO: REWRITE
utils.random = function(min, max)
    local buf = ffi.new("uint8_t[4]")
    ffi.copy(buf, openssl.random(4), 4)
    local num = 0
    for i = 0, 3 do
        num = bit.bor(bit.lshift(num, 8), buf[i])
    end
    return min + (num % (max - min + 1))
end

utils.pin = function()
    local o = ""
    for i = 1, 4 do
        o = o .. tostring(utils.random(0, 9))
    end
    return o
end

utils.uuid = function()
    local template = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'
    return string.gsub(template, '[xy]', function(c)
        local v =
            (c == 'x')
            and utils.random(0, 0xf)
            or utils.random(8, 0xb)

        return string.format('%x', v)
    end)
end

utils.hash = function(data)
    return openssl.digest.digest("sha256", data)
end

utils.decode_url = function(str)
    str = str:gsub('+', ' ') -- Convert + to space
    return str:gsub("%%(%x%x)", function(hex)
        return string.char(tonumber(hex, 16))
    end)
end

utils.parse_form = function(data)
    local result = {}
    for pair in data:gmatch("[^&]+") do
        local key, value = pair:match("([^=]+)=?(.*)")
        if key then
            result[utils.decode_url(key)] = utils.decode_url(value)
        end
    end
    return result
end

utils.parse_cookies = function(header)
    local cookies = {}

    if not header or header == "" then
        return cookies
    end

    for pair in header:gmatch("[^;]+") do
        local key, value = pair:match("%s*(.-)%s*=%s*(.*)")
        if key and value then
            cookies[key] = value
        end
    end

    return cookies
end

utils.is_valid_handle = function(handle)
    return #handle > 0
        and #handle <= 32
        and not handle:match("[^0-9A-Za-z._-]")
end

utils.is_valid_password = function(password)
    return #password >= 8
        and #password <= 32
        and password:match("%d")
        and password:match("%l")
        and password:match("%u")
        and password:match("[@$!%%*?&]")
end

utils.forms = function(req, res, go)
    if
        req.headers["content-type"] ==
        "application/x-www-form-urlencoded"
    then
        req.form = utils.parse_form(req.body)
    end

    go()
end

package.preload["./utils"] = utils

return utils