const fs = require('fs');

module.exports = function (app, opts) {
    async function oauthParseAuthHeader (auth) {
        if (!auth) {
            throw new Error('参数无效: 未包含Authorization头');
        }

        const authSplit = auth.split('Basic');
        if (authSplit.length != 2) {
            throw new Error('参数无效: Authorization头格式无效，请检查是否包含了"Basic "');
        }

        const authCode = authSplit[1];
        const apikey = Buffer.from(authCode, 'base64').toString();

        const keySplit = apikey.split(':');
        if (keySplit.length != 2) {
            throw new Error('参数无效：请检查Authorization头内容是否经过正确Base64编码');
        }
        
        return keySplit;
    }

    async function oauthParseBody (body, type) {
        let checked = true, token = '';
        if (type == 'apply' && body['grant_type'] != 'client_credentials') {
            checked = false;
        } else if (type == 'refresh') {
            if (body['grant_type'] != 'refresh_token' || body['token'] == null) {
                checked = false;
            } else {
                token = body['token'];
            }
        } else if (type == 'invalidate') {
            if (body['token'] == null) {
                checked = false;
            } else {
                token = body['token'];
            }
        }

        if (!checked) {
            throw new Error('参数无效：请求正文中未包含正确的信息');
        }

        return token;
    }

    return {
        oauthParseAuthHeader,
        oauthParseBody
    }
}