const graphqlHTTP = require('express-graphql');
const escape = require('escape-html');
const dateFormat = require('dateformat');
const { makeExecutableSchema } = require('graphql-tools');

module.exports = (app, resolvers) => {
    
    const typeDefs = require('./schema');
    
    const schema = makeExecutableSchema({
        typeDefs,
        resolvers
    });

    app.get('/json', async(req, res) => {
        
        const graphql = await graphqlHTTP((req, res, graphQLParams) => {
            
            graphQLParams.query = "{ helloWorld }";
            graphQLParams.operationName = null;
            graphQLParams.variables = {};
    
            return graphqlOpts()
        });
    
        res.real_end = res.end;
    
        res.end = (data) => {
            
            let toRet;
            const json = JSON.parse(data.toString('utf8'));
    
            if(json.data.helloWorld) {
                toRet = json.data.helloWorld;
            } else {
                toRet = { helloWorld: null };
            }
            
            setResponseHeaders(res, toRet.length);
    
            res.real_end(toRet);
        }
    
        await graphql(req, res);
    });
    
    app.get('/db', async (req, res) => {
        
        const graphql = await graphqlHTTP((req, res, graphQLParams) => {
        
            graphQLParams.query = "{ singleDatabaseQuery { id, randomNumber }}";
            graphQLParams.variables = {};
            graphQLParams.operationName = null;
        
            return graphqlOpts();
        });
    
        formatResData(res, "singleDatabaseQuery");
    
        await graphql(req, res);
    });
    
    app.get('/queries', async (req, res) => {
        
        const graphql = await graphqlHTTP((req, res, graphQLParams) => {
            
            let totalNumOfQueries = ensureQueryIsAnInt(req.query.queries);
    
            graphQLParams.query = `{ multipleDatabaseQueries(total: ${totalNumOfQueries}) { id, randomNumber }}`
            graphQLParams.variables = {};
            graphQLParams.operationName = null;
    
            return graphqlOpts();
        });
    
        formatResData(res, "multipleDatabaseQueries");
    
        await graphql(req, res);
    });
    
    app.get('/fortunes', async (req, res) => {
    
        const graphql = await graphqlHTTP((req, res, graphQLParams) => {
    
            graphQLParams.query = "{ getAllFortunes { id, message } }"
            graphQLParams.operationName = null;
            graphQLParams.variables = {};
    
            return graphqlOpts();
        });
    
        retrieveAndFormatAllFortunes(res);
        
        await graphql(req, res);
    });
    
    app.get('/updates', async (req, res) => {
    
        const totalNumOfQueries = ensureQueryIsAnInt(req.query.queries);
    
        const graphql = await graphqlHTTP((req, res, graphQLParams) => {
    
            graphQLParams.query = `{ getRandomAndUpdate(total: ${totalNumOfQueries}) { id, randomNumber } }`
            graphQLParams.operationName = null;
            graphQLParams.variables = {};
    
            return graphqlOpts();
        });
    
        formatResData(res, 'getRandomAndUpdate');
    
        await graphql(req, res);
    });
    
    app.get('/plaintext', (req, res) => {
    
        const responseTxt = "Hello, World!";
    
        res.setHeader('Content-Length', responseTxt.length);
        res.setHeader('Server', 'Express-GraphQL-MySQL');
        res.contentType('text/plain');
        res.status(200);
    
        res.send(responseTxt);
    });
    
    // Helper Functions
    
    const ensureQueryIsAnInt = (queryString) => {
    
        if(queryString === undefined) return 1;
    
        const possibleInt = parseInt(queryString);
        if(!possibleInt) return 1;
    
        return possibleInt;
    };
    
    const graphqlOpts = (params) => {
        return {
            schema,
            graphiql: false,
            context: params || {}
        }
    };
    
    const retrieveAndFormatAllFortunes = res => {
    
        res.real_end = res.end;
    
        res.end = async (data) => {
            let toRet;
            const json = JSON.parse(data.toString('utf8'));
    
            if(json.data.getAllFortunes) {
                toRet = json.data.getAllFortunes;
            } else {
                toRet = [];
            }
    
            const newFortune = { "id": 0, "message": "Additional fortune added at request time." };
            toRet.push(newFortune);
            toRet.sort((a, b) => (a.message < b.message) ? -1 : 1);
    
            const htmlToRet = await spoofHTML(toRet);
    
            res.contentType('html');
            res.setHeader('Server', 'GraphQL-MySQL');
            res.setHeader('Content-Length', htmlToRet.length + 32);
            res.status(200);
    
            res.real_end(htmlToRet);
        }
    };
    
    const spoofHTML = arr => {
    
        return new Promise((resolve, reject) => {
    
            let count = 0;
    
            let htmlToRet = `<!DOCTYPE html><html><head><title>Fortunes</title></head><body><table><tr><th>id</th><th>message</th></tr>`;
    
            for (let fortune of arr) {
    
                htmlToRet += `<tr><td>${escape(fortune.id)}</td><td>${escape(fortune.message)}</td></tr>`;
                count++;
            }
    
            htmlToRet += '</table></body></html>';
        
            if(count == arr.length)resolve(htmlToRet);
    
        });
    };
    
    const formatResData = (res, queryName) => {
    
        res.real_end = res.end;
        
        res.end = (data) => {
    
            const json = JSON.parse(data.toString('utf8'));
            
            let toRet = formatJson(queryName, json);
    
            const jsonToRet = JSON.stringify(toRet);
            
            setResponseHeaders(res, jsonToRet.length);
    
            res.real_end(jsonToRet);
        };
    };
    
    const formatJson = (queryName, jsonData) => {
    
        const isQueryReturningAnArray = {
    
            singleDatabaseQuery: false,
            multipleDatabaseQueries: true,
            getRandomAndUpdate: true
        };
    
        if (isQueryReturningAnArray[queryName] == false) {
    
            if(jsonData.data[`${queryName}`]) {
                return {
                    id: jsonData.data[`${queryName}`].id,
                    randomNumber: jsonData.data[`${queryName}`].randomNumber
                };
            } else {
                return {
                    id: null,
                    randomNumber: null
                }
            }
        } else {
    
            return jsonData.data[`${queryName}`] || [];
        }
    };
    
    const setResponseHeaders = (res, jsonLength) => {
    
        let now = new Date();
    
        res.status(200);
        res.contentType('application/json', 'charset=UTF-8');
        res.setHeader('Date', dateFormat(now, "ddd, dd mmm yyyy hh:MM:ss Z"));
        res.setHeader('Server', 'GraphQL-Express-MySQL');
        res.setHeader('Content-Length', jsonLength);
    };
}