/* eslint-disable max-lines */
const _ = require('lodash');
const HomebrewModel = require('./homebrew.model.js').model;
const router = require('express').Router();
const zlib = require('zlib');
const GoogleActions = require('./googleActions.js');
const Markdown = require('../shared/naturalcrit/markdown.js');
const yaml = require('js-yaml');
const asyncHandler = require('express-async-handler');
const { nanoid } = require('nanoid');

const { DEFAULT_BREW, DEFAULT_BREW_LOAD } = require('./brewDefaults.js');

// const getTopBrews = (cb) => {
// 	HomebrewModel.find().sort({ views: -1 }).limit(5).exec(function(err, brews) {
// 		cb(brews);
// 	});
// };

const MAX_TITLE_LENGTH = 100;

const api = {
	homebrewApi : router,
	getId       : (req)=>{
		// Set the id and initial potential google id, where the google id is present on the existing brew.
		let id = req.params.id, googleId = req.body?.googleId;

		// If the id is longer than 12, then it's a google id + the edit id. This splits the longer id up.
		if(id.length > 12) {
			googleId = id.slice(0, -12);
			id = id.slice(-12);
		}
		return { id, googleId };
	},
	getBrew : (accessType, stubOnly = false)=>{
		// Create middleware with the accessType passed in as part of the scope
		return async (req, res, next)=>{
			// Get relevant IDs for the brew
			const { id, googleId } = api.getId(req);

			// Try to find the document in the Homebrewery database -- if it doesn't exist, that's fine.
			let stub = await HomebrewModel.get(accessType === 'edit' ? { editId: id } : { shareId: id })
				.catch((err)=>{
					if(googleId) {
						console.warn(`Unable to find document stub for ${accessType}Id ${id}`);
					} else {
						console.warn(err);
					}
				});
			stub = stub?.toObject();

			// If there is a google id, try to find the google brew
			if(!stubOnly && (googleId || stub?.googleId)) {
				let googleError;
				const googleBrew = await GoogleActions.getGoogleBrew(googleId || stub?.googleId, id, accessType)
					.catch((err)=>{
						googleError = err;
					});
				// Throw any error caught while attempting to retrieve Google brew.
				if(googleError) throw googleError;
				// Combine the Homebrewery stub with the google brew, or if the stub doesn't exist just use the google brew
				stub = stub ? _.assign({ ...api.excludeStubProps(stub), stubbed: true }, api.excludeGoogleProps(googleBrew)) : googleBrew;
			}
			const authorsExist = stub?.authors?.length > 0;
			const isAuthor = stub?.authors?.includes(req.account?.username);
			const isInvited = stub?.invitedAuthors?.includes(req.account?.username);
			if(accessType === 'edit' && (authorsExist && !(isAuthor || isInvited))) {
				throw `The current logged in user does not have editor access to this brew.

If you believe you should have access to this brew, ask the file owner to invite you as an author by opening the brew, viewing the Properties tab, and adding your username to the "invited authors" list. You can then try to access this document again.`;
			}

			// If after all of that we still don't have a brew, throw an exception
			if(!stub && !stubOnly) {
				throw 'Brew not found in Homebrewery database or Google Drive';
			}

			// Clean up brew: fill in missing fields with defaults / fix old invalid values
			if(stub) {
				stub.tags     = stub.tags     || undefined; // Clear empty strings
				stub.renderer = stub.renderer || undefined; // Clear empty strings
				stub = _.defaults(stub, DEFAULT_BREW_LOAD); // Fill in blank fields
			}

			req.brew = stub ?? {};
			next();
		};
	},
	mergeBrewText : (brew)=>{
		let text = brew.text;
		if(brew.style !== undefined) {
			text = `\`\`\`css\n` +
				`${brew.style || ''}\n` +
				`\`\`\`\n\n` +
				`${text}`;
		}
		const metadata = _.pick(brew, ['title', 'description', 'tags', 'systems', 'renderer', 'theme']);
		text = `\`\`\`metadata\n` +
			`${yaml.dump(metadata)}\n` +
			`\`\`\`\n\n` +
			`${text}`;
		return text;
	},
	getGoodBrewTitle : (text)=>{
		const tokens = Markdown.marked.lexer(text);
		return (tokens.find((token)=>token.type === 'heading' || token.type === 'paragraph')?.text || 'No Title')
			.slice(0, MAX_TITLE_LENGTH);
	},
	excludePropsFromUpdate : (brew)=>{
		// Remove undesired properties
		const modified = _.clone(brew);
		const propsToExclude = ['_id', 'views', 'lastViewed'];
		for (const prop of propsToExclude) {
			delete modified[prop];
		}
		return modified;
	},
	excludeGoogleProps : (brew)=>{
		const modified = _.clone(brew);
		const propsToExclude = ['version', 'tags', 'systems', 'published', 'authors', 'owner', 'views', 'thumbnail'];
		for (const prop of propsToExclude) {
			delete modified[prop];
		}
		return modified;
	},
	excludeStubProps : (brew)=>{
		const propsToExclude = ['text', 'textBin', 'renderer', 'pageCount'];
		for (const prop of propsToExclude) {
			brew[prop] = undefined;
		}
		return brew;
	},
	beforeNewSave : (account, brew)=>{
		if(!brew.title) {
			brew.title = api.getGoodBrewTitle(brew.text);
		}

		brew.authors = (account) ? [account.username] : [];
		brew.text = api.mergeBrewText(brew);

		_.defaults(brew, DEFAULT_BREW);
	},
	newGoogleBrew : async (account, brew, res)=>{
		const oAuth2Client = GoogleActions.authCheck(account, res);

		const newBrew = api.excludeGoogleProps(brew);

		return await GoogleActions.newGoogleBrew(oAuth2Client, newBrew);
	},
	newBrew : async (req, res)=>{
		const brew = req.body;
		const { saveToGoogle } = req.query;

		delete brew.editId;
		delete brew.shareId;
		delete brew.googleId;

		api.beforeNewSave(req.account, brew);

		const newHomebrew = new HomebrewModel(brew);
		newHomebrew.editId = nanoid(12);
		newHomebrew.shareId = nanoid(12);

		let googleId, saved;
		if(saveToGoogle) {
			googleId = await api.newGoogleBrew(req.account, newHomebrew, res)
				.catch((err)=>{
					console.error(err);
					res.status(err?.status || err?.response?.status || 500).send(err?.message || err);
				});
			if(!googleId) return;
			api.excludeStubProps(newHomebrew);
			newHomebrew.googleId = googleId;
		} else {
			// Compress brew text to binary before saving
			newHomebrew.textBin = zlib.deflateRawSync(newHomebrew.text);
			// Delete the non-binary text field since it's not needed anymore
			newHomebrew.text = undefined;
		}

		saved = await newHomebrew.save()
			.catch((err)=>{
				console.error(err, err.toString(), err.stack);
				throw `Error while creating new brew, ${err.toString()}`;
			});
		if(!saved) return;
		saved = saved.toObject();

		res.status(200).send(saved);
	},
	updateBrew : async (req, res)=>{
		// Initialize brew from request and body, destructure query params, and set the initial value for the after-save method
		const brewFromClient = api.excludePropsFromUpdate(req.body);
		const brewFromServer = req.brew;
		if(brewFromServer.version && brewFromClient.version && brewFromServer.version > brewFromClient.version) {
			console.log(`Version mismatch on brew ${brewFromClient.editId}`);
			res.setHeader('Content-Type', 'application/json');
			return res.status(409).send(JSON.stringify({ message: `The brew has been changed on a different device. Please save your changes elsewhere, refresh, and try again.` }));
		}

		let brew = _.assign(brewFromServer, brewFromClient);
		const googleId = brew.googleId;
		const { saveToGoogle, removeFromGoogle } = req.query;
		let afterSave = async ()=>true;

		brew.text = api.mergeBrewText(brew);

		if(brew.googleId && removeFromGoogle) {
			// If the google id exists and we're removing it from google, set afterSave to delete the google brew and mark the brew's google id as undefined
			afterSave = async ()=>{
				return await api.deleteGoogleBrew(req.account, googleId, brew.editId, res)
					.catch((err)=>{
						console.error(err);
						res.status(err?.status || err?.response?.status || 500).send(err.message || err);
					});
			};

			brew.googleId = undefined;
		} else if(!brew.googleId && saveToGoogle) {
			// If we don't have a google id and the user wants to save to google, create the google brew and set the google id on the brew
			brew.googleId = await api.newGoogleBrew(req.account, api.excludeGoogleProps(brew), res)
				.catch((err)=>{
					console.error(err);
					res.status(err.status || err.response.status).send(err.message || err);
				});
			if(!brew.googleId) return;
		} else if(brew.googleId) {
			// If the google id exists and no other actions are being performed, update the google brew
			const updated = await GoogleActions.updateGoogleBrew(api.excludeGoogleProps(brew))
				.catch((err)=>{
					console.error(err);
					res.status(err?.response?.status || 500).send(err);
				});
			if(!updated) return;
		}

		if(brew.googleId) {
			// If the google id exists after all those actions, exclude the props that are stored in google and aren't needed for rendering the brew items
			api.excludeStubProps(brew);
		} else {
			// Compress brew text to binary before saving
			brew.textBin = zlib.deflateRawSync(brew.text);
			// Delete the non-binary text field since it's not needed anymore
			brew.text = undefined;
		}
		brew.updatedAt = new Date();
		brew.version = (brew.version || 1) + 1;

		if(req.account) {
			brew.authors = _.uniq(_.concat(brew.authors, req.account.username));
			brew.invitedAuthors = _.uniq(_.filter(brew.invitedAuthors, (a)=>req.account.username !== a));
		}

		// define a function to catch our save errors
		const saveError = (err)=>{
			console.error(err);
			res.status(err.status || 500).send(err.message || 'Unable to save brew to Homebrewery database');
		};
		let saved;
		if(!brew._id) {
			// if the brew does not have a stub id, create and save it, then write the new value back to the brew.
			saved = await new HomebrewModel(brew).save().catch(saveError);
		} else {
			// if the brew does have a stub id, update it using the stub id as the key.
			brew = _.assign(await HomebrewModel.findOne({ _id: brew._id }), brew);
			saved = await brew.save()
				.catch(saveError);
		}
		if(!saved) return;
		// Call and wait for afterSave to complete
		const after = await afterSave();
		if(!after) return;

		res.status(200).send(saved);
	},
	deleteGoogleBrew : async (account, id, editId, res)=>{
		const auth = await GoogleActions.authCheck(account, res);
		await GoogleActions.deleteGoogleBrew(auth, id, editId);
		return true;
	},
	deleteBrew : async (req, res, next)=>{
		// Delete an orphaned stub if its Google brew doesn't exist
		try {
			await api.getBrew('edit')(req, res, ()=>{});
		} catch (err) {
			const { id, googleId } = api.getId(req);
			console.warn(`No google brew found for id ${googleId}, the stub with id ${id} will be deleted.`);
			await HomebrewModel.deleteOne({ editId: id });
			return next();
		}

		let brew = req.brew;
		const { googleId, editId } = brew;
		const account = req.account;
		const isOwner = account && (brew.authors.length === 0 || brew.authors[0] === account.username);
		// If the user is the owner and the file is saved to google, mark the google brew for deletion
		const shouldDeleteGoogleBrew = googleId && isOwner;

		if(brew._id) {
			brew = _.assign(await HomebrewModel.findOne({ _id: brew._id }), brew);
			if(account) {
				// Remove current user as author
				brew.authors = _.pull(brew.authors, account.username);
			}

			if(brew.authors.length === 0) {
				// Delete brew if there are no authors left
				await brew.remove()
					.catch((err)=>{
						console.error(err);
						throw { status: 500, message: 'Error while removing' };
					});
			} else {
				if(shouldDeleteGoogleBrew) {
					// When there are still authors remaining, we delete the google brew but store the full brew in the Homebrewery database
					brew.googleId = undefined;
					brew.textBin = zlib.deflateRawSync(brew.text);
					brew.text = undefined;
				}

				// Otherwise, save the brew with updated author list
				await brew.save()
					.catch((err)=>{
						throw { status: 500, message: err };
					});
			}
		}
		if(shouldDeleteGoogleBrew) {
			const deleted = await api.deleteGoogleBrew(account, googleId, editId, res)
				.catch((err)=>{
					console.error(err);
					res.status(500).send(err);
				});
			if(!deleted) return;
		}

		res.status(204).send();
	}
};

router.use('/api', require('./middleware/check-client-version.js'));
router.post('/api', asyncHandler(api.newBrew));
router.put('/api/:id', asyncHandler(api.getBrew('edit', true)), asyncHandler(api.updateBrew));
router.put('/api/update/:id', asyncHandler(api.getBrew('edit', true)), asyncHandler(api.updateBrew));
router.delete('/api/:id', asyncHandler(api.deleteBrew));
router.get('/api/remove/:id', asyncHandler(api.deleteBrew));

module.exports = api;