import type {NextApiRequest, NextApiResponse} from "next";
import {app, storage} from "@/firebase";
import {getFirestore, doc, getDoc, updateDoc, getDocs, query, collection, where, documentId} from "firebase/firestore";
import {withIronSessionApiRoute} from "iron-session/next";
import {sessionOptions} from "@/lib/session";
import ReactPDF from "@react-pdf/renderer";
import GroupTestReport from "@/exams/pdf/group.test.report";
import {ref, uploadBytes, getDownloadURL} from "firebase/storage";
import {Stat, CorporateUser} from "@/interfaces/user";
import {User, DemographicInformation} from "@/interfaces/user";
import {Module} from "@/interfaces";
import {ModuleScore, StudentData} from "@/interfaces/module.scores";
import {SkillExamDetails} from "@/exams/pdf/details/skill.exam";
import {LevelExamDetails} from "@/exams/pdf/details/level.exam";
import {calculateBandScore, getLevelScore} from "@/utils/score";
import {generateQRCode, getRadialProgressPNG, streamToBuffer} from "@/utils/pdf";
import {Group} from "@/interfaces/user";
import moment from "moment-timezone";

interface GroupScoreSummaryHelper {
	score: [number, number];
	label: string;
	sessions: string[];
}
const db = getFirestore(app);

export default withIronSessionApiRoute(handler, sessionOptions);

async function handler(req: NextApiRequest, res: NextApiResponse) {
	if (req.method === "GET") return get(req, res);
	if (req.method === "POST") return post(req, res);
}

const getExamSummary = (score: number) => {
	if (score > 0.8) {
		return "Scoring between 81% and 100% on the English exam collectively demonstrates an outstanding level of proficiency in writing, speaking, listening, and reading for this group of students. Mastery of key concepts is evident across all language domains, showcasing not only a high level of skill but also a dedication to excellence. The group is encouraged to continue challenging themselves with advanced material in writing, speaking, listening, and reading to further refine their impressive command of the English language.";
	}

	if (score > 0.6) {
		return "The group's average scores between 61% and 80% on the English exam, encompassing writing, speaking, listening, and reading, reflect a commendable level of proficiency. There's evidence of a solid grasp of key concepts collectively, and effective application of skills. Room for refinement and deeper exploration in writing, speaking, listening, and reading remains, presenting an opportunity for the entire group to further their mastery.";
	}

	if (score > 0.4) {
		return "Scoring between 41% and 60% on the English exam across writing, speaking, listening, and reading indicates a moderate level of understanding for the group. While there's a commendable grasp of key concepts collectively, refining fundamental skills in writing, speaking, listening, and reading can lead to notable improvement. The group is encouraged to work together with consistent effort and targeted focus on weaker areas.";
	}

	if (score > 0.2) {
		return "The group's average scores between 21% and 40% on the English exam, encompassing writing, speaking, listening, and reading, show some understanding of key concepts in each domain. However, there's room for improvement in fundamental skills for the entire group. Strengthening writing, speaking, listening, and reading abilities collectively through consistent effort and focused group study will contribute to overall proficiency.";
	}

	return "The average performance of this group of students in English, covering writing, speaking, listening, and reading, indicates a collective need for improvement, with scores falling between 0% and 20%. Across all language domains, there's a significant gap in understanding key concepts. Strengthening fundamental skills in writing, speaking, listening, and reading is crucial for the entire group. Implementing a shared, consistent study routine and seeking group support in each area can contribute to substantial progress.";
};

const getLevelSummary = (score: number) => {
	if (score > 0.8) {
		return "Scoring between 81% and 100% on the English exam collectively demonstrates an outstanding level of proficiency for this group of students, showcasing a mastery of key concepts related to vocabulary and grammar. There's evidence of not only a high level of skill but also a dedication to excellence. The group is encouraged to continue challenging themselves with advanced material in vocabulary and grammar to further refine their impressive command of the English language.";
	}

	if (score > 0.6) {
		return "The group's average scores between 61% and 80% on the English exam reflect a commendable level of proficiency with solid grasp of key concepts related to vocabulary and grammar. Room for refinement and deeper exploration in these language skills remains, presenting an opportunity for the entire group to further their mastery. Consistent effort in honing nuanced aspects of vocabulary and grammar will contribute to even greater proficiency.";
	}

	if (score > 0.4) {
		return "Scoring between 41% and 60% on the English exam indicates a moderate level of understanding for the group, with commendable grasp of key concepts related to vocabulary and grammar. Refining these fundamental language skills can lead to notable improvement. The group is encouraged to work together with consistent effort and targeted focus on enhancing their vocabulary and grammar.";
	}

	if (score > 0.2) {
		return "The group's average scores between 21% and 40% on the English exam show some understanding of key concepts in vocabulary and grammar. However, there's room for improvement in these fundamental language skills for the entire group. Strengthening vocabulary and grammar collectively through consistent effort and focused group study will contribute to overall proficiency.";
	}

	return "The average performance of this group of students in English suggests a collective need for improvement, with scores falling between 0% and 20%. There's a significant gap in understanding key concepts related to vocabulary and grammar. Strengthening fundamental language skills, such as vocabulary and grammar, is crucial for the entire group. Implementing a shared, consistent study routine and seeking group support in these areas can contribute to substantial progress.";
};

const getPerformanceSummary = (module: Module, score: number) => {
	if (module === "level") return getLevelSummary(score);
	return getExamSummary(score);
};

const getScoreAndTotal = (stats: Stat[]) => {
	return stats.reduce(
		(acc, {score}) => {
			return {
				...acc,
				correct: acc.correct + score.correct,
				total: acc.total + score.total,
			};
		},
		{correct: 0, total: 0},
	);
};

const getLevelScoreForUserExams = (bandScore: number) => {
	const [level] = getLevelScore(bandScore);
	return level;
};

async function post(req: NextApiRequest, res: NextApiResponse) {
	// verify if it's a logged user that is trying to export
	if (req.session.user) {
		const {id} = req.query as {id: string};

		const docSnap = await getDoc(doc(db, "assignments", id));
		const data = docSnap.data() as {
			assigner: string;
			assignees: string[];
			results: any;
			exams: {module: Module}[];
			startDate: string;
			pdf: {
				path: string,
				version: string,
			},
		};
		if (!data) {
			res.status(400).end();
			return;
		}

		if (data.pdf && data.pdf.path && data.pdf.version === process.env.PDF_VERSION) {
			// if it does, return the pdf url
			const fileRef = ref(storage, data.pdf.path);
			const url = await getDownloadURL(fileRef);
			res.status(200).end(url);
			return;
		}

		try {
			const docUser = await getDoc(doc(db, "users", req.session.user.id));
			if (docUser.exists()) {
				// we'll need the user in order to get the user data (name, email, focus, etc);
				const user = docUser.data() as User;

				// generate the QR code for the report
				const qrcode = await generateQRCode((req.headers.origin || "") + req.url);

				if (!qrcode) {
					res.status(500).json({ok: false});
					return;
				}

				const flattenResults = data.results.reduce((accm: Stat[], entry: any) => {
					const stats = entry.stats as Stat[];
					return [...accm, ...stats];
				}, []) as Stat[];

				const docsSnap = await getDocs(query(collection(db, "users"), where(documentId(), "in", data.assignees)));
				const users = docsSnap.docs.map((d) => ({
					...d.data(),
					id: d.id,
				})) as User[];

				const flattenResultsWithGrade = flattenResults.map((e) => {
					const focus = users.find((u) => u.id === e.user)?.focus || "academic";
					const bandScore = calculateBandScore(e.score.correct, e.score.total, e.module, focus);

					return {...e, bandScore};
				});

				// in order to make sure we are using unique modules, generate the set based on them
				const uniqueModules = [...new Set(flattenResults.map(item => item.module))] as Module[];
				const moduleResults = uniqueModules.map((module) => {
					const moduleResults = flattenResultsWithGrade.filter((e) => e.module === module);
					const baseBandScore = moduleResults.reduce((accm, curr) => accm + curr.bandScore, 0) / moduleResults.length;
					const bandScore = isNaN(baseBandScore) ? 0 : baseBandScore;
					const {correct, total} = getScoreAndTotal(moduleResults);
					const png = getRadialProgressPNG("azul", correct, total);

					return {
						bandScore,
						png,
						module: module[0].toUpperCase() + module.substring(1),
						score: bandScore,
						total,
						code: module,
					};
				}) as ModuleScore[];

				const {correct: overallCorrect, total: overallTotal} = getScoreAndTotal(flattenResults);
				const baseOverallResult = overallCorrect / overallTotal;
				const overallResult = isNaN(baseOverallResult) ? 0 : baseOverallResult;

				const overallPNG = getRadialProgressPNG("laranja", overallCorrect, overallTotal);
				// generate the overall detail report
				const overallDetail = {
					module: "Overall",
					score: overallCorrect,
					total: overallTotal,
					png: overallPNG,
				} as ModuleScore;

				const testDetails = [overallDetail, ...moduleResults];
				// generate the performance summary based on the overall result
				const baseStat = data.exams[0];
				const performanceSummary = getPerformanceSummary(
					// from what I noticed, exams is either an array with the level module
					// or X modules, either way
					// as long as I verify the first entry I should be fine
					baseStat.module,
					overallResult,
				);

				const showLevel = baseStat.module === "level";

				// level exams have a different report structure than the skill exams
				const getCustomData = () => {
					if (showLevel) {
						return {
							title: "GROUP ENGLISH LEVEL TEST RESULT REPORT ",
							details: <LevelExamDetails detail={overallDetail} title="Group Average CEFR" />,
						};
					}

					return {
						title: "GROUP ENGLISH SKILLS TEST RESULT REPORT",
						details: <SkillExamDetails testDetails={testDetails} />,
					};
				};

				const {title, details} = getCustomData();

				const numberOfStudents = data.assignees.length;

				const getStudentsData = async (): Promise<StudentData[]> => {
					return data.assignees.map((id) => {
						const user = users.find((u) => u.id === id);
						const exams = flattenResultsWithGrade.filter((e) => e.user === id);
						const date =
							exams.length === 0
								? "N/A"
								: new Date(exams[0].date).toLocaleDateString(undefined, {
										year: "numeric",
										month: "numeric",
										day: "numeric",
								  });

						const bandScore = exams.length === 0 ? 0 : exams.reduce((accm, curr) => accm + curr.bandScore, 0) / exams.length;
						const {correct, total} = getScoreAndTotal(exams);

						const result = exams.length === 0 ? "N/A" : `${correct}/${total}`;

						const userDemographicInformation = user?.demographicInformation as DemographicInformation;

						return {
							id,
							name: user?.name || "N/A",
							email: user?.email || "N/A",
							gender: user?.demographicInformation?.gender || "N/A",
							date,
							result,
							level: showLevel ? getLevelScoreForUserExams(bandScore) : undefined,
							bandScore,
							passportId: userDemographicInformation?.passport_id || ""
						};
					});
				};

				const studentsData = await getStudentsData();

				const getGroupScoreSummary = () => {
					const resultHelper = studentsData.reduce((accm: GroupScoreSummaryHelper[], curr) => {
						const {bandScore, id} = curr;

						const flooredScore = Math.floor(bandScore);

						const hasMatch = accm.find((a) => a.score.includes(flooredScore));
						if (hasMatch) {
							return accm.map((a) => {
								if (a.score.includes(flooredScore)) {
									return {
										...a,
										sessions: [...a.sessions, id],
									};
								}

								return a;
							});
						}

						return [
							...accm,
							{
								score: [flooredScore, flooredScore + 0.5],
								label: `${flooredScore} - ${flooredScore + 0.5}`,
								sessions: [id],
							},
						];
					}, []) as GroupScoreSummaryHelper[];

					const result = resultHelper.map(({score, label, sessions}) => {
						const finalLabel = showLevel ? getLevelScore(score[0])[1] : label;
						return {
							label: finalLabel,
							percent: Math.floor((sessions.length / numberOfStudents) * 100),
							description: `No. Candidates ${sessions.length} of ${numberOfStudents}`,
						};
					});
					return result;
				};

				const getInstitution = async () => {
					try {
						// due to database inconsistencies, I'll be overprotective here
						const assignerUserSnap = await getDoc(doc(db, "users", data.assigner));
						if (assignerUserSnap.exists()) {
							// we'll need the user in order to get the user data (name, email, focus, etc);
							const assignerUser = assignerUserSnap.data() as User;

							if (assignerUser.type === "teacher") {
								// also search for groups where this user belongs
								const queryGroups = query(collection(db, "groups"), where("participants", "array-contains", assignerUser.id));
								const groupSnapshot = await getDocs(queryGroups);

								const groups = groupSnapshot.docs.map((doc) => ({
									id: doc.id,
									...doc.data(),
								})) as Group[];

								if (groups.length > 0) {
									const adminQuery = query(
										collection(db, "users"),
										where(
											documentId(),
											"in",
											groups.map((g) => g.admin),
										),
									);
									const adminUsersSnap = await getDocs(adminQuery);

									const admins = adminUsersSnap.docs.map((doc) => ({
										id: doc.id,
										...doc.data(),
									})) as CorporateUser[];

									const adminData = admins.find((a) => a.corporateInformation?.companyInformation?.name);
									if (adminData) {
										return adminData.corporateInformation.companyInformation.name;
									}
								}
							}

							if (assignerUser.type === "corporate" && assignerUser.corporateInformation?.companyInformation?.name) {
								return assignerUser.corporateInformation.companyInformation.name;
							}
						}
					} catch (err) {
						console.error(err);
					}
					return "";
				};

				const institution = await getInstitution();
				const groupScoreSummary = getGroupScoreSummary();
				const demographicInformation = user.demographicInformation as DemographicInformation;
				const pdfStream = await ReactPDF.renderToStream(
					<GroupTestReport
						title={title}
						date={moment(data.startDate)
							.tz(user.demographicInformation?.timezone || "UTC")
							.format("ll HH:mm:ss")}
						name={user.name}
						email={user.email}
						id={user.id}
						gender={demographicInformation?.gender}
						summary={performanceSummary}
						renderDetails={details}
						logo={"public/logo_title.png"}
						qrcode={qrcode}
						numberOfStudents={numberOfStudents}
						institution={institution}
						studentsData={studentsData}
						showLevel={showLevel}
						summaryPNG={overallPNG}
						summaryScore={`${Math.floor(overallResult * 100)}%`}
						groupScoreSummary={groupScoreSummary}
						passportId={demographicInformation?.passport_id || ""}
					/>,
				);

				// generate the file ref for storage
				const fileName = `${Date.now().toString()}.pdf`;
				const refName = `assignment_report/${fileName}`;
				const fileRef = ref(storage, refName);

				// upload the pdf to storage
				const pdfBuffer = await streamToBuffer(pdfStream);
				const snapshot = await uploadBytes(fileRef, pdfBuffer, {
					contentType: "application/pdf",
				});

				// update the stats entries with the pdf url to prevent duplication
				await updateDoc(docSnap.ref, {
					pdf: {
						path: refName,
						version: process.env.PDF_VERSION,
					},
				});
				const url = await getDownloadURL(fileRef);
				res.status(200).end(url);
				return;
			}

			res.status(401).json({ok: false});
			return;
		} catch (err) {
			console.error(err);
			res.status(500).json({ok: false});
			return;
		}
	}
}
async function get(req: NextApiRequest, res: NextApiResponse) {
	if (req.session.user) {
		const {id} = req.query as {id: string};

		const docSnap = await getDoc(doc(db, "assignments", id));
		const data = docSnap.data();
		if (!data) {
			res.status(400).end();
			return;
		}

		if (data.assigner !== req.session.user.id) {
			res.status(401).json({ok: false});
			return;
		}

		if (data.pdf?.path) {
			const fileRef = ref(storage, data.pdf.path);
			const url = await getDownloadURL(fileRef);
			return res.redirect(url);
		}

		res.status(404).end();
		return;
	}

	res.status(401).json({ok: false});
	return;
}
