package main

import (
	"encoding/csv"
	"encoding/json"
	"fmt"
	"log"
	"math/rand"
	"os"
	"strings"
	"time"

	"github.com/brianvoe/gofakeit/v6"
)

var course_type = []string{
	"A",
	"B",
	"C",
	"D",
	"E",
}

var course_information = []Section{
	{CourseNumber: "B560",
		CourseTitle: "Academic Legal Writing: Dissertation Fundamentals"},
	{CourseNumber: "B652",
		CourseTitle: "Accounting for Lawyers"},
	{CourseNumber: "B713",
		CourseTitle: "Administrative Law"},
	{CourseNumber: "B528",
		CourseTitle: "Advanced Appellate Advocacy"},
	{CourseNumber: "B631",
		CourseTitle: "Advanced Bankruptcy: Business Reorganization"},
	{CourseNumber: "B634",
		CourseTitle: "Advanced Constitutional Law: Issues Related to the Press"},
	{CourseNumber: "B634",
		CourseTitle: "Advanced Constitutional Law"},
	{CourseNumber: "B595",
		CourseTitle: "Advanced Environmental Law and Practice"},
	{CourseNumber: "B639",
		CourseTitle: "Advanced Legal Research"},
	{CourseNumber: "B639",
		CourseTitle: "Advanced Legal Research: LLMs and SJDs"},
	{CourseNumber: "B791",
		CourseTitle: "Advanced Legal Writing"},
	{CourseNumber: "B517",
		CourseTitle: "Advanced Patent Law"},
	{CourseNumber: "B720",
		CourseTitle: "Advanced Trial Practice"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: ABA"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: AIPLA"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: External Moot Court Team"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: IP"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: International Patent Drafting"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: LawMeet"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: Moot Court Board"},
	{CourseNumber: "B734",
		CourseTitle: "Advocacy: Pace Moot Court Team"},
	{CourseNumber: "B540",
		CourseTitle: "After Atrocities: Processes of Post-Conflict Justice"},
	{CourseNumber: "B570",
		CourseTitle: "American Constitutional Law for Foreign Lawyers"},
	{CourseNumber: "B659",
		CourseTitle: "American Legal History"},
	{CourseNumber: "B729",
		CourseTitle: "Antitrust Law"},
	{CourseNumber: "B642",
		CourseTitle: "Appellate Advocacy"},
	{CourseNumber: "B671",
		CourseTitle: "Appellate Practice and Procedure"},
	{CourseNumber: "B671",
		CourseTitle: "Appellate Practice and Procedure: Criminal Appeal: From Transcript to Argument"},
	{CourseNumber: "B710",
		CourseTitle: "Cybersecurity Clinic"},
	{CourseNumber: "B769",
		CourseTitle: "Banking Law"},
	{CourseNumber: "B725",
		CourseTitle: "Bankruptcy"},
	{CourseNumber: "B793",
		CourseTitle: "Business and Human Rights"},
	{CourseNumber: "B632",
		CourseTitle: "Business Planning"},
	{CourseNumber: "B614",
		CourseTitle: "Career Choices"},
	{CourseNumber: "B674",
		CourseTitle: "Center for Constitutional Democracy"},
	{CourseNumber: "B781",
		CourseTitle: "Children and the Law"},
	{CourseNumber: "B533",
		CourseTitle: "Civil Procedure"},
	{CourseNumber: "B534",
		CourseTitle: "Civil Procedure II"},
	{CourseNumber: "B580",
		CourseTitle: "Civil Rights Statutes"},
	{CourseNumber: "B506",
		CourseTitle: "Climate Law and Policy"},
	{CourseNumber: "B688",
		CourseTitle: "Community Legal Clinic"},
	{CourseNumber: "B748",
		CourseTitle: "Comparative Law: Comparative Legal Systems"},
	{CourseNumber: "B748",
		CourseTitle: "Comparative Law: Constitutional Design and the Economy"},
	{CourseNumber: "B748",
		CourseTitle: "Comparative Law: Islam and Human Rights"},
	{CourseNumber: "B667",
		CourseTitle: "Complex Litigation"},
	{CourseNumber: "B745",
		CourseTitle: "Conflict of Laws"},
	{CourseNumber: "B558",
		CourseTitle: "Conservation Law Clinic"},
	{CourseNumber: "B575",
		CourseTitle: "Constitutional Design in Multiethnic Societies"},
	{CourseNumber: "B760",
		CourseTitle: "Constitutional History Colloquium"},
	{CourseNumber: "B513",
		CourseTitle: "Constitutional Law"},
	{CourseNumber: "B668",
		CourseTitle: "Constitutional Law II"},
	{CourseNumber: "B606",
		CourseTitle: "Constitutional Litigation"},
	{CourseNumber: "B501",
		CourseTitle: "Contracts"},
	{CourseNumber: "B662",
		CourseTitle: "Copyright Law"},
	{CourseNumber: "B656",
		CourseTitle: "Corporate Finance Law"},
	{CourseNumber: "B700",
		CourseTitle: "Corporate Taxation"},
	{CourseNumber: "B653",
		CourseTitle: "Corporations"},
	{CourseNumber: "B511",
		CourseTitle: "Criminal Law"},
	{CourseNumber: "B545",
		CourseTitle: "Criminal Law Externship"},
	{CourseNumber: "B786",
		CourseTitle: "Criminal Procedure Capstone"},
	{CourseNumber: "B604",
		CourseTitle: "Criminal Procedure: LLM"},
	{CourseNumber: "B602",
		CourseTitle: "Criminal Procedure: Trial"},
	{CourseNumber: "B601",
		CourseTitle: "Criminal Process: Investigation"},
	{CourseNumber: "B587",
		CourseTitle: "Cybersecurity Law I"},
	{CourseNumber: "B738",
		CourseTitle: "Cybersecurity Law II"},
	{CourseNumber: "B710",
		CourseTitle: "Cybersecurity Law Clinic"},
	{CourseNumber: "B581",
		CourseTitle: "Decision Making for Lawyers: Concepts, Duties and Skills"},
	{CourseNumber: "B714",
		CourseTitle: "Deliberative Leadership"},
	{CourseNumber: "B563",
		CourseTitle: "Domestic Relations Mediation"},
	{CourseNumber: "B680",
		CourseTitle: "Employment Discrimination"},
	{CourseNumber: "B719",
		CourseTitle: "Employment Law"},
	{CourseNumber: "B590",
		CourseTitle: "Entertainment Law"},
	{CourseNumber: "B561",
		CourseTitle: "Entrepreneurship Law Clinic"},
	{CourseNumber: "B740",
		CourseTitle: "Estate Planning"},
	{CourseNumber: "B611",
		CourseTitle: "Ethics and Compliance"},
	{CourseNumber: "B755",
		CourseTitle: "European Union Law"},
	{CourseNumber: "B723",
		CourseTitle: "Evidence"},
	{CourseNumber: "B691",
		CourseTitle: "Family and Children Mediation Clinic"},
	{CourseNumber: "B608",
		CourseTitle: "Family Law"},
	{CourseNumber: "B532",
		CourseTitle: "Federal Circuit Advocacy"},
	{CourseNumber: "B739",
		CourseTitle: "Federal Criminal Law and White Collar Crime"},
	{CourseNumber: "B571",
		CourseTitle: "Federal Habeas Litigation"},
	{CourseNumber: "B733",
		CourseTitle: "Federal Jurisdiction"},
	{CourseNumber: "B789",
		CourseTitle: "Feminist Jurisprudence"},
	{CourseNumber: "B568",
		CourseTitle: "Gender and The Law"},
	{CourseNumber: "B536",
		CourseTitle: "Health Law"},
	{CourseNumber: "B536",
		CourseTitle: "Health Privacy Law"},
	{CourseNumber: "B793",
		CourseTitle: "Human Rights"},
	{CourseNumber: "B669",
		CourseTitle: "Immigration Law"},
	{CourseNumber: "B655",
		CourseTitle: "Information Privacy and Security Management Practicum"},
	{CourseNumber: "B708",
		CourseTitle: "Information Privacy Law I"},
	{CourseNumber: "B728",
		CourseTitle: "Information Privacy Law II"},
	{CourseNumber: "B587",
		CourseTitle: "Information Security Law"},
	{CourseNumber: "B710",
		CourseTitle: "Independent Clinical Project"},
	{CourseNumber: "B572",
		CourseTitle: "Intellectual Property Clinic"},
	{CourseNumber: "B551",
		CourseTitle: "Intellectual Property Externship"},
	{CourseNumber: "B544",
		CourseTitle: "Intellectual Property Transactions"},
	{CourseNumber: "B726",
		CourseTitle: "Intellectual Property/Antitrust"},
	{CourseNumber: "B620",
		CourseTitle: "International Business Negotiations"},
	{CourseNumber: "B735",
		CourseTitle: "International Business Transactions"},
	{CourseNumber: "B565",
		CourseTitle: "International Criminal Law"},
	{CourseNumber: "B783",
		CourseTitle: "International Environmental Law"},
	{CourseNumber: "B549",
		CourseTitle: "International Intellectual Property"},
	{CourseNumber: "B665",
		CourseTitle: "International Law"},
	{CourseNumber: "B666",
		CourseTitle: "International Securities Regulation"},
	{CourseNumber: "B759",
		CourseTitle: "International Trade"},
	{CourseNumber: "B792",
		CourseTitle: "Internet Law"},
	{CourseNumber: "B792",
		CourseTitle: "Internet Law: Political and Legal Dimensions"},
	{CourseNumber: "B638",
		CourseTitle: "Introduction to American Legal Research"},
	{CourseNumber: "B782",
		CourseTitle: "Introduction to Environmental Law"},
	{CourseNumber: "B650",
		CourseTitle: "Introduction to Income Tax"},
	{CourseNumber: "B504",
		CourseTitle: "Introduction to Law"},
	{CourseNumber: "B567",
		CourseTitle: "IP Practicum: Legal Aspects of Music"},
	{CourseNumber: "B698",
		CourseTitle: "Judicial Field Placements"},
	{CourseNumber: "B788",
		CourseTitle: "Labor and Employment Arbitration"},
	{CourseNumber: "B663",
		CourseTitle: "Labor Law I"},
	{CourseNumber: "B615",
		CourseTitle: "Land Use Controls"},
	{CourseNumber: "B661",
		CourseTitle: "Law and Biomedical Advance"},
	{CourseNumber: "B658",
		CourseTitle: "Law and Education: Advanced School Law"},
	{CourseNumber: "B658",
		CourseTitle: "Law and Education: Higher Education"},
	{CourseNumber: "B658",
		CourseTitle: "Law and Education: Leadership in Special Education"},
	{CourseNumber: "B658",
		CourseTitle: "Law and Education: Legal Perspectives on Education"},
	{CourseNumber: "B658",
		CourseTitle: "Law and Education: Workshop on Probs in Ed Leadership"},
	{CourseNumber: "B761",
		CourseTitle: "Law and Philanthropy"},
	{CourseNumber: "B592",
		CourseTitle: "Law and Political Theory: Institutional Analysis & Development"},
	{CourseNumber: "B730",
		CourseTitle: "Law and Religion"},
	{CourseNumber: "B744",
		CourseTitle: "Law and Social Psychology"},
	{CourseNumber: "B678",
		CourseTitle: "Law and Sports"},
	{CourseNumber: "B674",
		CourseTitle: "Law Journal: Indiana Journal of Global Legal Studies"},
	{CourseNumber: "B674",
		CourseTitle: "Law Journal: Indiana Law Journal"},
	{CourseNumber: "B674",
		CourseTitle: "Law Journal: Indiana Journal of Law and Social Equality"},
	{CourseNumber: "B685",
		CourseTitle: "The Lawyer as a Business Executive"},
	{CourseNumber: "B539",
		CourseTitle: "Lawyering in the Public Interest"},
	{CourseNumber: "B530",
		CourseTitle: "Legal Discourse and Legal Writing for LLM and MCL Students"},
	{CourseNumber: "B582",
		CourseTitle: "Legal Issues in Mergers and Acquisitions"},
	{CourseNumber: "B508",
		CourseTitle: "Legal Operations"},
	{CourseNumber: "B614",
		CourseTitle: "The Legal Profession (for 1Ls)"},
	{CourseNumber: "B614",
		CourseTitle: "Legal Profession for Foreign Lawyers"},
	{CourseNumber: "B542",
		CourseTitle: "Legal Research and Writing I"},
	{CourseNumber: "B543",
		CourseTitle: "Legal Research and Writing II"},
	{CourseNumber: "B554",
		CourseTitle: "Legislation"},
	{CourseNumber: "B564",
		CourseTitle: "Litigation Drafting"},
	{CourseNumber: "B771",
		CourseTitle: "Mediation"},
	{CourseNumber: "B771",
		CourseTitle: "Mediation for LLMs"},
	{CourseNumber: "B582",
		CourseTitle: "Mergers and Acquisitions"},
	{CourseNumber: "B508",
		CourseTitle: "Modern Small Firm Practice"},
	{CourseNumber: "B623",
		CourseTitle: "Negotiable Instruments"},
	{CourseNumber: "B620",
		CourseTitle: "Negotiations"},
	{CourseNumber: "B537",
		CourseTitle: "Nonprofit Law Clinic"},
	{CourseNumber: "B569",
		CourseTitle: "Nonprofit Organizations"},
	{CourseNumber: "B681",
		CourseTitle: "Partnership Tax"},
	{CourseNumber: "B743",
		CourseTitle: "Patent Law"},
	{CourseNumber: "B559",
		CourseTitle: "Patent Prosecution"},
	{CourseNumber: "B785",
		CourseTitle: "Patent Trial Practice"},
	{CourseNumber: "B643",
		CourseTitle: "Poverty Law"},
	{CourseNumber: "B564",
		CourseTitle: "Pre-trial Litigation"},
	{CourseNumber: "B564",
		CourseTitle: "Pre-trial Litigation: Courtroom Procedure"},
	{CourseNumber: "B564",
		CourseTitle: "Pre-trial Litigation: Criminal Practice"},
	{CourseNumber: "B564",
		CourseTitle: "Pre-trial Litigation: Depositions"},
	{CourseNumber: "B622",
		CourseTitle: "Principles of Law and Economics"},
	{CourseNumber: "B514",
		CourseTitle: "Private Practice Externship"},
	{CourseNumber: "B654",
		CourseTitle: "Products Liability"},
	{CourseNumber: "B515",
		CourseTitle: "Project Management"},
	{CourseNumber: "B521",
		CourseTitle: "Property"},
	{CourseNumber: "B564",
		CourseTitle: "Protection Order Litigation"},
	{CourseNumber: "B547",
		CourseTitle: "Public Interest Internship Program"},
	{CourseNumber: "B675",
		CourseTitle: "Public Natural Resources"},
	{CourseNumber: "B507",
		CourseTitle: "Public Speaking"},
	{CourseNumber: "B756",
		CourseTitle: "Race, American Society and the Law"},
	{CourseNumber: "B749",
		CourseTitle: "Real Estate Finance"},
	{CourseNumber: "B775",
		CourseTitle: "Real Estate Transactions"},
	{CourseNumber: "B603",
		CourseTitle: "Remedies and Equity"},
	{CourseNumber: "B524",
		CourseTitle: "Representing the State"},
	{CourseNumber: "B670",
		CourseTitle: "Sales"},
	{CourseNumber: "B672",
		CourseTitle: "Secured Transactions"},
	{CourseNumber: "B727",
		CourseTitle: "Securities Regulation"},
	{CourseNumber: "B538",
		CourseTitle: "Semester Public Interest Program"},
	{CourseNumber: "B649",
		CourseTitle: "State and Local Tax"},
	{CourseNumber: "B519",
		CourseTitle: "State Constitutional Law"},
	{CourseNumber: "B588",
		CourseTitle: "Strategies in Critical Reading and Writing: Family Law"},
	{CourseNumber: "B751",
		CourseTitle: "Survey of Intellectual Property"},
	{CourseNumber: "B526",
		CourseTitle: "Tax Policy Colloquium"},
	{CourseNumber: "B736",
		CourseTitle: "Topics in Tax: Strategic Business and Tax Planning"},
	{CourseNumber: "B531",
		CourseTitle: "Torts"},
	{CourseNumber: "B758",
		CourseTitle: "Trademark and Unfair Competition"},
	{CourseNumber: "B709",
		CourseTitle: "Transactional Drafting"},
	{CourseNumber: "B709",
		CourseTitle: "Transactional Drafting: Anatomy of a Deal"},
	{CourseNumber: "B709",
		CourseTitle: "Transactional Drafting: Real Estate"},
	{CourseNumber: "B709",
		CourseTitle: "Transactional Drafting: Tax"},
	{CourseNumber: "B722",
		CourseTitle: "Trial Advocacy"},
	{CourseNumber: "B768",
		CourseTitle: "Water Law"},
	{CourseNumber: "B550",
		CourseTitle: "Wildlife Law"},
	{CourseNumber: "B645",
		CourseTitle: "Wills & Trusts"},
	{CourseNumber: "L641",
		CourseTitle: "Constitutionalism in the Middle East"},
	{CourseNumber: "L710",
		CourseTitle: "Seminar in Law and Society: Immigration Law"},
	{CourseNumber: "L710",
		CourseTitle: "Seminar in Law and Society: Work, Family, and the Law"},
	{CourseNumber: "L710",
		CourseTitle: "Seminar in Law and Society: Law and Language"},
	{CourseNumber: "L782",
		CourseTitle: "Seminar in Administrative Law: Lawyering in the Modern Administrative State"},
	{CourseNumber: "L766",
		CourseTitle: "Seminar in Children and the Law: Reproduction and Childhood"},
	{CourseNumber: "L766",
		CourseTitle: "Seminar in Children and the Law"},
	{CourseNumber: "L703",
		CourseTitle: "Seminar in Commercial Law: Consumer Credit"},
	{CourseNumber: "L770",
		CourseTitle: "Seminar in Comparative Inequality"},
	{CourseNumber: "L770",
		CourseTitle: "Seminar in Comparative Law: Islamic Law"},
	{CourseNumber: "L736",
		CourseTitle: "Seminar in Congress, the Presidency and the Courts"},
	{CourseNumber: "L799",
		CourseTitle: "Seminar in Constitutional Law: The Courts, the Democratic Process, and the People"},
	{CourseNumber: "L684",
		CourseTitle: "Seminar in Constitutional Design: Rights, Gender, and States of Emergency"},
	{CourseNumber: "L799",
		CourseTitle: "Seminar in Constitutional Law"},
	{CourseNumber: "L799",
		CourseTitle: "Seminar in Constitutional Law: First Amendment"},
	{CourseNumber: "L799",
		CourseTitle: "Seminar in Constitutional Law: Second Amendment"},
	{CourseNumber: "L799",
		CourseTitle: "Seminar in Constitutional Law: Sexuality, Reproduction, and the Constitution"},
	{CourseNumber: "L690",
		CourseTitle: "Seminar in Corporate Law: Financial Regulation"},
	{CourseNumber: "L690",
		CourseTitle: "Seminar in Corporate Law: Law and Practice Intellegence Age"},
	{CourseNumber: "L776",
		CourseTitle: "Seminar in Criminal Law: Current Issues in Law and Procedure"},
	{CourseNumber: "L776",
		CourseTitle: "Seminar in Criminal Law: Federal Sentencing"},
	{CourseNumber: "L776",
		CourseTitle: "Seminar in Criminal Law: Punishment in Theory and Practice"},
	{CourseNumber: "L728",
		CourseTitle: "Seminar in Globalization"},
	{CourseNumber: "L664",
		CourseTitle: "Seminar in Information Privacy"},
	{CourseNumber: "L712",
		CourseTitle: "Seminar in International Law: Drone Law"},
	{CourseNumber: "L730",
		CourseTitle: "Seminar in Intellectual Property"},
	{CourseNumber: "L730",
		CourseTitle: "Seminar in Intellectual Property: Data Law and Policy"},
	{CourseNumber: "L637",
		CourseTitle: "Seminar in Introduction to Biotechnological Innovation"},
	{CourseNumber: "L797",
		CourseTitle: "Seminar in Jurisprudence"},
	{CourseNumber: "L750",
		CourseTitle: "Seminar in Law and Development"},
	{CourseNumber: "L713",
		CourseTitle: "Seminar in Law and Economics"},
	{CourseNumber: "L796",
		CourseTitle: "Seminar in Law and Medicine"},
	{CourseNumber: "L748",
		CourseTitle: "Seminar in Law and Psychology of Crime, Culpability, and Punishment"},
	{CourseNumber: "L724",
		CourseTitle: "Seminar in Law and Society of China"},
	{CourseNumber: "L773",
		CourseTitle: "Seminar in Tax Policy"},
	{CourseNumber: "L636",
		CourseTitle: "Seminar in Transnational Law"},
	{CourseNumber: "L639",
		CourseTitle: "Seminar in the Supreme Court as an Institution"},
	{CourseNumber: "L714",
		CourseTitle: "Seminar on Judicial Conduct"},
}

type User struct {
	UID          string `json:"uid"`
	FirstName    string `json:"first_name"`
	LastName     string `json:"last_name"`
	Status       string `json:"status"`
	ExamID       string `json:"exam_id"`
	Username     string `json:"username"`
	APIKey       string `json:"api_key"`
	PasswordHash string `json:"password_hash"`
}

type Section struct {
	SectionID    string `json:"section_id"`
	CourseNumber string `json:"course_number"`
	Instructor   string `json:"course_instructor"`
	CourseTitle  string `json:"course_title"`
	CourseType   string `json:"course_type"`
	GradesDue    string `json:"grades_due"`
}

type Config struct {
	NumberOfUsers         int            `json:"number_of_users"`
	NumberOfSections      int            `json:"number_of_sections"`
	EnrollmentsPerStudent int            `json:"enrollments_per_student"`
	PercentStatus         map[string]int `json:"percent_status"`
}

type InstructorsSections struct {
	InstructorID string `json:"uid"`
	SectionID string `json:"section_id"`
}

var statuses = []string{"JD", "LLM", "MCL", "PHD", "SJD", "MLS", "SPEC", "EXCH", "MNR", "CERT", "Admin", "Instructor"}

func GenerateUserData(config Config) []User {
	// Build a weighted list of statuses
	weightedStatuses := make([]string, 0, 100)
	for status, pct := range config.PercentStatus {
		for i := 0; i < pct; i++ {
			weightedStatuses = append(weightedStatuses, status)
		}
	}

	// Generate unique ExamIDs and UIDs
	examIDs := uniqueNumericStrings(4, config.NumberOfUsers)
	uids := uniqueNumericStrings(10, config.NumberOfUsers)

	users := make([]User, config.NumberOfUsers)
	for i := range users {
		users[i] = User{
			UID:          uids[i],
			FirstName:    gofakeit.FirstName(),
			LastName:     gofakeit.LastName(),
			Status:       weightedStatuses[rand.Intn(len(weightedStatuses))],
			ExamID:       examIDs[i],
			Username:     gofakeit.Username(),
			APIKey:       strings.ReplaceAll(gofakeit.UUID(), "-", ""),
			PasswordHash: gofakeit.Password(true, true, true, true, false, 16),
		}
	}

	return users

}

func SaveGeneratedUsers(users []User) {

	f, err := os.Create("users.csv")
	if err != nil {
		log.Fatalf("failed to create users.csv: %v", err)
	}
	defer f.Close()

	w := csv.NewWriter(f)
	if err := w.Write([]string{"uid", "first_name", "last_name", "status", "exam_id", "username", "api_key", "password_hash"}); err != nil {
		log.Fatalf("failed to write csv header: %v", err)
	}
	for _, u := range users {
		if err := w.Write([]string{u.UID, u.FirstName, u.LastName, u.Status, u.ExamID, u.Username, u.APIKey, u.PasswordHash}); err != nil {
			log.Fatalf("failed to write csv row: %v", err)
		}
	}
	w.Flush()
	if err := w.Error(); err != nil {
		log.Fatalf("csv flush error: %v", err)
	}

	fmt.Printf("Generated %d users to users.csv\n", len(users))
}

func GenerateSectionData(config Config, users []User) []Section {
	// Build list of instructor UIDs from users with Status "Instructor"
	instructorUIDs := make([]string, 0)
	for _, u := range users {
		if u.Status == "Instructor" {
			instructorUIDs = append(instructorUIDs, u.UID)
		}
	}
	if len(instructorUIDs) == 0 {
		log.Fatal("no users with Status \"Instructor\" found")
	}

	// Generate unique course numbers: one uppercase letter + 3 digits
	seenCourseNumbers := make(map[string]struct{}, config.NumberOfSections)
	courseNumbers := make([]string, 0, config.NumberOfSections)
	for len(courseNumbers) < config.NumberOfSections {
		cn := fmt.Sprintf("%c%03d", 'A'+rune(rand.Intn(26)), rand.Intn(1000))
		if _, exists := seenCourseNumbers[cn]; !exists {
			seenCourseNumbers[cn] = struct{}{}
			courseNumbers = append(courseNumbers, cn)
		}
	}

	sectionIDs := uniqueNumericStrings(5, config.NumberOfSections)

	now := time.Now()
	dueDates := []string{
		now.AddDate(0, 0, 7).Format("Monday 2 January 2006"),
		now.AddDate(0, 1, 0).Format("Monday 2 January 2006"),
	}

	sections := make([]Section, config.NumberOfSections)
	for i := range sections {

		my_section := course_information[rand.Intn(len(course_information))]
		my_section.SectionID = sectionIDs[i]
		my_section.Instructor = instructorUIDs[rand.Intn(len(instructorUIDs))]
		my_section.CourseType = "default"
		my_section.GradesDue = dueDates[rand.Intn(len(dueDates))]
		sections[i] = my_section

	}

	return sections
}

func SaveGeneratedSections(sections []Section) {

	f, err := os.Create("sections.csv")
	if err != nil {
		log.Fatalf("failed to create sections.csv: %v", err)
	}
	defer f.Close()

	w := csv.NewWriter(f)
	if err := w.Write([]string{"section_id", "course_number", "course_instructor", "course_title", "course_type", "grades_due"}); err != nil {
		log.Fatalf("failed to write csv header: %v", err)
	}
	for _, s := range sections {
		if err := w.Write([]string{s.SectionID, s.CourseNumber, s.Instructor, s.CourseTitle, s.CourseType, s.GradesDue}); err != nil {
			log.Fatalf("failed to write csv row: %v", err)
		}
	}
	w.Flush()
	if err := w.Error(); err != nil {
		log.Fatalf("csv flush error: %v", err)
	}

	fmt.Printf("Generated %d sections to sections.csv\n", len(sections))
}

func GenerateInstructorAssignmentData(users []User, sections []Section) []InstructorsSections {
	instructorUIDs := make([]string, 0)
	for _, u := range users {
		if u.Status == "Instructor" {
			instructorUIDs = append(instructorUIDs, u.UID)
		}
	}
	if len(instructorUIDs) == 0 {
		log.Fatal("no users with Status \"Instructor\" found")
	}

	assignments := make([]InstructorsSections, len(sections))
	for i, s := range sections {
		assignments[i] = InstructorsSections{
			InstructorID: instructorUIDs[i%len(instructorUIDs)],
			SectionID:    s.SectionID,
		}
	}
	return assignments
}

func SaveInstructorsSections(assignments []InstructorsSections) {
	f, err := os.Create("instructors_sections.csv")
	if err != nil {
		log.Fatalf("failed to create instructors_sections.csv: %v", err)
	}
	defer f.Close()

	w := csv.NewWriter(f)
	if err := w.Write([]string{"uid", "section_id"}); err != nil {
		log.Fatalf("failed to write csv header: %v", err)
	}
	for _, a := range assignments {
		if err := w.Write([]string{a.InstructorID, a.SectionID}); err != nil {
			log.Fatalf("failed to write csv row: %v", err)
		}
	}
	w.Flush()
	if err := w.Error(); err != nil {
		log.Fatalf("csv flush error: %v", err)
	}

	fmt.Printf("Generated %d instructor assignments to instructors_sections.csv\n", len(assignments))
}

type SectionEnrollment struct {
	SectionID string `json:"section_id"`
	UID       string `json:"uid"`
}

func GenerateSectionEnrollmentData(users []User, sections []Section, config Config) []SectionEnrollment {
	if config.EnrollmentsPerStudent > len(sections) {
		log.Fatalf("enrollments_per_student (%d) exceeds number of sections (%d)", config.EnrollmentsPerStudent, len(sections))
	}

	enrollments := make([]SectionEnrollment, 0, len(users)*config.EnrollmentsPerStudent)
	for _, u := range users {
		// Shuffle a copy of section indices and take the first EnrollmentsPerStudent
		indices := rand.Perm(len(sections))
		for _, idx := range indices[:config.EnrollmentsPerStudent] {
			enrollments = append(enrollments, SectionEnrollment{
				SectionID: sections[idx].SectionID,
				UID:       u.UID,
			})
		}
	}
	return enrollments
}

func SaveGeneratedSectionEnrollments(enrollments []SectionEnrollment) {
	f, err := os.Create("section_enrollments.csv")
	if err != nil {
		log.Fatalf("failed to create section_enrollments.csv: %v", err)
	}
	defer f.Close()

	w := csv.NewWriter(f)
	if err := w.Write([]string{"section_id", "uid"}); err != nil {
		log.Fatalf("failed to write csv header: %v", err)
	}
	for _, e := range enrollments {
		if err := w.Write([]string{e.SectionID, e.UID}); err != nil {
			log.Fatalf("failed to write csv row: %v", err)
		}
	}
	w.Flush()
	if err := w.Error(); err != nil {
		log.Fatalf("csv flush error: %v", err)
	}

	fmt.Printf("Generated %d section enrollments to section_enrollments.csv\n", len(enrollments))
}

func main() {
	data, err := os.ReadFile("config.json")
	if err != nil {
		log.Fatalf("failed to read config.json: %v", err)
	}

	var config Config
	if err := json.Unmarshal(data, &config); err != nil {
		log.Fatalf("failed to parse config.json: %v", err)
	}

	total := 0
	for _, v := range config.PercentStatus {
		total += v
	}
	if total != 100 {
		log.Fatalf("percent_status values must total 100, got %d", total)
	}

	generated_users := GenerateUserData(config)
	SaveGeneratedUsers(generated_users)

	generated_sections := GenerateSectionData(config, generated_users)
	SaveGeneratedSections(generated_sections)

	generated_assignments := GenerateInstructorAssignmentData(generated_users, generated_sections)
	SaveInstructorsSections(generated_assignments)

	generated_enrollments := GenerateSectionEnrollmentData(generated_users, generated_sections, config)
	SaveGeneratedSectionEnrollments(generated_enrollments)

}

// uniqueNumericStrings generates n unique zero-padded numeric strings of the given digit length.
func uniqueNumericStrings(digits, n int) []string {
	max := 1
	for i := 0; i < digits; i++ {
		max *= 10
	}
	if n > max {
		log.Fatalf("cannot generate %d unique %d-digit strings (max %d)", n, digits, max)
	}

	seen := make(map[int]struct{}, n)
	results := make([]string, 0, n)
	format := fmt.Sprintf("%%0%dd", digits)
	for len(results) < n {
		v := rand.Intn(max)
		if _, exists := seen[v]; !exists {
			seen[v] = struct{}{}
			results = append(results, fmt.Sprintf(format, v))
		}
	}
	return results
}