package main

import (
	"crypto/sha256"
	"crypto/subtle"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"os/user"
	"runtime"
	"strconv"
	"strings"
	"time"

	"github.com/ddworken/hishtory/shared"
	_ "github.com/lib/pq"
	"github.com/rodaine/table"
	"gorm.io/driver/postgres"

	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
)

const (
	// This password is for the postgres cluster running in my k8s cluster that is not publicly accessible. Some day I'll migrate it out of the code and rotate the password, but until then, this is fine.
	// TODO: Migrate this
	PostgresDb = "postgresql://postgres:O74Ji4735C@postgres-postgresql.default.svc.cluster.local:5432/hishtory?sslmode=disable"
)

var (
	GLOBAL_DB      *gorm.DB
	ReleaseVersion string = "UNKNOWN"
)

type UsageData struct {
	UserId            string    `json:"user_id" gorm:"not null; uniqueIndex:usageDataUniqueIndex"`
	DeviceId          string    `json:"device_id"  gorm:"not null; uniqueIndex:usageDataUniqueIndex"`
	LastUsed          time.Time `json:"last_used"`
	LastIp            string    `json:"last_ip"`
	NumEntriesHandled int       `json:"num_entries_handled"`
	LastQueried       time.Time `json:"last_queried"`
	NumQueries        int       `json:"num_queries"`
}

func getRequiredQueryParam(r *http.Request, queryParam string) string {
	val := r.URL.Query().Get(queryParam)
	if val == "" {
		panic(fmt.Sprintf("request to %s is missing required query param=%#v", r.URL, queryParam))
	}
	return val
}

func updateUsageData(r *http.Request, userId, deviceId string, numEntriesHandled int, isQuery bool) {
	var usageData []UsageData
	GLOBAL_DB.Where("user_id = ? AND device_id = ?", userId, deviceId).Find(&usageData)
	if len(usageData) == 0 {
		GLOBAL_DB.Create(&UsageData{UserId: userId, DeviceId: deviceId, LastUsed: time.Now(), NumEntriesHandled: numEntriesHandled})
	} else {
		GLOBAL_DB.Model(&UsageData{}).Where("user_id = ? AND device_id = ?", userId, deviceId).Update("last_used", time.Now()).Update("last_ip", getRemoteAddr(r))
		if numEntriesHandled > 0 {
			GLOBAL_DB.Exec("UPDATE usage_data SET num_entries_handled = COALESCE(num_entries_handled, 0) + ? WHERE user_id = ? AND device_id = ?", numEntriesHandled, userId, deviceId)
		}
	}
	if isQuery {
		GLOBAL_DB.Exec("UPDATE usage_data SET num_queries = COALESCE(num_queries, 0) + 1, last_queried = ? WHERE user_id = ? AND device_id = ?", time.Now(), userId, deviceId)
	}
}

func usageStatsHandler(w http.ResponseWriter, r *http.Request) {
	query := `
	SELECT 
		MIN(devices.registration_date) as registration_date, 
		COUNT(DISTINCT devices.device_id) as num_devices,
		SUM(usage_data.num_entries_handled) as num_history_entries,
		MAX(usage_data.last_used) as last_active,
		COALESCE(STRING_AGG(DISTINCT usage_data.last_ip, ' ') FILTER (WHERE usage_data.last_ip != 'Unknown'), 'Unknown')  as ip_addresses,
		COALESCE(SUM(usage_data.num_queries), 0) as num_queries,
		COALESCE(MAX(usage_data.last_queried), 'January 1, 1970') as last_queried
	FROM devices
	INNER JOIN usage_data ON devices.device_id = usage_data.device_id
	GROUP BY devices.user_id
	ORDER BY registration_date
	`
	rows, err := GLOBAL_DB.Raw(query).Rows()
	if err != nil {
		panic(err)
	}
	tbl := table.New("Registration Date", "Num Devices", "Num Entries", "Num Queries", "Last Active", "Last Query", "IPs")
	tbl.WithWriter(w)
	for rows.Next() {
		var registrationDate time.Time
		var numDevices int
		var numEntries int
		var lastUsedDate time.Time
		var ipAddresses string
		var numQueries int
		var lastQueried time.Time
		err = rows.Scan(&registrationDate, &numDevices, &numEntries, &lastUsedDate, &ipAddresses, &numQueries, &lastQueried)
		if err != nil {
			panic(err)
		}
		tbl.AddRow(registrationDate.Format("2006-01-02"), numDevices, numEntries, numQueries, lastUsedDate.Format("2006-01-02"), lastQueried.Format("2006-01-02"), ipAddresses)
	}
	tbl.Print()
}

func apiSubmitHandler(w http.ResponseWriter, r *http.Request) {
	data, err := ioutil.ReadAll(r.Body)
	if err != nil {
		panic(err)
	}
	var entries []shared.EncHistoryEntry
	err = json.Unmarshal(data, &entries)
	if err != nil {
		panic(fmt.Sprintf("body=%#v, err=%v", data, err))
	}
	fmt.Printf("apiSubmitHandler: received request containg %d EncHistoryEntry\n", len(entries))
	for _, entry := range entries {
		updateUsageData(r, entry.UserId, entry.DeviceId, 1, false)
		tx := GLOBAL_DB.Where("user_id = ?", entry.UserId)
		var devices []*shared.Device
		checkGormResult(tx.Find(&devices))
		if len(devices) == 0 {
			panic(fmt.Errorf("found no devices associated with user_id=%s, can't save history entry", entry.UserId))
		}
		fmt.Printf("apiSubmitHandler: Found %d devices\n", len(devices))
		for _, device := range devices {
			entry.DeviceId = device.DeviceId
			checkGormResult(GLOBAL_DB.Create(&entry))
		}
	}
}

func apiBootstrapHandler(w http.ResponseWriter, r *http.Request) {
	userId := getRequiredQueryParam(r, "user_id")
	deviceId := getRequiredQueryParam(r, "device_id")
	updateUsageData(r, userId, deviceId, 0, false)
	tx := GLOBAL_DB.Where("user_id = ?", userId)
	var historyEntries []*shared.EncHistoryEntry
	checkGormResult(tx.Find(&historyEntries))
	resp, err := json.Marshal(historyEntries)
	if err != nil {
		panic(err)
	}
	w.Write(resp)
}

func apiQueryHandler(w http.ResponseWriter, r *http.Request) {
	userId := getRequiredQueryParam(r, "user_id")
	deviceId := getRequiredQueryParam(r, "device_id")
	updateUsageData(r, userId, deviceId, 0, true)
	// Increment the count
	checkGormResult(GLOBAL_DB.Exec("UPDATE enc_history_entries SET read_count = read_count + 1 WHERE device_id = ?", deviceId))

	// Delete any entries that match a pending deletion request
	var deletionRequests []*shared.DeletionRequest
	checkGormResult(GLOBAL_DB.Where("destination_device_id = ? AND user_id = ?", deviceId, userId).Find(&deletionRequests))
	for _, request := range deletionRequests {
		_, err := applyDeletionRequestsToBackend(*request)
		if err != nil {
			panic(err)
		}
	}

	// Then retrieve, to avoid a race condition
	tx := GLOBAL_DB.Where("device_id = ? AND read_count < 5", deviceId)
	var historyEntries []*shared.EncHistoryEntry
	checkGormResult(tx.Find(&historyEntries))
	fmt.Printf("apiQueryHandler: Found %d entries for %s\n", len(historyEntries), r.URL)
	resp, err := json.Marshal(historyEntries)
	if err != nil {
		panic(err)
	}
	w.Write(resp)
}

func getRemoteAddr(r *http.Request) string {
	addr, ok := r.Header["X-Real-Ip"]
	if !ok || len(addr) == 0 {
		return "Unknown"
	}
	return addr[0]
}

func apiRegisterHandler(w http.ResponseWriter, r *http.Request) {
	userId := getRequiredQueryParam(r, "user_id")
	deviceId := getRequiredQueryParam(r, "device_id")
	var existingDevicesCount int64 = -1
	checkGormResult(GLOBAL_DB.Model(&shared.Device{}).Where("user_id = ?", userId).Count(&existingDevicesCount))
	fmt.Printf("apiRegisterHandler: existingDevicesCount=%d\n", existingDevicesCount)
	checkGormResult(GLOBAL_DB.Create(&shared.Device{UserId: userId, DeviceId: deviceId, RegistrationIp: getRemoteAddr(r), RegistrationDate: time.Now()}))
	if existingDevicesCount > 0 {
		checkGormResult(GLOBAL_DB.Create(&shared.DumpRequest{UserId: userId, RequestingDeviceId: deviceId, RequestTime: time.Now()}))
	}
	updateUsageData(r, userId, deviceId, 0, false)
}

func apiGetPendingDumpRequestsHandler(w http.ResponseWriter, r *http.Request) {
	userId := getRequiredQueryParam(r, "user_id")
	deviceId := getRequiredQueryParam(r, "device_id")
	var dumpRequests []*shared.DumpRequest
	// Filter out ones requested by the hishtory instance that sent this request
	checkGormResult(GLOBAL_DB.Where("user_id = ? AND requesting_device_id != ?", userId, deviceId).Find(&dumpRequests))
	respBody, err := json.Marshal(dumpRequests)
	if err != nil {
		panic(fmt.Errorf("failed to JSON marshall the dump requests: %v", err))
	}
	w.Write(respBody)
}

func apiSubmitDumpHandler(w http.ResponseWriter, r *http.Request) {
	userId := getRequiredQueryParam(r, "user_id")
	srcDeviceId := getRequiredQueryParam(r, "source_device_id")
	requestingDeviceId := getRequiredQueryParam(r, "requesting_device_id")
	data, err := ioutil.ReadAll(r.Body)
	if err != nil {
		panic(err)
	}
	var entries []shared.EncHistoryEntry
	err = json.Unmarshal(data, &entries)
	if err != nil {
		panic(fmt.Sprintf("body=%#v, err=%v", data, err))
	}
	fmt.Printf("apiSubmitDumpHandler: received request containg %d EncHistoryEntry\n", len(entries))
	err = GLOBAL_DB.Transaction(func(tx *gorm.DB) error {
		for _, entry := range entries {
			entry.DeviceId = requestingDeviceId
			if entry.UserId != userId {
				return fmt.Errorf("batch contains an entry with UserId=%#v, when the query param contained the user_id=%#v", entry.UserId, userId)
			}
			checkGormResult(tx.Create(&entry))
		}
		return nil
	})
	if err != nil {
		panic(fmt.Errorf("failed to execute transaction to add dumped DB: %v", err))
	}
	checkGormResult(GLOBAL_DB.Delete(&shared.DumpRequest{}, "user_id = ? AND requesting_device_id = ?", userId, requestingDeviceId))
	updateUsageData(r, userId, srcDeviceId, len(entries), false)
}

func apiBannerHandler(w http.ResponseWriter, r *http.Request) {
	commitHash := getRequiredQueryParam(r, "commit_hash")
	deviceId := getRequiredQueryParam(r, "device_id")
	forcedBanner := r.URL.Query().Get("forced_banner")
	fmt.Printf("apiBannerHandler: commit_hash=%#v, device_id=%#v, forced_banner=%#v\n", commitHash, deviceId, forcedBanner)
	w.Write([]byte(forcedBanner))
}

func getDeletionRequestsHandler(w http.ResponseWriter, r *http.Request) {
	userId := getRequiredQueryParam(r, "user_id")
	deviceId := getRequiredQueryParam(r, "device_id")

	// Increment the ReadCount
	checkGormResult(GLOBAL_DB.Exec("UPDATE deletion_requests SET read_count = read_count + 1 WHERE destination_device_id = ? AND user_id = ?", deviceId, userId))

	// Return all the deletion requests
	var deletionRequests []*shared.DeletionRequest
	checkGormResult(GLOBAL_DB.Where("user_id = ? AND destination_device_id = ?", userId, deviceId).Find(&deletionRequests))
	respBody, err := json.Marshal(deletionRequests)
	if err != nil {
		panic(fmt.Errorf("failed to JSON marshall the dump requests: %v", err))
	}
	w.Write(respBody)
}

func addDeletionRequestHandler(w http.ResponseWriter, r *http.Request) {
	data, err := ioutil.ReadAll(r.Body)
	if err != nil {
		panic(err)
	}
	var request shared.DeletionRequest
	err = json.Unmarshal(data, &request)
	if err != nil {
		panic(fmt.Sprintf("body=%#v, err=%v", data, err))
	}
	request.ReadCount = 0
	fmt.Printf("addDeletionRequestHandler: received request containg %d messages to be deleted\n", len(request.Messages.Ids))

	// Store the deletion request so all the devices will get it
	tx := GLOBAL_DB.Where("user_id = ?", request.UserId)
	var devices []*shared.Device
	checkGormResult(tx.Find(&devices))
	if len(devices) == 0 {
		panic(fmt.Errorf("found no devices associated with user_id=%s, can't save history entry", request.UserId))
	}
	fmt.Printf("addDeletionRequestHandler: Found %d devices\n", len(devices))
	for _, device := range devices {
		request.DestinationDeviceId = device.DeviceId
		checkGormResult(GLOBAL_DB.Create(&request))
	}

	// Also delete anything currently in the DB matching it
	numDeleted, err := applyDeletionRequestsToBackend(request)
	if err != nil {
		panic(err)
	}
	fmt.Printf("addDeletionRequestHandler: Deleted %d rows in the backend\n", numDeleted)
}

func applyDeletionRequestsToBackend(request shared.DeletionRequest) (int, error) {
	tx := GLOBAL_DB.Where("false")
	for _, message := range request.Messages.Ids {
		tx = tx.Or(GLOBAL_DB.Where("user_id = ? AND device_id = ? AND date = ?", request.UserId, message.DeviceId, message.Date))
	}
	result := tx.Delete(&shared.EncHistoryEntry{})
	checkGormResult(result)
	return int(result.RowsAffected), nil
}

func wipeDbHandler(w http.ResponseWriter, r *http.Request) {
	checkGormResult(GLOBAL_DB.Exec("DELETE FROM enc_history_entries"))
}

func isTestEnvironment() bool {
	u, err := user.Current()
	if err != nil {
		panic(err)
	}
	return os.Getenv("HISHTORY_TEST") != "" || u.Username == "david"
}

func OpenDB() (*gorm.DB, error) {
	if isTestEnvironment() {
		db, err := gorm.Open(sqlite.Open("file::memory:?cache=shared"), &gorm.Config{})
		if err != nil {
			return nil, fmt.Errorf("failed to connect to the DB: %v", err)
		}
		db.AutoMigrate(&shared.EncHistoryEntry{})
		db.AutoMigrate(&shared.Device{})
		db.AutoMigrate(&UsageData{})
		db.AutoMigrate(&shared.DumpRequest{})
		db.AutoMigrate(&shared.DeletionRequest{})
		db.Exec("PRAGMA journal_mode = WAL")
		return db, nil
	}

	db, err := gorm.Open(postgres.Open(PostgresDb), &gorm.Config{})
	if err != nil {
		return nil, fmt.Errorf("failed to connect to the DB: %v", err)
	}
	db.AutoMigrate(&shared.EncHistoryEntry{})
	db.AutoMigrate(&shared.Device{})
	db.AutoMigrate(&UsageData{})
	db.AutoMigrate(&shared.DumpRequest{})
	db.AutoMigrate(&shared.DeletionRequest{})
	return db, nil
}

func init() {
	if ReleaseVersion == "UNKNOWN" && !isTestEnvironment() {
		panic("server.go was built without a ReleaseVersion!")
	}
	InitDB()
	go runBackgroundJobs()
}

func cron() error {
	err := updateReleaseVersion()
	if err != nil {
		fmt.Println(err)
	}
	err = cleanDatabase()
	if err != nil {
		fmt.Println(err)
	}
	return nil
}

func runBackgroundJobs() {
	time.Sleep(5 * time.Second)
	for {
		err := cron()
		if err != nil {
			fmt.Printf("Cron failure: %v", err)
		}
		time.Sleep(10 * time.Minute)
	}
}

func triggerCronHandler(w http.ResponseWriter, r *http.Request) {
	err := cron()
	if err != nil {
		panic(err)
	}
}

type releaseInfo struct {
	Name string `json:"name"`
}

func updateReleaseVersion() error {
	resp, err := http.Get("https://api.github.com/repos/ddworken/hishtory/releases/latest")
	if err != nil {
		return fmt.Errorf("failed to get latest release version: %v", err)
	}
	respBody, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("failed to read github API response body: %v", err)
	}
	if resp.StatusCode == 403 && strings.Contains(string(respBody), "API rate limit exceeded for ") {
		return nil
	}
	if resp.StatusCode != 200 {
		return fmt.Errorf("failed to call github API, status_code=%d, body=%#v", resp.StatusCode, string(respBody))
	}
	var info releaseInfo
	err = json.Unmarshal(respBody, &info)
	if err != nil {
		return fmt.Errorf("failed to parse github API response: %v", err)
	}
	latestVersionTag := info.Name
	ReleaseVersion = decrementVersionIfInvalid(latestVersionTag)
	return nil
}

func decrementVersionIfInvalid(initialVersion string) string {
	// Decrements the version up to 5 times if the version doesn't have valid binaries yet.
	version := initialVersion
	for i := 0; i < 5; i++ {
		updateInfo := buildUpdateInfo(version)
		err := assertValidUpdate(updateInfo)
		if err == nil {
			fmt.Printf("Found a valid version: %v\n", version)
			return version
		}
		fmt.Printf("Found %s to be an invalid version: %v\n", version, err)
		version, err = decrementVersion(version)
		if err != nil {
			fmt.Printf("Failed to decrement version after finding the latest version was invalid: %v\n", err)
			return initialVersion
		}
	}
	fmt.Printf("Decremented the version 5 times and failed to find a valid version version number, initial version number: %v, last checked version number: %v\n", initialVersion, version)
	return initialVersion
}

func assertValidUpdate(updateInfo shared.UpdateInfo) error {
	urls := []string{updateInfo.LinuxAmd64Url, updateInfo.LinuxAmd64AttestationUrl,
		updateInfo.DarwinAmd64Url, updateInfo.DarwinAmd64UnsignedUrl, updateInfo.DarwinAmd64AttestationUrl,
		updateInfo.DarwinArm64Url, updateInfo.DarwinArm64UnsignedUrl, updateInfo.DarwinArm64AttestationUrl}
	for _, url := range urls {
		resp, err := http.Get(url)
		if err != nil {
			return fmt.Errorf("failed to retrieve URL %#v: %v", url, err)
		}
		if resp.StatusCode == 404 {
			return fmt.Errorf("URL %#v returned 404", url)
		}
	}
	return nil
}

func InitDB() {
	var err error
	GLOBAL_DB, err = OpenDB()
	if err != nil {
		panic(err)
	}
	tx, err := GLOBAL_DB.DB()
	if err != nil {
		panic(err)
	}
	err = tx.Ping()
	if err != nil {
		panic(err)
	}
}

func decrementVersion(version string) (string, error) {
	if version == "UNKNOWN" {
		return "", fmt.Errorf("cannot decrement UNKNOWN")
	}
	parts := strings.Split(version, ".")
	if len(parts) != 2 {
		return "", fmt.Errorf("invalid version: %s", version)
	}
	versionNumber, err := strconv.Atoi(parts[1])
	if err != nil {
		return "", fmt.Errorf("invalid version: %s", version)
	}
	return parts[0] + "." + strconv.Itoa(versionNumber-1), nil
}

func buildUpdateInfo(version string) shared.UpdateInfo {
	return shared.UpdateInfo{
		LinuxAmd64Url:             fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-linux-amd64", version),
		LinuxAmd64AttestationUrl:  fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-linux-amd64.intoto.jsonl", version),
		DarwinAmd64Url:            fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-darwin-amd64", version),
		DarwinAmd64UnsignedUrl:    fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-darwin-amd64-unsigned", version),
		DarwinAmd64AttestationUrl: fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-darwin-amd64.intoto.jsonl", version),
		DarwinArm64Url:            fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-darwin-arm64", version),
		DarwinArm64UnsignedUrl:    fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-darwin-arm64-unsigned", version),
		DarwinArm64AttestationUrl: fmt.Sprintf("https://github.com/ddworken/hishtory/releases/download/%s/hishtory-darwin-arm64.intoto.jsonl", version),
		Version:                   version,
	}
}

func apiDownloadHandler(w http.ResponseWriter, r *http.Request) {
	updateInfo := buildUpdateInfo(ReleaseVersion)
	resp, err := json.Marshal(updateInfo)
	if err != nil {
		panic(err)
	}
	w.Write(resp)
}

type loggedResponseData struct {
	size int
}

type loggingResponseWriter struct {
	http.ResponseWriter
	responseData *loggedResponseData
}

func (r *loggingResponseWriter) Write(b []byte) (int, error) {
	size, err := r.ResponseWriter.Write(b)
	r.responseData.size += size
	return size, err
}

func (r *loggingResponseWriter) WriteHeader(statusCode int) {
	r.ResponseWriter.WriteHeader(statusCode)
}

func withLogging(h func(http.ResponseWriter, *http.Request)) http.Handler {
	logFn := func(rw http.ResponseWriter, r *http.Request) {
		var responseData loggedResponseData
		lrw := loggingResponseWriter{
			ResponseWriter: rw,
			responseData:   &responseData,
		}
		start := time.Now()

		h(&lrw, r)

		duration := time.Since(start)
		fmt.Printf("%s %s %#v %s %s %s\n", r.RemoteAddr, r.Method, r.RequestURI, r.Header.Get("X-Hishtory-Version"), duration.String(), byteCountToString(responseData.size))
	}
	return http.HandlerFunc(logFn)
}

func byteCountToString(b int) string {
	const unit = 1000
	if b < unit {
		return fmt.Sprintf("%d B", b)
	}
	div, exp := int64(unit), 0
	for n := b / unit; n >= unit; n /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %cB", float64(b)/float64(div), "kMG"[exp])
}

func cleanDatabase() error {
	checkGormResult(GLOBAL_DB.Exec("DELETE FROM enc_history_entries WHERE read_count > 10"))
	checkGormResult(GLOBAL_DB.Exec("DELETE FROM deletion_requests WHERE read_count > 100"))
	// TODO(optimization): Clean the database by deleting entries for users that haven't been used in X amount of time
	return nil
}

func main() {
	fmt.Println("Listening on localhost:8080")
	http.Handle("/api/v1/submit", withLogging(apiSubmitHandler))
	http.Handle("/api/v1/get-dump-requests", withLogging(apiGetPendingDumpRequestsHandler))
	http.Handle("/api/v1/submit-dump", withLogging(apiSubmitDumpHandler))
	http.Handle("/api/v1/query", withLogging(apiQueryHandler))
	http.Handle("/api/v1/bootstrap", withLogging(apiBootstrapHandler))
	http.Handle("/api/v1/register", withLogging(apiRegisterHandler))
	http.Handle("/api/v1/banner", withLogging(apiBannerHandler))
	http.Handle("/api/v1/download", withLogging(apiDownloadHandler))
	http.Handle("/api/v1/trigger-cron", withLogging(triggerCronHandler))
	http.Handle("/api/v1/get-deletion-requests", withLogging(getDeletionRequestsHandler))
	http.Handle("/api/v1/add-deletion-request", withLogging(addDeletionRequestHandler))
	http.Handle("/internal/api/v1/usage-stats", withLogging(basicAuth(usageStatsHandler)))
	if isTestEnvironment() {
		http.Handle("/api/v1/wipe-db", withLogging(wipeDbHandler))
	}
	log.Fatal(http.ListenAndServe(":8080", nil))
}

func basicAuth(next http.HandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		username, password, ok := r.BasicAuth()
		if ok {
			// sha256sum of a random 32 byte hard coded password that I use for accessing the internal routes. Good luck brute forcing this :)
			unencodedHash := sha256.Sum256([]byte(password))
			passwordHash := hex.EncodeToString(unencodedHash[:])
			expectedPasswordHash := "137d125ff03808cf8306244aa9c018b570f504fdb94b3c98fd817b5a97a4bb80"

			usernameMatch := username == "ddworken"
			passwordMatch := (subtle.ConstantTimeCompare([]byte(passwordHash), []byte(expectedPasswordHash)) == 1)

			if usernameMatch && passwordMatch {
				next.ServeHTTP(w, r)
				return
			}
		}

		w.Header().Set("WWW-Authenticate", `Basic realm="restricted", charset="UTF-8"`)
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
	})
}

func checkGormResult(result *gorm.DB) {
	if result.Error != nil {
		_, filename, line, _ := runtime.Caller(1)
		panic(fmt.Sprintf("DB error at %s:%d: %v", filename, line, result.Error))
	}
}

// TODO(optimization): Maybe optimize the endpoints a bit to reduce the number of round trips required?