package controllers

import (
	"context"
	"crypto/md5"
	"crypto/rand"
	_ "embed"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"net"
	"net/http"
	"net/url"
	"sort"
	"strconv"
	"strings"
	"time"

	"git.golem15.com/golem15/fonoteka/plugins/golem15/user/classes"
	"git.golem15.com/golem15/fonoteka/plugins/golem15/user/models"
	"git.golem15.com/golem15/summercms/backpack"
	"git.golem15.com/golem15/summercms/bouncer"
	"git.golem15.com/golem15/summercms/compass"
	"git.golem15.com/golem15/summercms/lagoon"
	"git.golem15.com/golem15/summercms/lagoon/attach"
	"git.golem15.com/golem15/summercms/phrasebook"
	"git.golem15.com/golem15/summercms/postcard"
	"git.golem15.com/golem15/summercms/surf"
	"git.golem15.com/golem15/summercms/wire"
	"gocloud.dev/blob"
	"gorm.io/gorm"
)

const avatarMaxBytes = 4_096_000

//go:embed winter_error_page.html
var winterErrorPage []byte

var errNoAvatar = errors.New("golem15.user: no avatar")

const invalidLoginBody = "Invalid email or password"

// Login authenticates email and password and returns a JWT plus the user payload.
func Login(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, secret, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		email := strField(fields, "email")
		password := strField(fields, "password")
		ctx := classes.ContextWithThrottle(r.Context(), app)
		user, err := classes.LookupByEmail(ctx, gdb, email)
		if err != nil {
			writeOpaque500(w)
			return
		}
		ip := remoteIP(r)
		if user != nil {
			if err := classes.RejectIfThrottled(ctx, gdb, user, ip); err != nil {
				if classes.IsLoginRejected(err) {
					writeInvalidLogin(w, r, app)
					return
				}
				writeOpaque500(w)
				return
			}
		}
		if user == nil || !bouncer.CheckPassword(user.Password, password) {
			if user != nil {
				if err := classes.CheckAndRecordLogin(ctx, gdb, user, ip, false); err != nil && !classes.IsLoginRejected(err) {
					writeOpaque500(w)
					return
				}
			}
			writeInvalidLogin(w, r, app)
			return
		}
		if user.DeletedAt.Valid {
			if err := gdb.WithContext(ctx).Unscoped().Model(user).Update("deleted_at", nil).Error; err != nil {
				writeOpaque500(w)
				return
			}
			sendTemplateVars(ctx, app, mailName(ctx, user, "golem15.user::mail.reactivate"), user.Email, mailVars(displayName(user), "", ""))
		}
		if err := classes.CheckAndRecordLogin(ctx, gdb, user, ip, true); err != nil {
			if classes.IsLoginRejected(err) {
				writeInvalidLogin(w, r, app)
				return
			}
			writeOpaque500(w)
			return
		}
		cost := 10
		if app.Config != nil && app.Config.Int("golem15.user.password.bcrypt_cost") > 0 {
			cost = app.Config.Int("golem15.user.password.bcrypt_cost")
		}
		if bouncer.NeedsRehash(user.Password, cost) {
			if next, err := bouncer.HashPassword(cost, password); err == nil {
				_ = gdb.WithContext(ctx).Model(user).Update("password", next).Error
			}
		}
		token, err := mintFor(app, secret, user, requestURL(r))
		if err != nil {
			writeOpaque500(w)
			return
		}
		payload, err := apiArray(ctx, app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"token": token, "user": payload})
	}
}

// Logout forever-blacklists the presented bearer token.
func Logout(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		_, secret, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		raw := bearerToken(r)
		sub, _, exp, jti, err := bouncer.VerifyClaims(raw, secret)
		if err != nil || jti == "" {
			writeUnauthorized(w)
			return
		}
		id, err := strconv.ParseUint(sub, 10, 64)
		if err != nil || id == 0 {
			writeUnauthorized(w)
			return
		}
		principal, err := (classes.GormUsers{App: app}).FindByID(r.Context(), uint(id))
		if err != nil || principal == nil {
			writeUnauthorized(w)
			return
		}
		if bl, ok := app.Lookup[bouncer.BlacklistStore](); ok && bl != nil {
			if err := bl.Add(r.Context(), jti, exp, time.Now()); err != nil {
				writeOpaque500(w)
				return
			}
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": "Logged out"})
	}
}

// Fetch returns the authenticated user's payload.
func Fetch(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		user, ok := authenticate(w, r, app)
		if !ok {
			return
		}
		payload, err := apiArray(r.Context(), app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"user": payload})
	}
}

// Refresh slides a still-refreshable bearer token.
func Refresh(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		_, secret, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		raw := bearerToken(r)
		if raw == "" {
			writeJSON(w, http.StatusUnauthorized, map[string]any{"error": "Token not found"})
			return
		}
		var bl bouncer.BlacklistStore
		if store, ok := app.Lookup[bouncer.BlacklistStore](); ok {
			bl = store
		}
		next, err := bouncer.Refresh(secret, raw, refreshTTL(app), bl, blacklistGrace(app), requestURL(r))
		if err != nil {
			writeJSON(w, http.StatusUnauthorized, map[string]any{
				"error": "Could not refresh token",
				"msg":   err.Error(),
			})
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"token": next})
	}
}

// OAuthProviders reports that this app configures no social providers.
func OAuthProviders(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		writeJSON(w, http.StatusOK, map[string]any{
			"success":   true,
			"providers": wire.Slice([]any{}),
		})
	}
}

const forgotPasswordBody = "If that email exists, a reset link has been sent."

// ForgotPassword always returns the same 200 body. A real account also gets a reset mail.
func ForgotPassword(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, _, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		errs, err := lagoon.Validate(r.Context(), gdb, models.User{}, map[string]string{
			"email": "required|email|between:6,255",
		}, fields, appTranslator(app))
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeValidation(w, errs)
			return
		}
		ctx := codeContext(r.Context(), app)
		user, err := classes.LookupByEmail(ctx, gdb, strField(fields, "email"))
		if err != nil {
			slog.Default().Error("golem15.user: forgot-password lookup", "err", err)
			writeJSON(w, http.StatusOK, map[string]any{"message": forgotPasswordBody})
			return
		}
		if user != nil {
			code, err := classes.IssueResetCode(ctx, gdb, user)
			if err != nil {
				slog.Default().Error("golem15.user: issue reset code", "err", err)
			} else {
				packed := strconv.FormatUint(uint64(user.ID), 10) + "!" + code
				sendTemplateVars(ctx, app, mailName(ctx, user, "golem15.user::mail.restore"), user.Email, mailVars(displayName(user), resetLink(app, user.ID, code), packed))
			}
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": forgotPasswordBody})
	}
}

// ResetPassword consumes a "{id}!{code}" reset code and stores a new password.
func ResetPassword(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, _, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		errs, err := lagoon.Validate(r.Context(), gdb, models.User{}, map[string]string{
			"code":     "required",
			"password": "required|between:8,255|confirmed",
		}, fields, appTranslator(app))
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeValidation(w, errs)
			return
		}
		id, code, ok := splitCode(strField(fields, "code"))
		if !ok {
			writeJSON(w, http.StatusUnprocessableEntity, map[string]any{"error": "Invalid reset code"})
			return
		}
		user, verified := classes.VerifyResetCode(codeContext(r.Context(), app), gdb, id, code)
		if !verified || user == nil {
			writeJSON(w, http.StatusUnprocessableEntity, map[string]any{"error": "Invalid or expired reset code"})
			return
		}
		cost := 10
		if app.Config != nil && app.Config.Int("golem15.user.password.bcrypt_cost") > 0 {
			cost = app.Config.Int("golem15.user.password.bcrypt_cost")
		}
		hashed, err := bouncer.HashPassword(cost, strField(fields, "password"))
		if err != nil {
			writeOpaque500(w)
			return
		}
		now := time.Now()
		if err := gdb.WithContext(r.Context()).Model(&models.User{}).Where("id = ?", user.ID).Updates(map[string]any{
			"password":           hashed,
			"tokens_valid_after": now,
		}).Error; err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": "Password has been reset"})
	}
}

// Activate calls attempt-activation and always returns the user payload.
// A wrong code leaves is_activated unchanged, matching the PHP handler's missing check.
func Activate(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, _, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		user, ok := authenticate(w, r, app)
		if !ok {
			return
		}
		if user.IsActivated {
			writeWinterErrorPage(w)
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		_, _ = classes.VerifyActivationCode(codeContext(r.Context(), app), gdb, user.ID, strField(fields, "code"))
		if err := gdb.WithContext(r.Context()).Where("id = ?", user.ID).Take(user).Error; err != nil {
			writeOpaque500(w)
			return
		}
		payload, err := apiArray(r.Context(), app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"user": payload})
	}
}

// ActivateByCode activates from a public "{id}!{code}" value and mints a token.
func ActivateByCode(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, secret, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		errs, err := lagoon.Validate(r.Context(), gdb, models.User{}, map[string]string{
			"code": "required",
		}, fields, appTranslator(app))
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeValidation(w, errs)
			return
		}
		id, code, ok := splitCode(strField(fields, "code"))
		if !ok {
			writeJSON(w, http.StatusUnprocessableEntity, map[string]any{"error": "Invalid activation code"})
			return
		}
		already, err := classes.IsAlreadyActivated(codeContext(r.Context(), app), gdb, id)
		if err != nil {
			writeOpaque500(w)
			return
		}
		if already {
			writeWinterErrorPage(w)
			return
		}
		user, verified := classes.VerifyActivationCode(codeContext(r.Context(), app), gdb, id, code)
		if !verified || user == nil {
			writeJSON(w, http.StatusUnprocessableEntity, map[string]any{"error": "This activation link is invalid or has expired"})
			return
		}
		token, err := mintFor(app, secret, user, requestURL(r))
		if err != nil {
			writeOpaque500(w)
			return
		}
		payload, err := apiArray(r.Context(), app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{
			"message": "Account activated",
			"token":   token,
			"user":    payload,
		})
	}
}

// Update changes the signed-in user's name, surname, and email.
func Update(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, _, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		user, ok := authenticate(w, r, app)
		if !ok {
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		errs, err := lagoon.Validate(r.Context(), gdb, user, map[string]string{
			"name":    "required|between:2,255",
			"surname": "required|between:2,255",
			"email":   "required|between:6,255|email|unique:users",
		}, fields, appTranslator(app))
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeValidation(w, errs)
			return
		}
		name := strField(fields, "name")
		surname := strField(fields, "surname")
		if err := gdb.WithContext(r.Context()).Model(user).Updates(map[string]any{
			"name":    name,
			"surname": surname,
			"email":   strField(fields, "email"),
		}).Error; err != nil {
			writeOpaque500(w)
			return
		}
		user.Name = &name
		user.Surname = &surname
		user.Email = strField(fields, "email")
		payload, err := apiArray(r.Context(), app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": "Profile updated", "user": payload})
	}
}

// ChangePassword replaces a self-set password and invalidates older tokens.
// The token that made this call stays valid.
func ChangePassword(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, secret, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		raw := bearerToken(r)
		sub, iat, _, _, err := bouncer.VerifyClaims(raw, secret)
		if err != nil {
			writeUnauthorized(w)
			return
		}
		var bl bouncer.BlacklistStore
		if store, ok := app.Lookup[bouncer.BlacklistStore](); ok {
			bl = store
		}
		if _, err := bouncer.NewJWTGuard(secret, classes.GormUsers{App: app}, bl).Authenticate(r); err != nil {
			writeUnauthorized(w)
			return
		}
		id, err := strconv.ParseUint(sub, 10, 64)
		if err != nil || id == 0 {
			writeUnauthorized(w)
			return
		}
		var user models.User
		if err := gdb.WithContext(r.Context()).Where("id = ?", id).Take(&user).Error; err != nil {
			writeUnauthorized(w)
			return
		}
		if !user.HasSelfSetPassword {
			slog.Default().Error("golem15.user: change-password requires a self-set password", "user_id", user.ID)
			writeOpaque500(w)
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		minLen := 8
		if app.Config != nil && app.Config.Int("golem15.user.password.min_length") > 0 {
			minLen = app.Config.Int("golem15.user.password.min_length")
		}
		errs, err := lagoon.Validate(r.Context(), gdb, &user, map[string]string{
			"current_password": "required",
			"password":         "required|between:" + strconv.Itoa(minLen) + ",255|confirmed|different:current_password",
		}, fields, appTranslator(app))
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeValidation(w, errs)
			return
		}
		current := strField(fields, "current_password")
		if !bouncer.CheckPassword(user.Password, current) {
			msg := accountMessage(r.Context(), app, "invalid_login", invalidLoginBody)
			writeJSON(w, http.StatusUnprocessableEntity, map[string]any{
				"error": msg,
				"errors": map[string][]string{
					"current_password": {msg},
				},
			})
			return
		}
		cost := 10
		if app.Config != nil && app.Config.Int("golem15.user.password.bcrypt_cost") > 0 {
			cost = app.Config.Int("golem15.user.password.bcrypt_cost")
		}
		next := strField(fields, "password")
		hashed, err := bouncer.HashPassword(cost, next)
		if err != nil {
			writeOpaque500(w)
			return
		}
		cutoff := iat.Add(-time.Second)
		if err := gdb.WithContext(r.Context()).Model(&user).Updates(map[string]any{
			"password":              hashed,
			"must_change_password":  false,
			"has_self_set_password": true,
			"tokens_valid_after":    cutoff,
		}).Error; err != nil {
			writeOpaque500(w)
			return
		}
		user.MustChangePassword = false
		user.HasSelfSetPassword = true
		user.TokensValidAfter = &cutoff
		payload, err := apiArray(r.Context(), app, &user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": "Password changed", "user": payload})
	}
}

// MarketingConsent sets the signed-in user's marketing_consent flag.
func MarketingConsent(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, _, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		user, ok := authenticate(w, r, app)
		if !ok {
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		errs, err := lagoon.Validate(r.Context(), gdb, user, map[string]string{
			"marketing_consent": "required|boolean",
		}, fields, appTranslator(app))
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeValidation(w, errs)
			return
		}
		consent := laravelBool(fields["marketing_consent"])
		if err := gdb.WithContext(r.Context()).Model(user).Update("marketing_consent", consent).Error; err != nil {
			writeOpaque500(w)
			return
		}
		user.MarketingConsent = consent
		payload, err := apiArray(r.Context(), app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": "Marketing consent updated", "user": payload})
	}
}

// Register creates an account and follows activate_mode: auto, user, or admin.
func Register(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, secret, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		allow, throttle, mode, require := registrationSettings(app)
		ip := surf.ClientIP(r, surf.TrustedProxies(appConfig(app)))
		if !allow {
			writeSafe500(w, app, "Registrations are currently disabled.")
			return
		}
		if throttle && ip != "" && registrationsFromIP(r.Context(), gdb, ip) >= 3 {
			writeSafe500(w, app, "Registration is throttled. Please try again later.")
			return
		}
		fields, err := readFields(r)
		if err != nil {
			writeOpaque500(w)
			return
		}
		if _, exists := fields["password_confirmation"]; !exists {
			fields["password_confirmation"] = fields["password"]
		}
		rules := (models.User{}).Rules()
		errs, err := lagoon.Validate(r.Context(), gdb, models.User{}, rules, fields, appTranslator(app))
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeJSON(w, http.StatusUnprocessableEntity, map[string]any{
				"error":  firstValidationMessage(errs),
				"errors": errs,
			})
			return
		}
		password := strField(fields, "password")
		cost := 10
		if app.Config != nil && app.Config.Int("golem15.user.password.bcrypt_cost") > 0 {
			cost = app.Config.Int("golem15.user.password.bcrypt_cost")
		}
		hashed, err := bouncer.HashPassword(cost, password)
		if err != nil {
			writeOpaque500(w)
			return
		}
		fields["password"] = hashed
		if ip != "" {
			fields["created_ip_address"] = ip
			fields["last_ip_address"] = ip
		}
		user := &models.User{}
		production := app.Config == nil || !app.Config.Bool("app.debug")
		if err := lagoon.Fill(user, user.Fillable(), fields, production); err != nil {
			writeOpaque500(w)
			return
		}
		user.HasSelfSetPassword = true
		if mode == "auto" {
			user.IsActivated = true
			now := time.Now()
			user.ActivatedAt = &now
		}
		if err := gdb.WithContext(r.Context()).Create(user).Error; err != nil {
			writeOpaque500(w)
			return
		}
		if app.Events != nil {
			_ = app.Events.Fire(r.Context(), &classes.RegisterEvent{User: user})
		}
		ctx := r.Context()
		if mode == "user" {
			vars := mailVars(displayName(user), "", "")
			code, err := classes.IssueActivationCode(ctx, gdb, user)
			if err != nil {
				slog.Default().Error("golem15.user: issue activation code", "err", err)
			} else {
				packed := strconv.FormatUint(uint64(user.ID), 10) + "!" + code
				vars = mailVars(displayName(user), activationLink(app, user.ID, code), packed)
			}
			sendTemplateVars(ctx, app, mailName(ctx, user, "golem15.user::mail.activate"), user.Email, vars)
			writeJSON(w, http.StatusOK, map[string]any{"message": "Activation email sent"})
			return
		}
		if mode == "auto" || !require {
			token, err := mintFor(app, secret, user, requestURL(r))
			if err != nil {
				writeOpaque500(w)
				return
			}
			payload, err := apiArray(ctx, app, user)
			if err != nil {
				writeOpaque500(w)
				return
			}
			writeJSON(w, http.StatusOK, map[string]any{"token": token, "user": payload})
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{})
	}
}

func registrationSettings(app *backpack.App) (allow, throttle bool, mode string, require bool) {
	allow, throttle, require = true, true, true
	mode = "auto"
	if app == nil || app.Config == nil {
		return allow, throttle, mode, require
	}
	if app.Config.Has("golem15.user.registration.allow_registration") {
		allow = app.Config.Bool("golem15.user.registration.allow_registration")
	}
	if app.Config.Has("golem15.user.registration.use_register_throttle") {
		throttle = app.Config.Bool("golem15.user.registration.use_register_throttle")
	}
	if app.Config.Has("golem15.user.activation.activate_mode") {
		if s := strings.TrimSpace(app.Config.String("golem15.user.activation.activate_mode")); s != "" {
			mode = s
		}
	}
	if app.Config.Has("golem15.user.activation.require_activation") {
		require = app.Config.Bool("golem15.user.activation.require_activation")
	}
	return allow, throttle, mode, require
}

func registrationsFromIP(ctx context.Context, gdb *gorm.DB, ip string) int64 {
	var n int64
	_ = gdb.WithContext(ctx).Model(&models.User{}).
		Where("created_ip_address = ? AND created_at > ?", ip, time.Now().Add(-60*time.Minute)).
		Count(&n).Error
	return n
}

func firstValidationMessage(errs map[string][]string) string {
	keys := make([]string, 0, len(errs))
	for k := range errs {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	if len(keys) == 0 || len(errs[keys[0]]) == 0 {
		return "The given data was invalid."
	}
	return errs[keys[0]][0]
}

func writeSafe500(w http.ResponseWriter, app *backpack.App, message string) {
	if app != nil && app.Config != nil && app.Config.Bool("app.debug") {
		writeJSON(w, http.StatusInternalServerError, map[string]any{"error": message})
		return
	}
	writeJSON(w, http.StatusInternalServerError, map[string]any{"error": "Internal server error"})
}

func appConfig(app *backpack.App) *compass.Config {
	if app == nil {
		return nil
	}
	return app.Config
}

func authenticate(w http.ResponseWriter, r *http.Request, app *backpack.App) (*models.User, bool) {
	gdb, secret, ok := sessionDeps(w, app)
	if !ok {
		return nil, false
	}
	raw := bearerToken(r)
	sub, _, _, _, err := bouncer.VerifyClaims(raw, secret)
	if err != nil {
		writeUnauthorized(w)
		return nil, false
	}
	id, err := strconv.ParseUint(sub, 10, 64)
	if err != nil || id == 0 {
		writeUnauthorized(w)
		return nil, false
	}
	var bl bouncer.BlacklistStore
	if store, ok := app.Lookup[bouncer.BlacklistStore](); ok {
		bl = store
	}
	if _, err := bouncer.NewJWTGuard(secret, classes.GormUsers{App: app}, bl).Authenticate(r); err != nil {
		writeUnauthorized(w)
		return nil, false
	}
	var user models.User
	if err := gdb.WithContext(r.Context()).Where("id = ?", id).Take(&user).Error; err != nil {
		writeUnauthorized(w)
		return nil, false
	}
	return &user, true
}

func sessionDeps(w http.ResponseWriter, app *backpack.App) (*gorm.DB, string, bool) {
	if app == nil {
		writeOpaque500(w)
		return nil, "", false
	}
	gdb, ok := app.Lookup[*gorm.DB]()
	if !ok || gdb == nil {
		writeOpaque500(w)
		return nil, "", false
	}
	secret, err := classes.JWTSecret(app)
	if err != nil {
		writeOpaque500(w)
		return nil, "", false
	}
	return gdb, secret, true
}

func apiArray(ctx context.Context, app *backpack.App, user *models.User) (map[string]any, error) {
	payload := map[string]any{
		"id":                    user.ID,
		"name":                  user.Name,
		"surname":               user.Surname,
		"email":                 user.Email,
		"is_activated":          user.IsActivated,
		"permissions":           nil,
		"avatar":                gravatarURL(user.Email, 25),
		"avatar_url":            gravatarURL(user.Email, 128),
		"has_avatar":            false,
		"marketing_consent":     user.MarketingConsent,
		"groups":                []any{},
		"role":                  nil,
		"is_onboarded":          user.IsOnboarded,
		"has_self_set_password": user.HasSelfSetPassword,
		// feedback_widget_hidden stays false until a feedback plugin listens.
		"feedback_widget_hidden": false,
	}
	applyAvatar(ctx, app, user, payload)
	if app != nil && app.Events != nil {
		extra, err := app.Events.Collect(ctx, &classes.GetApiArrayEvent{User: user})
		if err != nil {
			return nil, err
		}
		for k, v := range extra {
			payload[k] = v
		}
	}
	return payload, nil
}

func mintFor(app *backpack.App, secret string, user *models.User, issuer string) (string, error) {
	ttl := 60 * time.Minute
	if app != nil && app.Config != nil && app.Config.Int("golem15.user.jwt.ttl") > 0 {
		ttl = time.Duration(app.Config.Int("golem15.user.jwt.ttl")) * time.Minute
	}
	token, _, err := bouncer.Mint(secret, strconv.FormatUint(uint64(user.ID), 10), issuer, ttl)
	return token, err
}

func refreshTTL(app *backpack.App) time.Duration {
	mins := 20160
	if app != nil && app.Config != nil && app.Config.Int("golem15.user.jwt.refresh_ttl") > 0 {
		mins = app.Config.Int("golem15.user.jwt.refresh_ttl")
	}
	return time.Duration(mins) * time.Minute
}

func blacklistGrace(app *backpack.App) time.Duration {
	secs := 0
	if app != nil && app.Config != nil && app.Config.Has("golem15.user.jwt.blacklist_grace") {
		secs = app.Config.Int("golem15.user.jwt.blacklist_grace")
	}
	return time.Duration(secs) * time.Second
}

func mailName(ctx context.Context, user *models.User, base string) string {
	return classes.MailTemplate(base, classes.ResolveMailLocale(ctx, user))
}

func sendTemplate(ctx context.Context, app *backpack.App, template, to string) {
	sendTemplateVars(ctx, app, template, to, nil)
}

func displayName(user *models.User) string {
	if user == nil || user.Name == nil {
		return ""
	}
	return *user.Name
}

func mailVars(name, link, code string) map[string]any {
	return map[string]any{
		"name": name, "Name": name,
		"link": link, "Link": link,
		"code": code, "Code": code,
	}
}

func sendTemplateVars(ctx context.Context, app *backpack.App, template, to string, vars map[string]any) {
	if app == nil || to == "" {
		return
	}
	mailer, ok := app.Lookup[postcard.Mailer]()
	if !ok || mailer == nil {
		slog.Default().Error("golem15.user: mailer is not configured", "template", template)
		return
	}
	if err := mailer.Send(ctx, postcard.Message{Template: template, To: []string{to}, Vars: vars}); err != nil {
		slog.Default().Error("golem15.user: send mail", "template", template, "err", err)
	}
}

func writeValidation(w http.ResponseWriter, errs map[string][]string) {
	writeJSON(w, http.StatusUnprocessableEntity, map[string]any{
		"error":  firstValidationMessage(errs),
		"errors": errs,
	})
}

func splitCode(raw string) (uint, string, bool) {
	idPart, code, ok := strings.Cut(raw, "!")
	if !ok || idPart == "" || code == "" || strings.Contains(code, "!") {
		return 0, "", false
	}
	id, err := strconv.ParseUint(idPart, 10, 64)
	if err != nil || id == 0 {
		return 0, "", false
	}
	return uint(id), code, true
}

func codeContext(ctx context.Context, app *backpack.App) context.Context {
	reset := 60 * time.Minute
	activation := 72 * time.Hour
	if app != nil && app.Config != nil {
		if n := app.Config.Int("golem15.user.activation.reset_ttl_minutes"); n > 0 {
			reset = time.Duration(n) * time.Minute
		}
		if n := app.Config.Int("golem15.user.activation.activation_ttl_hours"); n > 0 {
			activation = time.Duration(n) * time.Hour
		}
	}
	return classes.ContextWithCodeTTL(ctx, reset, activation)
}

func resetLink(app *backpack.App, id uint, code string) string {
	base := "/reset-password"
	if app != nil && app.Config != nil {
		if v := strings.TrimSpace(app.Config.String("golem15.user.reset_url_base")); v != "" {
			base = v
		} else if appURL := strings.TrimRight(strings.TrimSpace(app.Config.String("app.url")), "/"); appURL != "" {
			base = appURL + "/reset-password"
		}
	}
	q := url.Values{}
	q.Set("code", strconv.FormatUint(uint64(id), 10)+"!"+code)
	return base + "?" + q.Encode()
}

func activationLink(app *backpack.App, id uint, code string) string {
	base := "/activate"
	if app != nil && app.Config != nil {
		if v := strings.TrimSpace(app.Config.String("golem15.user.activation_url_base")); v != "" {
			base = v
		} else if appURL := strings.TrimRight(strings.TrimSpace(app.Config.String("app.url")), "/"); appURL != "" {
			base = appURL + "/activate"
		}
	}
	q := url.Values{}
	q.Set("code", strconv.FormatUint(uint64(id), 10)+"!"+code)
	return base + "?" + q.Encode()
}

func readFields(r *http.Request) (map[string]any, error) {
	ct := r.Header.Get("Content-Type")
	if strings.Contains(ct, "application/json") {
		var fields map[string]any
		dec := json.NewDecoder(r.Body)
		if err := dec.Decode(&fields); err != nil && !errors.Is(err, io.EOF) {
			return nil, err
		}
		if fields == nil {
			fields = map[string]any{}
		}
		return fields, nil
	}
	if err := r.ParseForm(); err != nil {
		return nil, err
	}
	fields := map[string]any{}
	for k, v := range r.Form {
		if len(v) > 0 {
			fields[k] = v[0]
		}
	}
	return fields, nil
}

func strField(fields map[string]any, key string) string {
	v, ok := fields[key]
	if !ok || v == nil {
		return ""
	}
	s, ok := v.(string)
	if !ok {
		return strings.TrimSpace(jsonNumber(v))
	}
	return strings.TrimSpace(s)
}

func jsonNumber(v any) string {
	switch n := v.(type) {
	case float64:
		return strconv.FormatFloat(n, 'f', -1, 64)
	default:
		return ""
	}
}

func bearerToken(r *http.Request) string {
	h := strings.TrimSpace(r.Header.Get("Authorization"))
	token, ok := strings.CutPrefix(h, "Bearer ")
	token = strings.TrimSpace(token)
	if !ok || token == "" {
		return ""
	}
	return token
}

func requestURL(r *http.Request) string {
	scheme := "http"
	if r.TLS != nil {
		scheme = "https"
	}
	if proto := strings.TrimSpace(r.Header.Get("X-Forwarded-Proto")); proto != "" {
		scheme = proto
	}
	return scheme + "://" + r.Host + r.URL.Path
}

func remoteIP(r *http.Request) string {
	if r.RemoteAddr == "" {
		return ""
	}
	host, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil {
		return r.RemoteAddr
	}
	return host
}

func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Cache-Control", "no-cache, private")
	wire.WriteJSON(w, status, v)
}

func writeInvalidLogin(w http.ResponseWriter, r *http.Request, app *backpack.App) {
	writeJSON(w, http.StatusUnauthorized, map[string]any{
		"error":   true,
		"message": accountMessage(r.Context(), app, "invalid_login", invalidLoginBody),
	})
}

func writeUnauthorized(w http.ResponseWriter) {
	writeJSON(w, http.StatusUnauthorized, map[string]any{"error": true, "message": "Unauthorized"})
}

func appTranslator(app *backpack.App) *phrasebook.Translator {
	if app == nil {
		return nil
	}
	tr, _ := app.Lookup[*phrasebook.Translator]()
	return tr
}

func requiredField(ctx context.Context, app *backpack.App, field string) string {
	tr := appTranslator(app)
	attr := strings.ReplaceAll(field, "_", " ")
	if tr != nil {
		s := tr.Get(ctx, "lagoon::validate.required", map[string]string{"attribute": attr})
		if s != "" && s != "lagoon::validate.required" {
			return s
		}
	}
	return "The " + attr + " field is required."
}

func accountMessage(ctx context.Context, app *backpack.App, key, fallback string) string {
	tr := appTranslator(app)
	if tr == nil {
		return fallback
	}
	s := tr.Get(ctx, "golem15.user::lang.account."+key, nil)
	if s == "" || s == "golem15.user::lang.account."+key {
		return fallback
	}
	return s
}

func writeWinterErrorPage(w http.ResponseWriter) {
	w.Header().Set("Content-Type", "text/html; charset=UTF-8")
	w.Header().Set("Cache-Control", "no-cache, private")
	w.WriteHeader(http.StatusInternalServerError)
	_, _ = w.Write(winterErrorPage)
}

func writeOpaque500(w http.ResponseWriter) {
	w.Header().Set("Cache-Control", "no-cache, private")
	wire.WriteOpaque500(w)
}

// UploadAvatar stores a sniffed image as the signed-in user's avatar.
func UploadAvatar(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, _, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		user, ok := authenticate(w, r, app)
		if !ok {
			return
		}
		if err := r.ParseMultipartForm(10 << 20); err != nil {
			writeValidation(w, map[string][]string{"avatar": {requiredField(r.Context(), app, "avatar")}})
			return
		}
		file, header, err := r.FormFile("avatar")
		if err != nil {
			writeValidation(w, map[string][]string{"avatar": {requiredField(r.Context(), app, "avatar")}})
			return
		}
		defer file.Close()
		data, err := io.ReadAll(file)
		if err != nil {
			writeOpaque500(w)
			return
		}
		sniffed := http.DetectContentType(data)
		if i := strings.IndexByte(sniffed, ';'); i >= 0 {
			sniffed = strings.TrimSpace(sniffed[:i])
		}
		ext, allowed := avatarExt(sniffed)
		if !allowed {
			writeValidation(w, map[string][]string{
				"avatar": {"The avatar must be a file of type: jpeg, jpg, png, webp, gif."},
			})
			return
		}
		size := int64(len(data))
		if header != nil && header.Size > size {
			size = header.Size
		}
		if size > avatarMaxBytes {
			writeValidation(w, map[string][]string{
				"avatar": {"The avatar must not be greater than 4000 kilobytes."},
			})
			return
		}
		bucket, ok := app.Lookup[*blob.Bucket]()
		if !ok || bucket == nil {
			slog.Default().Error("golem15.user: avatar bucket is not configured")
			writeOpaque500(w)
			return
		}
		if err := deleteAvatar(r.Context(), app, gdb, user); err != nil && !errors.Is(err, errNoAvatar) {
			writeOpaque500(w)
			return
		}
		raw := make([]byte, 16)
		if _, err := rand.Read(raw); err != nil {
			writeOpaque500(w)
			return
		}
		diskName := hex.EncodeToString(raw) + "." + ext
		wr, err := bucket.NewWriter(r.Context(), attach.BlobKey(diskName), &blob.WriterOptions{ContentType: sniffed})
		if err != nil {
			writeOpaque500(w)
			return
		}
		if _, err := wr.Write(data); err != nil {
			_ = wr.Close()
			writeOpaque500(w)
			return
		}
		if err := wr.Close(); err != nil {
			writeOpaque500(w)
			return
		}
		filename := "avatar." + ext
		if header != nil && strings.TrimSpace(header.Filename) != "" {
			filename = header.Filename
		}
		row := attach.File{
			DiskName:       diskName,
			FileName:       filename,
			FileSize:       int64(len(data)),
			ContentType:    sniffed,
			Field:          "avatar",
			AttachmentID:   strconv.FormatUint(uint64(user.ID), 10),
			AttachmentType: user.MorphName(),
		}
		if err := gdb.WithContext(r.Context()).Create(&row).Error; err != nil {
			writeOpaque500(w)
			return
		}
		payload, err := apiArray(r.Context(), app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": "Avatar updated", "user": payload})
	}
}

// RemoveAvatar deletes the signed-in user's display picture.
func RemoveAvatar(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		gdb, _, ok := sessionDeps(w, app)
		if !ok {
			return
		}
		user, ok := authenticate(w, r, app)
		if !ok {
			return
		}
		if err := deleteAvatar(r.Context(), app, gdb, user); err != nil {
			if errors.Is(err, errNoAvatar) {
				writeValidation(w, map[string][]string{
					"avatar": {accountMessage(r.Context(), app, "no_avatar", "Your account has no display picture to remove.")},
				})
				return
			}
			writeOpaque500(w)
			return
		}
		payload, err := apiArray(r.Context(), app, user)
		if err != nil {
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"message": "Avatar removed", "user": payload})
	}
}

func deleteAvatar(ctx context.Context, app *backpack.App, gdb *gorm.DB, user *models.User) error {
	id := strconv.FormatUint(uint64(user.ID), 10)
	var n int64
	if err := gdb.WithContext(ctx).Model(&attach.File{}).
		Where("attachment_type = ? AND attachment_id = ? AND field = ?", user.MorphName(), id, "avatar").
		Count(&n).Error; err != nil {
		return err
	}
	if n == 0 {
		return errNoAvatar
	}
	var keys []string
	err := gdb.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		return attach.DeleteForOwner(tx, user, id, func(blobKeys []string) error {
			keys = append(keys, blobKeys...)
			return nil
		})
	})
	if err != nil {
		return err
	}
	bucket, ok := app.Lookup[*blob.Bucket]()
	if !ok || bucket == nil || len(keys) == 0 {
		return nil
	}
	return attach.DeleteKeys(ctx, bucket, keys)
}

func gravatarURL(email string, size int) string {
	sum := md5.Sum([]byte(strings.ToLower(strings.TrimSpace(email))))
	return fmt.Sprintf("//www.gravatar.com/avatar/%x?s=%d&d=mm", sum, size)
}

func laravelBool(v any) bool {
	switch t := v.(type) {
	case bool:
		return t
	case string:
		s := strings.ToLower(strings.TrimSpace(t))
		return s == "1" || s == "true"
	case float64:
		return t != 0
	case int:
		return t != 0
	default:
		s := strings.ToLower(strings.TrimSpace(fmt.Sprint(v)))
		return s == "1" || s == "true"
	}
}

func applyAvatar(ctx context.Context, app *backpack.App, user *models.User, payload map[string]any) {
	if app == nil || user == nil || user.ID == 0 {
		return
	}
	gdb, ok := app.Lookup[*gorm.DB]()
	if !ok || gdb == nil {
		return
	}
	var f attach.File
	err := gdb.WithContext(ctx).
		Where("attachment_type = ? AND attachment_id = ? AND field = ?", user.MorphName(), strconv.FormatUint(uint64(user.ID), 10), "avatar").
		Take(&f).Error
	if err != nil {
		return
	}
	payload["has_avatar"] = true
	payload["avatar"] = f.DiskName
	bucket, ok := app.Lookup[*blob.Bucket]()
	if !ok || bucket == nil {
		return
	}
	url, err := f.Thumb(ctx, bucket, 128, 128, "auto")
	if err != nil {
		slog.Default().Error("golem15.user: avatar thumb", "err", err)
		payload["avatar_url"] = "/" + attach.BlobKey(f.DiskName)
		return
	}
	payload["avatar_url"] = url
}

func avatarExt(mime string) (string, bool) {
	switch mime {
	case "image/jpeg":
		return "jpg", true
	case "image/png":
		return "png", true
	case "image/gif":
		return "gif", true
	case "image/webp":
		return "webp", true
	default:
		return "", false
	}
}