package controllers

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"net"
	"net/http"
	"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/postcard"
	"git.golem15.com/golem15/summercms/wire"
	"gorm.io/gorm"
)

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)
					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)
			return
		}
		if user.DeletedAt.Valid {
			if err := gdb.WithContext(ctx).Unscoped().Model(user).Update("deleted_at", nil).Error; err != nil {
				writeOpaque500(w)
				return
			}
			sendTemplate(ctx, app, mailName(ctx, user, "golem15.user::mail.reactivate"), user.Email)
		}
		if err := classes.CheckAndRecordLogin(ctx, gdb, user, ip, true); err != nil {
			if classes.IsLoginRejected(err) {
				writeInvalidLogin(w)
				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
		}
		wire.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
			}
		}
		wire.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
		}
		wire.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 == "" {
			wire.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 {
			wire.WriteJSON(w, http.StatusUnauthorized, map[string]any{
				"error": "Could not refresh token",
				"msg":   err.Error(),
			})
			return
		}
		wire.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) {
		wire.WriteJSON(w, http.StatusOK, map[string]any{
			"success":   true,
			"providers": wire.Slice([]any{}),
		})
	}
}

// Register is filled in by the registration task. The route is declared now.
func Register(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		writeOpaque500(w)
	}
}

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) {
	name, surname := "", ""
	if user.Name != nil {
		name = *user.Name
	}
	if user.Surname != nil {
		surname = *user.Surname
	}
	payload := map[string]any{
		"id":                    user.ID,
		"name":                  name,
		"surname":               surname,
		"email":                 user.Email,
		"is_activated":          user.IsActivated,
		"permissions":           []string{},
		"avatar":                nil,
		"avatar_url":            nil,
		"has_avatar":            false,
		"marketing_consent":     user.MarketingConsent,
		"groups":                map[string]string{},
		"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,
	}
	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) {
	if app == nil || to == "" {
		return
	}
	mailer, ok := app.Lookup[postcard.Mailer]()
	if !ok || mailer == nil {
		return
	}
	_ = mailer.Send(ctx, postcard.Message{Template: template, To: []string{to}})
}

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 writeInvalidLogin(w http.ResponseWriter) {
	wire.WriteJSON(w, http.StatusUnauthorized, map[string]any{"error": true, "message": invalidLoginBody})
}

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

func writeOpaque500(w http.ResponseWriter) {
	wire.WriteOpaque500(w)
}