package api

import (
	"encoding/json"
	"net/http"
	"time"

	"github.com/archivmail/internal/audit"
	"github.com/archivmail/internal/mailer"
	"github.com/archivmail/internal/tokenstore"
	"github.com/archivmail/internal/userstore"
)

// handleSignup creates an inactive account and sends a verification email.
// POST /api/auth/signup  (PROJ-28)
func (s *Server) handleSignup(w http.ResponseWriter, r *http.Request) {
	if !s.mailer.IsConfigured() {
		writeError(w, http.StatusServiceUnavailable, "E-Mail-Versand nicht konfiguriert (smtp_out)")
		return
	}

	var body struct {
		Username string `json:"username"`
		Email    string `json:"email"`
		Password string `json:"password"`
		Invite   string `json:"invite"` // optional invite token
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body")
		return
	}
	if body.Username == "" || body.Email == "" || body.Password == "" {
		writeError(w, http.StatusBadRequest, "username, email and password required")
		return
	}
	if len(body.Password) < 8 {
		writeError(w, http.StatusBadRequest, "password must be at least 8 characters")
		return
	}

	req := userstore.CreateUserRequest{
		Username: body.Username,
		Email:    body.Email,
		Password: body.Password,
		Role:     userstore.RoleUser,
	}

	// If invite token provided, attach tenant
	if body.Invite != "" && s.tokenStore != nil {
		tok, err := s.tokenStore.Peek(r.Context(), tokenstore.TypeInvite, body.Invite)
		if err != nil {
			writeError(w, http.StatusBadRequest, "ungültiger oder abgelaufener Einladungslink")
			return
		}
		req.TenantID = tok.TenantID
	}

	u, err := s.users.CreateInactive(req)
	if err != nil {
		// Avoid info-leakage: same response for duplicate email/username
		writeJSON(w, http.StatusOK, map[string]string{"message": "Wenn die E-Mail-Adresse verfügbar ist, wurde eine Bestätigungs-E-Mail gesendet."})
		return
	}

	// Generate verification token
	uid := u.ID
	token, err := s.tokenStore.Create(r.Context(), tokenstore.TypeVerify, &uid, nil, 24*time.Hour)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "token error")
		return
	}

	// If invite token was used — consume it now
	if body.Invite != "" {
		_, _ = s.tokenStore.Use(r.Context(), tokenstore.TypeInvite, body.Invite)
	}

	// Send verification email
	go func() {
		html := mailer.VerifyEmailHTML(s.fqdn, token, u.Username)
		txt := mailer.VerifyEmailText(s.fqdn, token, u.Username)
		_ = s.mailer.Send(u.Email, "archivmail – E-Mail bestätigen", html, txt)
	}()

	if s.audlog != nil {
		s.audlog.Log(audit.Entry{
			EventType: "signup",
			Username:  u.Username,
			IPAddress: s.remoteIP(r),
			Success:   true,
		})
	}

	writeJSON(w, http.StatusOK, map[string]string{"message": "Wenn die E-Mail-Adresse verfügbar ist, wurde eine Bestätigungs-E-Mail gesendet."})
}

// handleVerifyEmail activates an account via a verification token.
// GET /api/auth/verify?token=...  (PROJ-28)
func (s *Server) handleVerifyEmail(w http.ResponseWriter, r *http.Request) {
	plain := r.URL.Query().Get("token")
	if plain == "" {
		writeError(w, http.StatusBadRequest, "token required")
		return
	}

	tok, err := s.tokenStore.Use(r.Context(), tokenstore.TypeVerify, plain)
	if err != nil {
		writeError(w, http.StatusBadRequest, "ungültiger oder abgelaufener Link")
		return
	}

	if tok.UserID == nil {
		writeError(w, http.StatusBadRequest, "invalid token")
		return
	}

	if err := s.users.Activate(r.Context(), *tok.UserID); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	if s.audlog != nil {
		s.audlog.Log(audit.Entry{
			EventType: "email_verified",
			IPAddress: s.remoteIP(r),
			Success:   true,
		})
	}

	writeJSON(w, http.StatusOK, map[string]string{"message": "E-Mail-Adresse bestätigt. Du kannst dich jetzt anmelden."})
}

// handleForgotPassword sends a password-reset email.
// POST /api/auth/forgot-password  (PROJ-28)
func (s *Server) handleForgotPassword(w http.ResponseWriter, r *http.Request) {
	// Always respond with same message to avoid info-leakage
	const msg = "Falls ein Account mit dieser E-Mail existiert, wurde ein Reset-Link gesendet."

	if !s.mailer.IsConfigured() {
		writeError(w, http.StatusServiceUnavailable, "E-Mail-Versand nicht konfiguriert")
		return
	}

	var body struct {
		Email string `json:"email"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil || body.Email == "" {
		writeJSON(w, http.StatusOK, map[string]string{"message": msg})
		return
	}

	u, err := s.users.GetByEmail(r.Context(), body.Email)
	if err != nil || u == nil {
		writeJSON(w, http.StatusOK, map[string]string{"message": msg})
		return
	}

	// LDAP users cannot reset password here
	if u.Source != "local" {
		writeJSON(w, http.StatusOK, map[string]string{"message": msg})
		return
	}

	uid := u.ID
	token, err := s.tokenStore.Create(r.Context(), tokenstore.TypeReset, &uid, nil, 1*time.Hour)
	if err != nil {
		writeJSON(w, http.StatusOK, map[string]string{"message": msg})
		return
	}

	go func() {
		html := mailer.ResetPasswordHTML(s.fqdn, token, u.Username)
		txt := mailer.ResetPasswordText(s.fqdn, token, u.Username)
		_ = s.mailer.Send(u.Email, "archivmail – Passwort zurücksetzen", html, txt)
	}()

	if s.audlog != nil {
		s.audlog.Log(audit.Entry{
			EventType: "password_reset_requested",
			Username:  u.Username,
			IPAddress: s.remoteIP(r),
			Success:   true,
		})
	}

	writeJSON(w, http.StatusOK, map[string]string{"message": msg})
}

// handleResetPassword sets a new password via a reset token.
// POST /api/auth/reset-password  (PROJ-28)
func (s *Server) handleResetPassword(w http.ResponseWriter, r *http.Request) {
	var body struct {
		Token    string `json:"token"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body")
		return
	}
	if body.Token == "" || body.Password == "" {
		writeError(w, http.StatusBadRequest, "token and password required")
		return
	}
	if len(body.Password) < 8 {
		writeError(w, http.StatusBadRequest, "password must be at least 8 characters")
		return
	}

	tok, err := s.tokenStore.Use(r.Context(), tokenstore.TypeReset, body.Token)
	if err != nil {
		writeError(w, http.StatusBadRequest, "ungültiger oder abgelaufener Link")
		return
	}

	if tok.UserID == nil {
		writeError(w, http.StatusBadRequest, "invalid token")
		return
	}

	if err := s.users.SetPassword(r.Context(), *tok.UserID, body.Password); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	if s.audlog != nil {
		s.audlog.Log(audit.Entry{
			EventType: "password_reset_done",
			IPAddress: s.remoteIP(r),
			Success:   true,
		})
	}

	writeJSON(w, http.StatusOK, map[string]string{"message": "Passwort erfolgreich zurückgesetzt."})
}