package handlers

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"strconv"
	"strings"
)

func (a *App) handleResendReset(w http.ResponseWriter, r *http.Request) {
	username := r.FormValue("username")
	if username == "" {
		if email := r.FormValue("email"); email != "" {
			username = sanitizeUsername(email)
		}
	}
	if username == "" {
		respondResendError(w, http.StatusBadRequest, "email or username required", 0)
		return
	}

	if ok, retryAfter := resendRateLimiter.allow(username); !ok {
		w.Header().Set("Retry-After", strconv.Itoa(retryAfter))
		respondResendError(w, http.StatusTooManyRequests,
			"please wait before requesting another email", retryAfter)
		return
	}

	if err := a.triggerPasswordReset(r, username); err != nil {
		log.Printf("resend-reset: failed for %s: %v", username, err)
		respondResendError(w, http.StatusInternalServerError, "failed to send email", 0)
		return
	}
	resendRateLimiter.record(username)
	log.Printf("resend-reset: password reset email sent for %s", username)
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]any{
		"ok":      true,
		"message": "Password setup email sent. Check your inbox.",
	})
}

func respondResendError(w http.ResponseWriter, code int, msg string, retryAfter int) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	body := map[string]any{"ok": false, "error": msg}
	if retryAfter > 0 {
		body["retry_after_seconds"] = retryAfter
	}
	json.NewEncoder(w).Encode(body)
}

func clientIP(r *http.Request) string {
	if s := r.Header.Get("X-Forwarded-For"); s != "" {
		if idx := strings.Index(s, ","); idx > 0 {
			return strings.TrimSpace(s[:idx])
		}
		return strings.TrimSpace(s)
	}
	if s := r.Header.Get("X-Real-IP"); s != "" {
		return s
	}
	if host, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
		return host
	}
	return r.RemoteAddr
}

func (a *App) triggerPasswordReset(r *http.Request, username string) error {
	url := a.cfg.AutheliaInternalURL + "/api/reset-password/identity/start"
	body, _ := json.Marshal(map[string]string{"username": username})

	log.Printf("triggerPasswordReset: POST %s for user %q", url, username)

	req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("authelia reset build request: %w", err)
	}

	externalHost := strings.TrimPrefix(strings.TrimPrefix(a.cfg.AutheliaURL, "https://"), "http://")
	proto := "http"
	if strings.HasPrefix(a.cfg.AutheliaURL, "https://") {
		proto = "https"
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("X-Forwarded-Host", externalHost)
	req.Header.Set("X-Forwarded-Proto", proto)
	req.Header.Set("X-Forwarded-For", clientIP(r))

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return fmt.Errorf("authelia reset request: %w", err)
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
	log.Printf("triggerPasswordReset: status=%d body=%s", resp.StatusCode, string(respBody))

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("authelia reset returned %d: %s", resp.StatusCode, string(respBody))
	}

	var result struct {
		Status string `json:"status"`
	}
	if json.Unmarshal(respBody, &result) == nil && result.Status == "KO" {
		return fmt.Errorf("authelia reset rejected: %s", string(respBody))
	}

	return nil
}