// Onboarding flow: signup → profile → plan → checkout
//
// Session is a signed cookie containing the in-progress onboarding state.
// HMAC-SHA256 keyed with ONBOARDING_SECRET (auto-generated if missing).

package main

import (
	"crypto/hmac"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"
	"time"
)

const onboardingCookieName = "clv_onb"
const onboardingCookieMaxAge = 3600 // 1 hour to complete the flow

// onboardingSecret is the HMAC key for signing the session cookie.
// Loaded from env or generated at startup (sessions are short-lived so
// regeneration on restart only kicks people back to step 1).
var onboardingSecret []byte

func initOnboardingSecret() {
	if s := readEnv("ONBOARDING_SECRET"); s != "" {
		onboardingSecret = []byte(s)
		return
	}
	buf := make([]byte, 32)
	rand.Read(buf)
	onboardingSecret = buf
	log.Println("onboarding: generated ephemeral session secret (set ONBOARDING_SECRET to persist)")
}

// onboardingState is what we carry across pages in the signed cookie.
// Kept small — Paddle billing fields are written to corporate.db immediately.
type onboardingState struct {
	Email      string `json:"email"`
	Provider   string `json:"provider"` // "email", "google", "apple", "meta"
	CustomerID string `json:"customer_id,omitempty"` // ctm_xxx after step 1
	AddressID  string `json:"address_id,omitempty"`  // add_xxx after step 2
	CreatedAt  int64  `json:"created_at"`
}

func setOnboardingCookie(w http.ResponseWriter, st *onboardingState) {
	st.CreatedAt = time.Now().Unix()
	payload, _ := json.Marshal(st)
	encoded := base64.RawURLEncoding.EncodeToString(payload)
	mac := hmac.New(sha256.New, onboardingSecret)
	mac.Write([]byte(encoded))
	sig := hex.EncodeToString(mac.Sum(nil))
	value := encoded + "." + sig

	http.SetCookie(w, &http.Cookie{
		Name:     onboardingCookieName,
		Value:    value,
		Path:     "/",
		MaxAge:   onboardingCookieMaxAge,
		HttpOnly: true,
		Secure:   !devMode,
		SameSite: http.SameSiteLaxMode,
	})
}

func getOnboardingState(r *http.Request) *onboardingState {
	c, err := r.Cookie(onboardingCookieName)
	if err != nil {
		return nil
	}
	parts := strings.SplitN(c.Value, ".", 2)
	if len(parts) != 2 {
		return nil
	}
	mac := hmac.New(sha256.New, onboardingSecret)
	mac.Write([]byte(parts[0]))
	expected := hex.EncodeToString(mac.Sum(nil))
	if !hmac.Equal([]byte(expected), []byte(parts[1])) {
		return nil
	}
	payload, err := base64.RawURLEncoding.DecodeString(parts[0])
	if err != nil {
		return nil
	}
	var st onboardingState
	if err := json.Unmarshal(payload, &st); err != nil {
		return nil
	}
	// Expire stale sessions
	if time.Now().Unix()-st.CreatedAt > onboardingCookieMaxAge {
		return nil
	}
	return &st
}

func clearOnboardingCookie(w http.ResponseWriter) {
	http.SetCookie(w, &http.Cookie{
		Name:     onboardingCookieName,
		Value:    "",
		Path:     "/",
		MaxAge:   -1,
		HttpOnly: true,
		Secure:   !devMode,
		SameSite: http.SameSiteLaxMode,
	})
}

// readEnv is a thin wrapper to make testing easier later.
func readEnv(key string) string {
	return os.Getenv(key)
}

// --- handlers ---

// handleSignupStart: GET /signup — renders the email/social choice page.
// (Wired in main.go via the existing /signup route.)

// handleSignupEmail: POST /onboarding/email — user typed an email address.
// Creates the customer in DB+Paddle, sets the cookie, redirects to /onboarding/profile.
func handleSignupEmail(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "method not allowed", 405)
		return
	}
	if corpDB == nil {
		jsonError(w, "onboarding offline (corporate.db not available)", 503)
		return
	}
	var req struct {
		Email string `json:"email"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonError(w, "invalid json", 400)
		return
	}
	email := strings.ToLower(strings.TrimSpace(req.Email))
	if !looksLikeEmail(email) {
		jsonError(w, "invalid email", 400)
		return
	}

	// If a customer with this email exists, reuse it (resume onboarding).
	ourID, _, found := findCustomerByEmail(email)
	if !found {
		res := tlwCreateCustomer(map[string]interface{}{"email": email})
		if res.Err != nil {
			log.Printf("onboarding: tlwCreateCustomer failed for %s: %v", email, res.Err)
			jsonError(w, "could not create account", 500)
			return
		}
		ourID = res.OurID
	}

	setOnboardingCookie(w, &onboardingState{
		Email:      email,
		Provider:   "email",
		CustomerID: ourID,
	})
	w.Header().Set("Content-Type", "application/json")
	w.Write([]byte(`{"ok":true,"next":"/onboarding/profile"}`))
}

// handleOnboardingProfile: POST /onboarding/profile — name + address.
// Updates the customer name and creates the billing address.
func handleOnboardingProfile(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "method not allowed", 405)
		return
	}
	st := getOnboardingState(r)
	if st == nil || st.CustomerID == "" {
		jsonError(w, "session expired", 401)
		return
	}
	var req struct {
		Name        string `json:"name"`
		Address1    string `json:"address1"`
		City        string `json:"city"`
		Region      string `json:"region"`
		Zip         string `json:"zip"`
		CountryCode string `json:"country_code"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonError(w, "invalid json", 400)
		return
	}
	if req.Name == "" || req.CountryCode == "" {
		jsonError(w, "name and country are required", 400)
		return
	}
	if len(req.CountryCode) != 2 {
		jsonError(w, "country must be a 2-letter ISO code", 400)
		return
	}

	// Update the customer name in our DB. (Paddle update is best-effort:
	// the customer was created with email only; we PATCH it on the next
	// /customers/{id} call. For now, just update locally — Paddle picks up
	// the name when we send the address creation.)
	corpDB.Exec(`UPDATE customers SET name = ?, updated_at = ? WHERE id = ?`,
		req.Name, time.Now().Unix(), st.CustomerID)

	// Create the address via TLW (writes to DB + Paddle).
	addr := map[string]interface{}{
		"customer_id":  st.CustomerID,
		"country_code": strings.ToUpper(req.CountryCode),
	}
	if req.City != "" {
		addr["city"] = req.City
	}
	if req.Region != "" {
		addr["region"] = req.Region
	}
	if req.Zip != "" {
		addr["zip_code"] = req.Zip
	}
	if req.Address1 != "" {
		addr["description"] = req.Address1
	}
	res := tlwCreateAddress(addr)
	if res.Err != nil {
		log.Printf("onboarding: tlwCreateAddress failed: %v", res.Err)
		jsonError(w, "could not save address", 500)
		return
	}

	st.AddressID = res.OurID
	setOnboardingCookie(w, st)
	w.Header().Set("Content-Type", "application/json")
	w.Write([]byte(`{"ok":true,"next":"/onboarding/plan"}`))
}

// handleOnboardingPlan: POST /onboarding/plan — user picked a subscription tier.
// Looks up the Paddle price ID, creates a transaction, returns the checkout URL.
func handleOnboardingPlan(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "method not allowed", 405)
		return
	}
	st := getOnboardingState(r)
	if st == nil || st.CustomerID == "" || st.AddressID == "" {
		jsonError(w, "session expired", 401)
		return
	}
	var req struct {
		Plan string `json:"plan"` // e.g. "personal", "family", "pro"
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonError(w, "invalid json", 400)
		return
	}
	priceID := lookupPriceID(req.Plan, "usd")
	if priceID == "" {
		jsonError(w, "unknown plan", 400)
		return
	}

	// Need the Paddle IDs for both customer and address to create a transaction.
	var paddleCust, paddleAddr string
	corpDB.QueryRow(`SELECT COALESCE(paddle_id,'') FROM customers WHERE id = ?`, st.CustomerID).Scan(&paddleCust)
	corpDB.QueryRow(`SELECT COALESCE(paddle_id,'') FROM addresses WHERE id = ?`, st.AddressID).Scan(&paddleAddr)
	if paddleCust == "" || paddleAddr == "" {
		// Paddle wasn't configured / sync failed. Don't fail — let the user
		// reach the success page; the operator can retry the sync from admin.
		clearOnboardingCookie(w)
		w.Header().Set("Content-Type", "application/json")
		w.Write([]byte(`{"ok":true,"checkout_url":"/onboarding/done?pending=1"}`))
		return
	}

	_, checkoutURL, err := tlwCreateTransaction(paddleCust, paddleAddr, priceID)
	if err != nil {
		log.Printf("onboarding: tlwCreateTransaction failed: %v", err)
		jsonError(w, "could not create checkout", 500)
		return
	}

	// Onboarding state is no longer needed — Paddle takes over.
	clearOnboardingCookie(w)
	w.Header().Set("Content-Type", "application/json")
	resp := map[string]interface{}{"ok": true, "checkout_url": checkoutURL}
	json.NewEncoder(w).Encode(resp)
}

// lookupPriceID maps a plan name to a Paddle price ID. Hardcoded for now —
// will move to DB-backed config later. Mirrors admin/paddle_checkout.go.
func lookupPriceID(plan, currency string) string {
	key := strings.ToLower(plan) + "_yearly_" + strings.ToLower(currency)
	priceIDs := map[string]string{
		"personal_yearly_usd": "pri_01knejm7ft2ska5r4qff2gm9r4",
		"family_yearly_usd":   "pri_01knejm7xs9kqt0vn61dx6q808",
		"pro_yearly_usd":      "pri_01knejm8djq4p63rmsxze7by58",
	}
	return priceIDs[key]
}

func looksLikeEmail(s string) bool {
	if len(s) < 3 || len(s) > 254 {
		return false
	}
	at := strings.Index(s, "@")
	if at < 1 || at == len(s)-1 {
		return false
	}
	if !strings.Contains(s[at:], ".") {
		return false
	}
	return true
}

func jsonError(w http.ResponseWriter, msg string, status int) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	fmt.Fprintf(w, `{"ok":false,"error":%q}`, msg)
}