package controllers

import (
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"math/big"
	"strings"
	"time"

	"doormile/config"
	"doormile/constants"
	"doormile/db"
	"doormile/internal/mail"
	"doormile/internal/sms"
	"doormile/models"
	"doormile/utils"

	"github.com/gofiber/fiber/v2"
	goredis "github.com/redis/go-redis/v9"
)

// Customer authentication — §4 of the contract.
//
// A 4-digit code to a phone or an email address, and no password anywhere. This
// is deliberately NOT the miler's phone+PIN flow: /miler/verify-pin exists and
// is not reused. A PIN is a stored secret a rider sets once and a console can
// reset, which is appropriate for a fleet of known employees; a customer base is
// not that, and the previous customer PIN flow shipped a reset endpoint that
// took over any account from a phone number alone.
//
// Every response here goes in `data`, auth included. /miler/verify-pin returns
// its payload outside the envelope and that inconsistency cost the miler client
// a release to discover — it is not repeated.

const (
	cxOtpTTL     = 5 * time.Minute
	cxOtpLength  = 4
	cxResendWait = 30 * time.Second
	// cxOtpMaxVerify is attempts per issued code. Three, then the code dies —
	// a 4-digit code is 10,000 combinations and generous retries make it
	// walkable.
	cxOtpMaxVerify = 3
	// cxOtpMaxRequests is codes per identifier per hour, so an attacker cannot
	// mint fresh codes to reset the attempt counter, and a victim cannot be
	// flooded with texts.
	cxOtpMaxRequests = 5
	cxOtpRequestWin  = time.Hour

	cxAccessTTL  = time.Hour
	cxRefreshTTL = 60 * 24 * time.Hour

	// cxCustomerRoleID is role 9 across this codebase.
	cxCustomerRoleID = 9
	cxDefaultConfig  = 1001
)

// ── Identifier handling ──────────────────────────────────────────────────────

// normalizeIdentifier canonicalises what the customer typed into either an
// E.164 phone number or a lowercased email address.
//
// The app currently sends "+91 98765 43210" with spaces and is being tightened
// to send E.164; both are accepted, and both must land on the SAME stored
// value, or a customer signing in from a newer build gets a second account.
func normalizeIdentifier(raw string) (identifier, kind string, ok bool) {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return "", "", false
	}
	if strings.Contains(raw, "@") {
		email := strings.ToLower(raw)
		// Cheap structural check only. Deliverability is proven by the code
		// arriving, not by a regex.
		at := strings.Index(email, "@")
		if at < 1 || at == len(email)-1 || !strings.Contains(email[at:], ".") {
			return "", "", false
		}
		return email, "email", true
	}
	return normalizePhone(raw)
}

// normalizePhone reduces any of the shapes the app and support staff use to
// E.164 for India.
func normalizePhone(raw string) (phone, kind string, ok bool) {
	var digits strings.Builder
	plus := strings.HasPrefix(strings.TrimSpace(raw), "+")
	for _, r := range raw {
		if r >= '0' && r <= '9' {
			digits.WriteRune(r)
		}
	}
	d := digits.String()

	switch {
	case plus && len(d) >= 11 && len(d) <= 15:
		// Already international, spaces and dashes removed.
		return "+" + d, "phone", true
	case len(d) == 10:
		// Bare national number, the common case from the keypad.
		return "+91" + d, "phone", true
	case len(d) == 12 && strings.HasPrefix(d, "91"):
		return "+" + d, "phone", true
	case len(d) == 11 && strings.HasPrefix(d, "0"):
		return "+91" + d[1:], "phone", true
	}
	return "", "", false
}

// splitName turns the single name field the app collects into the first/last
// columns appcustomers already has. A one-word name keeps an empty last name
// rather than being rejected — plenty of people have one.
func splitName(full string) (first, last string) {
	full = strings.Join(strings.Fields(full), " ")
	if len([]rune(full)) < 2 {
		return "", ""
	}
	if i := strings.LastIndex(full, " "); i > 0 {
		return full[:i], full[i+1:]
	}
	return full, ""
}

func fullName(c *models.AppCustomer) string {
	return strings.TrimSpace(c.Firstname + " " + c.Lastname)
}

// renderCustomer is the one shape the customer object is returned in — from
// verify, from refresh and from /auth/me — so a cold-start session restore
// cannot disagree with what sign-in returned.
//
// email is never null. The client types it as a non-nullable String and a null
// throws in the parser; an unknown address is the empty string.
func renderCustomer(c *models.AppCustomer) fiber.Map {
	return fiber.Map{
		"id":    fmt.Sprintf("cust_%d", c.Appcustomerid),
		"name":  fullName(c),
		"phone": c.Phone,
		"email": c.Email,
	}
}

// ── OTP storage ──────────────────────────────────────────────────────────────

func cxOtpKey(id string) string      { return "cx:otp:" + id }
func cxOtpTriesKey(id string) string { return "cx:otp:" + id + ":tries" }
func cxOtpSentKey(id string) string  { return "cx:otp:" + id + ":sent" }
func cxOtpRateKey(id string) string  { return "cx:otp:" + id + ":requests" }

func cxGenerateCode() string {
	max := big.NewInt(1)
	for i := 0; i < cxOtpLength; i++ {
		max.Mul(max, big.NewInt(10))
	}
	n, err := rand.Int(rand.Reader, max)
	if err != nil {
		return ""
	}
	return fmt.Sprintf("%0*d", cxOtpLength, n.Int64())
}

// issueCxOtp mints, stores and delivers a code, enforcing both the per-hour
// request cap and the resend cooldown. Returns the seconds the client must wait
// before it may ask again — the countdown is server-driven so it can be changed
// without an app release.
func issueCxOtp(cfg *config.Config, identifier, kind string) (resendAfter int, err error) {
	if db.Rdb == nil {
		return 0, fmt.Errorf("verification service unavailable")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer cancel()

	// Cooldown first: a customer hammering Resend should be told to wait, not
	// spend one of their five hourly codes on a request that sends nothing.
	if ttl, terr := db.Rdb.TTL(ctx, cxOtpSentKey(identifier)).Result(); terr == nil && ttl > 0 {
		return int(ttl.Seconds()) + 1, errCxResendTooSoon
	}

	count, ierr := db.Rdb.Incr(ctx, cxOtpRateKey(identifier)).Result()
	if ierr == nil && count == 1 {
		db.Rdb.Expire(ctx, cxOtpRateKey(identifier), cxOtpRequestWin)
	}
	if count > cxOtpMaxRequests {
		return int(cxOtpRequestWin.Seconds()), errCxTooManyRequests
	}

	code := sms.StagingCode()
	if code == "" {
		code = cxGenerateCode()
	}
	if code == "" {
		return 0, fmt.Errorf("could not generate a verification code")
	}

	if serr := db.Rdb.Set(ctx, cxOtpKey(identifier), code, cxOtpTTL).Err(); serr != nil {
		return 0, serr
	}
	db.Rdb.Del(ctx, cxOtpTriesKey(identifier))
	db.Rdb.Set(ctx, cxOtpSentKey(identifier), "1", cxResendWait)

	if kind == "email" {
		if merr := mail.SendOTPEmail(cfg, identifier, code); merr != nil {
			utils.Warn("cx auth: failed to send OTP email", "error", merr)
			return 0, merr
		}
	} else {
		if serr := sms.SendOTP(identifier, code); serr != nil {
			utils.Warn("cx auth: failed to send OTP sms", "error", serr)
			return 0, serr
		}
	}

	return int(cxResendWait.Seconds()), nil
}

var (
	errCxResendTooSoon   = fmt.Errorf("resend too soon")
	errCxTooManyRequests = fmt.Errorf("too many requests")
)

// consumeCxOtp checks a submitted code and burns it. A code is single-use, and
// a wrong answer costs one of three attempts before the code is destroyed
// outright — otherwise a 4-digit space is walkable.
func consumeCxOtp(identifier, submitted string) bool {
	if db.Rdb == nil {
		return false
	}
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer cancel()

	stored, err := db.Rdb.Get(ctx, cxOtpKey(identifier)).Result()
	if err == goredis.Nil || err != nil {
		return false
	}
	if stored != submitted {
		tries, _ := db.Rdb.Incr(ctx, cxOtpTriesKey(identifier)).Result()
		db.Rdb.Expire(ctx, cxOtpTriesKey(identifier), cxOtpTTL)
		if tries >= cxOtpMaxVerify {
			db.Rdb.Del(ctx, cxOtpKey(identifier), cxOtpTriesKey(identifier))
		}
		return false
	}
	db.Rdb.Del(ctx, cxOtpKey(identifier), cxOtpTriesKey(identifier))
	return true
}

// ── Handlers ─────────────────────────────────────────────────────────────────

// CxRequestOtp sends a sign-in code to a phone or an email address.
//
// It answers the same way whether or not the identifier has an account. Telling
// an anonymous caller "no account found" — which the old /customer/login did —
// turns this endpoint into a directory of who is registered.
func CxRequestOtp(cfg *config.Config) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var req struct {
			Identifier string `json:"identifier"`
		}
		if err := c.BodyParser(&req); err != nil {
			return utils.CxBadRequest(c, "We could not read that request")
		}

		identifier, kind, ok := normalizeIdentifier(req.Identifier)
		if !ok {
			return utils.CxBadRequest(c, "Enter a valid phone number or email address")
		}

		resendAfter, err := issueCxOtp(cfg, identifier, kind)
		switch {
		case err == errCxResendTooSoon:
			// Not an error to the customer — they simply have to wait, and the
			// screen already renders a countdown.
			return utils.CxOK(c, fiber.Map{
				"sent":               false,
				"resendAfterSeconds": resendAfter,
				"codeLength":         cxOtpLength,
			})
		case err == errCxTooManyRequests:
			c.Set("Retry-After", fmt.Sprintf("%d", resendAfter))
			return utils.CxFail(c, fiber.StatusTooManyRequests, utils.CxErrRateLimited,
				"Too many attempts. Try again in a minute")
		case err != nil:
			utils.Error("CxRequestOtp: could not issue code", "error", err)
			return utils.CxInternal(c)
		}

		return utils.CxOK(c, fiber.Map{
			"sent":               true,
			"resendAfterSeconds": resendAfter,
			"codeLength":         cxOtpLength,
		})
	}
}

// CxSignup creates the account and sends the code in one call.
//
// An existing phone number is NOT an error: it is treated as a sign-in and a
// code is sent. The app has no "account already exists" screen, and inventing
// one here would strand a returning customer who tapped Sign up out of habit.
func CxSignup(cfg *config.Config) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var req struct {
			Name  string `json:"name"`
			Phone string `json:"phone"`
			Email string `json:"email"`
		}
		if err := c.BodyParser(&req); err != nil {
			return utils.CxBadRequest(c, "We could not read that request")
		}

		first, last := splitName(req.Name)
		if first == "" {
			return utils.CxFail(c, fiber.StatusBadRequest, utils.CxErrInvalidName, "Enter your full name")
		}

		phone, _, ok := normalizePhone(req.Phone)
		if !ok {
			return utils.CxBadRequest(c, "Enter a valid phone number")
		}

		email := strings.ToLower(strings.TrimSpace(req.Email))

		var existing models.AppCustomer
		err := db.DB.Where("phone = ?", phone).First(&existing).Error
		if err != nil {
			// New account. It is created unverified in the sense that nothing
			// is signed in yet — the token is only issued once the code comes
			// back, so an unfinished signup leaves a row and no session.
			customer := models.AppCustomer{
				Firstname: first,
				Lastname:  last,
				Phone:     phone,
				Email:     email,
				Status:    constants.CustomerStatusActive,
				Configid:  cxDefaultConfig,
			}
			if cerr := db.DB.Create(&customer).Error; cerr != nil {
				utils.Error("CxSignup: could not create customer", "error", cerr)
				return utils.CxInternal(c)
			}
		} else if existing.Status == constants.CustomerStatusBlocked {
			return utils.CxForbidden(c, "You do not have access to this")
		}

		resendAfter, ierr := issueCxOtp(cfg, phone, "phone")
		switch {
		case ierr == errCxResendTooSoon:
			return utils.CxOK(c, fiber.Map{"sent": false, "resendAfterSeconds": resendAfter})
		case ierr == errCxTooManyRequests:
			c.Set("Retry-After", fmt.Sprintf("%d", resendAfter))
			return utils.CxFail(c, fiber.StatusTooManyRequests, utils.CxErrRateLimited,
				"Too many attempts. Try again in a minute")
		case ierr != nil:
			utils.Error("CxSignup: could not issue code", "error", ierr)
			return utils.CxInternal(c)
		}

		return utils.CxOK(c, fiber.Map{"sent": true, "resendAfterSeconds": resendAfter})
	}
}

// ── PIN auth (interim — until the OTP/SMS gateway is live) ───────────────────
//
// Mirrors the miler login flow (LoginMiler / SetMilerPin / VerifyMilerPin) for
// customers: a first-time customer sets their own PIN, a returning one enters
// it. This exists because no SMS/OTP provider is plugged in yet (see
// internal/sms). The OTP endpoints above stay in place — the app can switch back
// to them the moment a gateway is live.

// validCxPin accepts exactly a 4-digit PIN, matching the app's keypad.
func validCxPin(pin string) bool {
	pin = strings.TrimSpace(pin)
	if len(pin) != cxOtpLength {
		return false
	}
	for _, r := range pin {
		if r < '0' || r > '9' {
			return false
		}
	}
	return true
}

// CxPinLogin resolves a phone number to the screen the app shows next: register
// (no account), set-PIN (account, no PIN yet) or enter-PIN (account with a PIN).
func CxPinLogin(c *fiber.Ctx) error {
	var req struct {
		Phone string `json:"phone"`
	}
	if err := c.BodyParser(&req); err != nil {
		return utils.CxBadRequest(c, "We could not read that request")
	}
	phone, _, ok := normalizePhone(req.Phone)
	if !ok {
		return utils.CxBadRequest(c, "Enter a valid phone number")
	}

	var customer models.AppCustomer
	if db.DB.Where("phone = ?", phone).First(&customer).Error != nil {
		// No account yet — the app collects a name + a new PIN on the next screen.
		return utils.CxOK(c, fiber.Map{"phone": phone, "registered": false, "pin_set": false})
	}
	if customer.Status == constants.CustomerStatusBlocked {
		return utils.CxForbidden(c, "You do not have access to this")
	}
	return utils.CxOK(c, fiber.Map{
		"phone":      phone,
		"registered": true,
		"pin_set":    customer.Loginpinhash != "",
		"name":       strings.TrimSpace(customer.Firstname + " " + customer.Lastname),
	})
}

// CxSetPin creates a customer's PIN the first time — signing up a brand-new
// phone (name required) or setting the first PIN on an account that has none. It
// refuses to overwrite an existing PIN (409), so the phone-only unauthenticated
// path here cannot take over an account that already has one. On success the
// customer is logged in immediately.
func CxSetPin(cfg *config.Config) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var req struct {
			Phone  string `json:"phone"`
			NewPin string `json:"new_pin"`
			Name   string `json:"name"`
		}
		if err := c.BodyParser(&req); err != nil {
			return utils.CxBadRequest(c, "We could not read that request")
		}
		phone, _, ok := normalizePhone(req.Phone)
		if !ok {
			return utils.CxBadRequest(c, "Enter a valid phone number")
		}
		if !validCxPin(req.NewPin) {
			return utils.CxBadRequest(c, "Your PIN must be 4 digits")
		}
		pinHash, herr := utils.HashPassword(req.NewPin)
		if herr != nil {
			utils.Error("CxSetPin: could not hash PIN", "error", herr)
			return utils.CxInternal(c)
		}

		var customer models.AppCustomer
		if db.DB.Where("phone = ?", phone).First(&customer).Error != nil {
			// New account: a name is required, same as signup.
			first, last := splitName(req.Name)
			if first == "" {
				return utils.CxFail(c, fiber.StatusBadRequest, utils.CxErrInvalidName, "Enter your full name")
			}
			customer = models.AppCustomer{
				Firstname:    first,
				Lastname:     last,
				Phone:        phone,
				Loginpinhash: pinHash,
				Status:       constants.CustomerStatusActive,
				Configid:     cxDefaultConfig,
			}
			if cerr := db.DB.Create(&customer).Error; cerr != nil {
				utils.Error("CxSetPin: could not create customer", "error", cerr)
				return utils.CxInternal(c)
			}
			return issueCxSession(c, cfg, &customer)
		}

		if customer.Status == constants.CustomerStatusBlocked {
			return utils.CxForbidden(c, "You do not have access to this")
		}
		if customer.Loginpinhash != "" {
			return utils.CxFail(c, fiber.StatusConflict, utils.CxErrPinAlreadySet, "A PIN is already set — enter it to sign in")
		}
		customer.Loginpinhash = pinHash
		if err := db.DB.Save(&customer).Error; err != nil {
			utils.Error("CxSetPin: could not set PIN", "error", err)
			return utils.CxInternal(c)
		}
		return issueCxSession(c, cfg, &customer)
	}
}

// CxVerifyPin signs a returning customer in with their PIN.
func CxVerifyPin(cfg *config.Config) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var req struct {
			Phone string `json:"phone"`
			Pin   string `json:"pin"`
		}
		if err := c.BodyParser(&req); err != nil {
			return utils.CxBadRequest(c, "We could not read that request")
		}
		phone, _, ok := normalizePhone(req.Phone)
		if !ok || strings.TrimSpace(req.Pin) == "" {
			return utils.CxBadRequest(c, "Enter your PIN")
		}

		var customer models.AppCustomer
		if db.DB.Where("phone = ?", phone).First(&customer).Error != nil {
			// Same generic message for unknown phone and wrong PIN, so this can't
			// be used to enumerate who is registered.
			return utils.CxFail(c, fiber.StatusUnauthorized, utils.CxErrInvalidPin, "That phone number or PIN is incorrect")
		}
		if customer.Status == constants.CustomerStatusBlocked {
			return utils.CxForbidden(c, "You do not have access to this")
		}
		if customer.Loginpinhash == "" {
			return utils.CxFail(c, fiber.StatusConflict, utils.CxErrPinNotSet, "No PIN set yet — create one to continue")
		}
		if !utils.CheckPasswordHash(strings.TrimSpace(req.Pin), customer.Loginpinhash) {
			return utils.CxFail(c, fiber.StatusUnauthorized, utils.CxErrInvalidPin, "That phone number or PIN is incorrect")
		}
		now := time.Now()
		customer.Lastloginat = &now
		if err := db.DB.Save(&customer).Error; err != nil {
			utils.Warn("CxVerifyPin: could not stamp last login", "error", err)
		}
		return issueCxSession(c, cfg, &customer)
	}
}

// CxVerifyOtp exchanges a code for a session.
func CxVerifyOtp(cfg *config.Config) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var req struct {
			Identifier string `json:"identifier"`
			Code       string `json:"code"`
			Name       string `json:"name"`
		}
		if err := c.BodyParser(&req); err != nil {
			return utils.CxBadRequest(c, "We could not read that request")
		}

		identifier, kind, ok := normalizeIdentifier(req.Identifier)
		if !ok || strings.TrimSpace(req.Code) == "" {
			return utils.CxBadRequest(c, "Enter the code we sent you")
		}

		if !consumeCxOtp(identifier, strings.TrimSpace(req.Code)) {
			return utils.CxFail(c, fiber.StatusUnauthorized, utils.CxErrInvalidOtp, "That code did not match")
		}

		var customer models.AppCustomer
		column := "phone"
		if kind == "email" {
			column = "email"
		}
		lookupErr := db.DB.Where(column+" = ?", identifier).First(&customer).Error

		if lookupErr != nil {
			// Verified an identifier with no account behind it. That is a
			// signup completing, and it needs a name — the account is worth
			// nothing without one and the app collects it on the same screen.
			if kind != "phone" {
				return utils.CxNotFound(c, "We could not find an account for that address")
			}
			first, last := splitName(req.Name)
			if first == "" {
				return utils.CxFail(c, fiber.StatusBadRequest, utils.CxErrInvalidName, "Enter your full name")
			}
			customer = models.AppCustomer{
				Firstname: first,
				Lastname:  last,
				Phone:     identifier,
				Status:    constants.CustomerStatusActive,
				Configid:  cxDefaultConfig,
			}
			if cerr := db.DB.Create(&customer).Error; cerr != nil {
				utils.Error("CxVerifyOtp: could not create customer", "error", cerr)
				return utils.CxInternal(c)
			}
		}

		if customer.Status == constants.CustomerStatusBlocked {
			return utils.CxForbidden(c, "You do not have access to this")
		}

		// A name supplied on a verify for an existing account that has none
		// (possible for a row created by ops or migrated in) is accepted; it is
		// never allowed to overwrite a name already on file from a request that
		// only proves possession of the phone.
		if first, last := splitName(req.Name); first != "" && customer.Firstname == "" {
			customer.Firstname, customer.Lastname = first, last
		}
		now := time.Now()
		customer.Lastloginat = &now
		if err := db.DB.Save(&customer).Error; err != nil {
			utils.Warn("CxVerifyOtp: could not stamp last login", "error", err)
		}

		return issueCxSession(c, cfg, &customer)
	}
}

// CxRefresh rotates a refresh token for a new pair.
//
// Rotation, not reuse: the presented token is revoked and a new one issued, so
// a token captured from an old device stops working the moment the real device
// refreshes. The chain is recorded via Replacedbyid, which is what makes a
// replayed old token identifiable rather than merely rejected.
func CxRefresh(cfg *config.Config) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var req struct {
			RefreshToken string `json:"refreshToken"`
		}
		if err := c.BodyParser(&req); err != nil {
			return utils.CxBadRequest(c, "We could not read that request")
		}
		presented := strings.TrimSpace(req.RefreshToken)
		if presented == "" {
			return utils.CxUnauthorized(c, "Please sign in again")
		}

		var row models.CustomerRefreshToken
		if err := db.DB.Where("tokenhash = ?", hashToken(presented)).First(&row).Error; err != nil {
			return utils.CxUnauthorized(c, "Please sign in again")
		}
		if row.Revokedat != nil {
			// A revoked token coming back means either a stale client or a
			// stolen one, and there is no way to tell them apart. Killing the
			// whole chain costs the honest customer one sign-in and costs an
			// attacker the session.
			utils.Warn("cx auth: revoked refresh token replayed — revoking the customer's sessions",
				"customer_id", row.Appcustomerid)
			revokeCxSessions(row.Appcustomerid)
			return utils.CxUnauthorized(c, "Please sign in again")
		}
		if utils.IST(row.Expiresat).Before(time.Now()) {
			return utils.CxUnauthorized(c, "Please sign in again")
		}

		var customer models.AppCustomer
		if err := db.DB.First(&customer, row.Appcustomerid).Error; err != nil {
			return utils.CxUnauthorized(c, "Please sign in again")
		}
		if customer.Status == constants.CustomerStatusBlocked {
			return utils.CxForbidden(c, "You do not have access to this")
		}

		revoked := time.Now()
		row.Revokedat = &revoked
		if err := db.DB.Save(&row).Error; err != nil {
			utils.Error("CxRefresh: could not revoke the presented token", "error", err)
			return utils.CxInternal(c)
		}

		return issueCxSession(c, cfg, &customer)
	}
}

// CxLogout revokes the session and unregisters the device's push token, so a
// signed-out phone stops receiving another person's parcel updates.
func CxLogout(c *fiber.Ctx) error {
	customerID := c.Locals("userid").(int)

	var req struct {
		RefreshToken string `json:"refreshToken"`
		DeviceToken  string `json:"deviceToken"`
	}
	_ = c.BodyParser(&req)

	now := time.Now()
	if strings.TrimSpace(req.RefreshToken) != "" {
		// A failed revoke must not answer signedOut — the 60-day refresh token
		// would stay valid while the customer believes they logged out.
		if err := db.DB.Model(&models.CustomerRefreshToken{}).
			Where("tokenhash = ? AND appcustomerid = ?", hashToken(req.RefreshToken), customerID).
			Update("revokedat", now).Error; err != nil {
			utils.Error("CxLogout: could not revoke the presented token", "customer_id", customerID, "error", err)
			return utils.CxInternal(c)
		}
	} else {
		// No token supplied — sign out everywhere rather than leave a session
		// the customer believes they ended.
		revokeCxSessions(customerID)
	}

	if strings.TrimSpace(req.DeviceToken) != "" {
		if err := db.DB.Where("appcustomerid = ? AND token = ?", customerID, req.DeviceToken).
			Delete(&models.CustomerDevice{}).Error; err != nil {
			// The session is already revoked above; a stuck device row only means a
			// stray push, so log and still report signed out rather than fail.
			utils.Warn("CxLogout: could not remove device token", "customer_id", customerID, "error", err)
		}
	}

	return utils.CxOK(c, fiber.Map{"signedOut": true})
}

// CxMe returns the signed-in customer, for cold-start session restore.
func CxMe(c *fiber.Ctx) error {
	customerID := c.Locals("userid").(int)

	var customer models.AppCustomer
	if err := db.DB.First(&customer, customerID).Error; err != nil {
		return utils.CxUnauthorized(c, "Please sign in again")
	}
	if customer.Status == constants.CustomerStatusBlocked {
		return utils.CxForbidden(c, "You do not have access to this")
	}
	return utils.CxOK(c, renderCustomer(&customer))
}

// ── Session issuing ──────────────────────────────────────────────────────────

// issueCxSession mints the access/refresh pair and answers in the shape verify
// and refresh both promise.
func issueCxSession(c *fiber.Ctx, cfg *config.Config, customer *models.AppCustomer) error {
	// The JWT carries tenantid like every other token in this system. B2C
	// bookings are not attributed to a tenant yet (that is an open business
	// decision, not something to guess), so it is 0 here — but the claim is
	// present, and every customer read is scoped by appcustomerid regardless.
	access, err := utils.GenerateTokenWithTTL(
		customer.Appcustomerid, customer.Phone, cxCustomerRoleID, 0,
		customer.Configid, cfg.JWTSecret, cxAccessTTL)
	if err != nil {
		utils.Error("issueCxSession: could not mint access token", "error", err)
		return utils.CxInternal(c)
	}

	refresh, err := newRefreshToken()
	if err != nil {
		utils.Error("issueCxSession: could not mint refresh token", "error", err)
		return utils.CxInternal(c)
	}
	row := models.CustomerRefreshToken{
		Appcustomerid: customer.Appcustomerid,
		Tokenhash:     hashToken(refresh),
		Expiresat:     utils.DBNow().Add(cxRefreshTTL),
	}
	if err := db.DB.Create(&row).Error; err != nil {
		utils.Error("issueCxSession: could not store refresh token", "error", err)
		return utils.CxInternal(c)
	}

	return utils.CxOK(c, fiber.Map{
		"accessToken":  access,
		"refreshToken": refresh,
		"expiresIn":    int(cxAccessTTL.Seconds()),
		"customer":     renderCustomer(customer),
	})
}

// newRefreshToken returns 32 bytes of entropy, hex encoded. Long enough that
// guessing is not a threat model.
func newRefreshToken() (string, error) {
	b := make([]byte, 32)
	if _, err := rand.Read(b); err != nil {
		return "", err
	}
	return hex.EncodeToString(b), nil
}

// hashToken is what actually lands in the database. A refresh token is a
// bearer credential valid for sixty days; storing it in plaintext would make a
// database read equivalent to sixty days of account access.
func hashToken(token string) string {
	sum := sha256.Sum256([]byte(token))
	return hex.EncodeToString(sum[:])
}

func revokeCxSessions(customerID int) {
	if err := db.DB.Model(&models.CustomerRefreshToken{}).
		Where("appcustomerid = ? AND revokedat IS NULL", customerID).
		Update("revokedat", time.Now()).Error; err != nil {
		utils.Error("revokeCxSessions: failed", "customer_id", customerID, "error", err)
	}
}

// joinNonEmpty builds a display line from the parts that actually exist, so a
// missing landmark does not leave ", , " in the middle of an address.
func joinNonEmpty(sep string, parts ...string) string {
	kept := make([]string, 0, len(parts))
	for _, p := range parts {
		if s := strings.TrimSpace(p); s != "" {
			kept = append(kept, s)
		}
	}
	return strings.Join(kept, sep)
}