package web

import (
	"crypto/sha256"
	"encoding/hex"
	"net/http"
	"time"

	"gitea.dooplex.hu/admin/felhom-hub/internal/configgen"
)

// selfbind_mint.go — the OPERATOR side of customer self-bind (v0.66.0, R-27 slice 1): the "Send
// self-bind link" button on the customer page mints a 7-day capability token and emails the customer
// a public bind link. The customer side (the public /bind/ page) lives in selfbind.go. No hub
// customer-login exists — the emailed link IS the auth model.

// selfBindTTL is the capability link's lifetime. After it, self-bind falls back to operator-bind
// unchanged (the token simply reads as expired; nothing else regresses).
const selfBindTTL = 7 * 24 * time.Hour

// selfBindBaseURL is the hub's public origin, matching the hardcoded origin used elsewhere
// (configgen). The link is https://hub.felhom.eu/bind/<token>.
const selfBindBaseURL = "https://hub.felhom.eu"

// SelfBindMailer delivers the self-bind capability link to the registered customer address. The
// notify.Dispatcher implements it (a sibling of the claim mailer — NOT routed through claim). The
// signature takes plain strings so the implementation needs no import of this package.
type SelfBindMailer interface {
	SendSelfBindEmail(customerID, email, link string) error
}

// SetSelfBindMailer wires the self-bind link sender (v0.66.0). Absent → the button returns 502.
func (s *Server) SetSelfBindMailer(m SelfBindMailer) { s.selfBindMailer = m }

func selfBindHash(token string) string {
	sum := sha256.Sum256([]byte(token))
	return hex.EncodeToString(sum[:])
}

// selfBindOutcome is what mintAndSendSelfBindLink did, so each caller can decide how loud to be.
// The operator BUTTON turns these into flashes; the AUTO-MINT callers (create / RESET completion)
// only log, because neither may fail an otherwise-successful operation over a courtesy email.
type selfBindOutcome int

const (
	selfBindSent            selfBindOutcome = iota // minted + emailed
	selfBindSkippedNoMailer                        // no mailer wired on this hub
	selfBindSkippedNoEmail                         // F1: customer has no registered address
	selfBindSendFailed                             // F2: send failed, token invalidated
	selfBindMintFailed                             // token generation or DB write failed
)

// mintAndSendSelfBindLink is the shared mint+send core (v0.67.0). It was extracted from
// handleSelfBindLinkSend so the auto-mint callers reuse the SAME honesty rules rather than
// re-implementing them:
//
//   - F1: no registered email → nothing is minted (a link nobody can receive is worse than none).
//   - F2: send failed → the just-minted token is DELETED, never left silently live.
//
// The plaintext token exists only between minting and the send: never logged (only an 8-char hash
// prefix), never persisted (only its sha256). Callers get the outcome and the underlying error;
// nothing here writes an HTTP response, which is what makes it reusable off the request path.
func (s *Server) mintAndSendSelfBindLink(customerID, email string) (selfBindOutcome, error) {
	if s.selfBindMailer == nil {
		return selfBindSkippedNoMailer, nil
	}
	if email == "" {
		return selfBindSkippedNoEmail, nil
	}

	token, err := configgen.RandomHex(32) // 256-bit capability token
	if err != nil {
		return selfBindMintFailed, err
	}
	hash := selfBindHash(token)
	if err := s.store.MintSelfBindToken(customerID, hash, selfBindTTL); err != nil {
		return selfBindMintFailed, err
	}

	link := selfBindBaseURL + "/bind/" + token
	if err := s.selfBindMailer.SendSelfBindEmail(customerID, email, link); err != nil {
		if derr := s.store.DeleteSelfBindTokens(customerID); derr != nil {
			s.logger.Printf("[ERROR] self-bind link for %s: send failed AND cleanup failed: send=%v cleanup=%v", customerID, err, derr)
		} else {
			s.logger.Printf("[ERROR] self-bind link for %s: email send failed, token invalidated (hash %s…): %v", customerID, hash[:8], err)
		}
		return selfBindSendFailed, err
	}
	if err := s.store.MarkSelfBindEmailed(hash); err != nil {
		s.logger.Printf("[WARN] self-bind link sent to %s but emailed_at not recorded: %v", customerID, err)
	}
	s.logger.Printf("[INFO] self-bind link (hash %s…, valid 7 days) emailed to the registered address of %s", hash[:8], customerID)
	return selfBindSent, nil
}

// autoMintSelfBindLink is the fire-and-log wrapper used at customer creation and at RESET
// completion (v0.67.0, R-36 sub-item). The box's console banner tells the customer to open „az
// e-mailben kapott link", so that email should already exist by the time anyone reads the banner —
// previously it existed only once the operator remembered to press the button.
//
// It NEVER fails the caller's operation: a customer create that provisioned Cloudflare, offsite and
// PBS successfully must not 500 because a courtesy email bounced. Every outcome is logged; the
// operator can always re-send from the Setup tab.
func (s *Server) autoMintSelfBindLink(customerID, email, occasion string) {
	outcome, err := s.mintAndSendSelfBindLink(customerID, email)

	// Invariant both call sites need: once this returns, the only live capability token for this
	// customer is one we just minted — or none at all. It matters on the RESET path, because
	// PurgeCustomerResetDBState does NOT clear selfbind_tokens, so a link minted BEFORE the reset
	// would otherwise stay live across it. A successful mint already replaces it (MintSelfBindToken
	// deletes-then-inserts, single-active); the skip paths are the ones that would leave it behind.
	if outcome == selfBindSkippedNoMailer || outcome == selfBindSkippedNoEmail {
		if derr := s.store.DeleteSelfBindTokens(customerID); derr != nil {
			s.logger.Printf("[WARN] self-bind: could not clear stale tokens for %s on %s: %v", customerID, occasion, derr)
		}
	}

	switch outcome {
	case selfBindSent:
		s.logger.Printf("[INFO] self-bind link auto-minted for %s on %s (the console banner's promised email now exists)", customerID, occasion)
	case selfBindSkippedNoMailer:
		s.logger.Printf("[INFO] self-bind link NOT auto-minted for %s on %s: no mailer configured on this hub", customerID, occasion)
	case selfBindSkippedNoEmail:
		s.logger.Printf("[WARN] self-bind link NOT auto-minted for %s on %s: no registered email address (F1) — set one, then send from the Setup tab", customerID, occasion)
	case selfBindSendFailed:
		s.logger.Printf("[WARN] self-bind link auto-mint for %s on %s FAILED to send; token invalidated — re-send from the Setup tab: %v", customerID, occasion, err)
	case selfBindMintFailed:
		s.logger.Printf("[ERROR] self-bind link auto-mint for %s on %s failed to mint: %v", customerID, occasion, err)
	}
}

// handleSelfBindLinkSend — POST /customers/{id}/selfbind-link. Mints a single-active capability token
// for the customer and emails the public bind link. Honesty rules:
//   - F1: no registered email → nothing is minted, LOUD flash (a link no one can receive is useless).
//   - F2: email send fails → the just-minted token is deleted (not left silently live), LOUD flash.
//
// The plaintext token exists only between minting and the send; it is never logged (only an 8-char
// hash prefix) and never persisted (only its sha256).
func (s *Server) handleSelfBindLinkSend(w http.ResponseWriter, r *http.Request, customerID string) {
	if s.selfBindMailer == nil {
		http.Error(w, "Self-bind mailer is not configured on this hub", http.StatusBadGateway)
		return
	}
	cfg, err := s.store.GetCustomerConfig(customerID)
	if err != nil || cfg == nil {
		http.NotFound(w, r)
		return
	}
	// The honesty rules (F1/F2) live in the shared core so the button and the auto-mint callers
	// cannot drift apart; the button's job is only to turn the outcome into an operator-visible flash.
	switch outcome, err := s.mintAndSendSelfBindLink(customerID, cfg.Email); outcome {
	case selfBindSkippedNoEmail:
		s.logger.Printf("[WARN] self-bind link for %s NOT sent: customer has no registered email", customerID)
		http.Redirect(w, r, "/customers/"+customerID+"?flash=selfbind-no-email#tab=setup", http.StatusSeeOther)
	case selfBindSendFailed:
		http.Redirect(w, r, "/customers/"+customerID+"?flash=selfbind-send-failed#tab=setup", http.StatusSeeOther)
	case selfBindMintFailed:
		s.logger.Printf("[ERROR] self-bind link for %s: %v", customerID, err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
	default: // selfBindSent (the no-mailer case was refused above)
		http.Redirect(w, r, "/customers/"+customerID+"?flash=selfbind-sent#tab=setup", http.StatusSeeOther)
	}
}