package api

import (
	"database/sql"
	"encoding/base64"
	"encoding/json"
	"io"
	"net/http"
	"time"

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

// Slice 10D — DR capstone, hub side. The hub ORCHESTRATES recovery (recovery-mode toggle, directive
// serving, re-enroll + its OWN agent↔hub credential rotation) but holds **no usable secret and no
// Cloudflare write-power**: the escrow blobs it serves are opaque (need R, which the hub never has),
// and the destructive tunnel/PBS rotation is the operator's step from a trusted environment. A
// compromised hub can at most hand out opaque blobs + revoke/rotate its own per-host credential.

const (
	defaultRecoveryTTL = 30 * time.Minute // bounded auto-expiry default
	maxRecoveryTTL     = 4 * time.Hour
)

func writeJSON(w http.ResponseWriter, code int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	json.NewEncoder(w).Encode(v)
}

// handleSetRecoveryMode arms recovery mode for a host (GLOBAL/operator key only). Body:
// {"ttl_seconds": N} (clamped to [60, maxRecoveryTTL]; default 30m). The directive + re-enroll are
// served ONLY while this is active; it auto-expires.
func (h *Handler) handleSetRecoveryMode(w http.ResponseWriter, r *http.Request, hostID string) {
	if _, _, isGlobal, ok := h.checkAuthHost(r); !ok || !isGlobal {
		http.Error(w, "Forbidden: global key required", http.StatusForbidden)
		return
	}
	if hostID == "" {
		http.Error(w, "Missing host_id", http.StatusBadRequest)
		return
	}
	body, _ := io.ReadAll(io.LimitReader(r.Body, 1<<16))
	var req struct {
		TTLSeconds int `json:"ttl_seconds"`
	}
	json.Unmarshal(body, &req)
	ttl := defaultRecoveryTTL
	if req.TTLSeconds > 0 {
		ttl = time.Duration(req.TTLSeconds) * time.Second
	}
	if ttl < time.Minute {
		ttl = time.Minute
	}
	if ttl > maxRecoveryTTL {
		ttl = maxRecoveryTTL
	}
	until := time.Now().UTC().Add(ttl)
	if err := h.store.SetRecoveryMode(hostID, until); err == sql.ErrNoRows {
		http.Error(w, "Unknown host_id", http.StatusNotFound)
		return
	} else if err != nil {
		h.logger.Printf("[ERROR] set recovery mode for %s: %v", hostID, err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}
	h.logger.Printf("[INFO] DR: recovery mode ARMED for host %s until %s (auto-expires)", hostID, until.Format(time.RFC3339))
	writeJSON(w, http.StatusOK, map[string]any{"status": "ok", "recovery_mode_until": until.Format(time.RFC3339)})
}

// handleClearRecoveryMode disables recovery mode (GLOBAL key).
func (h *Handler) handleClearRecoveryMode(w http.ResponseWriter, r *http.Request, hostID string) {
	if _, _, isGlobal, ok := h.checkAuthHost(r); !ok || !isGlobal {
		http.Error(w, "Forbidden: global key required", http.StatusForbidden)
		return
	}
	if err := h.store.ClearRecoveryMode(hostID); err != nil {
		h.logger.Printf("[ERROR] clear recovery mode for %s: %v", hostID, err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}
	h.logger.Printf("[INFO] DR: recovery mode DISABLED for host %s", hostID)
	writeJSON(w, http.StatusOK, map[string]any{"status": "ok"})
}

// reEnrollResponse is the re-enroll / restore-directive payload (slice 10D). The blobs are OPAQUE.
type reEnrollResponse struct {
	HostID            string          `json:"host_id"`
	APIKeyRotated     bool            `json:"api_key_rotated"`
	Directive         json.RawMessage `json:"directive"`            // non-secret DR directive
	KEscrowB64        string          `json:"k_escrow_b64"`         // opaque PBS-key escrow blob
	IdentityEscrowB64 string          `json:"identity_escrow_b64"`  // opaque identity escrow blob
}

// handleReEnroll is the re-enroll handshake (slice 10D.2). Gated ONLY on RECOVERY MODE (the lost box
// has no key, so no old-key auth) — the operator armed recovery mode (operational gate) after
// out-of-band validation. The new box posts a fresh api_key; the hub ROTATES the host's credential
// to it (the old box's hub access is revoked instantly) and returns the DR directive + opaque blobs.
// Without recovery mode → 403. The blobs are useless without R (zero-knowledge): even a wrongful
// re-enroll within the window leaks nothing recoverable.
func (h *Handler) handleReEnroll(w http.ResponseWriter, r *http.Request, hostID string) {
	if hostID == "" {
		http.Error(w, "Missing host_id", http.StatusBadRequest)
		return
	}
	host, err := h.store.GetHost(hostID)
	if err != nil {
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}
	if host == nil {
		http.Error(w, "Unknown host_id", http.StatusNotFound)
		return
	}
	// THE GATE: recovery mode must be active (operator-armed, not expired).
	if !host.InRecoveryMode(time.Now().UTC()) {
		h.logger.Printf("[WARN] DR: re-enroll REFUSED for %s — recovery mode not active", hostID)
		http.Error(w, "Forbidden: host not in recovery mode (operator must arm it)", http.StatusForbidden)
		return
	}
	body, _ := io.ReadAll(io.LimitReader(r.Body, 1<<16))
	var req struct {
		NewAPIKey string `json:"new_api_key"`
	}
	if json.Unmarshal(body, &req) != nil || req.NewAPIKey == "" {
		// If the box did not supply one, mint it (still rotates the credential).
		req.NewAPIKey, _ = configgen.RandomHex(32)
	}
	// Rotate the agent↔hub credential to the new box — the old box's key is revoked here.
	if err := h.store.RotateHostAPIKey(hostID, req.NewAPIKey); err != nil {
		h.logger.Printf("[ERROR] re-enroll rotate key for %s: %v", hostID, err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}
	resp := reEnrollResponse{HostID: hostID, APIKeyRotated: true, Directive: json.RawMessage("{}")}
	if bundle, err := h.store.GetHostDRBundle(hostID); err == nil && bundle != nil {
		resp.KEscrowB64 = base64.StdEncoding.EncodeToString(bundle.KEscrowBlob)
		resp.IdentityEscrowB64 = base64.StdEncoding.EncodeToString(bundle.IdentityBlob)
		if bundle.DirectiveJSON != "" {
			resp.Directive = json.RawMessage(bundle.DirectiveJSON)
		}
	}
	h.logger.Printf("[INFO] DR: host %s RE-ENROLLED (hub credential rotated; old key revoked; directive served)", hostID)
	// The new key is returned so the box can use it; the operator sees the rotation in the response.
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(map[string]any{
		"host_id": hostID, "api_key_rotated": true, "new_api_key": req.NewAPIKey,
		"directive": resp.Directive, "k_escrow_b64": resp.KEscrowB64, "identity_escrow_b64": resp.IdentityEscrowB64,
	})
}

// handleGetRestoreDirective serves the directive to an already-re-enrolled box (its rotated per-host
// key), gated on recovery mode. Lets the box re-fetch without re-rotating.
func (h *Handler) handleGetRestoreDirective(w http.ResponseWriter, r *http.Request, hostID string) {
	authHostID, _, isGlobal, ok := h.checkAuthHost(r)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}
	if !isGlobal && authHostID != hostID {
		http.Error(w, "Forbidden: host_id mismatch", http.StatusForbidden)
		return
	}
	host, err := h.store.GetHost(hostID)
	if err != nil || host == nil {
		http.Error(w, "Unknown host_id", http.StatusNotFound)
		return
	}
	if !host.InRecoveryMode(time.Now().UTC()) {
		http.Error(w, "Forbidden: host not in recovery mode", http.StatusForbidden)
		return
	}
	resp := reEnrollResponse{HostID: hostID, Directive: json.RawMessage("{}")}
	if bundle, err := h.store.GetHostDRBundle(hostID); err == nil && bundle != nil {
		resp.KEscrowB64 = base64.StdEncoding.EncodeToString(bundle.KEscrowBlob)
		resp.IdentityEscrowB64 = base64.StdEncoding.EncodeToString(bundle.IdentityBlob)
		if bundle.DirectiveJSON != "" {
			resp.Directive = json.RawMessage(bundle.DirectiveJSON)
		}
	}
	writeJSON(w, http.StatusOK, resp)
}