//go:build commercial

// Package api - Commercial replication handler.
// This file is built ONLY when the "commercial" build tag is specified.
package api

import (
	"encoding/json"
	"net/http"
	"time"

	"github.com/johanj/clavitor/edition"
	"github.com/johanj/clavitor/lib"
)

// HandleReplicationApply is the HTTP handler for incoming replication.
// Validates vault credentials (L0/L1) before accepting.
func (h *Handlers) HandleReplicationApply(w http.ResponseWriter, r *http.Request) {
	// Only accept POST
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// Extract vault credentials from headers
	l0Hdr := r.Header.Get("X-Clavitor-L0")
	l1Hdr := r.Header.Get("X-Clavitor-L1")
	if l0Hdr == "" || l1Hdr == "" {
		http.Error(w, "Missing auth headers", http.StatusUnauthorized)
		return
	}

	l0, err := lib.Base64URLDecode(l0Hdr)
	if err != nil {
		http.Error(w, "Invalid L0", http.StatusBadRequest)
		return
	}
	l1, err := lib.Base64URLDecode(l1Hdr)
	if err != nil {
		http.Error(w, "Invalid L1", http.StatusBadRequest)
		return
	}

	// Validate L0/L1 and get DB
	db, err := lib.ValidateL0L1(h.Cfg.DataDir, l0, l1)
	if err != nil {
		// Alert on auth failure
		sourcePOP := r.Header.Get("X-Clavitor-POP")
		edition.Current.AlertOperator(r.Context(), "replication_auth_failed",
			"Invalid L0/L1 in replication request", map[string]any{
				"source_ip":  r.RemoteAddr,
				"source_pop": sourcePOP,
				"error":      err.Error(),
			})
		http.Error(w, "Invalid credentials", http.StatusUnauthorized)
		return
	}
	defer db.Close()

	// Decode request
	var req edition.ReplicationRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid JSON", http.StatusBadRequest)
		return
	}

	// Validate timestamp (anti-replay: 5 minute window)
	now := time.Now().UnixMilli()
	if req.Timestamp < now-5*60*1000 || req.Timestamp > now+5*60*1000 {
		http.Error(w, "Request expired or future dated", http.StatusBadRequest)
		return
	}

	// Apply entries to local DB
	accepted, rejected := h.applyReplicationEntries(db, req.Entries)

	// Audit alert (only unusual activity)
	if len(rejected) > 0 {
		edition.Current.AlertOperator(r.Context(), "replication_received",
			"Replication batch received with rejections", map[string]any{
				"source_pop": req.SourcePOP,
				"accepted":   len(accepted),
				"rejected":   len(rejected),
			})
	}

	// Respond
	resp := edition.ReplicationResponse{
		Accepted: accepted,
		Rejected: rejected,
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(resp)
}

// applyReplicationEntries writes replicated entries to local DB.
func (h *Handlers) applyReplicationEntries(db *lib.DB, entries []edition.ReplicatedEntry) (accepted, rejected []string) {
	for _, e := range entries {
		// Convert EntryID from hex string to int64
		entryID, err := lib.HexToID(e.EntryID)
		if err != nil {
			rejected = append(rejected, e.EntryID)
			continue
		}

		// Convert ReplicatedEntry to Entry
		entry := lib.Entry{
			EntryID:   lib.HexID(entryID),
			Type:      e.Type,
			Title:     e.Title,
			TitleIdx:  []byte(e.TitleIdx),
			Data:      e.Data,
			DataLevel: e.DataLevel,
			Scopes:    e.Scopes,
			CreatedAt: e.CreatedAt,
			UpdatedAt: e.UpdatedAt,
			Version:   e.Version,
		}

		// Upsert (insert or update if newer version)
		existing, _ := lib.EntryGet(db, nil, int64(entry.EntryID))
		if existing == nil {
			// Insert new
			if err := lib.EntryCreate(db, nil, &entry); err != nil {
				rejected = append(rejected, e.EntryID)
				continue
			}
		} else if entry.Version > existing.Version {
			// Update if newer
			if err := lib.EntryUpdate(db, nil, &entry); err != nil {
				rejected = append(rejected, e.EntryID)
				continue
			}
		} else {
			// Same or older version - skip (not an error)
		}

		// Mark as replicated (we received it)
		lib.EntryMarkReplicated(db, int64(entry.EntryID))
		accepted = append(accepted, e.EntryID)
	}
	return
}