package httpapi

import (
	"database/sql"
	"errors"
	"fmt"
	"net"
	"net/http"
	"net/netip"
	"time"

	"cloudipvalidator/internal/db"
)

func (s *Server) handleAgentRegister(w http.ResponseWriter, r *http.Request) {
	var req registerAgentRequest
	if err := readJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body: "+err.Error())
		return
	}
	if req.ValidatorID == "" {
		writeError(w, http.StatusBadRequest, "validator_id is required")
		return
	}
	// os_port_id is supplied via control-api's own config (config.ValidatorConfig),
	// not by the agent, so registration only touches hostname/version here;
	// RegisterValidator preserves any existing os_port_id row.
	existing, _ := s.DB.GetValidator(r.Context(), req.ValidatorID)
	osPortID := ""
	if existing != nil {
		osPortID = existing.OSPortID
	}
	if err := s.DB.RegisterValidator(r.Context(), req.ValidatorID, req.Hostname, osPortID, req.AgentVersion); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	s.Orch.RecordEvent(r.Context(), "validator-agent", req.ValidatorID, nil, "registered", "")
	writeJSON(w, http.StatusOK, registerAgentResponse{OK: true, PollIntervalSeconds: s.Orch.Cfg.PollIntervalSeconds})
}

func (s *Server) handleAgentHeartbeat(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	var req heartbeatRequest
	_ = readJSON(r, &req) // heartbeat body is informational only; tolerate empty/missing
	if err := s.DB.Heartbeat(r.Context(), id); err != nil {
		writeError(w, http.StatusNotFound, "unknown validator: "+id)
		return
	}
	writeJSON(w, http.StatusOK, okResponse{OK: true})
}

func (s *Server) handleAgentAssignment(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	item, checks, err := s.Orch.AssignmentForValidator(r.Context(), id)
	if err != nil {
		writeError(w, http.StatusNotFound, "unknown validator: "+id)
		return
	}
	if item == nil {
		w.WriteHeader(http.StatusNoContent)
		return
	}
	var cfg []checkConfigDTO
	for _, c := range checks {
		cfg = append(cfg, checkConfigDTO{Type: c.Type, Targets: c.Targets})
	}
	writeJSON(w, http.StatusOK, assignmentResponse{
		IPID: item.ID, IPAddress: item.IPAddress, Phase: item.State, CheckConfig: cfg,
	})
}

// handleAgentObservedIP tells a validator which source address control-api
// sees for its connection, so the agent's self-check can confirm the floating
// IP without a third-party IP-echo service. The route is open, so it is
// limited to known validators to keep it from becoming a public "what is my
// IP" service.
func (s *Server) handleAgentObservedIP(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if _, err := s.DB.GetValidator(r.Context(), id); err != nil {
		if errors.Is(err, sql.ErrNoRows) || errors.Is(err, db.ErrNotFound) {
			writeError(w, http.StatusNotFound, "unknown validator: "+id)
			return
		}
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	ip, err := clientIP(r)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, http.StatusOK, observedIPResponse{IP: ip, Source: "remote_addr"})
}

// clientIP returns the peer address of the TCP connection in canonical form
// (IPv4-mapped IPv6 unmapped to plain IPv4). It deliberately ignores
// X-Forwarded-For / X-Real-IP: validators connect directly, and trusting a
// client-supplied header would let a validator forge the address and pass
// the self-check.
func clientIP(r *http.Request) (string, error) {
	host, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil {
		return "", fmt.Errorf("parse remote address %q: %w", r.RemoteAddr, err)
	}
	addr, err := netip.ParseAddr(host)
	if err != nil {
		return "", fmt.Errorf("parse remote address %q: %w", r.RemoteAddr, err)
	}
	return addr.Unmap().String(), nil
}

func (s *Server) handleAgentSelfCheck(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	var req selfCheckRequest
	if err := readJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body: "+err.Error())
		return
	}
	detail := req.Detail
	if req.DetectedEgress != "" {
		detail = "detected_egress_ip=" + req.DetectedEgress + " " + detail
	}
	if err := s.Orch.SelfCheckResult(r.Context(), id, req.IPID, req.Success, detail); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, http.StatusOK, okResponse{OK: true})
}

func (s *Server) handleAgentEvent(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	var req agentEventRequest
	if err := readJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body: "+err.Error())
		return
	}
	if req.EventType == "" {
		writeError(w, http.StatusBadRequest, "event_type is required")
		return
	}
	s.Orch.RecordEvent(r.Context(), "validator-agent", id, req.IPID, req.EventType, req.Payload)
	writeJSON(w, http.StatusOK, okResponse{OK: true})
}

func (s *Server) handleAgentResults(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	var req agentResultsRequest
	if err := readJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body: "+err.Error())
		return
	}
	for _, res := range req.Results {
		item, err := s.DB.GetIP(r.Context(), res.IPID)
		if err != nil {
			writeError(w, http.StatusNotFound, "unknown ip_id")
			return
		}
		checkedAt, err := time.Parse(time.RFC3339Nano, res.CheckedAt)
		if err != nil {
			checkedAt = db.Now()
		}
		err = s.Orch.RecordCheck(r.Context(), db.Check{
			IPID: item.ID, IPAddress: item.IPAddress, AttemptNumber: item.AttemptNumber,
			ValidatorID: id, Source: db.SourceEgress, CheckType: res.CheckType, Target: res.Target,
			Success: res.Success, LatencyMS: res.LatencyMS, Detail: res.Detail, CheckedAt: checkedAt,
		})
		if err != nil {
			writeError(w, http.StatusInternalServerError, err.Error())
			return
		}
	}
	writeJSON(w, http.StatusOK, okResponse{OK: true})
}

func (s *Server) handleAgentComplete(w http.ResponseWriter, r *http.Request) {
	var req agentCompleteRequest
	if err := readJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body: "+err.Error())
		return
	}
	if err := s.Orch.MarkEgressComplete(r.Context(), req.IPID); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, http.StatusOK, okResponse{OK: true})
}