package assignment

import (
	"encoding/json"
	"time"

	"doormile/db"
	"doormile/models"
	"doormile/utils"
)

// assignmentFailedSubject is the JetStream subject the AI layer's DispatchAgent
// binds its durable consumer to. It must be present on the ASSIGNMENTS stream
// before anything publishes here — JetStream drops messages on subjects the
// stream does not cover, silently and with a successful-looking publish.
const assignmentFailedSubject = "booking.assignment_failed"

// Reasons carried on the failure event. Kept coarse on purpose: the consumer
// branches on booking_id and coordinates, and treats reason as diagnostic only.
const (
	reasonNoMilerAvailable = "NO_MILER_AVAILABLE"
)

// publishAssignmentFailed emits booking.assignment_failed after auto-assignment
// has genuinely given up on a booking.
//
// Call this only from the terminal branch of an assignment entry point — after
// every retry is exhausted — never from inside a single attempt. The per-attempt
// paths (no eligible candidates, decision-engine escalation) fire up to
// maxRetries times for a booking that may still succeed on a later attempt, and
// publishing there would report failures that never happened.
//
// Mirrors publishAssignment/publishCustomerAssignment: non-fatal, so a NATS
// outage degrades to a log line rather than breaking the assignment goroutine.
func publishAssignmentFailed(bookingID int, reason string) {
	if db.Js == nil {
		return
	}

	payload := map[string]interface{}{
		"booking_id": bookingID,
		"reason":     reason,
		"failed_at":  time.Now().UnixMilli(),
	}

	// Pickup coordinates drive the consumer's coverage sweep. They aren't in
	// scope at the call site, so re-read the booking — one indexed lookup on a
	// path that only runs after retries have already been exhausted. If the
	// read fails we still publish: the consumer treats missing coordinates as
	// "skip the sweep" and degrades safely rather than losing the event.
	var booking models.PickupBooking
	if err := db.DB.Select("pickuplatitude", "pickuplongitude", "bookingno").
		First(&booking, bookingID).Error; err != nil {
		utils.Warn("Assignment: could not load booking for failure event; publishing without coordinates",
			"booking_id", bookingID, "error", err)
	} else {
		payload["booking_no"] = booking.Bookingno
		if booking.Pickuplatitude != 0 || booking.Pickuplongitude != 0 {
			payload["lat"] = booking.Pickuplatitude
			payload["lon"] = booking.Pickuplongitude
		}
	}

	data, err := json.Marshal(payload)
	if err != nil {
		utils.Warn("Assignment: failed to marshal assignment-failed payload",
			"booking_id", bookingID, "error", err)
		return
	}

	if _, err := db.Js.Publish(assignmentFailedSubject, data); err != nil {
		utils.Warn("Assignment: NATS publish failed for assignment-failed event",
			"booking_id", bookingID, "error", err)
		return
	}

	utils.Info("Assignment: published "+assignmentFailedSubject,
		"booking_id", bookingID, "reason", reason)
}