// Package events defines safe inspection records shared by logs and the future viewer.
package events

import (
	"encoding/base64"
	"encoding/json"
	"time"
	"unicode/utf8"

	"robot-market/test-mqtt-5/internal/contracts"
)

type Direction string

const (
	In       Direction = "in"
	Out      Direction = "out"
	Internal Direction = "internal"
)

type Kind string

const (
	PublishAttempt   Kind = "publish_attempt"
	TransportAck     Kind = "transport_ack"
	MessageReceived  Kind = "message_received"
	ValidationFailed Kind = "validation_failed"
	CommandAccepted  Kind = "command_accepted"
	CommandCompleted Kind = "command_completed"
	CommandTimeout   Kind = "command_timeout"
	LateAck          Kind = "late_ack"
	DuplicateRequest Kind = "duplicate_request"
	ConnectionUp     Kind = "connection_up"
	ConnectionDown   Kind = "connection_down"
	EventGap         Kind = "event_gap"
)

type Properties struct {
	ResponseTopic        string  `json:"response_topic,omitempty"`
	CorrelationData      []byte  `json:"correlation_data,omitempty"`
	MessageExpirySeconds *uint32 `json:"message_expiry_seconds,omitempty"`
}

// Event contains inspection data only. Configuration and connection credentials
// are never attached. Raw MQTT payloads require the explicit diagnostics opt-in.
type Event struct {
	Scenario   *ScenarioResult `json:"scenario,omitempty"`
	ID         uint64          `json:"id"`
	ObservedAt time.Time       `json:"observed_at"`
	Kind       Kind            `json:"kind"`
	Direction  Direction       `json:"direction"`
	ClientID   string          `json:"client_id,omitempty"`
	DeviceID   string          `json:"device_id,omitempty"`
	Topic      string          `json:"topic,omitempty"`
	QoS        byte            `json:"qos"`
	Retain     bool            `json:"retain"`
	Duplicate  *bool           `json:"duplicate,omitempty"`
	Payload    Preview         `json:"payload"`
	Properties Properties      `json:"properties"`
	RequestID  string          `json:"request_id,omitempty"`
	Outcome    string          `json:"outcome,omitempty"`
	LatencyMS  *int64          `json:"latency_ms,omitempty"`
}

// ScenarioResult is reported test evidence, never inferred hardware compatibility.
type ScenarioResult struct {
	Feature     string    `json:"feature"`
	Environment string    `json:"environment"`
	Endpoint    string    `json:"endpoint"`
	Version     string    `json:"version"`
	Status      string    `json:"status"`
	Observation string    `json:"observation"`
	Time        time.Time `json:"time"`
}
type Preview struct {
	Bytes     int    `json:"bytes"`
	Text      string `json:"text,omitempty"`
	Omitted   bool   `json:"omitted"`
	Truncated bool   `json:"truncated"`
}

// SafePreview only renders validated contract fields. Unknown fields (including
// credentials) cause the entire payload to be omitted. Free-form error messages
// are always redacted. The original payload is never retained in this value.
func SafePreview(kind, device string, payload []byte, limit int) Preview {
	p := Preview{Bytes: len(payload), Omitted: true}
	if limit < 1 {
		return p
	}
	if limit > 4096 {
		limit = 4096
	}
	msg, err := contracts.Decode(kind, payload, device)
	if err != nil {
		return p
	}
	if ack, ok := msg.(*contracts.Ack); ok && ack.Error != nil {
		ack.Error.Message = "[redacted]"
	}
	encoded, err := json.Marshal(msg)
	if err != nil {
		return p
	}
	if len(encoded) > limit {
		encoded = encoded[:limit]
		for len(encoded) > 0 && !utf8.Valid(encoded) {
			encoded = encoded[:len(encoded)-1]
		}
		p.Truncated = true
	}
	p.Text = string(encoded)
	p.Omitted = false
	return p
}

// RawPreview is opt-in diagnostics for this isolated test harness. It displays
// received bytes without treating them as a valid contract or execution evidence.
func RawPreview(payload []byte, limit int) Preview {
	p := Preview{Bytes: len(payload)}
	if limit < 1 {
		p.Omitted = true
		return p
	}
	limit = min(limit, 4096)
	text := string(payload)
	if !utf8.Valid(payload) {
		text = "[base64] " + base64.StdEncoding.EncodeToString(payload)
	}
	if len(text) > limit {
		text = text[:limit]
		for !utf8.ValidString(text) {
			text = text[:len(text)-1]
		}
		p.Truncated = true
	}
	p.Text = text
	return p
}