package agent

import (
	"encoding/json"
	"errors"
	"fmt"
	"time"

	"git.ipao.vip/rogee/go-sip/internal/contract"
)

// EventWriter keeps Agent-produced realtime facts in the approved event
// vocabulary before they are handed to Dispatcher/MQ. Transcript text is
// written to the Agent spool as an archive as well as returned for realtime
// publication; the archive is not a substitute for transcript.updated.
type EventWriter struct {
	TenantID  string
	TenantKey string
	TraceID   string
}

func (w EventWriter) TranscriptUpdated(now time.Time, eventID, callID, turnID, segmentID, role, text string, revision int64, final bool, startMS, endMS int64) ([]byte, error) {
	if eventID == "" || callID == "" || turnID == "" || segmentID == "" || role == "" {
		return nil, errors.New("transcript event identity is required")
	}
	if revision < 1 || startMS < 0 || endMS < startMS {
		return nil, errors.New("transcript timing or revision is invalid")
	}
	return (contract.EventBuilder{
		TenantID: w.TenantID, TenantKey: w.TenantKey, TraceID: w.TraceID,
		EventType: "transcript.updated", Aggregate: "transcript_segment", AggregateID: segmentID, Version: revision,
		Payload: map[string]any{
			"call_id": callID, "turn_id": turnID, "segment_id": segmentID,
			"role": role, "revision": revision, "text": text, "is_final": final,
			"start_ms": startMS, "end_ms": endMS, "playback_state": "not_applicable",
		},
	}).Marshal(now, eventID)
}

func (w EventWriter) RecordingReady(now time.Time, eventID, callID, recordingID, ossID, format string, channels int32, sampleRateHz int32, durationMS, sizeBytes int64, checksum string) ([]byte, error) {
	if eventID == "" || callID == "" || recordingID == "" || ossID == "" || checksum == "" {
		return nil, errors.New("verified recording identity and checksum are required")
	}
	if sizeBytes < 1 || durationMS < 0 || channels != 1 || sampleRateHz < 8000 {
		return nil, errors.New("recording metadata is invalid")
	}
	return (contract.EventBuilder{
		TenantID: w.TenantID, TenantKey: w.TenantKey, TraceID: w.TraceID,
		EventType: "recording.ready", Aggregate: "recording", AggregateID: recordingID, Version: 1,
		Payload: map[string]any{
			"call_id": callID, "recording_id": recordingID, "oss_id": ossID,
			"format": format, "channels": channels, "sample_rate_hz": sampleRateHz,
			"duration_ms": durationMS, "size_bytes": sizeBytes, "checksum_sha256": checksum,
		},
	}).Marshal(now, eventID)
}

func (s *Spool) AppendApprovedEvent(executionID string, event []byte) error {
	var envelope struct {
		EventType string `json:"event_type"`
	}
	if err := json.Unmarshal(event, &envelope); err != nil {
		return fmt.Errorf("decode event envelope: %w", err)
	}
	if envelope.EventType != "transcript.updated" {
		return fmt.Errorf("Agent transcript archive accepts transcript.updated only, got %q", envelope.EventType)
	}
	if err := contract.ValidateEvent(event); err != nil {
		return err
	}
	return s.AppendTranscript(executionID, event)
}