package services

// Streaming + recovery support for AichatPaliadinService (t-paliad-235).
//
// =============================================================================
// Upstream contract — /chat/turn/stream
// =============================================================================
//
// Source of truth: m/mAi internal/aichat/api/stream.go. Captured here as
// inline doc so future debugging doesn't require chasing across repos:
//
// Request body: same shape as POST /chat/turn (TurnRequest mirror in
// aichat_paliadin.go). Persona must support streaming; paliad's
// "paliadin" persona does.
//
// Response: text/event-stream. Two SSE event flavours:
//
//   1. The default unnamed `data:` event carries a discriminated-union
//      JSON object keyed by `"type"`:
//
//        {"type":"chunk","content":"…"}
//        {"type":"meta","used_tools":[…],"rows_seen":[…],"classifier_tag":"…"}
//        {"type":"done","turn_id":"…","conversation_id":"…",
//                       "duration_ms":1234,"pane_spawned":false,"resumed":false}
//        {"type":"error","code":"…","message":"…","retryable":true}
//
//   2. The named `event: heartbeat` event carries:
//
//        {"elapsed_seconds": N}
//
//      Emitted every 5 s by the upstream while the runner has been
//      silent (no content). aichat keeps emitting these for the lifetime
//      of the runner so the client can render "Paliadin denkt nach
//      (N s)" without conflating with actual content.
//
// Errors before the stream starts (auth failure, persona unknown,
// validation) come back as a normal JSON envelope with the appropriate
// HTTP status — not SSE. Those land in callHTTP via decodeAichatError.
//
// =============================================================================
// Conversation-based late recovery
// =============================================================================
//
// Aichat exposes:
//
//   GET /chat/conversations?persona=…&username=…&user_id=…
//        → list of ConversationSummary, ordered last_turn_at DESC
//   GET /chat/conversations/{id}/turns
//        → list of TurnRow (role=user|assistant, body, created_at)
//
// When paliad's stream drops mid-turn we:
//   1. Look up paliad.paliadin_turns.aichat_conversation_id for the row.
//   2. If unset (stream dropped before the `done` frame): list the user's
//      conversations and take the most recent one for the persona —
//      that's the pane our turn ran against (aichat owns one active
//      conversation per persona+user, see m/mAi#243).
//   3. GET that conversation's turns. Find the latest assistant turn
//      whose preceding user-role turn body matches our user_message.
//   4. Persist the response (completeTurnLate) and return it.
//
// If aichat returns no matching assistant turn → the turn is truly lost
// (transport drop + upstream crash). Recovery returns (nil, nil) and
// the handler degrades the UI to "verloren".

import (
	"bufio"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"strings"
	"time"

	"github.com/google/uuid"
)

// =============================================================================
// Streaming RunTurnStream
// =============================================================================

// RunTurnStream drives one /chat/turn/stream turn against aichat and
// relays incremental events onto `events`. Closes `events` before
// returning. Implements StreamingPaliadin.
func (s *AichatPaliadinService) RunTurnStream(ctx context.Context, req TurnRequest, events chan<- StreamEvent) (*TurnResult, error) {
	defer close(events)

	s.turnMu.Lock()
	defer s.turnMu.Unlock()

	turnID := uuid.New()
	startedAt := time.Now().UTC()

	if err := s.insertTurnRow(ctx, &PaliadinTurn{
		TurnID:      turnID,
		UserID:      req.UserID,
		SessionID:   req.SessionID,
		StartedAt:   startedAt,
		UserMessage: req.UserMessage,
		PageOrigin:  optionalString(req.PageOrigin),
	}, req.Context); err != nil {
		return nil, fmt.Errorf("paliadin: insert turn row: %w", err)
	}

	if err := s.healthGate(ctx); err != nil {
		_ = s.markTurnError(ctx, turnID, "mriver_unreachable")
		safeSendStream(ctx, events, StreamEvent{
			Kind:    StreamError,
			Code:    "mriver_unreachable",
			Message: err.Error(),
		})
		return nil, err
	}

	username := s.usernameFor(ctx, req.UserID)
	session := s.cfg.Persona + ":" + username
	primer := s.buildPrimerExchanges(ctx, session, req)

	jwt, err := s.mintJWTIfConfigured(req.UserID)
	if err != nil {
		_ = s.markTurnError(ctx, turnID, "jwt_mint_failed")
		safeSendStream(ctx, events, StreamEvent{
			Kind:    StreamError,
			Code:    "shim_error",
			Message: fmt.Sprintf("mint turn jwt: %v", err),
		})
		return nil, fmt.Errorf("paliadin: mint turn jwt: %w", err)
	}

	body := aichatTurnRequest{
		Persona:   s.cfg.Persona,
		Username:  username,
		UserID:    req.UserID.String(),
		SessionID: req.SessionID,
		Message:   sanitiseForTmux(req.UserMessage),
		JWT:       jwt,
		Primer:    primer,
		Meta:      buildAichatMeta(req),
	}

	// Stream the upstream call. acc accumulates the full text so we can
	// persist the row + return a TurnResult on success.
	var (
		acc            strings.Builder
		streamMeta     trailerMeta
		convID         string
		paneSpawned    bool
		upstreamDoneMs int64
	)

	streamErr := s.callStreamingHTTP(ctx, "/chat/turn/stream", body, func(frame streamFrame) {
		switch {
		case frame.event == "heartbeat":
			safeSendStream(ctx, events, StreamEvent{
				Kind:           StreamHeartbeat,
				ElapsedSeconds: frame.heartbeat.ElapsedSeconds,
			})
		case frame.data.Type == "chunk":
			if frame.data.Content == "" {
				return
			}
			acc.WriteString(frame.data.Content)
			safeSendStream(ctx, events, StreamEvent{
				Kind:    StreamChunk,
				Content: frame.data.Content,
			})
		case frame.data.Type == "meta":
			streamMeta = trailerMeta{
				UsedTools:     append([]string(nil), frame.data.UsedTools...),
				RowsSeen:      coerceAichatRowsSeen(frame.data.RowsSeen),
				ClassifierTag: frame.data.ClassifierTag,
			}
			safeSendStream(ctx, events, StreamEvent{
				Kind:          StreamMeta,
				UsedTools:     streamMeta.UsedTools,
				RowsSeen:      streamMeta.RowsSeen,
				ClassifierTag: streamMeta.ClassifierTag,
			})
		case frame.data.Type == "done":
			if frame.data.ConversationID != "" {
				convID = frame.data.ConversationID
				safeSendStream(ctx, events, StreamEvent{
					Kind:           StreamConversation,
					ConversationID: convID,
				})
			}
			paneSpawned = frame.data.PaneSpawned
			upstreamDoneMs = frame.data.DurationMs
		case frame.data.Type == "error":
			// Forward as a stream error AND mark for non-nil err
			// propagation via the streamErr captured below.
			safeSendStream(ctx, events, StreamEvent{
				Kind:      StreamError,
				Code:      frame.data.Code,
				Message:   frame.data.Message,
				Retryable: frame.data.Retryable,
			})
		}
	})

	cleanBody := acc.String()
	tokens := approxTokenCount(cleanBody)
	chipCount := countChips(cleanBody)
	finished := time.Now().UTC()
	durationMS := int(finished.Sub(startedAt) / time.Millisecond)
	if upstreamDoneMs > 0 {
		durationMS = int(upstreamDoneMs)
	}

	// Persist the conversation id we learned (best-effort — failure here
	// just means recovery for THIS turn will have to list conversations
	// rather than fast-path to a single id).
	if convID != "" {
		if err := s.setAichatConversationID(ctx, turnID, convID); err != nil {
			log.Printf("paliadin: persist aichat conversation id %s: %v", convID, err)
		}
	}

	if streamErr != nil {
		// Aichat persona without streaming support — graceful fallback to
		// the one-shot /chat/turn endpoint. Same body shape; we adapt the
		// non-streaming response into a single StreamChunk so the caller
		// sees identical event ordering.
		if strings.Contains(streamErr.Error(), "unsupported_streaming") {
			log.Printf("paliadin: persona %q lacks streaming support — falling back to one-shot turn %s", s.cfg.Persona, turnID)
			return s.fallbackOneShotFromStream(ctx, turnID, body, events, startedAt, session)
		}
		// Don't overwrite an existing error_code we may have set above.
		_ = s.markTurnError(ctx, turnID, classifyAichatError(streamErr))
		return nil, streamErr
	}

	// Aichat is stateless on user content; the client owns the primer.
	if paneSpawned {
		s.clearPrimed(session)
	} else {
		s.markPrimed(session)
	}

	if cleanBody == "" {
		// Upstream closed cleanly with no error event but no content
		// either (unexpected — log + treat as upstream_error so the
		// handler doesn't ship an empty bubble).
		_ = s.markTurnError(ctx, turnID, "shim_error")
		return nil, errors.New("aichat: stream closed with no content and no error")
	}

	if err := s.completeTurn(ctx, turnID, finished, durationMS, cleanBody, tokens, streamMeta, chipCount); err != nil {
		log.Printf("paliadin: complete turn %s: %v", turnID, err)
	}

	return &TurnResult{
		TurnID:        turnID,
		Response:      cleanBody,
		UsedTools:     streamMeta.UsedTools,
		RowsSeen:      streamMeta.RowsSeen,
		ChipCount:     chipCount,
		ClassifierTag: streamMeta.ClassifierTag,
		DurationMS:    durationMS,
	}, nil
}

// fallbackOneShotFromStream runs the same `body` against aichat's
// non-streaming /chat/turn endpoint and adapts the response into the
// StreamingPaliadin contract — a single StreamChunk + StreamMeta +
// StreamConversation, followed by `events` being closed by the
// outer RunTurnStream's defer. Used when the configured persona doesn't
// support streaming (aichat returns HTTP 400 unsupported_streaming).
//
// Identical persistence shape as the one-shot RunTurn: completeTurn +
// markPrimed/clearPrimed. No new turn row (already inserted by
// RunTurnStream). No primer rebuild (already in body).
func (s *AichatPaliadinService) fallbackOneShotFromStream(
	ctx context.Context,
	turnID uuid.UUID,
	body aichatTurnRequest,
	events chan<- StreamEvent,
	startedAt time.Time,
	session string,
) (*TurnResult, error) {
	var resp aichatTurnResponse
	if err := s.callHTTP(ctx, http.MethodPost, "/chat/turn", body, &resp); err != nil {
		_ = s.markTurnError(ctx, turnID, classifyAichatError(err))
		safeSendStream(ctx, events, StreamEvent{
			Kind:    StreamError,
			Code:    classifyAichatError(err),
			Message: err.Error(),
		})
		return nil, err
	}

	if resp.PaneSpawned {
		s.clearPrimed(session)
	} else {
		s.markPrimed(session)
	}

	cleanBody := resp.Response
	tokens := approxTokenCount(cleanBody)
	chipCount := countChips(cleanBody)
	finished := time.Now().UTC()
	durationMS := int(finished.Sub(startedAt) / time.Millisecond)

	tmeta := trailerMeta{
		UsedTools:     resp.Meta.UsedTools,
		ClassifierTag: resp.Meta.ClassifierTag,
		RowsSeen:      coerceAichatRowsSeen(resp.Meta.RowsSeen),
	}

	// Emit the response as a single chunk so the frontend renders it.
	safeSendStream(ctx, events, StreamEvent{
		Kind:    StreamChunk,
		Content: cleanBody,
	})
	safeSendStream(ctx, events, StreamEvent{
		Kind:          StreamMeta,
		UsedTools:     tmeta.UsedTools,
		ClassifierTag: tmeta.ClassifierTag,
		RowsSeen:      tmeta.RowsSeen,
	})

	if err := s.completeTurn(ctx, turnID, finished, durationMS, cleanBody, tokens, tmeta, chipCount); err != nil {
		log.Printf("paliadin: complete turn %s (fallback one-shot): %v", turnID, err)
	}

	return &TurnResult{
		TurnID:        turnID,
		Response:      cleanBody,
		UsedTools:     tmeta.UsedTools,
		RowsSeen:      tmeta.RowsSeen,
		ChipCount:     chipCount,
		ClassifierTag: tmeta.ClassifierTag,
		DurationMS:    durationMS,
	}, nil
}

// streamFrame is one decoded SSE event.
type streamFrame struct {
	event     string // "" → default (data:) event
	data      streamDataFrame
	heartbeat streamHeartbeatFrame
}

type streamDataFrame struct {
	Type           string   `json:"type"`
	Content        string   `json:"content,omitempty"`
	UsedTools      []string `json:"used_tools,omitempty"`
	RowsSeen       []string `json:"rows_seen,omitempty"`
	ClassifierTag  string   `json:"classifier_tag,omitempty"`
	TurnID         string   `json:"turn_id,omitempty"`
	ConversationID string   `json:"conversation_id,omitempty"`
	DurationMs     int64    `json:"duration_ms,omitempty"`
	PaneSpawned    bool     `json:"pane_spawned,omitempty"`
	Resumed        bool     `json:"resumed,omitempty"`
	Code           string   `json:"code,omitempty"`
	Message        string   `json:"message,omitempty"`
	Retryable      bool     `json:"retryable,omitempty"`
}

type streamHeartbeatFrame struct {
	ElapsedSeconds int `json:"elapsed_seconds"`
}

// callStreamingHTTP opens a streaming POST to aichat and invokes `emit`
// for each parsed SSE frame. Returns once the stream closes; surfaces
// non-2xx responses via decodeAichatError, transport errors via the
// underlying http.Client error.
//
// Tests can override the parsing path by setting streamHook (kept null
// in production).
func (s *AichatPaliadinService) callStreamingHTTP(ctx context.Context, path string, body any, emit func(streamFrame)) error {
	if s.streamHook != nil {
		return s.streamHook(ctx, path, body, emit)
	}

	buf, err := json.Marshal(body)
	if err != nil {
		return fmt.Errorf("aichat: encode %s body: %w", path, err)
	}
	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, s.cfg.BaseURL+path, strings.NewReader(string(buf)))
	if err != nil {
		return fmt.Errorf("aichat: build %s request: %w", path, err)
	}
	httpReq.Header.Set("Content-Type", "application/json")
	httpReq.Header.Set("Accept", "text/event-stream")
	if s.cfg.BearerToken != "" {
		httpReq.Header.Set("Authorization", "Bearer "+s.cfg.BearerToken)
	}

	// Use a dedicated client without the short Timeout — for streaming
	// we rely on the silence_timeout watch (no events for > 90 s ⇒ fail)
	// rather than a hard ceiling on the whole turn. The aichat upstream
	// keeps emitting heartbeats while it's alive, so a true upstream
	// stall is observable here.
	client := s.streamingClient()
	resp, err := client.Do(httpReq)
	if err != nil {
		return fmt.Errorf("aichat: POST %s: %w", path, err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		respBytes, _ := io.ReadAll(io.LimitReader(resp.Body, 64<<10))
		return decodeAichatError(resp.StatusCode, respBytes)
	}

	return parseSSEStream(ctx, resp.Body, emit)
}

// streamingClient returns an HTTP client tuned for streaming — no
// per-request Timeout (kills mid-stream), but a long IdleConnTimeout so
// the connection stays usable for multi-minute turns.
func (s *AichatPaliadinService) streamingClient() *http.Client {
	if s.cfg.HTTPClient == nil {
		return &http.Client{Timeout: 0}
	}
	c := *s.cfg.HTTPClient
	c.Timeout = 0
	return &c
}

// parseSSEStream tokenises an SSE byte stream into streamFrame events
// and calls emit for each. Returns nil on clean EOF; returns the read
// error otherwise.
//
// Frame format (per https://html.spec.whatwg.org/multipage/server-sent-events.html):
//
//   event: <name>\n
//   data: <payload>\n
//   <blank line>\n
//
// Multiple `data:` lines per event are concatenated with `\n`. Lines
// starting with `:` are comments and ignored.
func parseSSEStream(ctx context.Context, r io.Reader, emit func(streamFrame)) error {
	br := bufio.NewReaderSize(r, 64<<10)
	var (
		eventName string
		dataLines []string
	)
	flush := func() {
		if len(dataLines) == 0 && eventName == "" {
			return
		}
		payload := strings.Join(dataLines, "\n")
		eventName = strings.TrimSpace(eventName)
		dataLines = nil
		eventOut := eventName
		eventName = ""
		if eventOut == "heartbeat" {
			var hb streamHeartbeatFrame
			if err := json.Unmarshal([]byte(payload), &hb); err != nil {
				return
			}
			emit(streamFrame{event: "heartbeat", heartbeat: hb})
			return
		}
		// Default event (unnamed) — discriminated by `type` field.
		var d streamDataFrame
		if err := json.Unmarshal([]byte(payload), &d); err != nil {
			return
		}
		emit(streamFrame{event: "", data: d})
	}

	for {
		if err := ctx.Err(); err != nil {
			return err
		}
		line, err := br.ReadString('\n')
		if err != nil {
			if errors.Is(err, io.EOF) {
				// Final frame may not be terminated by a blank line on
				// abrupt close — flush whatever we accumulated.
				if line != "" {
					processSSELine(line, &eventName, &dataLines)
				}
				flush()
				return nil
			}
			return fmt.Errorf("aichat: read sse: %w", err)
		}
		// Normalise line endings (some intermediaries send \r\n).
		line = strings.TrimRight(line, "\r\n")
		if line == "" {
			flush()
			continue
		}
		processSSELine(line, &eventName, &dataLines)
	}
}

// processSSELine handles one line of the SSE wire format.
func processSSELine(line string, eventName *string, dataLines *[]string) {
	if strings.HasPrefix(line, ":") {
		return // comment / keep-alive
	}
	if idx := strings.IndexByte(line, ':'); idx >= 0 {
		field := line[:idx]
		value := line[idx+1:]
		if strings.HasPrefix(value, " ") {
			value = value[1:]
		}
		switch field {
		case "event":
			*eventName = value
		case "data":
			*dataLines = append(*dataLines, value)
		}
		return
	}
	// Field with no value (rare). Treat the whole line as field name
	// per spec.
}

// =============================================================================
// AichatRecoverer — late recovery via the conversation API
// =============================================================================

// RecoverTurn asks aichat whether the given paliad turn has a response.
// Returns the up-to-date row on success (including a freshly persisted
// response when aichat had one), nil + nil when aichat doesn't know
// either, or an error on transport / DB failures.
func (s *AichatPaliadinService) RecoverTurn(ctx context.Context, callerID, turnID uuid.UUID) (*PaliadinTurn, error) {
	row, err := s.GetTurn(ctx, callerID, turnID)
	if err != nil {
		return nil, err
	}
	// Fast path: the row already has a response (the janitor or a
	// concurrent stream finished writing). Return it as-is.
	if row.Response != nil && *row.Response != "" {
		return row, nil
	}

	convID, err := s.resolveAichatConversationID(ctx, row)
	if err != nil {
		log.Printf("paliadin: recover %s: resolve conversation: %v", turnID, err)
		return nil, nil
	}
	if convID == "" {
		return nil, nil
	}

	turns, err := s.fetchAichatConversationTurns(ctx, convID)
	if err != nil {
		log.Printf("paliadin: recover %s: fetch turns: %v", turnID, err)
		return nil, nil
	}

	assistantBody := matchAssistantResponse(turns, row.UserMessage)
	if assistantBody == "" {
		return nil, nil
	}

	finished := time.Now().UTC()
	durationMS := int(finished.Sub(row.StartedAt) / time.Millisecond)
	tokens := approxTokenCount(assistantBody)
	chipCount := countChips(assistantBody)

	if err := s.completeTurnLate(ctx, turnID, finished, durationMS, assistantBody, tokens, trailerMeta{}, chipCount); err != nil {
		log.Printf("paliadin: recover %s: complete late: %v", turnID, err)
		return nil, err
	}

	// Re-read so the caller gets a row that reflects the late-write.
	return s.GetTurn(ctx, callerID, turnID)
}

// resolveAichatConversationID returns the conversation the turn lived
// in. Fast path: read the column on the row. Fallback: list aichat
// conversations for the user+persona and take the most recent.
func (s *AichatPaliadinService) resolveAichatConversationID(ctx context.Context, row *PaliadinTurn) (string, error) {
	stored, err := s.getAichatConversationID(ctx, row.TurnID)
	if err != nil {
		return "", err
	}
	if stored != "" {
		return stored, nil
	}
	username := s.usernameFor(ctx, row.UserID)
	convs, err := s.listAichatConversations(ctx, username, row.UserID.String())
	if err != nil {
		return "", err
	}
	if len(convs) == 0 {
		return "", nil
	}
	// Aichat orders by last_turn_at DESC; the head is the most recently
	// active conversation, which is the pane the lost turn ran against.
	return convs[0].ID, nil
}

// matchAssistantResponse walks the aichat turn list and returns the
// body of the latest assistant turn whose preceding user-role turn body
// matches `userMessage` (verbatim — aichat persists the raw message
// the same way paliad does).
//
// Falls back to "the last assistant body in the conversation" when no
// match is found but the conversation has assistant content. This
// covers cases where aichat persisted the user turn with envelope
// prefixes that don't exactly match our user_message (e.g. an embedded
// [ctx …] block).
func matchAssistantResponse(turns []aichatConversationTurn, userMessage string) string {
	wantedNorm := normaliseForMatch(userMessage)

	for i := 0; i < len(turns)-1; i++ {
		t := turns[i]
		if t.Role != "user" {
			continue
		}
		if normaliseForMatch(t.Body) != wantedNorm {
			continue
		}
		next := turns[i+1]
		if next.Role == "assistant" && next.Body != "" {
			return next.Body
		}
	}

	for i := len(turns) - 1; i >= 0; i-- {
		t := turns[i]
		if t.Role == "assistant" && t.Body != "" {
			return t.Body
		}
	}
	return ""
}

// normaliseForMatch lowercases, strips surrounding whitespace, and
// collapses internal whitespace runs. Comparison only — no semantic
// meaning beyond "did aichat persist the same prompt we sent".
func normaliseForMatch(s string) string {
	s = strings.TrimSpace(strings.ToLower(s))
	for strings.Contains(s, "  ") {
		s = strings.ReplaceAll(s, "  ", " ")
	}
	return s
}

// =============================================================================
// aichat conversation API client helpers
// =============================================================================

type aichatConversationSummary struct {
	ID         string `json:"id"`
	Persona    string `json:"persona"`
	LastTurnAt string `json:"last_turn_at"`
}

type aichatListConversationsResponse struct {
	Conversations []aichatConversationSummary `json:"conversations"`
}

type aichatConversationTurn struct {
	ID        string `json:"id"`
	Seq       int    `json:"seq"`
	Role      string `json:"role"`
	Body      string `json:"body"`
	CreatedAt string `json:"created_at"`
}

type aichatGetConversationTurnsResponse struct {
	ConversationID string                   `json:"conversation_id"`
	Turns          []aichatConversationTurn `json:"turns"`
	HasMore        bool                     `json:"has_more"`
}

// listAichatConversations calls GET /chat/conversations for the user.
func (s *AichatPaliadinService) listAichatConversations(ctx context.Context, username, userID string) ([]aichatConversationSummary, error) {
	q := url.Values{}
	q.Set("persona", s.cfg.Persona)
	q.Set("username", username)
	q.Set("user_id", userID)
	q.Set("limit", "5")
	path := "/chat/conversations?" + q.Encode()
	var resp aichatListConversationsResponse
	if err := s.callHTTP(ctx, http.MethodGet, path, nil, &resp); err != nil {
		return nil, err
	}
	return resp.Conversations, nil
}

// fetchAichatConversationTurns calls GET /chat/conversations/{id}/turns.
func (s *AichatPaliadinService) fetchAichatConversationTurns(ctx context.Context, convID string) ([]aichatConversationTurn, error) {
	q := url.Values{}
	q.Set("persona", s.cfg.Persona)
	q.Set("limit", "20")
	path := "/chat/conversations/" + url.PathEscape(convID) + "/turns?" + q.Encode()
	var resp aichatGetConversationTurnsResponse
	if err := s.callHTTP(ctx, http.MethodGet, path, nil, &resp); err != nil {
		return nil, err
	}
	return resp.Turns, nil
}

// =============================================================================
// DB helpers for paliadin_turns.aichat_conversation_id (migration 118)
// =============================================================================

func (s *AichatPaliadinService) setAichatConversationID(ctx context.Context, turnID uuid.UUID, convID string) error {
	if convID == "" {
		return nil
	}
	convUUID, err := uuid.Parse(convID)
	if err != nil {
		return fmt.Errorf("invalid conversation id %q: %w", convID, err)
	}
	_, err = s.db.ExecContext(ctx, `
		UPDATE paliad.paliadin_turns
		   SET aichat_conversation_id = $2
		 WHERE turn_id = $1
		   AND aichat_conversation_id IS DISTINCT FROM $2
	`, turnID, convUUID)
	return err
}

func (s *AichatPaliadinService) getAichatConversationID(ctx context.Context, turnID uuid.UUID) (string, error) {
	var convID *uuid.UUID
	err := s.db.QueryRowxContext(ctx,
		`SELECT aichat_conversation_id FROM paliad.paliadin_turns WHERE turn_id = $1`,
		turnID).Scan(&convID)
	if err != nil {
		return "", err
	}
	if convID == nil {
		return "", nil
	}
	return convID.String(), nil
}

// Compile-time interface conformance — fail the build if a streaming
// method drifts off this backend.
var _ StreamingPaliadin = (*AichatPaliadinService)(nil)
var _ AichatRecoverer = (*AichatPaliadinService)(nil)