kandev/apps/backend/internal/linear/poller.go

package linear

import (
	"context"
	"sync"
	"time"

	"go.uber.org/zap"

	"github.com/kandev/kandev/internal/common/logger"
	"github.com/kandev/kandev/internal/integrations/healthpoll"
)

// defaultIssuePollTickInterval is how often the issue-watch loop wakes up to
// consider every enabled watcher. The actual GraphQL search is only re-run for
// a watcher when its per-watch `PollIntervalSeconds` has elapsed since
// `LastPolledAt`, so this is the *minimum* granularity, not the *actual*
// cadence.
const defaultIssuePollTickInterval = 60 * time.Second

// Poller drives two background loops sharing a single Service:
//   - auth health: probes stored credentials so the UI can show connect status.
//     Delegated to internal/integrations/healthpoll for the loop semantics.
//   - issue watches: runs each enabled watcher's filter and emits
//     NewLinearIssueEvent for every matching issue the orchestrator hasn't yet
//     seen.
//
// Both loops are cancelled together via Stop.
type Poller struct {
	service       *Service
	logger        *logger.Logger
	auth          *healthpoll.Poller
	issueInterval time.Duration

	mu              sync.Mutex
	cancelIssueLoop context.CancelFunc
	wg              sync.WaitGroup
	started         bool
}

// NewPoller returns a poller using the default cadences. Returns nil when svc
// is nil so the caller's nil-check still works after the indirection.
func NewPoller(svc *Service, log *logger.Logger) *Poller {
	if svc == nil {
		return nil
	}
	return &Poller{
		service:       svc,
		logger:        log,
		auth:          healthpoll.New("linear", svcProber{svc}, log),
		issueInterval: defaultIssuePollTickInterval,
	}
}

// Start launches both background loops. Calling Start more than once without
// Stop is a no-op. A nil receiver is also a no-op.
func (p *Poller) Start(ctx context.Context) {
	if p == nil {
		return
	}
	p.mu.Lock()
	defer p.mu.Unlock()
	if p.started || p.service == nil {
		return
	}
	p.started = true
	issueCtx, cancel := context.WithCancel(ctx)
	p.cancelIssueLoop = cancel
	p.auth.Start(ctx)
	p.wg.Add(1)
	go p.issueWatchLoop(issueCtx)
}

// Stop cancels both loops and waits for them to drain.
func (p *Poller) Stop() {
	if p == nil {
		return
	}
	p.mu.Lock()
	if !p.started {
		p.mu.Unlock()
		return
	}
	cancel := p.cancelIssueLoop
	p.mu.Unlock()
	if cancel != nil {
		cancel()
	}
	p.auth.Stop()
	p.wg.Wait()
	p.mu.Lock()
	p.started = false
	p.mu.Unlock()
}

func (p *Poller) issueWatchLoop(ctx context.Context) {
	defer p.wg.Done()
	ticker := time.NewTicker(p.issueInterval)
	defer ticker.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			p.checkIssueWatches(ctx)
		}
	}
}

func (p *Poller) checkIssueWatches(ctx context.Context) {
	watches, err := p.service.Store().ListEnabledIssueWatches(ctx)
	if err != nil {
		p.logger.Warn("linear poller: list enabled issue watches failed", zap.Error(err))
		return
	}
	if len(watches) == 0 {
		return
	}
	for _, w := range watches {
		if ctx.Err() != nil {
			return
		}
		if !isIssueWatchDue(w, time.Now()) {
			continue
		}
		newIssues, err := p.service.CheckIssueWatch(ctx, w)
		if err != nil {
			p.logger.Debug("linear poller: check issue watch failed",
				zap.String("watch_id", w.ID), zap.Error(err))
			continue
		}
		for _, issue := range newIssues {
			p.logger.Info("new linear issue found for watch",
				zap.String("watch_id", w.ID),
				zap.String("identifier", issue.Identifier),
				zap.String("title", issue.Title))
			p.service.publishNewLinearIssueEvent(ctx, w, issue)
		}
	}
}

// isIssueWatchDue reports whether enough time has passed since the watch was
// last polled to re-run its search.
func isIssueWatchDue(w *IssueWatch, now time.Time) bool {
	if w.LastPolledAt == nil {
		return true
	}
	interval := w.PollIntervalSeconds
	if interval <= 0 {
		interval = DefaultIssueWatchPollInterval
	}
	return now.Sub(*w.LastPolledAt) >= time.Duration(interval)*time.Second
}

// svcProber adapts *Service to healthpoll.Prober without leaking the shared
// interface into Service's public API.
type svcProber struct{ svc *Service }

func (s svcProber) HasConfig(ctx context.Context) (bool, error) {
	return s.svc.Store().HasConfig(ctx)
}

func (s svcProber) RecordAuthHealth(ctx context.Context) {
	s.svc.RecordAuthHealth(ctx)
}