feat: escalate brain search to web when facts cannot confirm

internal/websearch/lookup.go

@@ -0,0 +1,122 @@
+package websearch
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	StatusSkipped = "skipped"
+	StatusRefused = "refused"
+)
+
+type LookupOpt struct {
+	Limit     int
+	Timeout   time.Duration
+	EnvPath   string
+	CachePath string
+	Client    *http.Client
+	Now       func() float64
+	Sleep     func(context.Context, time.Duration) error
+}
+
+func Lookup(ctx context.Context, query string, opt LookupOpt) Output {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	if opt.Limit <= 0 {
+		opt.Limit = DefaultLimit
+	}
+	if opt.Timeout <= 0 {
+		opt.Timeout = 25 * time.Second
+	}
+	nowFn := opt.Now
+	if nowFn == nil {
+		nowFn = func() float64 { return float64(time.Now().Unix()) }
+	}
+	sleepFn := opt.Sleep
+	if sleepFn == nil {
+		sleepFn = func(ctx context.Context, d time.Duration) error {
+			t := time.NewTimer(d)
+			defer t.Stop()
+			select {
+			case <-t.C:
+				return nil
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}
+	}
+
+	if reason := PHIReason(query); reason != "" {
+		return Output{Query: query, Status: StatusRefused, Note: reason}
+	}
+
+	cachePath := opt.CachePath
+	if cachePath == "" {
+		cachePath = os.Getenv("BRAIN_SEARCH_CACHE")
+	}
+	if cachePath == "" {
+		cachePath = os.Getenv("HOME") + "/.cache/brain/web-search.sqlite"
+	}
+	cache, err := OpenCache(cachePath)
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "cache: " + err.Error()}
+	}
+	defer cache.Close()
+
+	key := CacheKey(query, nil)
+	now := nowFn()
+	if cached, err := cache.Get(key, CacheTTL, now); err == nil && cached != nil {
+		out := Project(*cached, opt.Limit, DefaultSnippetChars)
+		out.Cached = true
+		return out
+	}
+
+	envPath := opt.EnvPath
+	if envPath == "" {
+		envPath = os.Getenv("BRAIN_SEARCH_ENV")
+	}
+	if envPath == "" {
+		envPath = os.Getenv("HOME") + "/.config/brain/search.env"
+	}
+	conf, err := LoadConfig(envPath)
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "no BRAIN_SEARCH_URL; second source not consulted"}
+	}
+
+	lock, err := os.OpenFile(cachePath+".lock", os.O_CREATE|os.O_RDWR, 0o600)
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "lock: " + err.Error()}
+	}
+	defer lock.Close()
+	if err := unix.Flock(int(lock.Fd()), unix.LOCK_EX); err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "lock: " + err.Error()}
+	}
+	defer unix.Flock(int(lock.Fd()), unix.LOCK_UN)
+
+	last, err := cache.LastCall()
+	if err != nil {
+		return Output{Query: query, Status: StatusSkipped, Note: "cache: " + err.Error()}
+	}
+	if delay := WaitFor(last, nowFn(), MinInterval); delay > 0 {
+		if err := sleepFn(ctx, time.Duration(delay*float64(time.Second))); err != nil {
+			return Output{Query: query, Status: StatusSkipped, Note: "cancelled"}
+		}
+	}
+	_ = cache.MarkCall(nowFn())
+
+	payload, err := Fetch(opt.Client, conf, query, nil, opt.Timeout)
+	if err != nil {
+		return Output{Query: query, Status: StatusThrottled, Note: fmt.Sprintf("request failed: %v", err)}
+	}
+	if Classify(payload) == StatusOK {
+		_ = cache.Put(key, payload, nowFn())
+	}
+	return Project(payload, opt.Limit, DefaultSnippetChars)
+}