email_agent/cmd/email-agent/main.go

// Command email-agent runs the Email Agent HTTP service.
package main

import (
	"context"
	"flag"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/classify"
	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/config"
	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/mailfetch"
	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/server"
	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/store"
	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/version"
)

func main() {
	var (
		showVersion = flag.Bool("version", false, "print version information and exit")
		healthcheck = flag.Bool("healthcheck", false, "probe the local /health endpoint and exit")
		fetchNow    = flag.Bool("fetch", false, "run one Gmail IMAP scan and exit")
		classifyNow = flag.Bool("classify", false, "classify pending messages with JEV and exit")
		classifyAll = flag.Bool("classify-all", false, "re-classify every stored message with JEV and exit")
	)
	flag.Parse()

	if *showVersion {
		fmt.Printf("email-agent %s (commit %s)\n", version.Version, version.Commit)
		return
	}

	cfg, err := config.Load()
	if err != nil {
		fmt.Fprintf(os.Stderr, "config error: %v\n", err)
		os.Exit(1)
	}

	logger := newLogger(cfg.LogLevel)
	slog.SetDefault(logger)

	if *healthcheck {
		if err := probeHealth(cfg.Port); err != nil {
			fmt.Fprintf(os.Stderr, "healthcheck failed: %v\n", err)
			os.Exit(1)
		}
		return
	}

	if *fetchNow {
		if err := runFetch(cfg, logger); err != nil {
			fmt.Fprintf(os.Stderr, "fetch failed: %v\n", err)
			os.Exit(1)
		}
		return
	}

	if *classifyNow || *classifyAll {
		if err := runClassify(cfg, logger, *classifyAll); err != nil {
			fmt.Fprintf(os.Stderr, "classify failed: %v\n", err)
			os.Exit(1)
		}
		return
	}

	if err := run(cfg, logger); err != nil {
		logger.Error("fatal", "error", err)
		os.Exit(1)
	}
}

func run(cfg *config.Config, logger *slog.Logger) error {
	logger.Info("starting email-agent",
		"version", version.Version,
		"commit", version.Commit,
		"env", cfg.Env,
	)

	if cfg.SessionSecret == "" && cfg.Password == "" {
		logger.Warn("no EMAIL_AGENT_PASSWORD or EMAIL_AGENT_SESSION_SECRET set; login is disabled until one is configured")
	}

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	st, err := store.Open(ctx, cfg.DBPath)
	if err != nil {
		return fmt.Errorf("open store: %w", err)
	}
	defer func() {
		if cerr := st.Close(); cerr != nil {
			logger.Error("close store", "error", cerr)
		}
	}()

	schemaVersion, err := st.SchemaVersion(ctx)
	if err != nil {
		return fmt.Errorf("read schema version: %w", err)
	}
	logger.Info("database ready", "path", st.Path(), "schema_version", schemaVersion)

	srv, err := server.New(cfg, st, logger)
	if err != nil {
		return fmt.Errorf("build server: %w", err)
	}

	return srv.Run(ctx)
}

// runFetch performs a single IMAP scan and exits. It is the entry point n8n
// (FR-1) and manual operations use to trigger a sync without the HTTP UI.
func runFetch(cfg *config.Config, logger *slog.Logger) error {
	if !cfg.GmailConfigured() {
		return mailfetch.ErrNoCredentials
	}
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	st, err := store.Open(ctx, cfg.DBPath)
	if err != nil {
		return fmt.Errorf("open store: %w", err)
	}
	defer func() { _ = st.Close() }()

	sum, err := mailfetch.NewFetcher(cfg, st, logger).Fetch(ctx)
	if err != nil {
		return err
	}
	fmt.Printf("fetched=%d stored=%d uidvalidity=%d since=%s\n",
		sum.Fetched, sum.Stored, sum.UIDValidity, sum.Since.Format("2006-01-02"))
	return nil
}

// runClassify classifies messages and exits. It is the n8n/CLI entry point for
// FR-3, separate from the HTTP service so a scheduled scan can be bounded and
// observed. all=true re-classifies every message, for use after the category
// list or rules change.
func runClassify(cfg *config.Config, logger *slog.Logger, all bool) error {
	if !cfg.JEVConfigured() {
		return classify.ErrNotConfigured
	}
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	st, err := store.Open(ctx, cfg.DBPath)
	if err != nil {
		return fmt.Errorf("open store: %w", err)
	}
	defer func() { _ = st.Close() }()

	classifier := classify.NewClassifier(
		classify.NewClient(cfg.JEVBaseURL, cfg.JEVAPIKey, cfg.JEVModel, logger),
		st, logger, cfg.ClassifyConcurrency, cfg.ClassifyMaxMessages,
	)
	var sum classify.Summary
	if all {
		sum, err = classifier.RunAll(ctx)
	} else {
		sum, err = classifier.Run(ctx)
	}
	if err != nil {
		return err
	}
	fmt.Printf("considered=%d classified=%d failed=%d remaining=%d model=%s rules_version=%d\n",
		sum.Considered, sum.Classified, sum.Failed, sum.Remaining, sum.Model, sum.RulesVersion)
	return nil
}

// probeHealth requests the local health endpoint. It exists so the container
// healthcheck does not need an external HTTP client in the image.
func probeHealth(port int) error {
	client := &http.Client{Timeout: 3 * time.Second}
	url := fmt.Sprintf("http://127.0.0.1:%d/health", port)
	resp, err := client.Get(url)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("unexpected status %d from %s", resp.StatusCode, url)
	}
	return nil
}

func newLogger(level string) *slog.Logger {
	var lvl slog.Level
	if err := lvl.UnmarshalText([]byte(level)); err != nil {
		lvl = slog.LevelInfo
	}
	handler := slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: lvl})
	return slog.New(handler)
}