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

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

	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/apprise"
	"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/hub"
	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/mailfetch"
	"gitea.lab.audasmedia.com.au/sam/email_agent/internal/mailops"
	"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/summary"
	"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")
		checkSMTP   = flag.Bool("check-smtp", false, "verify the Gmail SMTP connection (IPv4 + STARTTLS + login) and exit; sends no mail")
		checkThread = flag.Int64("check-thread", 0, "verify that a stored message's Gmail thread has a sent reply (read-only), then exit")
		summary     = flag.Bool("summary", false, "build today's inbox summary, store it, and print it; sends nothing")
		summarySend = flag.Bool("summary-send", false, "build today's inbox summary and deliver it by email via Apprise")
		notify      = flag.Bool("notify", false, "send one test notification to the Hub (POST /notify) and exit")
		retain      = flag.Bool("retain", false, "enforce retention (AGENTS.md §7): clear old message bodies and cap actions_log, then 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 *checkSMTP {
		if err := runCheckSMTP(cfg, logger); err != nil {
			fmt.Fprintf(os.Stderr, "smtp check failed: %v\n", err)
			os.Exit(1)
		}
		fmt.Println("smtp check ok: ipv4 + starttls + auth (no mail sent)")
		return
	}

	if *checkThread > 0 {
		if err := runCheckThread(cfg, logger, *checkThread); err != nil {
			fmt.Fprintf(os.Stderr, "thread check failed: %v\n", err)
			os.Exit(1)
		}
		return
	}

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

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

	if *retain {
		if err := runRetain(cfg, logger); err != nil {
			fmt.Fprintf(os.Stderr, "retain 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
}

// runCheckSMTP verifies the Gmail submission path (IPv4 + STARTTLS + app
// password) without sending a message. It is the safe part of the Phase 5 send
// verification; the real send needs Sam's explicit approval.
func runCheckSMTP(cfg *config.Config, logger *slog.Logger) error {
	if !cfg.GmailConfigured() {
		return mailops.ErrNotConfigured
	}
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()
	return mailops.New(cfg, logger).CheckSMTP(ctx)
}

// runCheckThread reports whether a stored message's Gmail thread already has a
// message in the Sent mailbox. It is read-only and exists so the Phase 5 thread
// check can be exercised against real Gmail without sending anything.
func runCheckThread(cfg *config.Config, logger *slog.Logger, messageID int64) error {
	if !cfg.GmailConfigured() {
		return mailops.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() }()

	msg, err := st.MessageByID(ctx, messageID)
	if err != nil {
		return err
	}
	if strings.TrimSpace(msg.ThreadID) == "" {
		return fmt.Errorf("message %d has no Gmail thread id", messageID)
	}
	ok, err := mailops.New(cfg, logger).VerifyThreadUpdated(ctx, msg.ThreadID)
	if err != nil {
		return err
	}
	fmt.Printf("message=%d thread=%s sent_reply_in_thread=%v\n", messageID, msg.ThreadID, ok)
	return nil
}

// runSummary builds today's inbox summary (FR-10). With send=false it stores and
// prints the summary and sends nothing; with send=true it also delivers it by
// email through Apprise. The n8n schedule runs the send form once a day.
func runSummary(cfg *config.Config, logger *slog.Logger, send bool) error {
	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() }()

	data, err := summary.New(st).Build(ctx)
	if err != nil {
		return fmt.Errorf("build summary: %w", err)
	}
	id, err := st.SaveSummary(ctx, data.Date, data.Text(), "")
	if err != nil {
		return err
	}
	fmt.Print(data.Text())

	if !send {
		fmt.Printf("\nsummary stored id=%d (not sent)\n", id)
		return nil
	}
	if !cfg.AppriseConfigured() {
		return fmt.Errorf("apprise is not configured: set APPRISE_URL and APPRISE_KEY (or APPRISE_URLS)")
	}
	if err := apprise.New(cfg.AppriseURL, cfg.AppriseKey, cfg.AppriseURLs, cfg.AppriseToken, 0).
		Send(ctx, data.Subject(), data.Text()); err != nil {
		return fmt.Errorf("deliver summary: %w", err)
	}
	if err := st.MarkSummaryDelivered(ctx, id, cfg.SummaryTo); err != nil {
		logger.Error("mark summary delivered", "error", err)
	}
	fmt.Printf("\nsummary delivered id=%d to=%s\n", id, cfg.SummaryTo)
	return nil
}

// runNotify sends one test notification to the Hub's POST /notify. It exists so
// the outbound notify path (ask-contract.md) can be exercised without the UI.
func runNotify(cfg *config.Config, logger *slog.Logger) error {
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	n := hub.NewNotifier(cfg.HubBaseURL, cfg.HubToken, cfg.HubNotifyTimeout, nil)
	if err := n.Notify(ctx, hub.NotifyRequest{
		From:    hub.ProjectName,
		Level:   "info",
		Message: "Email Agent notify path check.",
		Person:  "sam",
	}); err != nil {
		return err
	}
	fmt.Printf("notify ok: %s/notify\n", cfg.HubBaseURL)
	return nil
}

// runRetain enforces the AGENTS.md §7 data rules: message bodies older than the
// configured window are cleared (metadata stays), and the append-only
// actions_log is capped. It is a bounded, explicit job for the n8n schedule;
// the HTTP service never runs it on a request. Running it twice is safe.
func runRetain(cfg *config.Config, logger *slog.Logger) error {
	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() }()

	policy := store.RetentionPolicy{
		BodyMaxAge:        time.Duration(cfg.RetentionDays) * 24 * time.Hour,
		ActionsLogMaxRows: cfg.ActionsLogMaxRows,
	}
	res, err := st.Retain(ctx, policy)
	if err != nil {
		return err
	}
	if err := st.LogAction(ctx, "retain", "scheduler",
		fmt.Sprintf("bodies_cleared=%d actions_deleted=%d retention_days=%d max_rows=%d",
			res.BodiesCleared, res.ActionsDeleted, cfg.RetentionDays, cfg.ActionsLogMaxRows)); err != nil {
		// Retention already committed; a failed audit row must not fail the job.
		logger.Error("log retention action", "error", err)
	}

	cutoff := "disabled"
	if !res.BodyCutoff.IsZero() {
		cutoff = res.BodyCutoff.Format("2006-01-02")
	}
	fmt.Printf("bodies_cleared=%d body_cutoff=%s actions_deleted=%d actions_max_rows=%d\n",
		res.BodiesCleared, cutoff, res.ActionsDeleted, cfg.ActionsLogMaxRows)
	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)
}