// Command harness is the MOPAC harness CLI. v0 surface: `harness once`,
// `harness loop`, `harness events`.
package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"sort"
	"strings"
	"syscall"
	"time"

	"ukrrs.com/mopac/harness/internal/config"
	"ukrrs.com/mopac/harness/internal/events"
	"ukrrs.com/mopac/harness/internal/loop"
	"ukrrs.com/mopac/harness/internal/quota"
	"ukrrs.com/mopac/harness/internal/serve"
)

const usage = `MOPAC harness (v0)

Usage:
  harness once [-config PATH] [-dry-run] [-demo] [-task-id ID]
  harness loop [-config PATH] [-interval DUR] [-once] [-dry-run]
  harness events [-config PATH] [-listen ADDR]
  harness serve [-config PATH] [-listen ADDR]
  harness quota <status|probe|gate> [-config PATH]

once runs ONE conductor iteration and exits (chain by re-invoking; no daemon):
  intake (Redmine scope, or the [demo] issue) -> plan/model routing ->
  bounded turn via LiteLLM -> REPORT file writeback.

loop is the self-hosting daemon: Redmine is the SoR, the loop is the worker.
  It polls the intake on an interval, runs ONE bounded turn per new/updated
  issue (sequentially), notes the REPORT back on the issue, transitions
  status per [redmine.status_map], optionally commits the REPORT to gitea
  ([gitea] commit_reports). State is append-only loop.jsonl, dedup by
  issue id + updated_on. --once = single scan (cron-able). SIGINT stops.

events runs the webhook receiver until SIGINT/SIGTERM: Redmine/Discourse/
  Gitea webhooks are verified, normalized, stored append-only (dedup by
  provider event id) and handed to the conductor (dispatch stub for now).
  Routes: POST /hooks/{redmine,discourse,gitea}, GET /healthz.

serve runs the OpenAI-compatible front door until SIGINT/SIGTERM (the
  OpenWebUI connection): GET /v1/models lists the servable models (one per
  [models.classes] class, named mopac-<class>), POST /v1/chat/completions
  runs ONE bounded stateless conductor turn over the sent history and
  returns the final text + usage. Bearer vkey auth ([serve] vkey_ref);
  non-streaming v0; tools off. Own port - coexists with events.
  Routes: POST /v1/chat/completions, GET /v1/models, GET /healthz.

quota is the Redmine 490/491 gate surface:
  status  one-shot: quota snapshot (polled or estimated), peak window,
          host resources, and the per-class token+credit usage table from
          the loop state (the Discourse usage-report feed)
  probe   poll [quota] usage_url once and print the parsed buckets (or the
          raw error; bearer key never printed)
  gate    evaluate the back-pressure gates NOW: the decision for every
          [models.classes] class + resource thresholds

Flags:
  -config PATH    config file (default $HARNESS_CONFIG or ./harness.toml)
  -dry-run        once/loop: intake + plan only; no LLM call, no REPORT,
                  no state writes
  -demo           once: run the [demo] issue instead of Redmine intake
  -task-id ID     once: run only the task/issue with this id
  -interval DUR   loop: poll interval (overrides [loop] poll_interval_secs)
  -once           loop: single scan then exit (cron-able)
  -listen ADDR    events/serve: bind address (overrides [events]/[serve] listen)
Exit codes:
  0 ok (including "no tasks in scope"; loop: clean SIGINT stop)
  1 usage / config / routing / writeback error
  2 intake error
  4 llm / turn error
`

func main() {
	os.Exit(run(os.Args[1:]))
}

func run(args []string) int {
	if len(args) == 0 {
		fmt.Fprint(os.Stderr, usage)
		return 1
	}
	switch args[0] {
	case "help", "-h", "--help":
		fmt.Print(usage)
		return 0
	case "once":
		return runOnce(args[1:])
	case "loop":
		return runLoop(args[1:])
	case "events":
		return runEvents(args[1:])
	case "serve":
		return runServe(args[1:])
	case "quota":
		return runQuota(args[1:])
	default:
		fmt.Fprintf(os.Stderr, "harness: unknown command %q\n\n%s", args[0], usage)
		return 1
	}
}

func runOnce(args []string) int {
	fs := flag.NewFlagSet("once", flag.ContinueOnError)
	cfgPath := fs.String("config", "", "config file path")
	dryRun := fs.Bool("dry-run", false, "intake + plan only, no LLM call")
	demo := fs.Bool("demo", false, "use the [demo] issue instead of Redmine")
	taskID := fs.String("task-id", "", "run only this task id")
	if err := fs.Parse(args); err != nil {
		return 1
	}
	if fs.NArg() > 0 {
		fmt.Fprintf(os.Stderr, "harness: unexpected argument %q\n", fs.Arg(0))
		return 1
	}

	if *cfgPath == "" {
		*cfgPath = os.Getenv("HARNESS_CONFIG")
	}
	if *cfgPath == "" {
		*cfgPath = "harness.toml"
	}
	cfg, err := config.Load(*cfgPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	conductor, err := loop.New(cfg, os.Stdout)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}

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

	_, err = conductor.Once(ctx, loop.OnceOpts{
		DryRun: *dryRun,
		Demo:   *demo,
		TaskID: *taskID,
	})
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		switch {
		case errors.Is(err, loop.ErrIntake):
			return 2
		case errors.Is(err, loop.ErrLLM):
			return 4
		default:
			return 1
		}
	}
	return 0
}

func runLoop(args []string) int {
	fs := flag.NewFlagSet("loop", flag.ContinueOnError)
	cfgPath := fs.String("config", "", "config file path")
	interval := fs.Duration("interval", 0, "poll interval (overrides [loop] poll_interval_secs)")
	once := fs.Bool("once", false, "single scan then exit (cron-able)")
	dryRun := fs.Bool("dry-run", false, "scan and print what would dispatch; no turns, no state writes")
	if err := fs.Parse(args); err != nil {
		return 1
	}
	if fs.NArg() > 0 {
		fmt.Fprintf(os.Stderr, "harness: unexpected argument %q\n", fs.Arg(0))
		return 1
	}

	if *cfgPath == "" {
		*cfgPath = os.Getenv("HARNESS_CONFIG")
	}
	if *cfgPath == "" {
		*cfgPath = "harness.toml"
	}
	cfg, err := config.Load(*cfgPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	conductor, err := loop.New(cfg, os.Stdout)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}

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

	if err := conductor.RunLoop(ctx, loop.LoopOpts{
		Interval: *interval,
		Once:     *once,
		DryRun:   *dryRun,
	}); err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		switch {
		case errors.Is(err, loop.ErrIntake):
			return 2
		default:
			return 1
		}
	}
	return 0
}

func runQuota(args []string) int {
	sub := "status"
	var rest []string
	if len(args) > 0 && !strings.HasPrefix(args[0], "-") {
		sub = args[0]
		rest = args[1:]
	}
	switch sub {
	case "status", "probe", "gate":
	default:
		fmt.Fprintf(os.Stderr, "harness: quota: unknown subcommand %q (want status|probe|gate)\n", sub)
		return 1
	}
	fs := flag.NewFlagSet("quota "+sub, flag.ContinueOnError)
	cfgPath := fs.String("config", "", "config file path")
	if err := fs.Parse(rest); err != nil {
		return 1
	}
	if fs.NArg() > 0 {
		fmt.Fprintf(os.Stderr, "harness: unexpected argument %q\n", fs.Arg(0))
		return 1
	}
	if *cfgPath == "" {
		*cfgPath = os.Getenv("HARNESS_CONFIG")
	}
	if *cfgPath == "" {
		*cfgPath = "harness.toml"
	}
	cfg, err := config.Load(*cfgPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	conductor, err := loop.New(cfg, os.Stdout)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	gate := conductor.Gate()

	switch sub {
	case "probe":
		if gate == nil || cfg.Quota.UsageURL == "" {
			fmt.Println("harness: quota: no [quota] usage_url configured (running on estimates)")
			return 0
		}
		snap := gate.Snapshot(context.Background())
		fmt.Printf("harness: quota: account=%s source=%s fetched=%s\n", snap.Account, snap.Source, snap.FetchedAt.Format(time.RFC3339))
		for _, b := range snap.Buckets {
			reset := "-"
			if !b.WindowReset.IsZero() {
				reset = b.WindowReset.Format(time.RFC3339)
			}
			fmt.Printf("  %-7s used=%.0f limit=%.0f (%.1f%%) resets=%s\n", b.ID, b.Used, b.Limit, b.UsedPct(), reset)
		}
		return 0

	case "gate":
		if gate == nil {
			fmt.Println("harness: quota gate off ([quota] enabled = false)")
			return 0
		}
		fmt.Printf("harness: quota gate: %s\n", conductor.GateStatusLine(context.Background()))
		for _, class := range sortedClasses(cfg) {
			d := gate.Decide(context.Background(), class)
			tag := "ALLOW"
			if d.Action == quota.ActionDefer {
				tag = "DEFER"
			}
			fmt.Printf("  %-6s class=%-12s %s\n", tag, class, d.Reason)
		}
		return 0
	}

	// status
	if gate == nil && !cfg.Resources.Enabled {
		fmt.Println("harness: quota gate off ([quota]/[resources] enabled = false)")
	} else if gate != nil {
		fmt.Printf("harness: quota: %s\n", conductor.GateStatusLine(context.Background()))
		fmt.Printf("  peak window: %s-%s %s weekdays_only=%v currently=%v\n",
			cfg.Quota.PeakStart, cfg.Quota.PeakEnd, cfg.Quota.Timezone, cfg.Quota.PeakWeekdaysOnly, gate.InPeak())
	}
	if st, ok := conductor.ResourceSample(); ok {
		fmt.Printf("harness: resources: load=%.2f memAvail=%.0fMB diskFree=%.0fMB ioDelay=%.1f%%(psi=%v)\n",
			st.LoadAvg1m, st.MemAvailable, st.DiskFree, st.IODelayPct, st.HasPSI)
	}
	report, err := loop.UsageReport(cfg.Loop.StateDir)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: usage report: %v\n", err)
		return 0
	}
	fmt.Printf("harness: usage by class (%s):\n%s", cfg.Loop.StateDir, report)
	return 0
}

func sortedClasses(cfg *config.Config) []string {
	out := make([]string, 0, len(cfg.Models.Classes))
	for class := range cfg.Models.Classes {
		out = append(out, class)
	}
	sort.Strings(out)
	return out
}

func runEvents(args []string) int {
	fs := flag.NewFlagSet("events", flag.ContinueOnError)
	cfgPath := fs.String("config", "", "config file path")
	listen := fs.String("listen", "", "bind address (overrides [events] listen)")
	if err := fs.Parse(args); err != nil {
		return 1
	}
	if fs.NArg() > 0 {
		fmt.Fprintf(os.Stderr, "harness: unexpected argument %q\n", fs.Arg(0))
		return 1
	}

	if *cfgPath == "" {
		*cfgPath = os.Getenv("HARNESS_CONFIG")
	}
	if *cfgPath == "" {
		*cfgPath = "harness.toml"
	}
	cfg, err := config.Load(*cfgPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	// The conductor is the event dispatcher (stub until phase 3 wiring).
	conductor, err := loop.New(cfg, os.Stdout)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	srv, err := events.NewServer(cfg.Events, conductor, os.Stdout)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	defer srv.Close()
	if *listen == "" {
		*listen = cfg.Events.Listen
	}

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

	httpSrv := &http.Server{
		Addr:              *listen,
		Handler:           srv.Handler(),
		ReadHeaderTimeout: 10 * time.Second,
	}
	go func() {
		<-ctx.Done()
		shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		_ = httpSrv.Shutdown(shutdownCtx)
	}()

	fmt.Printf("harness: events receiver on %s (state: %s)\n", *listen, cfg.Events.StateDir)
	err = httpSrv.ListenAndServe()
	if err != nil && !errors.Is(err, http.ErrServerClosed) {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	fmt.Printf("harness: events receiver stopped\n")
	return 0
}

func runServe(args []string) int {
	fs := flag.NewFlagSet("serve", flag.ContinueOnError)
	cfgPath := fs.String("config", "", "config file path")
	listen := fs.String("listen", "", "bind address (overrides [serve] listen)")
	if err := fs.Parse(args); err != nil {
		return 1
	}
	if fs.NArg() > 0 {
		fmt.Fprintf(os.Stderr, "harness: unexpected argument %q\n", fs.Arg(0))
		return 1
	}

	if *cfgPath == "" {
		*cfgPath = os.Getenv("HARNESS_CONFIG")
	}
	if *cfgPath == "" {
		*cfgPath = "harness.toml"
	}
	cfg, err := config.Load(*cfgPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	// The conductor owns the turn machinery and the model router the
	// catalog is built from.
	conductor, err := loop.New(cfg, os.Stdout)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	srv, err := serve.NewServer(cfg.Serve, conductor.Router(), conductor, os.Stdout)
	if err != nil {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	if *listen == "" {
		*listen = cfg.Serve.Listen
	}

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

	httpSrv := &http.Server{
		Addr:              *listen,
		Handler:           srv.Handler(),
		ReadHeaderTimeout: 10 * time.Second,
	}
	go func() {
		<-ctx.Done()
		shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		_ = httpSrv.Shutdown(shutdownCtx)
	}()

	fmt.Printf("harness: serve (OpenAI-compatible) on %s (models: %s)\n", *listen, strings.Join(srv.ModelNames(), ", "))
	err = httpSrv.ListenAndServe()
	if err != nil && !errors.Is(err, http.ErrServerClosed) {
		fmt.Fprintf(os.Stderr, "harness: %v\n", err)
		return 1
	}
	fmt.Printf("harness: serve stopped\n")
	return 0
}