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

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

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

const usage = `MOPAC harness (v0)

Usage:
  harness once [-config PATH] [-dry-run] [-demo] [-task-id ID]
  harness events [-config PATH] [-listen ADDR]

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.

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.

Flags:
  -config PATH   config file (default $HARNESS_CONFIG or ./harness.toml)
  -dry-run       intake + plan only; no LLM call, no REPORT
  -demo          run the [demo] issue instead of Redmine intake
  -task-id ID    run only the task/issue with this id
  -listen ADDR   events: bind address (overrides [events] listen)

Exit codes:
  0 ok (including "no tasks in scope")
  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 "events":
		return runEvents(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 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
}