// Command school is the Compass / NHS service (school.lab.audasmedia.com.au).
//
// Phase 1 skeleton: Go service, SQLite schema (AGENTS.md §7), the service's own
// session login, HTMX server-rendered shell, and GET /health. It does not scan
// the school; the Compass login and fetch are Phase 2.
package main

import (
	"context"
	"crypto/rand"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"golang.org/x/crypto/bcrypt"

	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/auth"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/config"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/store"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/web"
)

// version is injected with -ldflags at build time.
var version = "dev"

// seedChildren is the fixed set from AGENTS.md: Harry and Finn.
var seedChildren = []string{"Harry", "Finn"}

func main() {
	if len(os.Args) > 1 {
		switch os.Args[1] {
		case "hash-password":
			hashPassword(os.Args[2:])
			return
		case "gen-secret":
			genSecret()
			return
		case "parse":
			parseCommand(os.Args[2:])
			return
		case "session":
			sessionCommand(os.Args[2:])
			return
		case "scan":
			scanCommand(os.Args[2:])
			return
		case "items":
			itemsCommand(os.Args[2:])
			return
		case "brief":
			briefCommand(os.Args[2:])
			return
		case "calendar":
			calendarCommand(os.Args[2:])
			return
		case "version":
			fmt.Println(version)
			return
		}
	}
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, "school:", err)
		os.Exit(1)
	}
}

func run() error {
	started := time.Now()

	cfg, err := config.Load()
	if err != nil {
		return err
	}
	cfg.Version = version

	log := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: cfg.LogLevel}))
	slog.SetDefault(log)

	st, err := store.Open(cfg.DBPath)
	if err != nil {
		return err
	}
	defer st.Close()

	if err := st.Migrate(context.Background()); err != nil {
		return err
	}
	if err := st.SeedChildren(context.Background(), seedChildren...); err != nil {
		return err
	}

	am, err := auth.New(cfg.SessionSecret, cfg.SessionTTL, cfg.CookieSecure,
		cfg.AdminUsername, cfg.AdminPasswordHash, cfg.AdminPassword)
	if err != nil {
		return err
	}
	if !am.Hashed() {
		log.Warn("admin password is plaintext; set SCHOOL_ADMIN_PASSWORD_HASH to use bcrypt")
	}

	srv, err := web.New(cfg, st, am, log)
	if err != nil {
		return err
	}

	httpServer := &http.Server{
		Addr:              cfg.Addr,
		Handler:           srv.Handler(),
		ReadHeaderTimeout: 10 * time.Second,
		ReadTimeout:       30 * time.Second,
		WriteTimeout:      30 * time.Second,
		IdleTimeout:       60 * time.Second,
	}

	errCh := make(chan error, 1)
	go func() {
		log.Info("school service listening",
			"addr", cfg.Addr, "db", cfg.DBPath, "env", cfg.AppEnv, "version", version)
		if err := httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			errCh <- err
		}
	}()

	stop := make(chan os.Signal, 1)
	signal.Notify(stop, syscall.SIGINT, syscall.SIGTERM)

	select {
	case err := <-errCh:
		return err
	case sig := <-stop:
		log.Info("shutting down", "signal", sig.String())
	}

	ctxShutdown, cancelShutdown := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancelShutdown()
	if err := httpServer.Shutdown(ctxShutdown); err != nil {
		return fmt.Errorf("shutdown: %w", err)
	}
	log.Info("stopped", "uptime", time.Since(started).Round(time.Second).String())
	return nil
}

// hashPassword prints a bcrypt hash for the password given as an argument or
// read from stdin. It never prints the password itself.
func hashPassword(args []string) {
	var password string
	if len(args) > 0 {
		password = args[0]
	} else {
		b, err := io.ReadAll(os.Stdin)
		if err != nil {
			fmt.Fprintln(os.Stderr, "school:", err)
			os.Exit(1)
		}
		password = string(b)
	}
	if password == "" {
		fmt.Fprintln(os.Stderr, "school: empty password")
		os.Exit(2)
	}
	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		fmt.Fprintln(os.Stderr, "school:", err)
		os.Exit(1)
	}
	fmt.Println(string(hash))
}

// genSecret prints a fresh 32-byte hex secret. Use it to set
// SCHOOL_SESSION_SECRET without pasting a secret into a shell history file by
// hand. It never reads or stores anything.
func genSecret() {
	b := make([]byte, 32)
	if _, err := rand.Read(b); err != nil {
		fmt.Fprintln(os.Stderr, "school:", err)
		os.Exit(1)
	}
	fmt.Printf("%x\n", b)
}