package api

import (
	"context"
	"errors"
	"net/http"

	"github.com/danielgtaylor/huma/v2"

	"github.com/v10networks/nmon/internal/auth"
	"github.com/v10networks/nmon/internal/store"
)

// Setup errors the app returns; the handlers map them to 409.
var (
	// ErrSetupClosed means install mode is off: setup was completed, or a sign-in was configured from the start.
	ErrSetupClosed = errors.New("setup is closed")
	// ErrSetupNoSignIn means setup cannot finish because no sign-in method is configured yet.
	ErrSetupNoSignIn = errors.New("no sign-in method is configured yet")
)

// OIDCSecretName is where the wizard stores the OIDC client secret.
const OIDCSecretName = "oidc-client"

// SetupAdmin is the part of the running app the wizard drives. Install mode is a property of the process, so the
// API asks the app rather than keeping its own copy.
type SetupAdmin interface {
	// InstallMode reports whether install mode is on right now.
	InstallMode() bool
	// SetupCompleted reports whether setup was ever completed (the stored one-way flag).
	SetupCompleted(ctx context.Context) (bool, error)
	// SignIn writes the break-glass file, stores the OIDC secret and sets auth.* in config.yaml. A bad value wraps
	// ErrInvalidSettings; install mode being off is ErrSetupClosed.
	SignIn(ctx context.Context, actor string, in SetupSignInBody) (SetupSignIn, error)
	// Complete re-checks the sign-in, marks setup completed for good and swaps the live authentication in. It
	// returns ErrSetupClosed or ErrSetupNoSignIn.
	Complete(ctx context.Context, actor string) (SetupComplete, error)
}

func (s *server) registerSetup(api huma.API) {
	tags := []string{"setup"}
	huma.Register(api, huma.Operation{
		OperationID: "get-setup", Method: http.MethodGet, Path: "/api/v1/setup", Tags: tags,
		Summary: "First-install state",
		Description: "Public. Says whether install mode is on (the UI then sends every page to /setup) and whether setup was " +
			"completed. Progress counts are filled in only while install mode is on.",
	}, s.getSetup)
	huma.Register(api, huma.Operation{
		OperationID: "setup-sign-in", Method: http.MethodPost, Path: "/api/v1/setup/signin", Tags: tags,
		Summary: "Set up sign-in (install mode only)",
		Description: "Creates the break-glass admin (bcrypt, written to <data-dir>/breakglass with mode 0600) and optionally " +
			"OIDC. 409 once setup is completed.",
		Errors: []int{http.StatusConflict, http.StatusUnprocessableEntity, http.StatusServiceUnavailable},
	}, s.setupSignIn)
	huma.Register(api, huma.Operation{
		OperationID: "setup-recommended-policies", Method: http.MethodPost, Path: "/api/v1/setup/recommended-policies", Tags: tags,
		Summary: "Create the recommended alert policies (install mode only)",
		Description: "device_down, device_warning, interface_errors, cpu_high, memory_high and disk_full, each for everything. " +
			"Idempotent: a policy that exists by name, or any policy already bound to the rule, is left alone.",
		Errors: []int{http.StatusConflict, http.StatusServiceUnavailable},
	}, s.setupPolicies)
	huma.Register(api, huma.Operation{
		OperationID: "setup-complete", Method: http.MethodPost, Path: "/api/v1/setup/complete", Tags: tags,
		Summary: "Finish setup (install mode only)",
		Description: "409 unless a sign-in method is configured. Ends install mode permanently and switches authentication on " +
			"without a restart; the browser then signs in at the returned URL.",
		Errors: []int{http.StatusConflict, http.StatusServiceUnavailable},
	}, s.setupComplete)
}

func (s *server) setupAdmin() (SetupAdmin, error) {
	if s.Setup == nil {
		return nil, errNotConfigured("setup")
	}
	return s.Setup, nil
}

func (s *server) getSetup(ctx context.Context, _ *struct{}) (*struct{ Body SetupState }, error) {
	a, err := s.setupAdmin()
	if err != nil {
		return nil, err
	}
	done, err := a.SetupCompleted(ctx)
	if err != nil {
		return nil, s.storeErr(err)
	}
	out := SetupState{InstallMode: a.InstallMode(), Completed: done, Defaults: setupDefaults()}
	if out.InstallMode {
		out.Steps = s.setupSteps(ctx)
	}
	return &struct{ Body SetupState }{out}, nil
}

func setupDefaults() SetupDefaults {
	d := formDefaults()
	return SetupDefaults{BreakGlassUser: "admin", MinSignInLength: auth.MinBreakGlassPassword, OIDCSecretName: OIDCSecretName,
		Timezone: d.Timezone, Retention: d.Retention, PollInterval: d.PollerInterval}
}

// setupSteps counts what exists. A failed read counts as nothing: it only decides which step the UI opens on.
func (s *server) setupSteps(ctx context.Context) SetupSteps {
	var st SetupSteps
	if _, total, err := s.Store.ListDevices(ctx, store.DeviceFilter{}, store.Page{Limit: 1}); err == nil {
		st.Devices = int(total)
	}
	if ps, err := s.Store.ListAlertPolicies(ctx); err == nil {
		st.Policies = len(ps)
	}
	if f, err := s.formAdmin(); err == nil {
		cfg, _ := f.CurrentConfig()
		st.Receivers = len(cfg.Alerting.Receivers)
		st.SignIn = cfg.Auth.OIDC != nil || cfg.Auth.BreakGlassFile != ""
	}
	return st
}

// setupErr maps the app's setup errors to problems.
func (s *server) setupErr(err error) error {
	switch {
	case errors.Is(err, ErrSetupClosed):
		return huma.Error409Conflict("setup is closed: it was completed, or a sign-in method was configured before first start")
	case errors.Is(err, ErrSetupNoSignIn):
		return huma.Error409Conflict("set up a sign-in method first: setup cannot finish without one")
	case errors.Is(err, ErrInvalidSettings):
		return settingsProblem(trimSentinel(err, ErrInvalidSettings), err)
	}
	s.Logger.Error("setup", "err", err)
	return huma.Error500InternalServerError("setup failed; see the log")
}

func (s *server) setupSignIn(ctx context.Context, in *struct{ Body SetupSignInBody }) (*struct{ Body SetupSignIn }, error) {
	a, err := s.setupAdmin()
	if err != nil {
		return nil, err
	}
	out, err := a.SignIn(ctx, actorOf(ctx), in.Body)
	if err != nil {
		return nil, s.setupErr(err)
	}
	return &struct{ Body SetupSignIn }{out}, nil
}

func (s *server) setupComplete(ctx context.Context, _ *struct{}) (*struct{ Body SetupComplete }, error) {
	a, err := s.setupAdmin()
	if err != nil {
		return nil, err
	}
	out, err := a.Complete(ctx, actorOf(ctx))
	if err != nil {
		return nil, s.setupErr(err)
	}
	return &struct{ Body SetupComplete }{out}, nil
}