// Package auth defines the auth-method abstraction vault-tui uses for every
// login flow. A Method declares only which fields it needs (Fields); the
// TUI and headless CLI both render that declaration generically — a
// textinput form in the TUI, a TTY prompt or env/flag lookup on the CLI —
// so adding a new method never requires UI code (see prefill.go and
// registry.go).
package auth

import (
	"context"
	"time"

	"github.com/hashicorp/vault/api"
)

// FieldKind tells a renderer how to present a field.
type FieldKind uint8

const (
	FieldText FieldKind = iota
	FieldSecret
	FieldBool
	FieldSelect
	FieldPath
	FieldInt
)

// Field declares one credential input a Method needs.
type Field struct {
	Name     string
	Label    string
	Help     string
	Kind     FieldKind
	Required bool
	Default  string
	Options  []string

	// EnvFallback lists env vars consulted during Prefill, in order, before
	// falling back to config params. Mirrors Vault CLI behaviour (e.g.
	// VAULT_AUTH_GITHUB_TOKEN-style env overrides).
	EnvFallback []string

	// ConfigKey is the key looked up in profile.auth.params. Empty => Name.
	ConfigKey string

	// Validate runs before Login and must not have side effects.
	Validate func(value string) error
}

// Credentials is a filled-in form: field name -> value.
type Credentials map[string]string

func (c Credentials) Get(name string) string { return c[name] }
func (c Credentials) Has(name string) bool {
	v, ok := c[name]
	return ok && v != ""
}

// Redacted returns a copy safe for logs: every FieldSecret value becomes
// "***". This is the only sanctioned way to log a Credentials map.
func (c Credentials) Redacted(fields []Field) map[string]string {
	secret := map[string]bool{}
	for _, f := range fields {
		if f.Kind == FieldSecret {
			secret[f.Name] = true
		}
	}
	out := make(map[string]string, len(c))
	for k, v := range c {
		if secret[k] {
			out[k] = "***"
		} else {
			out[k] = v
		}
	}
	return out
}

// EventKind classifies out-of-band progress from a long-running login (OIDC
// browser wait, Okta push polling).
type EventKind uint8

const (
	EventStatus EventKind = iota
	EventOpenURL
	EventWarning
)

// Event is one piece of progress emitted on Request.Events.
type Event struct {
	Kind    EventKind
	Message string
	URL     string
}

// Request is everything a Method needs to perform one login.
type Request struct {
	Mount     string
	Namespace string
	Creds     Credentials
	// Events, if non-nil, receives progress notifications. Login must send
	// non-blockingly (see emit) so a stalled consumer can never deadlock it.
	Events  chan<- Event
	Timeout time.Duration
}

// Emit sends a progress event to Request.Events, non-blocking. Safe to
// call even when Events is nil (a headless caller that doesn't want
// progress) or when nobody is currently draining the channel.
func (r Request) Emit(e Event) {
	if r.Events == nil {
		return
	}
	select {
	case r.Events <- e:
	default:
	}
}

// Result is the normalised outcome of a login.
type Result struct {
	Secret    *api.Secret
	Token     string
	Accessor  string
	Renewable bool
	TTL       time.Duration
	Policies  []string
	Namespace string
}

func (r *Result) String() string {
	if r == nil {
		return "<nil result>"
	}
	return "<login result accessor=" + r.Accessor + ">"
}
func (r *Result) GoString() string { return r.String() }

// NewResult normalises an *api.Secret returned by a successful Login.
func NewResult(sec *api.Secret, namespace string) (*Result, error) {
	if sec == nil || sec.Auth == nil {
		return nil, errNoAuth
	}
	ttl, _ := sec.TokenTTL()
	policies, _ := sec.TokenPolicies()
	accessor, _ := sec.TokenAccessor()
	return &Result{
		Secret:    sec,
		Token:     sec.Auth.ClientToken,
		Accessor:  accessor,
		Renewable: sec.Auth.Renewable,
		TTL:       ttl,
		Policies:  policies,
		Namespace: namespace,
	}, nil
}

// Method is the single abstraction every auth method implements.
//
// Contract: Fields() is pure and cheap. Login must respect ctx cancellation
// and must never read os.Stdin — interactive prompting is the caller's job
// (TUI form or CLI prompt), driven by Fields()/Missing(). Login must not
// mutate client's token; token persistence is internal/token's job.
type Method interface {
	Name() string
	DisplayName() string
	DefaultMount() string
	Fields() []Field
	Login(ctx context.Context, client *api.Client, req Request) (*api.Secret, error)
}

// Describable is optional; implemented by methods with extra help text.
type Describable interface{ Description() string }