package adminapi

import (
	"context"
	"encoding/json"
	"log/slog"
	"net/http"
	"strings"
	"time"
)

// AuthAdmin is what the sign-in endpoints need: how people sign in now, a
// directory's settings tried before they are kept, and where the secrets
// those settings name are kept for every control plane.
type AuthAdmin struct {
	Status func() AuthView
	// TestLDAP tries an auth.ldap block, as YAML, binding with password
	// when one is given rather than the one the block names.
	TestLDAP func(ctx context.Context, settings, password string) ([]CheckView, error)
	Secrets  interface {
		SetClusterSecret(ctx context.Context, name, value string) error
	}
	Log *slog.Logger
}

// SetAuth enables the sign-in endpoints.
func (a *API) SetAuth(x *AuthAdmin) { a.auth = x }

// AuthView is how people sign in on this gateway.
type AuthView struct {
	SignupOpen bool `json:"signup_open"`
	// OIDC is single sign-on through an identity provider: Entra ID,
	// Keycloak, Okta.
	OIDC *OIDCView `json:"oidc,omitempty"`
	// LDAP is sign-in checked by a directory: Active Directory.
	LDAP *LDAPView `json:"ldap,omitempty"`
	// SCIM is whether a provider may keep accounts in step.
	SCIM bool `json:"scim"`
	// BaseURL is the portal's address, when the settings say it: what a
	// provider's redirect address is made from.
	BaseURL string `json:"base_url,omitempty"`
}

// OIDCView is auth.oidc as it is in force.
type OIDCView struct {
	Issuer         string `json:"issuer"`
	ClientID       string `json:"client_id"`
	Label          string `json:"label,omitempty"`
	CreateAccounts bool   `json:"create_accounts"`
	NoPasswords    bool   `json:"no_passwords"`
}

// LDAPView is auth.ldap as it is in force, and how its last sync went.
type LDAPView struct {
	URLs   []string `json:"urls"`
	BaseDN string   `json:"base_dn"`
	BindDN string   `json:"bind_dn"`
	Label  string   `json:"label,omitempty"`
	// Off is why this control plane could not use the settings, when it
	// could not; local accounts still sign in.
	Off      string             `json:"off,omitempty"`
	LastSync *DirectorySyncView `json:"last_sync,omitempty"`
}

// DirectorySyncView is the last time the leader read the directory.
type DirectorySyncView struct {
	At           time.Time `json:"at"`
	People       int       `json:"people"`
	Accounts     int       `json:"accounts"`
	Suspended    int       `json:"suspended"`
	Reinstated   int       `json:"reinstated"`
	RolesChanged int       `json:"roles_changed"`
	Error        string    `json:"error,omitempty"`
}

// CheckView is one step of trying a directory.
type CheckView struct {
	Step   string `json:"step"`
	OK     bool   `json:"ok"`
	Detail string `json:"detail"`
}

// LDAPTestRequest is an auth.ldap block to try, as YAML, and the service
// account's password when it is not kept yet.
type LDAPTestRequest struct {
	Settings string `json:"settings"`
	Password string `json:"password,omitempty"`
}

// LDAPTestView is how trying the directory went.
type LDAPTestView struct {
	OK     bool        `json:"ok"`
	Checks []CheckView `json:"checks"`
}

// SecretRequest is a secret for the store to keep.
type SecretRequest struct {
	Value string `json:"value"`
}

// authSecrets are the secrets an operator may give through the API, and
// the reference the settings then name each by.
var authSecrets = map[string]bool{"ldap-bind": true, "oidc-client-secret": true, "scim-token": true}

// AuthSecretRef is the reference auth's settings name a kept secret by.
func AuthSecretRef(name string) string { return "store:auth/" + name }

func (a *API) registerAuth(mux Mux) {
	need := func(w http.ResponseWriter) bool {
		if a.auth == nil {
			writeError(w, http.StatusNotImplemented, "this control plane has no accounts")
			return false
		}
		return true
	}
	mux.HandleFunc("GET /api/v1/auth", func(w http.ResponseWriter, r *http.Request) {
		if !need(w) {
			return
		}
		writeJSON(w, http.StatusOK, a.auth.Status())
	})
	mux.HandleFunc("POST /api/v1/auth/ldap/test", func(w http.ResponseWriter, r *http.Request) {
		if !need(w) {
			return
		}
		var req LDAPTestRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		checks, err := a.auth.TestLDAP(r.Context(), req.Settings, req.Password)
		if err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		v := LDAPTestView{OK: len(checks) > 0, Checks: checks}
		for _, c := range checks {
			v.OK = v.OK && c.OK
		}
		writeJSON(w, http.StatusOK, v)
	})
	mux.HandleFunc("PUT /api/v1/auth/secrets/{name}", func(w http.ResponseWriter, r *http.Request) {
		if !need(w) {
			return
		}
		name := r.PathValue("name")
		if !authSecrets[name] {
			writeError(w, http.StatusNotFound, "no such secret: ldap-bind, oidc-client-secret or scim-token")
			return
		}
		var req SecretRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if strings.TrimSpace(req.Value) == "" {
			writeError(w, http.StatusBadRequest, "an empty secret")
			return
		}
		if err := a.auth.Secrets.SetClusterSecret(r.Context(), "auth/"+name, req.Value); err != nil {
			writeError(w, http.StatusInternalServerError, err.Error())
			return
		}
		if a.auth.Log != nil {
			// What changed and who changed it; never the value.
			a.auth.Log.Info("a sign-in secret was set", "secret", name, "by", actorOf(r))
		}
		writeJSON(w, http.StatusOK, map[string]string{"ref": AuthSecretRef(name)})
	})
}