package auth

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/labstack/echo/v4"

	"dynatron.me/x/blasphem/internal/generate"
	"dynatron.me/x/blasphem/pkg/auth/provider"
)

/*
   {
     "id": "18912b07b66e48558a44c058bf90f1d4",
     "user_id": "1bd642b0ed9f410280f622d1d358102b",
     "client_id": "https://oauth-redirect.googleusercontent.com/",
     "client_name": null,
     "client_icon": null,
     "token_type": "normal",
     "created_at": "2021-12-13T04:34:47.169033+00:00",
     "access_token_expiration": 1800.0,
     "token": "f93f87557ca616508c675f05b85921d07fdf764efc34c74a81daeebd71ab899a6e8cd5dec94d0ae36499ff281f2efcf715c763ad73eabadd2f586b827057043d",
     "jwt_key": "f4507c01fe19b1d99c4b628cadc8208f7838dbdda0a9a051fd029cefdf6f619b0728d6b0a4d3d96ee68614b035054952faa14c48ae36bd212e28d602864f6d1c",
     "last_used_at": "2021-12-13T04:34:47.169738+00:00",
     "last_used_ip": "108.177.68.93",
     "credential_id": "5daeb186d2a943328cbb984f135974cb",
     "version": "2021.12.0"
   },
*/

type (
	TokenType      string
	TokenTimestamp time.Time
	RefreshTokenID string
	ExpSeconds     float64
)

func (f ExpSeconds) MarshalJSON() ([]byte, error) {
	if float64(f) == float64(int(f)) {
		return []byte(strconv.FormatFloat(float64(f), 'f', 1, 32)), nil
	}
	return []byte(strconv.FormatFloat(float64(f), 'f', -1, 32)), nil
}

const PytTimeFormat = "2006-01-02T15:04:05.999999-07:00"

func (t *TokenTimestamp) MarshalJSON() ([]byte, error) {
	rv := fmt.Sprintf("%q", time.Time(*t).Format(PytTimeFormat))
	return []byte(rv), nil
}

func (t *TokenTimestamp) UnmarshalJSON(b []byte) error {
	s := strings.Trim(string(b), `"`)
	tm, err := time.Parse(PytTimeFormat, s)
	*t = TokenTimestamp(tm)

	return err
}

type RefreshToken struct {
	ID                    RefreshTokenID  `json:"id"`
	UserID                UserID          `json:"user_id"`
	ClientID              *ClientID       `json:"client_id"`
	ClientName            *string         `json:"client_name"`
	ClientIcon            *string         `json:"client_icon"`
	TokenType             TokenType       `json:"token_type"`
	CreatedAt             *TokenTimestamp `json:"created_at"`
	AccessTokenExpiration ExpSeconds      `json:"access_token_expiration"`
	Token                 string          `json:"token"`
	JWTKey                string          `json:"jwt_key"`
	LastUsedAt            *TokenTimestamp `json:"last_used_at"`
	LastUsedIP            *string         `json:"last_used_ip"`
	CredentialID          *CredID         `json:"credential_id"`
	Version               *string         `json:"version"`
}

type AccessSessionStore struct {
	s        map[AccessTokenID]*AccessToken
	lastCull time.Time
}

type AccessTokenID string

func (t *AccessTokenID) IsValid() bool {
	// TODO: more validation than this
	return *t != ""
}

type AccessToken struct { // TODO: jwt bro
	ID      AccessTokenID
	Ctime   time.Time
	Expires time.Time
	Addr    string

	user provider.ProviderUser `json:"-"`
}

func (ss *AccessSessionStore) init() {
	ss.s = make(map[AccessTokenID]*AccessToken)
}

const cullInterval = 5 * time.Minute

func (ss *AccessSessionStore) cull() {
	if now := time.Now(); now.Sub(ss.lastCull) > cullInterval {
		for k, v := range ss.s {
			if now.After(v.Expires) {
				delete(ss.s, k)
			}
		}
	}
}

func (ss *AccessSessionStore) register(t *AccessToken) {
	ss.cull()
	ss.s[t.ID] = t
}

func (ss *AccessSessionStore) verify(tr *TokenRequest, r *http.Request) (provider.ProviderUser, bool) {
	if t, hasToken := ss.s[tr.Code]; hasToken {
		// TODO: JWT
		if t.Expires.After(time.Now()) {
			return t.user, true
		} else {
			delete(ss.s, t.ID)
		}
	}

	return nil, false
}

type Credential struct {
	ID               CredID                `json:"id"`
	UserID           UserID                `json:"user_id"`
	AuthProviderType string                `json:"auth_provider_type"`
	AuthProviderID   *string               `json:"auth_provider_id"`
	DataRaw          *json.RawMessage      `json:"data,omitempty"`
	user             provider.ProviderUser `json:"-"`
}

func (cred *Credential) MarshalJSON() ([]byte, error) {
	type CredAlias Credential // alias so ø method set and we don't recurse
	nCd := (*CredAlias)(cred)

	if cred.user != nil {
		providerData := cred.user.UserData()
		if providerData != nil {
			b, err := json.Marshal(providerData)
			if err != nil {
				return nil, err
			}

			dr := json.RawMessage(b)
			nCd.DataRaw = &dr
		}
	}

	return json.Marshal(nCd)
}

func (a *Authenticator) verifyAndGetCredential(tr *TokenRequest, r *http.Request) *Credential {
	user, success := a.sessions.verify(tr, r)
	if !success {
		return nil
	}

	cred := &Credential{
		user: user,
	}

	return cred
}

const defaultExpiration = 15 * time.Minute

func (a *Authenticator) NewAccessToken(r *http.Request, user provider.ProviderUser, f *Flow) AccessTokenID {
	id := AccessTokenID(generate.UUID())
	now := time.Now()

	t := &AccessToken{
		ID:      id,
		Ctime:   now,
		Expires: now.Add(defaultExpiration),
		Addr:    r.RemoteAddr,

		user: user,
	}

	a.sessions.register(t)

	return id
}

type GrantType string

const (
	GTAuthorizationCode GrantType = "authorization_code"
	GTRefreshToken      GrantType = "refresh_token"
)

type ClientID string

func (c *ClientID) IsValid() bool {
	// TODO: || !indieauth.VerifyClientID(rq.ClientID)?
	return *c != ""
}

type TokenRequest struct {
	ClientID  ClientID      `form:"client_id"`
	Code      AccessTokenID `form:"code"`
	GrantType GrantType     `form:"grant_type"`
}

func (a *Authenticator) TokenHandler(c echo.Context) error {
	rq := new(TokenRequest)
	err := c.Bind(rq)
	if err != nil {
		return err
	}

	switch rq.GrantType {
	case GTAuthorizationCode:
		if !rq.ClientID.IsValid() {
			return c.JSON(http.StatusBadRequest, AuthError{Error: "invalid_request", Description: "invalid client ID"})
		}

		if !rq.Code.IsValid() {
			return c.JSON(http.StatusBadRequest, AuthError{Error: "invalid_request", Description: "invalid code"})
		}

		if cred := a.verifyAndGetCredential(rq, c.Request()); cred != nil {
			// TODO: success
			user, err := a.getOrCreateUser(cred)
			if err != nil {
				return c.JSON(http.StatusUnauthorized, AuthError{Error: "access_denied", Description: err.Error()})
			}

			if err := user.allowedToAuth(); err != nil {
				return c.JSON(http.StatusUnauthorized, AuthError{Error: "access_denied", Description: err.Error()})
			}
			return c.String(http.StatusOK, "token good I guess")
		}
	case GTRefreshToken:
		return c.String(http.StatusNotImplemented, "not implemented")
	}

	return c.String(http.StatusUnauthorized, "token bad I guess")
}