dinheiro

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package auth

import (
	"context"
	"fmt"
	"errors"
	"net/http"
	"strings"
	"time"
	"encoding/json"
	"log"

	"golang.org/x/crypto/bcrypt"

	"git.eletrotupi.com/git/dinheiro/db"
	"git.eletrotupi.com/git/dinheiro/types"
	"git.eletrotupi.com/git/dinheiro/keys"
)

var authCtxKey = &contextKey{"auth"}

type contextKey struct {
	name string
}

// This is the representation of our currentUser
type AuthContext struct {
	UserID		int
	Email		string
	CreatedAt	time.Time
	UpdatedAt	time.Time
}

type AuthCookie struct {
	Email	string	`json:"email"`
}

func authError(writer http.ResponseWriter, reason string, statusCode int) {
	writer.WriteHeader(statusCode)
	writer.Write([]byte(reason))
}

func LookupUserAndGenerateCtx(ctx context.Context, email string) (*AuthContext, error) {
	var (
		authCtx AuthContext
		err error
	)

	dbConn := db.ForContext(ctx)
	row := dbConn.QueryRow(`SELECT id, email, created_at, updated_at FROM users WHERE email = $1`, email)

	if err = row.Scan(&authCtx.UserID, &authCtx.Email, &authCtx.CreatedAt, &authCtx.UpdatedAt); err != nil {
		return nil, fmt.Errorf("Something went off when creating the auth context %s", err)
	}

	return &authCtx, nil
}

// This method authenticate the user, populate a AuthContext and set the cookie
// on the request
func authenticate(w http.ResponseWriter, r *http.Request, next http.Handler) {
	var (
		//authCookie AuthCookie
		user types.User
		err error
	)

	err = r.ParseForm()
	if err != nil {
		authError(w, "Couldn't parse form", http.StatusInternalServerError)
	}

	email := r.Form.Get("email")
	password := r.Form.Get("password")

	log.Printf("User email %s", email)

	dbConn := db.ForContext(r.Context())
	row := dbConn.QueryRow(
		`SELECT id, email, encrypted_password FROM users WHERE email = $1`,
		email)

	if err = row.Scan(&user.ID, &user.Email, &user.EncryptedPassword); err != nil {
		authError(w, "Email wasn't found", http.StatusUnauthorized)
		return
	}

	err = bcrypt.CompareHashAndPassword([]byte(user.EncryptedPassword), []byte(password))
	if err != nil {
		authError(w, "Incorrect Password", http.StatusUnauthorized)

		return
	}

	authCtx, err := LookupUserAndGenerateCtx(r.Context(), user.Email)
	if err != nil {
		authError(w, err.Error(), http.StatusForbidden)

		return
	}

	authCookie := AuthCookie{Email: user.Email}

	cookieJson, err := json.Marshal(authCookie)
	signedCookie := keys.Encrypt(cookieJson)

	cookie := http.Cookie{Name: "dinheiro.v1", Value: string(signedCookie)}
	http.SetCookie(w, &cookie)

	ctx := context.WithValue(r.Context(), authCtxKey, authCtx)
	r = r.WithContext(ctx)
	next.ServeHTTP(w, r)
}

// This authenticate from an existing cookie sent by the browser
// It'll decrypt the cookie, unmarshal into a AuthCookie struct
// Then populate the AuthContext (our current user)
func authFromCookie(cookie *http.Cookie, w http.ResponseWriter, r *http.Request, next http.Handler) {
	payload := keys.DecryptWithoutExpiration([]byte(cookie.Value))
	if payload == nil {
		authError(w, "Invalid cookie content", http.StatusForbidden)
	}

	var authCookie AuthCookie
	err := json.Unmarshal(payload, &authCookie)
	if err != nil {
		panic("aaaaa")
	}

	authCtx, err := LookupUserAndGenerateCtx(r.Context(), authCookie.Email)
	if err != nil {
		authError(w, err.Error(), http.StatusForbidden)

		return
	}

	ctx := context.WithValue(r.Context(), authCtxKey, authCtx)
	r = r.WithContext(ctx)
	next.ServeHTTP(w, r)
}

func Middleware() func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			cookie, err := r.Cookie("dinheiro.v1")
			if err == nil {
				authFromCookie(cookie, w, r, next)

				return
			}

			if strings.HasPrefix(r.URL.Path, "/auth") {
				authenticate(w, r, next)

				return
			}

			next.ServeHTTP(w, r)
			return
		})
	}
}

func ForContext(ctx context.Context) (*AuthContext, error) {
	raw, ok := ctx.Value(authCtxKey).(*AuthContext)
	if !ok {
		return nil, errors.New("No User")
	}

	return raw, nil
}