package main

import (
	"encoding/base64"
	"errors"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt"
	lm "github.com/hrfee/jfa-go/logmessages"
	"github.com/hrfee/mediabrowser"
	"github.com/lithammer/shortuuid/v3"
)

const (
	TOKEN_VALIDITY_SEC         = 20 * 60
	REFRESH_TOKEN_VALIDITY_SEC = 3600 * 24
)

func (app *appContext) logIpInfo(gc *gin.Context, user bool, out string) {
	if (user && LOGIPU) || (!user && LOGIP) {
		out += fmt.Sprintf(" (ip=%s)", gc.ClientIP())
	}
	app.info.Println(out)
}
func (app *appContext) logIpDebug(gc *gin.Context, user bool, out string) {
	if (user && LOGIPU) || (!user && LOGIP) {
		out += fmt.Sprintf(" (ip=%s)", gc.ClientIP())
	}
	app.debug.Println(out)
}
func (app *appContext) logIpErr(gc *gin.Context, user bool, out string) {
	if (user && LOGIPU) || (!user && LOGIP) {
		out += fmt.Sprintf(" (ip=%s)", gc.ClientIP())
	}
	app.err.Println(out)
}

func (app *appContext) webAuth() gin.HandlerFunc {
	if NO_API_AUTH_DO_NOT_USE {
		return app.bogusAuthenticate
	} else {
		return app.authenticate
	}
}

func (app *appContext) authLog(v any) { app.debug.PrintfCustomLevel(4, lm.FailedAuthRequest, v) }

// CreateToken returns a web token as well as a refresh token, which can be used to obtain new tokens.
func CreateToken(userId, jfId string, admin bool) (string, string, error) {
	var token, refresh string
	claims := jwt.MapClaims{
		"valid": true,
		"id":    userId,
		"exp":   time.Now().Add(time.Second * TOKEN_VALIDITY_SEC).Unix(),
		"jfid":  jfId,
		"admin": admin,
		"type":  "bearer",
	}
	tk := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	token, err := tk.SignedString([]byte(os.Getenv("JFA_SECRET")))
	if err != nil {
		return "", "", err
	}
	claims["exp"] = time.Now().Add(time.Second * REFRESH_TOKEN_VALIDITY_SEC).Unix()
	claims["type"] = "refresh"
	tk = jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	refresh, err = tk.SignedString([]byte(os.Getenv("JFA_SECRET")))
	if err != nil {
		return "", "", err
	}
	return token, refresh, nil
}

// Caller should return if this returns false.
func (app *appContext) decodeValidateAuthHeader(gc *gin.Context) (claims jwt.MapClaims, ok bool) {
	ok = false
	header := strings.SplitN(gc.Request.Header.Get("Authorization"), " ", 2)
	if header[0] != "Bearer" {
		app.authLog(lm.InvalidAuthHeader)
		respond(401, "Unauthorized", gc)
		return
	}
	token, err := jwt.Parse(string(header[1]), checkToken)
	if err != nil {
		app.authLog(fmt.Sprintf(lm.FailedParseJWT, err))
		respond(401, "Unauthorized", gc)
		return
	}
	claims, ok = token.Claims.(jwt.MapClaims)
	if !ok {
		app.authLog(lm.FailedCastJWT)
		respond(401, "Unauthorized", gc)
		return
	}
	expiryUnix := int64(claims["exp"].(float64))
	expiry := time.Unix(expiryUnix, 0)
	if !(ok && token.Valid && claims["type"].(string) == "bearer" && expiry.After(time.Now())) {
		app.authLog(lm.InvalidJWT)
		// app.debug.Printf("Expiry: %+v, OK: %t, Valid: %t, ClaimType: %s\n", expiry, ok, token.Valid, claims["type"].(string))
		respond(401, "Unauthorized", gc)
		ok = false
		return
	}
	ok = true
	return
}

// Check header for token
func (app *appContext) authenticate(gc *gin.Context) {
	claims, ok := app.decodeValidateAuthHeader(gc)
	if !ok {
		return
	}
	isAdminToken := claims["admin"].(bool)
	if !isAdminToken {
		app.authLog(lm.NonAdminToken)
		respond(401, "Unauthorized", gc)
		return
	}

	userID := claims["id"].(string)
	jfID := claims["jfid"].(string)
	match := false
	for _, user := range app.adminUsers {
		if user.UserID == userID {
			match = true
			break
		}
	}
	if !match {
		app.authLog(fmt.Sprintf(lm.NonAdminUser, userID))
		respond(401, "Unauthorized", gc)
		return
	}
	gc.Set("jfId", jfID)
	gc.Set("userId", userID)
	gc.Set("userMode", false)
	gc.Next()
}

// bogusAuthenticate is for use with NO_API_AUTH_DO_NOT_USE, it sets the jfId/userId value from NO_API_AUTH_FORCE_JF_ID.
func (app *appContext) bogusAuthenticate(gc *gin.Context) {
	gc.Set("jfId", NO_API_AUTH_FORCE_JFID)
	gc.Set("userId", NO_API_AUTH_FORCE_JFID)
	gc.Next()
}

func checkToken(token *jwt.Token) (interface{}, error) {
	if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
		return nil, fmt.Errorf("Unexpected signing method %v", token.Header["alg"])
	}
	return []byte(os.Getenv("JFA_SECRET")), nil
}

type getTokenDTO struct {
	Token string `json:"token" example:"kjsdklsfdkljfsjsdfklsdfkldsfjdfskjsdfjklsdf"` // API token for use with everything else.
}

func (app *appContext) decodeValidateLoginHeader(gc *gin.Context, userpage bool) (username, password string, ok bool) {
	header := strings.SplitN(gc.Request.Header.Get("Authorization"), " ", 2)
	auth, _ := base64.StdEncoding.DecodeString(header[1])
	creds := strings.SplitN(string(auth), ":", 2)
	username = creds[0]
	password = creds[1]
	ok = false
	if username == "" || password == "" {
		app.logIpDebug(gc, userpage, fmt.Sprintf(lm.FailedAuthRequest, lm.EmptyUserOrPass))
		respond(401, "Unauthorized", gc)
		return
	}
	ok = true
	return
}

func (app *appContext) canAccessAdminPage(user mediabrowser.User, emailStore EmailAddress) bool {
	// 1. "Allow all" is enabled, so simply being a user implies access.
	if app.config.Section("ui").Key("allow_all").MustBool(false) && user.ID != "" {
		return true
	}
	// 2. You've been made an "accounts admin" from the accounts tab.
	if emailStore.Admin {
		return true
	}
	// 3. (Jellyfin) "Admins only" is enabled, and you're one.
	if app.config.Section("ui").Key("admin_only").MustBool(true) && user.ID != "" && user.Policy.IsAdministrator {
		return true
	}
	return false
}

func (app *appContext) canAccessAdminPageByID(jfID string) bool {
	user, err := app.jf.UserByID(jfID, false)
	if err != nil {
		return false
	}
	emailStore, _ := app.storage.GetEmailsKey(jfID)
	return app.canAccessAdminPage(user, emailStore)
}

func (app *appContext) validateJellyfinCredentials(username, password string, gc *gin.Context, userpage bool) (user mediabrowser.User, ok bool) {
	ok = false
	user, err := app.authJf.Authenticate(username, password)
	if err != nil {
		if errors.As(err, &mediabrowser.ErrUnauthorized{}) {
			app.logIpInfo(gc, userpage, fmt.Sprintf(lm.FailedAuthRequest, lm.InvalidUserOrPass))
			respond(401, "Unauthorized", gc)
			return
		} else if errors.As(err, &mediabrowser.ErrForbidden{}) {
			app.logIpInfo(gc, userpage, fmt.Sprintf(lm.FailedAuthRequest, lm.UserDisabled))
			respond(403, "yourAccountWasDisabled", gc)
			return
		}
		app.authLog(fmt.Sprintf(lm.FailedAuthJellyfin, app.jf.Server, 0, err))
		respond(500, "Jellyfin error", gc)
		return
	}
	ok = true
	return
}

// @Summary Grabs an API token using username & password.
// @description If viewing docs locally, click the lock icon next to this, login with your normal jfa-go credentials. Click 'try it out', then 'execute' and an API Key will be returned, copy it (not including quotes). On any of the other routes, click the lock icon and set the API key as "Bearer `your api key`".
// @Produce json
// @Success 200 {object} getTokenDTO
// @Failure 401 {object} stringResponse
// @Router /token/login [get]
// @tags Auth
// @Security getTokenAuth
func (app *appContext) getTokenLogin(gc *gin.Context) {
	app.logIpInfo(gc, false, fmt.Sprintf(lm.RequestingToken, lm.TokenLoginAttempt))
	username, password, ok := app.decodeValidateLoginHeader(gc, false)
	if !ok {
		return
	}
	var userID, jfID string
	match := false
	for _, user := range app.adminUsers {
		if user.Username == username && user.Password == password {
			match = true
			userID = user.UserID
			break
		}
	}
	if !app.jellyfinLogin && !match {
		app.logIpInfo(gc, false, fmt.Sprintf(lm.FailedAuthRequest, lm.InvalidUserOrPass))
		respond(401, "Unauthorized", gc)
		return
	}
	if !match {
		user, ok := app.validateJellyfinCredentials(username, password, gc, false)
		if !ok {
			return
		}
		jfID = user.ID
		emailStore, _ := app.storage.GetEmailsKey(jfID)
		accountsAdmin := app.canAccessAdminPage(user, emailStore)
		if !accountsAdmin {
			app.authLog(fmt.Sprintf(lm.NonAdminUser, username))
			respond(401, "Unauthorized", gc)
			return
		}
		// New users are only added when using jellyfinLogin.
		userID = shortuuid.New()
		newUser := User{
			UserID: userID,
		}
		app.debug.Printf(lm.GenerateToken, username)
		app.adminUsers = append(app.adminUsers, newUser)
	}
	token, refresh, err := CreateToken(userID, jfID, true)
	if err != nil {
		app.err.Printf(lm.FailedGenerateToken, err)
		respond(500, "Couldn't generate token", gc)
		return
	}
	host := app.ExternalDomainNoPort(gc)

	// Before you think this is broken: the first "true" arg is for "secure", i.e. only HTTPS!
	gc.SetCookie("refresh", refresh, REFRESH_TOKEN_VALIDITY_SEC, "/", host, true, true)
	gc.JSON(200, getTokenDTO{token})
}

func (app *appContext) decodeValidateRefreshCookie(gc *gin.Context, cookieName string) (claims jwt.MapClaims, ok bool) {
	ok = false
	cookie, err := gc.Cookie(cookieName)
	if err != nil || cookie == "" {
		app.authLog(fmt.Sprintf(lm.FailedGetCookies, cookieName, err))
		respond(400, "Couldn't get token", gc)
		return
	}
	for _, token := range app.invalidTokens {
		if cookie == token {
			app.authLog(lm.LocallyInvalidatedJWT)
			respond(401, lm.InvalidJWT, gc)
			return
		}
	}
	token, err := jwt.Parse(cookie, checkToken)
	if err != nil {
		app.authLog(fmt.Sprintf(lm.FailedParseJWT, err))
		respond(400, lm.InvalidJWT, gc)
		return
	}
	claims, ok = token.Claims.(jwt.MapClaims)
	expiryUnix := int64(claims["exp"].(float64))
	expiry := time.Unix(expiryUnix, 0)
	if !(ok && token.Valid && claims["type"].(string) == "refresh" && expiry.After(time.Now())) {
		app.authLog(lm.InvalidJWT)
		respond(401, lm.InvalidJWT, gc)
		ok = false
		return
	}
	ok = true
	return
}

// @Summary Grabs an API token using a refresh token from cookies.
// @Produce json
// @Success 200 {object} getTokenDTO
// @Failure 401 {object} stringResponse
// @Router /token/refresh [get]
// @tags Auth
func (app *appContext) getTokenRefresh(gc *gin.Context) {
	app.logIpInfo(gc, false, fmt.Sprintf(lm.RequestingToken, lm.TokenRefresh))
	claims, ok := app.decodeValidateRefreshCookie(gc, "refresh")
	if !ok {
		return
	}
	userID := claims["id"].(string)
	jfID := claims["jfid"].(string)
	jwt, refresh, err := CreateToken(userID, jfID, true)
	if err != nil {
		app.err.Printf(lm.FailedGenerateToken, err)
		respond(500, "Couldn't generate token", gc)
		return
	}
	// host := gc.Request.URL.Hostname()
	host := app.ExternalDomainNoPort(gc)
	gc.SetCookie("refresh", refresh, REFRESH_TOKEN_VALIDITY_SEC, "/", host, true, true)
	gc.JSON(200, getTokenDTO{jwt})
}
