package handlers

import (
	"fmt"
	"net/url"
	"strings"

	"github.com/authelia/authelia/v4/internal/duo"
	"github.com/authelia/authelia/v4/internal/middlewares"
	"github.com/authelia/authelia/v4/internal/model"
	"github.com/authelia/authelia/v4/internal/session"
	"github.com/authelia/authelia/v4/internal/utils"
)

// DuoDevicesGET handler for retrieving available devices and capabilities from duo api.
func DuoDevicesGET(duoAPI duo.API) middlewares.RequestHandler {
	return func(ctx *middlewares.AutheliaCtx) {
		var (
			userSession session.UserSession
			err         error
		)

		if userSession, err = ctx.GetSession(); err != nil {
			ctx.Error(fmt.Errorf("failed to get session data: %w", err), messageMFAValidationFailed)
			return
		}

		values := url.Values{}
		values.Set("username", userSession.Username)

		ctx.Logger.Debugf("Starting Duo PreAuth for %s", userSession.Username)

		result, message, devices, enrollURL, err := DuoPreAuth(ctx, &userSession, duoAPI)
		if err != nil {
			ctx.Error(fmt.Errorf("duo PreAuth API errored: %w", err), messageMFAValidationFailed)
			return
		}

		if result == auth {
			if devices == nil {
				ctx.Logger.Debugf("No applicable device/method available for Duo user %s", userSession.Username)

				if err := ctx.SetJSONBody(DuoDevicesResponse{Result: enroll}); err != nil {
					ctx.Error(fmt.Errorf("unable to set JSON body in response"), messageMFAValidationFailed)
				}

				return
			}

			if err := ctx.SetJSONBody(DuoDevicesResponse{Result: auth, Devices: devices}); err != nil {
				ctx.Error(fmt.Errorf("unable to set JSON body in response"), messageMFAValidationFailed)
			}

			return
		}

		if result == allow {
			ctx.Logger.Debugf("Device selection not possible for user %s, because Duo authentication was bypassed - Defaults to Auto Push", userSession.Username)

			if err := ctx.SetJSONBody(DuoDevicesResponse{Result: allow}); err != nil {
				ctx.Error(fmt.Errorf("unable to set JSON body in response"), messageMFAValidationFailed)
			}

			return
		}

		if result == enroll {
			ctx.Logger.Debugf("Duo user: %s not enrolled", userSession.Username)

			if err := ctx.SetJSONBody(DuoDevicesResponse{Result: enroll, EnrollURL: enrollURL}); err != nil {
				ctx.Error(fmt.Errorf("unable to set JSON body in response"), messageMFAValidationFailed)
			}

			return
		}

		if result == deny {
			ctx.Logger.Debugf("Duo User not allowed to authenticate: %s", userSession.Username)

			if err := ctx.SetJSONBody(DuoDevicesResponse{Result: deny}); err != nil {
				ctx.Error(fmt.Errorf("unable to set JSON body in response"), messageMFAValidationFailed)
			}

			return
		}

		ctx.Error(fmt.Errorf("duo PreAuth API errored for %s: %s - %s", userSession.Username, result, message), messageMFAValidationFailed)
	}
}

// DuoDevicePOST update the user preferences regarding Duo device and method.
func DuoDevicePOST(ctx *middlewares.AutheliaCtx) {
	bodyJSON := DuoDeviceBody{}

	var (
		userSession session.UserSession
		err         error
	)

	if err = ctx.ParseBody(&bodyJSON); err != nil {
		ctx.Error(err, messageMFAValidationFailed)
		return
	}

	if !utils.IsStringInSlice(bodyJSON.Method, duo.PossibleMethods) {
		ctx.Error(fmt.Errorf("unknown method '%s', it should be one of %s", bodyJSON.Method, strings.Join(duo.PossibleMethods, ", ")), messageMFAValidationFailed)
		return
	}

	if userSession, err = ctx.GetSession(); err != nil {
		ctx.Error(err, messageMFAValidationFailed)
		return
	}

	ctx.Logger.Debugf("Save new preferred Duo device and method of user %s to %s using %s", userSession.Username, bodyJSON.Device, bodyJSON.Method)
	err = ctx.Providers.StorageProvider.SavePreferredDuoDevice(ctx, model.DuoDevice{Username: userSession.Username, Device: bodyJSON.Device, Method: bodyJSON.Method})

	if err != nil {
		ctx.Error(fmt.Errorf("unable to save new preferred Duo device and method: %w", err), messageMFAValidationFailed)
		return
	}

	ctx.ReplyOK()
}

// DuoDeviceDELETE deletes the useres preferred Duo device and method.
func DuoDeviceDELETE(ctx *middlewares.AutheliaCtx) {
	var (
		userSession session.UserSession
		err         error
	)

	if userSession, err = ctx.GetSession(); err != nil {
		ctx.Error(fmt.Errorf("unable to get session to delete preferred Duo device and method: %w", err), messageMFAValidationFailed)
		return
	}

	ctx.Logger.Debugf("Deleting preferred Duo device and method of user %s", userSession.Username)

	if err = ctx.Providers.StorageProvider.DeletePreferredDuoDevice(ctx, userSession.Username); err != nil {
		ctx.Error(fmt.Errorf("unable to delete preferred Duo device and method: %w", err), messageMFAValidationFailed)
		return
	}

	ctx.ReplyOK()
}