package handlers

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"net/url"
	"path"
	"time"

	"github.com/google/uuid"

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

// OpenIDConnectConsentGET handles requests to provide consent for OpenID Connect.
func OpenIDConnectConsentGET(ctx *middlewares.AutheliaCtx) {
	var (
		consentID uuid.UUID
		err       error
	)

	if consentID, err = uuid.ParseBytes(ctx.RequestCtx.QueryArgs().PeekBytes(qryArgID)); err != nil {
		ctx.Logger.Errorf("Unable to convert '%s' into a UUID: %+v", ctx.RequestCtx.QueryArgs().PeekBytes(qryArgID), err)
		ctx.ReplyForbidden()

		return
	}

	var (
		consent *model.OAuth2ConsentSession
		client  oidc.Client
		handled bool
	)

	if _, consent, client, handled = oidcConsentGetSessionsAndClient(ctx, consentID); handled {
		return
	}

	if err = ctx.SetJSONBody(client.GetConsentResponseBody(consent)); err != nil {
		ctx.Error(fmt.Errorf("unable to set JSON body: %v", err), "Operation failed")
	}
}

// OpenIDConnectConsentPOST handles consent responses for OpenID Connect.
func OpenIDConnectConsentPOST(ctx *middlewares.AutheliaCtx) {
	var (
		consentID uuid.UUID
		bodyJSON  oidc.ConsentPostRequestBody
		err       error
	)

	if err = json.Unmarshal(ctx.Request.Body(), &bodyJSON); err != nil {
		ctx.Logger.Errorf("Failed to parse JSON bodyJSON in consent POST: %+v", err)
		ctx.SetJSONError(messageOperationFailed)

		return
	}

	if consentID, err = uuid.Parse(bodyJSON.ConsentID); err != nil {
		ctx.Logger.Errorf("Unable to convert '%s' into a UUID: %+v", bodyJSON.ConsentID, err)
		ctx.ReplyForbidden()

		return
	}

	var (
		userSession session.UserSession
		consent     *model.OAuth2ConsentSession
		client      oidc.Client
		handled     bool
	)

	if userSession, consent, client, handled = oidcConsentGetSessionsAndClient(ctx, consentID); handled {
		return
	}

	if consent.ClientID != bodyJSON.ClientID {
		ctx.Logger.Errorf("User '%s' consented to scopes of another client (%s) than expected (%s). Beware this can be a sign of attack",
			userSession.Username, bodyJSON.ClientID, consent.ClientID)
		ctx.SetJSONError(messageOperationFailed)

		return
	}

	if bodyJSON.Consent {
		consent.Grant()

		if bodyJSON.PreConfigure {
			if client.GetConsentPolicy().Mode == oidc.ClientConsentModePreConfigured {
				config := model.OAuth2ConsentPreConfig{
					ClientID:  consent.ClientID,
					Subject:   consent.Subject.UUID,
					CreatedAt: time.Now(),
					ExpiresAt: sql.NullTime{Time: time.Now().Add(client.GetConsentPolicy().Duration), Valid: true},
					Scopes:    consent.GrantedScopes,
					Audience:  consent.GrantedAudience,
				}

				var id int64

				if id, err = ctx.Providers.StorageProvider.SaveOAuth2ConsentPreConfiguration(ctx, config); err != nil {
					ctx.Logger.Errorf("Failed to save the consent pre-configuration to the database: %+v", err)
					ctx.SetJSONError(messageOperationFailed)

					return
				}

				consent.PreConfiguration = sql.NullInt64{Int64: id, Valid: true}

				ctx.Logger.Debugf("Consent session with id '%s' for user '%s': pre-configured and set to expire at %v", consent.ChallengeID, userSession.Username, config.ExpiresAt.Time)
			} else {
				ctx.Logger.Warnf("Consent session with id '%s' for user '%s': consent pre-configuration was requested and was ignored because it is not permitted on this client", consent.ChallengeID, userSession.Username)
			}
		}
	}

	if err = ctx.Providers.StorageProvider.SaveOAuth2ConsentSessionResponse(ctx, *consent, bodyJSON.Consent); err != nil {
		ctx.Logger.Errorf("Failed to save the consent session response to the database: %+v", err)
		ctx.SetJSONError(messageOperationFailed)

		return
	}

	var (
		redirectURI *url.URL
		query       url.Values
	)

	redirectURI = ctx.RootURL()

	if query, err = url.ParseQuery(consent.Form); err != nil {
		ctx.Logger.Errorf("Failed to parse the consent form values: %+v", err)
		ctx.SetJSONError(messageOperationFailed)

		return
	}

	query.Set(queryArgConsentID, consent.ChallengeID.String())

	redirectURI.Path = path.Join(redirectURI.Path, oidc.EndpointPathAuthorization)
	redirectURI.RawQuery = query.Encode()

	response := oidc.ConsentPostResponseBody{RedirectURI: redirectURI.String()}

	if err = ctx.SetJSONBody(response); err != nil {
		ctx.Error(fmt.Errorf("unable to set JSON bodyJSON in response"), "Operation failed")
	}
}

func oidcConsentGetSessionsAndClient(ctx *middlewares.AutheliaCtx, consentID uuid.UUID) (userSession session.UserSession, consent *model.OAuth2ConsentSession, client oidc.Client, handled bool) {
	var (
		err error
	)

	if userSession, err = ctx.GetSession(); err != nil {
		ctx.Logger.Errorf("Unable to load user session for challenge id '%s': %v", consentID, err)
		ctx.ReplyForbidden()

		return userSession, nil, nil, true
	}

	if consent, err = ctx.Providers.StorageProvider.LoadOAuth2ConsentSessionByChallengeID(ctx, consentID); err != nil {
		ctx.Logger.Errorf("Unable to load consent session with challenge id '%s': %v", consentID, err)
		ctx.ReplyForbidden()

		return userSession, nil, nil, true
	}

	if client, err = ctx.Providers.OpenIDConnect.GetFullClient(consent.ClientID); err != nil {
		ctx.Logger.Errorf("Unable to find related client configuration with name '%s': %v", consent.ClientID, err)
		ctx.ReplyForbidden()

		return userSession, nil, nil, true
	}

	if err = verifyOIDCUserAuthorizedForConsent(ctx, client, userSession, consent, uuid.UUID{}); err != nil {
		ctx.Logger.Errorf("Could not authorize the user user '%s' for the consent session with challenge id '%s' on client with id '%s': %v", userSession.Username, consent.ChallengeID, client.GetID(), err)

		ctx.ReplyForbidden()

		return userSession, nil, nil, true
	}

	switch client.GetConsentPolicy().Mode {
	case oidc.ClientConsentModeImplicit:
		ctx.Logger.Errorf("Unable to perform OpenID Connect Consent for user '%s' and client id '%s': the client is using the implicit consent mode", userSession.Username, consent.ClientID)
		ctx.ReplyForbidden()

		return
	default:
		switch {
		case consent.Responded():
			ctx.Logger.Errorf("Unable to perform OpenID Connect Consent for user '%s' and client id '%s': the client is using the explicit consent mode and this consent session has already been responded to", userSession.Username, consent.ClientID)
			ctx.ReplyForbidden()

			return userSession, nil, nil, true
		case !consent.CanGrant():
			ctx.Logger.Errorf("Unable to perform OpenID Connect Consent for user '%s' and client id '%s': the specified consent session cannot be granted", userSession.Username, consent.ClientID)
			ctx.ReplyForbidden()

			return userSession, nil, nil, true
		}
	}

	if !client.IsAuthenticationLevelSufficient(userSession.AuthenticationLevel) {
		ctx.Logger.Errorf("Unable to perform OpenID Connect Consent for user '%s' and client id '%s': the user is not sufficiently authenticated", userSession.Username, consent.ClientID)
		ctx.ReplyForbidden()

		return userSession, nil, nil, true
	}

	return userSession, consent, client, false
}