package clientmiddleware

import (
	"context"

	"github.com/grafana/grafana-plugin-sdk-go/backend"

	"github.com/grafana/grafana/pkg/services/contexthandler"
)

const forwardIDHeaderName = "X-Grafana-Id"

// NewForwardIDMiddleware creates a new backend.HandlerMiddleware that will
// set grafana id header on outgoing backend.Handler requests
func NewForwardIDMiddleware() backend.HandlerMiddleware {
	return backend.HandlerMiddlewareFunc(func(next backend.Handler) backend.Handler {
		return &ForwardIDMiddleware{
			BaseHandler: backend.NewBaseHandler(next),
		}
	})
}

type ForwardIDMiddleware struct {
	backend.BaseHandler
}

func (m *ForwardIDMiddleware) applyToken(ctx context.Context, pCtx backend.PluginContext, req backend.ForwardHTTPHeaders) error {
	reqCtx := contexthandler.FromContext(ctx)
	// no HTTP request context => skip middleware
	if req == nil || reqCtx == nil || reqCtx.SignedInUser == nil {
		return nil
	}

	if token := reqCtx.SignedInUser.GetIDToken(); token != "" {
		req.SetHTTPHeader(forwardIDHeaderName, token)
	}

	return nil
}

func (m *ForwardIDMiddleware) QueryData(ctx context.Context, req *backend.QueryDataRequest) (*backend.QueryDataResponse, error) {
	if req == nil {
		return m.BaseHandler.QueryData(ctx, req)
	}

	err := m.applyToken(ctx, req.PluginContext, req)
	if err != nil {
		return nil, err
	}

	return m.BaseHandler.QueryData(ctx, req)
}

func (m *ForwardIDMiddleware) CallResource(ctx context.Context, req *backend.CallResourceRequest, sender backend.CallResourceResponseSender) error {
	if req == nil {
		return m.BaseHandler.CallResource(ctx, req, sender)
	}

	err := m.applyToken(ctx, req.PluginContext, req)
	if err != nil {
		return err
	}

	return m.BaseHandler.CallResource(ctx, req, sender)
}

func (m *ForwardIDMiddleware) CheckHealth(ctx context.Context, req *backend.CheckHealthRequest) (*backend.CheckHealthResult, error) {
	if req == nil {
		return m.BaseHandler.CheckHealth(ctx, req)
	}

	err := m.applyToken(ctx, req.PluginContext, req)
	if err != nil {
		return nil, err
	}

	return m.BaseHandler.CheckHealth(ctx, req)
}