package flatads

import (
	"fmt"
	"net/http"
	"text/template"

	"github.com/prebid/openrtb/v20/openrtb2"
	"github.com/prebid/prebid-server/v4/adapters"
	"github.com/prebid/prebid-server/v4/config"
	"github.com/prebid/prebid-server/v4/errortypes"
	"github.com/prebid/prebid-server/v4/macros"
	"github.com/prebid/prebid-server/v4/openrtb_ext"
	"github.com/prebid/prebid-server/v4/util/jsonutil"
)

type adapter struct {
	endpoint *template.Template
}

func Builder(bidderName openrtb_ext.BidderName, config config.Adapter, server config.Server) (adapters.Bidder, error) {
	endpointTemplate, err := template.New("endpointTemplate").Parse(config.Endpoint)
	if err != nil {
		return nil, fmt.Errorf("unable to parse endpoint template: %v", err)
	}

	bidder := &adapter{
		endpoint: endpointTemplate,
	}
	return bidder, nil
}

func (a *adapter) MakeRequests(request *openrtb2.BidRequest, requestInfo *adapters.ExtraRequestInfo) ([]*adapters.RequestData, []error) {
	var requests []*adapters.RequestData
	var errs []error

	headers := http.Header{}
	headers.Add("Content-Type", "application/json;charset=utf-8")
	headers.Add("Accept", "application/json")
	if request.Device != nil {
		if len(request.Device.UA) > 0 {
			headers.Add("User-Agent", request.Device.UA)
		}

		if len(request.Device.IPv6) > 0 {
			headers.Add("X-Forwarded-For", request.Device.IPv6)
		}

		if len(request.Device.IP) > 0 {
			headers.Add("X-Forwarded-For", request.Device.IP)
		}
	}
	for _, imp := range request.Imp {
		requestCopy := *request
		requestCopy.Imp = []openrtb2.Imp{imp}

		endpoint, err := a.buildEndpointFromRequest(&imp)
		if err != nil {
			errs = append(errs, err)
			continue
		}

		requestJSON, err := jsonutil.Marshal(requestCopy)
		if err != nil {
			errs = append(errs, err)
			continue
		}

		r := &adapters.RequestData{
			Method:  http.MethodPost,
			Body:    requestJSON,
			Uri:     endpoint,
			Headers: headers,
			ImpIDs:  openrtb_ext.GetImpIDs(requestCopy.Imp),
		}

		requests = append(requests, r)
	}

	return requests, errs
}

func (a *adapter) buildEndpointFromRequest(imp *openrtb2.Imp) (string, error) {
	var impExt adapters.ExtImpBidder
	if err := jsonutil.Unmarshal(imp.Ext, &impExt); err != nil {
		return "", &errortypes.BadInput{
			Message: fmt.Sprintf("Failed to deserialize bidder impression extension: %v", err),
		}
	}

	var flatadsExt openrtb_ext.ImpExtFlatads
	if err := jsonutil.Unmarshal(impExt.Bidder, &flatadsExt); err != nil {
		return "", &errortypes.BadInput{
			Message: fmt.Sprintf("Failed to deserialize Flatads extension: %v", err),
		}
	}

	endpointParams := macros.EndpointTemplateParams{
		TokenID:     flatadsExt.Token,
		PublisherID: flatadsExt.PublisherId,
	}

	return macros.ResolveMacros(a.endpoint, endpointParams)
}

func (a *adapter) MakeBids(request *openrtb2.BidRequest, requestData *adapters.RequestData, responseData *adapters.ResponseData) (*adapters.BidderResponse, []error) {
	if adapters.IsResponseStatusCodeNoContent(responseData) {
		return nil, nil
	}

	err := adapters.CheckResponseStatusCodeForErrors(responseData)
	if err != nil {
		return nil, []error{err}
	}
	var response openrtb2.BidResponse
	if err := jsonutil.Unmarshal(responseData.Body, &response); err != nil {
		return nil, []error{err}
	}

	bidResponse := adapters.NewBidderResponseWithBidsCapacity(len(request.Imp))
	if len(response.Cur) != 0 {
		bidResponse.Currency = response.Cur
	}

	var errors []error
	for _, seatBid := range response.SeatBid {
		for i := range seatBid.Bid {
			bidMediaType, err := getMediaTypeForBid(seatBid.Bid[i].ImpID, request.Imp)
			if err != nil {
				errors = append(errors, err)
				continue
			}
			bidResponse.Bids = append(bidResponse.Bids, &adapters.TypedBid{
				Bid:     &seatBid.Bid[i],
				BidType: bidMediaType,
			})
		}
	}
	return bidResponse, errors
}

func getMediaTypeForBid(impID string, imps []openrtb2.Imp) (openrtb_ext.BidType, error) {
	for _, imp := range imps {
		if imp.ID == impID {
			if imp.Banner != nil {
				return openrtb_ext.BidTypeBanner, nil
			} else if imp.Video != nil {
				return openrtb_ext.BidTypeVideo, nil
			} else if imp.Native != nil {
				return openrtb_ext.BidTypeNative, nil
			}
		}
	}
	return "", &errortypes.BadServerResponse{
		Message: fmt.Sprintf("The impression with ID %s is not present into the request", impID),
	}
}