package eusupply

import (
	"encoding/json"
	"strings"

	"git.avsdev.uk/Go/job-search/internal/types"
)

// The opportunities Convert makes.
const (
	// UUIDPrefix starts the UUID of every opportunity from the UK portal;
	// the tender's id follows it.
	UUIDPrefix = "eusupply-uk-"
	// uuidType is their UUIDType.
	uuidType = "eusupply"
	// releaseTag is their one release's tag: the portal lists open tenders.
	releaseTag = "tender"
)

// mainCategories maps the portal's types of contract to OCDS's
// mainProcurementCategory, as Find a Tender's opportunities have.
var mainCategories = map[string]string{
	"Supplies": "goods",
	"Services": "services",
	"Works":    "works",
}

// UUID returns the UUID of the opportunity for the tender with id.
func UUID(id string) string {
	return UUIDPrefix + id
}

// ReleaseID returns the id of the one release of the opportunity for
// tender: its id, as the portal gives each tender one page.
func ReleaseID(tender Tender) string {
	return tender.ID
}

// Convert returns the opportunity for each tender, with one release whose
// JSON is the tender as read.
func Convert(tenders []Tender) []*types.Opportunity {
	opportunities := make([]*types.Opportunity, 0, len(tenders))
	for _, tender := range tenders {
		opportunities = append(opportunities, convertOne(tender))
	}
	return opportunities
}

// convertOne builds the opportunity for one tender.
func convertOne(tender Tender) *types.Opportunity {
	published := tender.Published
	opportunity := &types.Opportunity{
		UUID:              UUID(tender.ID),
		UUIDType:          uuidType,
		Title:             tender.Title,
		Status:            "active",
		Description:       tender.Description,
		BuyerName:         tender.Buyer,
		Classifications:   classifications(tender),
		MainCategory:      mainCategories[tender.ContractType],
		MultiLot:          tender.Lots > 1,
		StartDate:         &published,
		EndDate:           tender.Deadline,
		Source:            Source,
		LatestReleaseDate: tender.Published,
	}

	release := types.OpportunityRelease{
		UUID:        opportunity.UUID,
		ReleaseID:   ReleaseID(tender),
		ReleaseDate: tender.Published,
		Tags: []types.OpportunityReleaseTag{
			{
				Tag: releaseTag,
			},
		},
	}
	// A Tender is plain data, so marshalling it can't fail.
	if encoded, err := json.Marshal(tender); err == nil {
		release.JSON = string(encoded)
	}
	opportunity.Releases = []types.OpportunityRelease{release}

	return opportunity
}

// classifications returns the tender's CPV codes as Find a Tender's are
// stored: without the check digit ("48000000", not "48000000-8").
func classifications(tender Tender) []types.ClassificationCode {
	codes := make([]types.ClassificationCode, 0, len(tender.CPVCodes))
	for _, cpv := range tender.CPVCodes {
		code, _, _ := strings.Cut(cpv.Code, "-")
		codes = append(codes, types.ClassificationCode{
			IsCPV:          true,
			Code:           code,
			Classification: cpv.Description,
		})
	}
	return codes
}