package provider

// Support for the ARIN IRR.
// ARIN is special. We have to query them via whois. It's also not the same
// whois as you usually see. And also not many autnums (even big players like
// AS15169 and AS112) have IRR entries at all.

import (
	"context"
	"fmt"
	"strings"

	"code.hackerspace.pl/hscloud/bgpwtf/cccampix/irr/whois"
	pb "code.hackerspace.pl/hscloud/bgpwtf/cccampix/proto"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

const ARINWhois = "rr.arin.net:43"

type arin struct {
	sem chan struct{}
}

func NewARIN(limit int) Provider {
	return &arin{
		sem: make(chan struct{}, limit),
	}
}

func (a *arin) Query(ctx context.Context, asn uint64) (*pb.IRRQueryResponse, error) {
	a.sem <- struct{}{}
	defer func() {
		<-a.sem
	}()

	data, err := whois.Query(ctx, ARINWhois, fmt.Sprintf("AS%d", asn))
	if err != nil {
		return nil, status.Errorf(codes.Unavailable, "could not contact ARIN IRR: %v", err)
	}

	lines := strings.Split(data, "\n")

	// Convert possibly 'continued' RPSL entries into single-line entries.
	// eg.
	//   import:         from AS6083
	//                   action pref=10;
	//                   accept ANY
	// into
	//  'import', 'from AS6083, action pref=10; accept ANY'

	attrs := []rpslRawAttribute{}
	for _, line := range lines {
		if strings.HasPrefix(strings.TrimSpace(line), "%") {
			// Comment
			continue
		}
		if strings.TrimSpace(line) == "" {
			// Empty line
			continue
		}

		if strings.HasPrefix(line, " ") {
			// Continuation
			if len(attrs) < 1 {
				return nil, status.Errorf(codes.Unavailable, "unparseable IRR, continuation with no previous atribute name: %q", line)
			}

			attrs[len(attrs)-1].value += " " + strings.TrimSpace(line)
		} else {
			parts := strings.SplitN(line, ":", 2)
			if len(parts) != 2 {
				return nil, status.Errorf(codes.Unavailable, "unparseable IRR, line with no attribute key: %q", line)
			}
			name := strings.TrimSpace(parts[0])
			value := strings.TrimSpace(parts[1])
			attrs = append(attrs, rpslRawAttribute{
				name:  name,
				value: value,
			})
		}
	}

	if len(attrs) == 0 {
		return nil, status.Errorf(codes.NotFound, "no such ASN")
	}

	return &pb.IRRQueryResponse{
		Source:     pb.IRRQueryResponse_SOURCE_ARIN,
		Attributes: parseAttributes(attrs),
	}, nil
}