package torrent

import (
	"bitbucket.org/anacrolix/go.torrent/peer_protocol"
	"testing"
)

func r(i, b, l peer_protocol.Integer) request {
	return request{i, chunkSpec{b, l}}
}

// Check the given Request is correct for various torrent offsets.
func TestTorrentRequest(t *testing.T) {
	const s = 472183431 // Length of torrent.
	for _, _case := range []struct {
		off int64   // An offset into the torrent.
		req request // The expected Request. The zero value means !ok.
	}{
		// Invalid offset.
		{-1, request{}},
		{0, r(0, 0, 16384)},
		// One before the end of a piece.
		{1<<18 - 1, r(0, 1<<18-16384, 16384)},
		// Offset beyond torrent length.
		{472 * 1 << 20, request{}},
		// One before the end of the torrent. Complicates the chunk length.
		{s - 1, r((s-1)/(1<<18), (s-1)%(1<<18)/(16384)*(16384), 12935)},
		{1, r(0, 0, 16384)},
		// One before end of chunk.
		{16383, r(0, 0, 16384)},
		// Second chunk.
		{16384, r(0, 16384, 16384)},
	} {
		req, ok := torrentOffsetRequest(472183431, 1<<18, 16384, _case.off)
		if (_case.req == request{}) == ok {
			t.Fatalf("expected %v, got %v", _case.req, req)
		}
		if req != _case.req {
			t.Fatalf("expected %v, got %v", _case.req, req)
		}
	}
}