package decision

import (
	"math"
	"math/rand"
	"sort"
	"strings"
	"testing"

	key "github.com/ipfs/go-ipfs/blocks/key"
	"github.com/ipfs/go-ipfs/exchange/bitswap/wantlist"
	"github.com/ipfs/go-ipfs/util/testutil"
)

func TestPushPop(t *testing.T) {
	prq := newPRQ()
	partner := testutil.RandPeerIDFatal(t)
	alphabet := strings.Split("abcdefghijklmnopqrstuvwxyz", "")
	vowels := strings.Split("aeiou", "")
	consonants := func() []string {
		var out []string
		for _, letter := range alphabet {
			skip := false
			for _, vowel := range vowels {
				if letter == vowel {
					skip = true
				}
			}
			if !skip {
				out = append(out, letter)
			}
		}
		return out
	}()
	sort.Strings(alphabet)
	sort.Strings(vowels)
	sort.Strings(consonants)

	// add a bunch of blocks. cancel some. drain the queue. the queue should only have the kept entries

	for _, index := range rand.Perm(len(alphabet)) { // add blocks for all letters
		letter := alphabet[index]
		t.Log(partner.String())
		prq.Push(wantlist.Entry{Key: key.Key(letter), Priority: math.MaxInt32 - index}, partner)
	}
	for _, consonant := range consonants {
		prq.Remove(key.Key(consonant), partner)
	}

	var out []string
	for {
		received := prq.Pop()
		if received == nil {
			break
		}

		out = append(out, string(received.Entry.Key))
	}

	// Entries popped should already be in correct order
	for i, expected := range vowels {
		if out[i] != expected {
			t.Fatal("received", out[i], "expected", expected)
		}
	}
}

// This test checks that peers wont starve out other peers
func TestPeerRepeats(t *testing.T) {
	prq := newPRQ()
	a := testutil.RandPeerIDFatal(t)
	b := testutil.RandPeerIDFatal(t)
	c := testutil.RandPeerIDFatal(t)
	d := testutil.RandPeerIDFatal(t)

	// Have each push some blocks

	for i := 0; i < 5; i++ {
		prq.Push(wantlist.Entry{Key: key.Key(i)}, a)
		prq.Push(wantlist.Entry{Key: key.Key(i)}, b)
		prq.Push(wantlist.Entry{Key: key.Key(i)}, c)
		prq.Push(wantlist.Entry{Key: key.Key(i)}, d)
	}

	// now, pop off four entries, there should be one from each
	var targets []string
	var tasks []*peerRequestTask
	for i := 0; i < 4; i++ {
		t := prq.Pop()
		targets = append(targets, t.Target.Pretty())
		tasks = append(tasks, t)
	}

	expected := []string{a.Pretty(), b.Pretty(), c.Pretty(), d.Pretty()}
	sort.Strings(expected)
	sort.Strings(targets)

	t.Log(targets)
	t.Log(expected)
	for i, s := range targets {
		if expected[i] != s {
			t.Fatal("unexpected peer", s, expected[i])
		}
	}

	// Now, if one of the tasks gets finished, the next task off the queue should
	// be for the same peer
	for blockI := 0; blockI < 4; blockI++ {
		for i := 0; i < 4; i++ {
			// its okay to mark the same task done multiple times here (JUST FOR TESTING)
			tasks[i].Done()

			ntask := prq.Pop()
			if ntask.Target != tasks[i].Target {
				t.Fatal("Expected task from peer with lowest active count")
			}
		}
	}
}
