package gitutil

import (
	"fmt"
	"testing"
	"time"
)

func (k *keyedMutex) entries() int {
	k.mu.Lock()
	defer k.mu.Unlock()
	return len(k.m)
}

func TestKeyedMutexForgetsKeysNobodyHolds(t *testing.T) {
	var k keyedMutex
	for i := range 100 {
		k.lock(fmt.Sprintf("/repos/did:web:made-up-%d", i))()
	}
	if got := k.entries(); got != 0 {
		t.Fatalf("%d entries left after every lock was released, want 0", got)
	}

	unlock := k.lock("same")
	entered := make(chan struct{})
	go func() {
		k.lock("same")()
		close(entered)
	}()
	select {
	case <-entered:
		t.Fatal("a second holder got in while the first still held the key")
	case <-time.After(50 * time.Millisecond):
	}
	if got := k.entries(); got != 1 {
		t.Fatalf("%d entries while one holds and one waits, want 1", got)
	}
	unlock()
	select {
	case <-entered:
	case <-time.After(5 * time.Second):
		t.Fatal("the waiter never got the key after the holder let go")
	}
	// the waiter drops its entry just after signaling, wait for that
	deadline := time.Now().Add(5 * time.Second)
	for k.entries() != 0 && time.Now().Before(deadline) {
		time.Sleep(5 * time.Millisecond)
	}
	if got := k.entries(); got != 0 {
		t.Fatalf("%d entries left after the waiter finished, want 0", got)
	}
}