package buildrun

import (
	"context"
	"strings"
	"testing"
	"time"
)

func acquireAsync(p *Places, node string) chan func() {
	got := make(chan func(), 1)
	go func() {
		release, err := p.Acquire(context.Background(), node)
		if err != nil {
			close(got)
			return
		}
		got <- release
	}()
	return got
}

func TestThreeStepsOnANodeOfCapacityTwoRunTwoAtOnceAndTheThirdStartsWhenOneEnds(t *testing.T) { // round 3
	p := &Places{Capacity: map[string]int{"ace": 2}}
	a, b := acquireAsync(p, "ace"), acquireAsync(p, "ace")
	ra, rb := <-a, <-b
	third := acquireAsync(p, "ace")
	select {
	case <-third:
		t.Fatal("a third step started on a node of capacity 2 with two running")
	case <-time.After(10 * time.Millisecond):
	}
	if p.Running()["ace"] != 2 {
		t.Errorf("running = %v, want 2 on ace", p.Running())
	}
	ra()
	select {
	case r := <-third:
		r()
	case <-time.After(2 * time.Second):
		t.Fatal("the third step did not start when one ended")
	}
	rb()
}

func TestANodeWithNoSettingRunsOneStepAtATime(t *testing.T) { // round 3
	p := &Places{Capacity: map[string]int{"shanks": 3}}
	first := <-acquireAsync(p, "g14")
	second := acquireAsync(p, "g14")
	select {
	case <-second:
		t.Fatal("two steps on a node without a setting")
	case <-time.After(10 * time.Millisecond):
	}
	first()
	r := <-second
	r()
	if p.CapacityOf("g14") != 1 || p.CapacityOf("shanks") != 3 {
		t.Errorf("capacities = %d, %d", p.CapacityOf("g14"), p.CapacityOf("shanks"))
	}
}

func TestAWaitingStepStopsWhenItsContextEnds(t *testing.T) { // round 3
	p := &Places{}
	r := <-acquireAsync(p, "ace")
	defer r()
	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan error, 1)
	go func() { _, err := p.Acquire(ctx, "ace"); done <- err }()
	cancel()
	select {
	case err := <-done:
		if err == nil {
			t.Error("Acquire returned no error for a cancelled wait")
		}
	case <-time.After(2 * time.Second):
		t.Fatal("a cancelled wait did not return")
	}
}

// The operator's decision of 2026-10-21 13:40: the builder builds on shanks and ace only; a capacity of 0 keeps it off a node.
func TestACapacityOfZeroKeepsThePartOffTheNodeAndANodeNotNamedKeepsOne(t *testing.T) { // issue 1661
	p := &Places{Capacity: map[string]int{"shanks": 3, "ace": 2, "g14": 0, "novox": 0}}
	if p.CapacityOf("g14") != 0 || p.CapacityOf("novox") != 0 || p.CapacityOf("ace") != 2 || p.CapacityOf("other") != DefaultCapacity {
		t.Errorf("capacities = %d %d %d %d, want 0 0 2 and the default for a node not named", p.CapacityOf("g14"), p.CapacityOf("novox"), p.CapacityOf("ace"), p.CapacityOf("other"))
	}
	entries := tcs("go", "go1.27.1", "ace", "g14", "novox", "shanks", "other")
	for i := 0; i < 6; i++ {
		nodes, _, err := ChooseNodes("go", entries, p, nil, 2)
		if err != nil {
			t.Fatal(err)
		}
		for _, n := range nodes {
			if n == "g14" || n == "novox" {
				t.Fatalf("choice %d: %v includes a node of capacity 0", i, nodes)
			}
		}
	}
	// Only nodes of capacity 0 report: nothing qualifies, and the build says why.
	_, _, err := ChooseNodes("go", tcs("go", "go1.27.1", "g14", "novox"), p, nil, 2)
	if err == nil || !strings.Contains(err.Error(), "capacity") {
		t.Errorf("only capacity-0 nodes: error = %v, want it to name the capacity", err)
	}
}