package appconfig

import (
	"errors"
	"os"
	"path/filepath"
	"testing"

	"github.com/carlosframework/platform/internal/registry"
)

// Astra plan 6 R1 #1 (plan Q3): the first non-default swap policy on an app
// with no config.json creates the bundle, which renders no vars. Config
// sync must not turn that into a new, empty config file and a restart of a
// running instance: the instance's file is absent before and after, which
// is the state of every app never configured. No file, no restart, no
// delivered revision for the release scheduler, no ack. The first real var
// then converges as it always did: written, restarted, delivered, acked.
func TestAPolicyOnlyBundleNeitherWritesTheFileNorRestarts(t *testing.T) {
	ctx, s, reg, dd, priv, _ := execKit(t)
	pk, err := ParsePrivateKey(priv, "test")
	if err != nil {
		t.Fatal(err)
	}
	if err := reg.Upsert(registry.Route{
		Host: "inst.example.com", Kind: "instance", App: "eleven", Account: "bab",
		Status: "ready", Socket: "/run/carlos/inst.sock",
	}); err != nil {
		t.Fatal(err)
	}
	var bounced, delivered []string
	var acks []ConfigAck
	cb := Callbacks{
		Restart:   func(h string) error { bounced = append(bounced, h); return nil },
		Ack:       func(a ConfigAck) { acks = append(acks, a) },
		Delivered: func(h, rev string) { delivered = append(delivered, h+" "+rev) },
	}
	pass := func() {
		t.Helper()
		bounced, delivered, acks = nil, nil, nil
		if err := SyncExecWithCallbacks(ctx, reg, s, pk, dd, "", cb); err != nil {
			t.Fatalf("SyncExec: %v", err)
		}
	}
	path := filepath.Join(dd, "inst.example.com.config.env")

	pass() // no config.json: nothing to do
	if _, err := SetSwapPolicy(ctx, s, "bab", "eleven", SwapHold, 3); err != nil {
		t.Fatalf("SetSwapPolicy: %v", err)
	}
	if m, err := Get(ctx, s, "bab", "eleven"); err != nil || m == nil {
		t.Fatalf("the policy write did not create the bundle: %v, %v", m, err)
	}
	pass()
	if _, err := os.Stat(path); !errors.Is(err, os.ErrNotExist) {
		t.Errorf("a policy-only bundle created the config file: %v", err)
	}
	if len(bounced)+len(delivered)+len(acks) != 0 {
		t.Fatalf("a policy-only bundle restarted %v, delivered %v, acked %d", bounced, delivered, len(acks))
	}
	pass() // and it stays quiet
	if len(bounced)+len(delivered)+len(acks) != 0 {
		t.Fatalf("a second pass restarted %v, delivered %v, acked %d", bounced, delivered, len(acks))
	}

	if err := SetEnv(ctx, s, "bab", "eleven", map[string]string{"LOG_LEVEL": "debug"}); err != nil {
		t.Fatal(err)
	}
	pass()
	if got, err := os.ReadFile(path); err != nil || string(got) != "LOG_LEVEL=debug\n" {
		t.Fatalf("config env = %q, %v", got, err)
	}
	if len(bounced) != 1 || len(delivered) != 1 || len(acks) != 1 {
		t.Fatalf("the first real var restarted %v, delivered %v, acked %d: want one of each", bounced, delivered, len(acks))
	}
}

// The skip is for an ABSENT file only. A file that exists keeps converging
// on its bytes: an empty file an older agent wrote stays (no restart), and
// a file with vars whose bundle now renders none is emptied and restarted,
// as before.
func TestAnEmptyRenderStillConvergesAnExistingFile(t *testing.T) {
	ctx, s, reg, dd, priv, _ := execKit(t)
	pk, err := ParsePrivateKey(priv, "test")
	if err != nil {
		t.Fatal(err)
	}
	for _, h := range []string{"empty.example.com", "full.example.com"} {
		if err := reg.Upsert(registry.Route{Host: h, Kind: "instance", App: "eleven", Account: "bab",
			Status: "ready", Socket: "/run/carlos/" + h + ".sock"}); err != nil {
			t.Fatal(err)
		}
	}
	if err := os.WriteFile(filepath.Join(dd, "empty.example.com.config.env"), nil, 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dd, "full.example.com.config.env"), []byte("LOG_LEVEL=debug\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	if _, err := SetSwapPolicy(ctx, s, "bab", "eleven", SwapHold, 0); err != nil {
		t.Fatal(err)
	}
	var bounced []string
	if err := SyncExec(ctx, reg, s, pk, dd, func(h string) error { bounced = append(bounced, h); return nil }, "", nil); err != nil {
		t.Fatal(err)
	}
	if got, err := os.ReadFile(filepath.Join(dd, "full.example.com.config.env")); err != nil || len(got) != 0 {
		t.Fatalf("full file = %q, %v: want it emptied", got, err)
	}
	if _, err := os.Stat(filepath.Join(dd, "empty.example.com.config.env")); err != nil {
		t.Fatalf("the existing empty file went away: %v", err)
	}
	if len(bounced) != 1 || bounced[0] != "full.example.com" {
		t.Fatalf("bounced %v, want only full.example.com", bounced)
	}
}