package apply

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"git.novox.be/novox/mesh-sdk/go/declaration"
	"github.com/novox/mesh-host/internal/store"
)

// Defends novox/hq ADR 0547 §8: the bus node writes the bus's user list alone, with no want, through the apply's own
// file step: only when it differs, mode 0600, read back and recorded as the module's, and nothing else moves.
func TestAFileWrittenAloneMovesNothingElse(t *testing.T) {
	const was, now = "user a\n", "user a\nuser b\n"
	for _, c := range []struct {
		name, fields, before string
		recorded             bool
		recordedAs           string // the id the record has, when not the composition's
		action, refused      string
		after                string
	}{
		{name: "no record of it", fields: `"content":%q,"mode":"0600"`, before: was, refused: "holds no record", after: was},
		{name: "changed", fields: `"content":%q,"mode":"0600"`, before: was, recorded: true, action: "updated", after: now},
		{name: "the same", fields: `"content":%q,"mode":"0600"`, before: now, recorded: true, action: "unchanged", after: now},
		{name: "recorded under the id from before the switch", fields: `"content":%q,"mode":"0600"`, before: was,
			recorded: true, recordedAs: "bus-users", action: "updated", after: now},
		{name: "absent with a record", fields: `"content":%q,"mode":"0600"`, recorded: true, action: "created", after: now},
		{name: "written into", fields: `"content":%q,"into":"block","owner-at-runtime":"managed"`, before: was,
			recorded: true, refused: "only such a file", after: was},
		{name: "sealed", fields: `"sealed":"c2VhbGVk"`, before: was, recorded: true,
			refused: "only such a file", after: was},
	} {
		t.Run(c.name, func(t *testing.T) {
			path := filepath.Join(t.TempDir(), "accounts.conf")
			if c.before != "" {
				if err := os.WriteFile(path, []byte(c.before), 0o600); err != nil {
					t.Fatal(err)
				}
			}
			fields := strings.Replace(c.fields, "%q", fmt.Sprintf("%q", now), 1)
			d := parseTrusted(t, fmt.Sprintf(`{"declaration":1,"resources":[{"id":"nats.bus-users","module":"nats",
			  "type":"file","path":%q,`+fields+`}]}`, path))
			file := d.Resources[0].(*declaration.File)
			known := store.State{}
			id := file.ID
			if c.recordedAs != "" {
				id = c.recordedAs
			}
			if c.recorded {
				known.Record(store.Applied{ID: id, Type: string(declaration.TypeFile), Module: "nats", Target: path,
					Origin: store.OriginDeclared, Wrote: digestOf(c.before)})
			}
			calls := 0
			counting := func(context.Context, string, ...string) (string, error) { calls++; return "", nil }
			out, after, err := WriteAlone(context.Background(), archHost(t), file, known, counting, nil)
			if c.refused != "" {
				if err == nil || !strings.Contains(err.Error(), c.refused) {
					t.Fatalf("not refused with %q: %v", c.refused, err)
				}
			} else if err != nil {
				t.Fatal(err)
			} else if out.Action != c.action {
				t.Errorf("action %q, want %q", out.Action, c.action)
			}
			if got := readText(t, path); got != c.after {
				t.Errorf("file holds %q, want %q", got, c.after)
			}
			if calls != 0 {
				t.Errorf("%d commands were run: a file written alone moves nothing", calls)
			}
			if c.refused != "" {
				return
			}
			if m := modeAt(t, path); m != 0o600 {
				t.Errorf("mode %o", m)
			}
			rec, ok := after.Find(id)
			if !ok || rec.Wrote != digestOf(now) || rec.Target != path {
				t.Errorf("record %+v (found %v), want it to say %s was written", rec, ok, digestOf(now))
			}
			if n := len(after.Resources); n != 1 {
				t.Errorf("%d records of one file", n)
			}
		})
	}
}