package stateobjects

import (
	"bytes"
	"encoding/json"
	"slices"
	"strings"
	"testing"

	"git.novox.be/novox/mesh-sdk/go/kvlimit"
)

// big is a JSON value of about n bytes.
func big(n int) map[string]string { return map[string]string{"text": strings.Repeat("x", n)} }

// valueRows is what every backend of Values holds: a value of 1x, 10x and 100x the limit is read back whole, a replace
// leaves the old object and a delete leaves its object, both listed key-gone until the drop (ADR 0666 §16, ADR 0595 §4).
func valueRows(t *testing.T, v Values, multiples ...int) {
	t.Helper()
	limit := kvlimit.ModuleStateValueBytes
	for _, times := range multiples {
		key := map[int]string{1: "one", 10: "ten", 100: "hundred"}[times]
		want := big(times * limit)
		if err := v.Put(key, want); err != nil {
			t.Errorf("%dx: put: %v", times, err)
			return
		}
		var got map[string]string
		if ok, err := v.Get(key, &got); err != nil || !ok || got["text"] != want["text"] {
			t.Errorf("%dx: read back %v, found %v, %v", times, len(got["text"]), ok, err)
			return
		}
		e, _ := v.KV.Get(key)
		if _, isRef := ReadRef(e.Value); !isRef {
			t.Errorf("%dx: the key holds the value, not a reference", times)
			return
		}
	}
	if err := v.Put("small", map[string]int{"a": 1}); err != nil {
		t.Error(err)
		return
	}
	if e, _ := v.KV.Get("small"); !bytes.Equal(e.Value, []byte(`{"a":1}`)) {
		t.Errorf("a small value is kept in its key, got %s", e.Value)
		return
	}
	// a replace leaves the object it replaced, listed key-gone (ADR 0595 §4); the same value again adds none
	before, _ := v.Objects.List()
	if err := v.Put("one", big(2*limit)); err != nil {
		t.Error(err)
		return
	}
	if err := v.Put("one", big(2*limit)); err != nil {
		t.Error(err)
		return
	}
	after, _ := v.Objects.List()
	if len(after) != len(before)+1 {
		t.Errorf("a replace left %d objects, %d before it: the old one must stay", len(after), len(before))
		return
	}
	if err := v.Put("one", "small now"); err != nil {
		t.Error(err)
		return
	}
	if now, _ := v.Objects.List(); len(now) != len(after) {
		t.Errorf("replacing by a small value changed the objects: %d, want %d", len(now), len(after))
		return
	}
	// a delete leaves the object, listed key-gone, and the drop removes it alone
	if err := v.Delete("ten"); err != nil {
		t.Error(err)
		return
	}
	kept, err := v.Kept()
	if err != nil {
		t.Error(err)
		return
	}
	var gone []string
	for _, k := range kept {
		if k.KeyGone {
			gone = append(gone, k.Key)
		}
	}
	slices.Sort(gone)
	if !slices.Equal(gone, []string{"one", "one", "ten"}) {
		t.Errorf("the objects whose key is gone: %v, want the two replaced of one and ten's", gone)
		return
	}
	dropped, err := v.DropKeyGone()
	if err != nil || len(dropped) != 3 {
		t.Errorf("dropped %v, %v", dropped, err)
		return
	}
	if left, _ := v.Objects.List(); len(left) != len(kept)-3 {
		t.Errorf("the drop left %d objects of %d", len(left), len(kept))
		return
	}
	if err := v.Put("ref", json.RawMessage(Wrap(Ref{Store: "s", Object: "o", Digest: strings.Repeat("a", 64), Form: FormVersion}))); err == nil {
		t.Error("a value that is exactly a reference was accepted")
		return
	}
}

// ADR 0666 §16, C-S3, C-S5: values of 1x, 10x and 100x the limit through a bundle's runtime, whole.
func TestValuesOfAnySizeThroughTheRuntime(t *testing.T) {
	m := newMemory()
	out := runtimeOf(t, m, func() (any, error) {
		v := ForState("views")
		valueRows(t, v, 1, 10) // a bundle puts at most 8 MiB in an object: 100x is a process's
		return "done", nil
	})
	if !strings.Contains(out.(string), "done") {
		t.Fatalf("the bundle answered %v", out)
	}
}

// A write another writer won first leaves the object it put removed and the key as it found it.
func TestAWriteLostLeavesNoObjectBehind(t *testing.T) {
	m := newMemory()
	v := m.values()
	if err := v.Put("k", big(3*kvlimit.ModuleStateValueBytes)); err != nil {
		t.Fatal(err)
	}
	// another writer changes the key between this writer's read and write
	racing := &raceKV{KV: m, then: func() { _ = m.Update("k", []byte(`"other"`), 1) }}
	lost := Values{KV: racing, Objects: memObjects{m}, Store: "s"}
	if err := lost.Put("k", big(4*kvlimit.ModuleStateValueBytes)); err == nil || err != ErrChanged {
		t.Fatalf("the lost write: %v", err)
	}
	if l, _ := (memObjects{m}).List(); len(l) != 1 {
		t.Fatalf("%d objects, want the first value's only", len(l))
	}
	m.failPuts = true
	if err := v.Put("k2", big(3*kvlimit.ModuleStateValueBytes)); err == nil {
		t.Fatal("a put into a full store was accepted")
	}
	if e, _ := m.Get("k2"); e != nil {
		t.Fatal("the key was written though its object was not")
	}
}

// raceKV runs then once, after the first Get, as another writer would.
type raceKV struct {
	KV
	then func()
}

func (r *raceKV) Get(key string) (*Entry, error) {
	e, err := r.KV.Get(key)
	if r.then != nil {
		then := r.then
		r.then = nil
		then()
	}
	return e, err
}

// A store that takes no object as large as the value refuses it, loudly, and writes nothing.
func TestAValueLargerThanTheStoreTakesIsRefused(t *testing.T) {
	m := newMemory()
	m.most = 100_000
	v := m.values()
	err := v.Put("k", big(5*kvlimit.ModuleStateValueBytes))
	if err == nil || !strings.Contains(err.Error(), "refused") {
		t.Fatalf("the put: %v", err)
	}
	if e, _ := m.Get("k"); e != nil || len(m.objects) != 0 {
		t.Fatal("a refused value left a key or an object")
	}
}