package delivery

import (
	"bytes"
	"compress/gzip"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"sort"
	"strings"
	"testing"

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

// capturedDeclaration is a node's declaration as the controller's `plan` verb answered it on 2026-10-24 at 16:19
// (testdata/declaration-<node>.json.gz; the resources carrying a sealed value or a secret taken out, and the filled
// files that named them), never typed by hand.
type capturedDeclaration struct {
	Builds      map[string]string `json:"builds"`
	Resources   []json.RawMessage `json:"resources"`
	Filled      []string          `json:"filled_files"`
	Provisioner string            `json:"provisioner_account"`
}

func readCaptured(t *testing.T, node string) capturedDeclaration {
	t.Helper()
	f, err := os.Open("testdata/declaration-" + node + ".json.gz")
	if err != nil {
		t.Fatal(err)
	}
	defer f.Close()
	z, err := gzip.NewReader(f)
	if err != nil {
		t.Fatal(err)
	}
	raw, err := io.ReadAll(z)
	if err != nil {
		t.Fatal(err)
	}
	var c capturedDeclaration
	if err := json.Unmarshal(raw, &c); err != nil {
		t.Fatal(err)
	}
	return c
}

// fpOfBuild stands for each module's fingerprint in a captured declaration, which names builds, not fingerprints.
func fpOfBuild(build string) string {
	var b strings.Builder
	for b.Len() < 64 {
		b.WriteString(fmt.Sprintf("%x", []byte(build)))
	}
	return SourcePrefix2 + b.String()[:64]
}

func splitCaptured(t *testing.T, node string, c capturedDeclaration) map[string]Composed {
	t.Helper()
	fps := map[string]string{}
	for m, b := range c.Builds {
		fps[m] = fpOfBuild(b)
	}
	// mesh-wireguard's resources are composed with no build of it named; its fingerprint is the indexer's, as every
	// module's is, and stood in for here by its name.
	for _, r := range c.Resources {
		var head struct {
			Module string `json:"module"`
		}
		_ = json.Unmarshal(r, &head)
		if _, ok := fps[head.Module]; head.Module != "" && !ok {
			fps[head.Module] = fpOfBuild(head.Module)
		}
	}
	split, err := SplitComposed(node, c.Resources, fps, c.Filled, NodeOwn{Provisioner: c.Provisioner})
	if err != nil {
		t.Fatalf("SplitComposed(%s): %v", node, err)
	}
	return split
}

func canonical(t *testing.T, raw json.RawMessage) string {
	t.Helper()
	var v any
	d := json.NewDecoder(bytes.NewReader(raw))
	d.UseNumber()
	if err := d.Decode(&v); err != nil {
		t.Fatal(err)
	}
	out, _ := json.Marshal(v)
	return string(out)
}

// 1943/AC2: each module's slice of a captured declaration of each node, and the node's own resources, round-trip
// through the composition's encoding with the same digest; together they are the declaration's resources, each once,
// each in the composition of the module it says.
func TestCompositionsOfACapturedDeclaration(t *testing.T) {
	t.Parallel()
	for _, node := range []string{"ace", "g14"} {
		t.Run(node, func(t *testing.T) {
			t.Parallel()
			oneCapturedDeclaration(t, node)
		})
	}
}

func oneCapturedDeclaration(t *testing.T, node string) {
	{
		c := readCaptured(t, node)
		split := splitCaptured(t, node, c)
		modules := map[string]bool{}
		for m := range c.Builds {
			modules[m] = true
		}
		var union []string
		for key, comp := range split {
			n, module, fp, isNode, err := ParseComposedKey(key)
			if err != nil || n != node || comp.Node != node || comp.Module != module || comp.FP != fp {
				t.Fatalf("%s: key %q holds %s/%s/%s (%v)", node, key, comp.Node, comp.Module, comp.FP, err)
			}
			if !isNode && !modules[module] && module != "mesh-wireguard" {
				t.Errorf("%s: a composition of %s, which the declaration names no build of", node, module)
			}
			raw, err := EncodeComposed(comp)
			if err != nil {
				t.Fatalf("%s: EncodeComposed(%s): %v", node, key, err)
			}
			back, err := DecodeComposed(raw)
			if err != nil {
				t.Fatalf("%s: DecodeComposed(%s): %v", node, key, err)
			}
			if !SameComposed(back, comp) {
				t.Errorf("%s: %s did not round-trip", node, key)
			}
			// SameComposed encodes both, so the digest of what was read back, a hash of its encoding, is the one written.
			if d, err := ComposedDigestOf(back); err != nil || !digestForm.MatchString(d) {
				t.Errorf("%s: %s digests %q (%v)", node, key, d, err)
			}
			for _, r := range back.Resources {
				var head struct {
					Module string `json:"module"`
				}
				_ = json.Unmarshal(r, &head)
				if head.Module != module {
					t.Errorf("%s: %s holds a resource of %q", node, key, head.Module)
				}
				union = append(union, canonical(t, r))
			}
		}
		var want []string
		for _, r := range c.Resources {
			want = append(want, canonical(t, r))
		}
		sort.Strings(union)
		sort.Strings(want)
		if strings.Join(union, "\n") != strings.Join(want, "\n") {
			t.Errorf("%s: the compositions hold %d resources, the declaration %d, or they differ", node, len(union), len(want))
		}
	}
}

// 1943/AC2: one changed byte of a resource is another digest; the same composition written with its keys in another
// order is the same digest.
func TestComposedDigestFollowsTheContent(t *testing.T) {
	c := readCaptured(t, "g14")
	split := splitCaptured(t, "g14", c)
	var comp Composed
	for _, v := range split {
		if v.Module != "" && len(v.Resources) > 1 {
			comp = v
			break
		}
	}
	d1, _ := ComposedDigestOf(comp)
	var m map[string]json.RawMessage
	_ = json.Unmarshal(comp.Resources[0], &m)
	var keys []string
	for k := range m {
		keys = append(keys, k)
	}
	sort.Sort(sort.Reverse(sort.StringSlice(keys)))
	var parts []string
	for _, k := range keys {
		parts = append(parts, fmt.Sprintf("%q :  %s", k, m[k]))
	}
	reordered := json.RawMessage("{ " + strings.Join(parts, ",\n ") + " }")
	shuffled := comp
	shuffled.Resources = append([]json.RawMessage{reordered}, comp.Resources[1:]...)
	if d2, _ := ComposedDigestOf(shuffled); d2 != d1 {
		t.Errorf("the same resources in another order and spacing digest %s and %s", d1, d2)
	}
	changed := comp
	changed.Resources = append([]json.RawMessage{json.RawMessage(strings.Replace(canonical(t, comp.Resources[0]), `"id":"`, `"id":"x`, 1))}, comp.Resources[1:]...)
	if d3, _ := ComposedDigestOf(changed); d3 == d1 {
		t.Errorf("a changed resource kept its digest")
	}
	revised := comp
	revised.Data = !comp.Data
	if d4, _ := ComposedDigestOf(revised); d4 == d1 {
		t.Errorf("a changed data flag kept its digest")
	}
}

// 1943/AC2: a file over 64 KiB is carried by digest and size, its content handed back to be put in the node's object
// bucket; a composition that carries such a file whole is refused.
func TestAComposedFileOver64KiBIsCarriedByDigest(t *testing.T) {
	c := readCaptured(t, "g14")
	split := splitCaptured(t, "g14", c)
	var comp Composed
	var at int
	for _, v := range split {
		for i, r := range v.Resources {
			var f map[string]any
			_ = json.Unmarshal(r, &f)
			if f["type"] == "file" && v.Module != "" && f["bytes"] == nil && f["into"] == nil {
				comp, at = v, i
				break
			}
		}
		if comp.Module != "" {
			break
		}
	}
	var f map[string]any
	_ = json.Unmarshal(comp.Resources[at], &f)
	// Grown past the threshold from a captured file: no captured file of this node is over 64 KiB.
	body := strings.Repeat("x", declaration.FileReferenceThreshold+1)
	f["content"] = body
	big, _ := json.Marshal(f)
	comp.Resources = append([]json.RawMessage{}, comp.Resources...)
	comp.Resources[at] = big
	if _, err := EncodeComposed(comp); err == nil || !strings.Contains(err.Error(), "by digest") {
		t.Fatalf("a file over 64 KiB carried whole = %v, want refused", err)
	}
	byDigest, objects, err := comp.ByDigest()
	if err != nil {
		t.Fatal(err)
	}
	var ref map[string]any
	_ = json.Unmarshal(byDigest.Resources[at], &ref)
	digest := declaration.DigestOf([]byte(body))
	if ref["digest"] != digest || ref["size"] != float64(len(body)) || ref["content"] != nil {
		t.Errorf("the file became %v, want digest %s and size %d", ref, digest, len(body))
	}
	if string(objects[digest]) != body || len(objects) != 1 {
		t.Errorf("the objects handed back are %d, want the file's content under its digest", len(objects))
	}
	if _, err := EncodeComposed(byDigest); err != nil {
		t.Errorf("the composition by digest is refused: %v", err)
	}
}

// 1943/AC2: an unknown version is refused as one; a module's composition carrying the node's own parts, a resource of
// another module, a resource its kind refuses, or no fingerprint, is refused, naming why.
func TestComposedRefusals(t *testing.T) {
	fp := fp2of('a')
	file := json.RawMessage(`{"id":"m.f","type":"file","module":"m","path":"/etc/m","content":"x"}`)
	ok := Composed{Node: "ace", Module: "m", FP: fp, Resources: []json.RawMessage{file}}
	raw, err := EncodeComposed(ok)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := DecodeComposed(bytes.Replace(raw, []byte(`"v":1`), []byte(`"v":2`), 1)); !errors.Is(err, ErrUnknownVersion) {
		t.Errorf("version 2 = %v, want ErrUnknownVersion", err)
	}
	refusals := []struct {
		c   Composed
		why string
	}{
		{Composed{Node: "ace", Module: "m", Resources: []json.RawMessage{file}}, "fingerprint"},
		{Composed{Node: "", Module: "m", FP: fp, Resources: []json.RawMessage{file}}, "node name is empty"},
		{Composed{Node: "ace", Module: "other", FP: fp, Resources: []json.RawMessage{file}}, `of "m"`},
		{Composed{Node: "ace", Module: "m", FP: fp, Resources: []json.RawMessage{file}, Own: NodeOwn{Provisioner: "p"}}, "node's own"},
		{Composed{Node: "ace", FP: fp, Resources: []json.RawMessage{}}, "names no fingerprint"},
		{Composed{Node: "ace", Resources: []json.RawMessage{file}}, `of "m"`},
		{Composed{Node: "ace", Module: "m", FP: fp, Resources: []json.RawMessage{json.RawMessage(`{"id":"m.f","type":"file","module":"m","path":"/etc/m","content":"x","image":"y"}`)}}, `"image"`},
		{Composed{Node: "ace", Module: "m", FP: fp, Resources: []json.RawMessage{json.RawMessage(`{"id":"m.a","type":"action","module":"m"}`)}}, "action"},
	}
	for _, r := range refusals {
		if _, err := EncodeComposed(r.c); err == nil || !strings.Contains(err.Error(), r.why) {
			t.Errorf("EncodeComposed(%s/%s) = %v, want a refusal saying %q", r.c.Node, r.c.Module, err, r.why)
		}
	}
}

// 1943/AC2 (issue 1150): a module whose name holds a dot keys its have, its want and its composition escaped, and the
// parsers give its name back; a name with a wildcard, whitespace or an escape of its own is still refused.
func TestADottedModuleKeysEscaped(t *testing.T) {
	fp := fp2of('f')
	have, err := HaveKey("ace", "novox.be")
	if err != nil || have != "ace.novox=2ebe" {
		t.Fatalf("HaveKey = %q, %v", have, err)
	}
	if n, m, isNode, err := ParseHaveKey(have); err != nil || n != "ace" || m != "novox.be" || isNode {
		t.Errorf("ParseHaveKey(%q) = %q, %q, %v, %v", have, n, m, isNode, err)
	}
	want, err := WantKey("ace", "novox.be")
	if err != nil || want != "want.ace.novox=2ebe" {
		t.Fatalf("WantKey = %q, %v", want, err)
	}
	if n, m, err := ParseWantKey(want); err != nil || n != "ace" || m != "novox.be" {
		t.Errorf("ParseWantKey(%q) = %q, %q, %v", want, n, m, err)
	}
	comp, err := ComposedKey("ace", "novox.be", fp)
	if err != nil || comp != "ace.novox=2ebe."+strings.Repeat("f", 64) {
		t.Fatalf("ComposedKey = %q, %v", comp, err)
	}
	if n, m, back, _, err := ParseComposedKey(comp); err != nil || n != "ace" || m != "novox.be" || back != fp {
		t.Errorf("ParseComposedKey(%q) = %q, %q, %q, %v", comp, n, m, back, err)
	}
	for _, bad := range []string{"m*", "m x", "m=2e", "m>", ".m", "m.", "a..b"} {
		if _, err := HaveKey("ace", bad); err == nil {
			t.Errorf("HaveKey(ace, %q) accepted", bad)
		}
	}
	for _, bad := range []string{"ace.m=2", "ace.m=2E", "ace.m=41", "ace.=6eode"} {
		if _, _, _, err := ParseHaveKey(bad); err == nil {
			t.Errorf("ParseHaveKey(%q) accepted", bad)
		}
	}
}