// SPDX-License-Identifier: Apache-2.0

package bundle

import (
	"bytes"
	"crypto/ed25519"
	"strings"
	"testing"
	"time"
)

var testTime = time.Date(2026, 10, 13, 12, 0, 0, 0, time.UTC)

func testKey(t *testing.T) (ed25519.PublicKey, ed25519.PrivateKey) {
	t.Helper()
	seed := bytes.Repeat([]byte{7}, ed25519.SeedSize)
	priv := ed25519.NewKeyFromSeed(seed)
	return priv.Public().(ed25519.PublicKey), priv
}

func sample() []Artifact {
	return []Artifact{
		{Path: "ddi-suite.conf", Mode: 0o640, Content: []byte("zone \"a.test\" {};\n")},
		{Path: "zones/db.a.test", Mode: 0o640, Content: []byte("$TTL 3600\n")},
		{Path: "zones/db.dyn.test", Mode: 0o640, Content: []byte("dyn\n"), CreateOnly: true},
	}
}

func contents(arts []Artifact) map[string][]byte {
	m := make(map[string][]byte, len(arts))
	for _, a := range arts {
		m[a.Path] = a.Content
	}
	return m
}

func TestSignVerifyRoundTrip(t *testing.T) {
	pub, priv := testKey(t)
	arts := sample()
	man, sig, err := Sign(priv, "agent-1", "dns", 42, testTime, arts)
	if err != nil {
		t.Fatal(err)
	}
	m, err := Verify(pub, man, sig, contents(arts), Expect{AgentID: "agent-1", Role: "dns", MinRevision: 42})
	if err != nil {
		t.Fatal(err)
	}
	if m.Revision != 42 || len(m.Files) != 3 || !m.Files[2].CreateOnly || m.Files[0].Mode != 0o640 ||
		!m.CreatedAt.Equal(testTime) || m.Files[1].Size != int64(len(arts[1].Content)) {
		t.Errorf("manifest %+v", m)
	}
	// Signing is deterministic: same input, same bytes.
	man2, sig2, _ := Sign(priv, "agent-1", "dns", 42, testTime, arts)
	if !bytes.Equal(man, man2) || !bytes.Equal(sig, sig2) {
		t.Error("signing is not deterministic")
	}
}

func TestVerifyRejects(t *testing.T) {
	pub, priv := testKey(t)
	arts := sample()
	man, sig, err := Sign(priv, "agent-1", "dns", 5, testTime, arts)
	if err != nil {
		t.Fatal(err)
	}
	ok := Expect{AgentID: "agent-1", Role: "dns"}
	otherPub, _, _ := ed25519.GenerateKey(nil)

	tampered := bytes.Replace(man, []byte(`"revision":5`), []byte(`"revision":6`), 1)
	changed := contents(arts)
	changed["zones/db.a.test"] = []byte("$TTL 3601\n")
	missing := contents(arts)
	delete(missing, "zones/db.a.test")
	extra := contents(arts)
	extra["other"] = nil
	short := contents(arts)
	short["zones/db.a.test"] = []byte("x")

	cases := []struct {
		name     string
		pub      ed25519.PublicKey
		man, sig []byte
		files    map[string][]byte
		want     Expect
		msg      string
	}{
		{"wrong key", otherPub, man, sig, contents(arts), ok, "signature"},
		{"bad key length", pub[:5], man, sig, contents(arts), ok, "signing key"},
		{"tampered manifest", pub, tampered, sig, contents(arts), ok, "signature"},
		{"other agent", pub, man, sig, contents(arts), Expect{AgentID: "agent-2", Role: "dns"}, "agent"},
		{"other role", pub, man, sig, contents(arts), Expect{AgentID: "agent-1", Role: "dhcp"}, "role"},
		{"replay", pub, man, sig, contents(arts), Expect{AgentID: "agent-1", Role: "dns", MinRevision: 6}, "older"},
		{"changed content", pub, man, sig, changed, ok, "SHA-256"},
		{"wrong size", pub, man, sig, short, ok, "size"},
		{"missing file", pub, man, sig, missing, ok, "files"},
		{"extra file", pub, man, sig, extra, ok, "files"},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			_, err := Verify(c.pub, c.man, c.sig, c.files, c.want)
			if err == nil || !strings.Contains(err.Error(), c.msg) {
				t.Errorf("err = %v, want %q", err, c.msg)
			}
		})
	}
}

func TestVerifyRejectsUnsafeManifests(t *testing.T) {
	pub, priv := testKey(t)
	sign := func(raw string) ([]byte, []byte) { return []byte(raw), ed25519.Sign(priv, []byte(raw)) }
	cases := map[string]string{
		"format":   `{"format":2,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[]}`,
		"no rev":   `{"format":1,"agent_id":"a","role":"dns","revision":0,"created_at":"2026-10-13T12:00:00Z","files":[]}`,
		"unknown":  `{"format":1,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[],"x":1}`,
		"trailing": `{"format":1,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[]} {}`,
		"escape":   `{"format":1,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[{"path":"../etc/passwd","mode":420,"sha256":"","size":0}]}`,
		"mode":     `{"format":1,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[{"path":"x","mode":2048,"sha256":"","size":0}]}`,
		"dup":      `{"format":1,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[{"path":"x","mode":420,"sha256":"","size":0},{"path":"x","mode":420,"sha256":"","size":0}]}`,
		"negative": `{"format":1,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[{"path":"x","mode":420,"sha256":"","size":-1}]}`,
		"huge":     `{"format":1,"agent_id":"a","role":"dns","revision":1,"created_at":"2026-10-13T12:00:00Z","files":[{"path":"x","mode":420,"sha256":"","size":1073741824}]}`,
	}
	for name, raw := range cases {
		t.Run(name, func(t *testing.T) {
			man, sig := sign(raw)
			if _, err := Verify(pub, man, sig, map[string][]byte{}, Expect{AgentID: "a", Role: "dns"}); err == nil {
				t.Error("accepted")
			}
		})
	}
	if _, _, err := Sign(priv[:3], "a", "dns", 1, testTime, nil); err == nil {
		t.Error("Sign accepted a short key")
	}
	if _, _, err := Sign(priv, "a", "dns", 1, testTime, []Artifact{{Path: "/abs"}}); err == nil {
		t.Error("Sign accepted an absolute path")
	}
}

func TestCheckPath(t *testing.T) {
	good := []string{"ddi-suite.conf", "zones/db.office.test", "kea-dhcp4.conf", "a/b/c+d@e_f-g"}
	bad := []string{"", "/abs", "../x", "a/../b", "a//b", "a/", ".hidden", "zones/.x", "a b", "a\\b", "ä",
		strings.Repeat("a", MaxPathLen+1)}
	for _, p := range good {
		if err := CheckPath(p); err != nil {
			t.Errorf("%q: %v", p, err)
		}
	}
	for _, p := range bad {
		if CheckPath(p) == nil {
			t.Errorf("%q accepted", p)
		}
	}
}

func FuzzVerify(f *testing.F) {
	pub, priv := testKey(&testing.T{})
	man, _, _ := Sign(priv, "a", "dns", 1, testTime, sample())
	f.Add(man)
	f.Fuzz(func(t *testing.T, raw []byte) {
		// Whatever is signed, Verify must not panic and must never accept a
		// path outside the root.
		m, err := Verify(pub, raw, ed25519.Sign(priv, raw), map[string][]byte{}, Expect{AgentID: "a", Role: "dns"})
		if err != nil {
			return
		}
		for _, file := range m.Files {
			if CheckPath(file.Path) != nil {
				t.Fatalf("accepted unsafe path %q", file.Path)
			}
		}
	})
}