package main

import (
	"bytes"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
	"time"

	"filippo.io/age"

	datekeys "g.activething.com/go/DateKeys"
	"g.activething.com/go/DateKeys/internal/inspectview"
	"g.activething.com/go/DateKeys/internal/testkit"
	"g.activething.com/go/DateKeys/profile"
)

const fixtures = "../../testdata/fixtures"

// relay serves the known Quicknet releases like a drand HTTP relay.
func relay(t *testing.T) string {
	t.Helper()
	p := profile.Quicknet()
	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		for _, round := range testkit.Rounds {
			if r.URL.Path == fmt.Sprintf("/v2/chains/%s/rounds/%d", p.ChainHashHex(), round) {
				fmt.Fprintf(w, `{"round":%d,"signature":"%s"}`, round, hex.EncodeToString(testkit.Release(round).Signature))
				return
			}
		}
		http.NotFound(w, r)
	}))
	t.Cleanup(s.Close)
	return s.URL
}

func cli(t *testing.T, now time.Time, args ...string) (string, string, error) {
	t.Helper()
	var out, errOut bytes.Buffer
	err := run(args, &out, &errOut, func() time.Time { return now })
	return out.String(), errOut.String(), err
}

var later = time.Date(2026, 9, 25, 12, 0, 0, 0, time.UTC)

func TestOutputNotPublishedOnFailureOrOverwrite(t *testing.T) {
	dir := t.TempDir()
	out := filepath.Join(dir, "output")
	err := writeAtomic(out, func(w io.Writer) error {
		_, _ = w.Write([]byte("partial plaintext"))
		return errors.New("invalid authentication tag")
	})
	if err == nil {
		t.Fatal("expected failure")
	}
	if _, err := os.Stat(out); !errors.Is(err, os.ErrNotExist) {
		t.Fatal("published partial output")
	}
	if err := os.WriteFile(out, []byte("keep me"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := writeAtomic(out, func(io.Writer) error { t.Fatal("should not run"); return nil }); err == nil {
		t.Fatal("overwrote output")
	}
	if b, _ := os.ReadFile(out); string(b) != "keep me" {
		t.Fatal("output changed")
	}
	if files, _ := filepath.Glob(filepath.Join(dir, ".datekeys-*")); len(files) != 0 {
		t.Fatal("temporary file left behind")
	}
	if err := copyExclusive(out, out); err == nil {
		t.Fatal("exclusive copy replaced a file")
	}
}

func TestDecryptFixtures(t *testing.T) {
	url := relay(t)
	for _, tc := range []struct{ name, dkk string }{
		{"time_only", ""},
		{"time_only_extensions", ""},
		{"empty_payload", ""},
		{"time_and_key_portable", "time_and_key_portable.dkk"},
	} {
		t.Run(tc.name, func(t *testing.T) {
			out := filepath.Join(t.TempDir(), "plain")
			args := []string{"decrypt", "-in", filepath.Join(fixtures, tc.name+".dkc"), "-out", out, "-relay", url}
			if tc.dkk != "" {
				args = append(args, "-dkk", filepath.Join(fixtures, tc.dkk))
			}
			if _, stderr, err := cli(t, later, args...); err != nil {
				t.Fatalf("%v\n%s", err, stderr)
			}
			got, _ := os.ReadFile(out)
			want, _ := os.ReadFile(filepath.Join(fixtures, tc.name+".plaintext"))
			if !bytes.Equal(got, want) {
				t.Fatal("plaintext differs")
			}
		})
	}
}

func TestDecryptWithIdentityFile(t *testing.T) {
	var f testkit.DKCFixture
	if err := testkit.ReadJSON(filepath.Join(fixtures, "time_and_key_recipients.json"), &f); err != nil {
		t.Fatal(err)
	}
	dir := t.TempDir()
	key := filepath.Join(dir, "key.txt")
	os.WriteFile(key, []byte("# test identity\n"+f.Identities[1]+"\n"), 0o600)
	out := filepath.Join(dir, "plain")
	if _, stderr, err := cli(t, later, "decrypt", "-in", filepath.Join(fixtures, f.File), "-out", out, "-identity", key, "-relay", relay(t)); err != nil {
		t.Fatalf("%v\n%s", err, stderr)
	}
}

func TestDecryptFailuresLeaveNothing(t *testing.T) {
	dir := t.TempDir()
	b, _ := os.ReadFile(filepath.Join(fixtures, "time_only.dkc"))
	bad := filepath.Join(dir, "bad.dkc")
	b[len(b)-1] ^= 1
	os.WriteFile(bad, b, 0o600)
	out := filepath.Join(dir, "plain")
	_, _, err := cli(t, later, "decrypt", "-in", bad, "-out", out, "-relay", relay(t))
	if !errors.Is(err, datekeys.ErrIntegrity) {
		t.Fatalf("got %v", err)
	}
	if entries, _ := os.ReadDir(dir); len(entries) != 1 {
		t.Fatalf("left files behind: %v", entries)
	}
	// time_and_key without credentials fails before contacting any relay.
	_, _, err = cli(t, later, "decrypt", "-in", filepath.Join(fixtures, "time_and_key_portable.dkc"), "-out", out, "-relay", "http://127.0.0.1:1")
	if !errors.Is(err, datekeys.ErrAccessRequired) {
		t.Fatalf("got %v", err)
	}
}

// Spec §63 step 9.a, §69.1: the CLI hands the .dkk to capsule.Open still
// encoded, so its errors come at step 9 of a time_and_key capsule, after any
// failure of steps 1 to 8, and a time_only capsule ignores it.
func TestDecryptAccessKeyOrder(t *testing.T) {
	dir := t.TempDir()
	notDKK := filepath.Join(dir, "not.dkk")
	os.WriteFile(notDKK, []byte("not a .dkk"), 0o600)
	b, _ := os.ReadFile(filepath.Join(fixtures, "time_and_key_portable.dkc"))
	b[5] = 1
	flags := filepath.Join(dir, "flags.dkc")
	os.WriteFile(flags, b, 0o600)
	for _, tc := range []struct {
		name, in string
		want     error
	}{
		{"time_and_key and bytes that are not a .dkk", filepath.Join(fixtures, "time_and_key_portable.dkc"), datekeys.ErrInvalidMagic},
		{"FLAGS 1 and bytes that are not a .dkk", flags, datekeys.ErrInvalidFlags},
	} {
		_, _, err := cli(t, later, "decrypt", "-in", tc.in, "-out", filepath.Join(dir, "plain"), "-dkk", notDKK, "-relay", "http://127.0.0.1:1")
		if !errors.Is(err, tc.want) {
			t.Errorf("%s: got %v, want %s", tc.name, err, datekeys.Code(tc.want))
		}
	}
	out := filepath.Join(dir, "plain")
	if _, stderr, err := cli(t, later, "decrypt", "-in", filepath.Join(fixtures, "time_only.dkc"), "-out", out, "-dkk", notDKK, "-relay", relay(t)); err != nil {
		t.Fatalf("time_only and bytes that are not a .dkk: %v\n%s", err, stderr)
	}
}

func TestEncryptDecryptRoundTrip(t *testing.T) {
	dir := t.TempDir()
	in := filepath.Join(dir, "secret.txt")
	os.WriteFile(in, []byte("round trip through the CLI"), 0o600)
	p := profile.Quicknet()
	unlock := time.Unix(p.GenesisTime+999*3, 0).UTC() // round 1000
	genesis := time.Unix(p.GenesisTime, 0)
	x, _ := age.GenerateX25519Identity()
	key := filepath.Join(dir, "x.txt")
	os.WriteFile(key, []byte(x.String()+"\n"), 0o600)

	dkc, dkk := filepath.Join(dir, "s.dkc"), filepath.Join(dir, "s.dkk")
	_, stderr, err := cli(t, genesis, "encrypt", "-at", unlock.Format(time.RFC3339), "-in", in, "-out", dkc,
		"-policy", "time_and_key", "-recipient", x.Recipient().String(), "-dkk", dkk)
	if err != nil {
		t.Fatalf("%v\n%s", err, stderr)
	}
	if !strings.Contains(stderr, "round 1000") || strings.Contains(stderr, "not post-quantum") {
		t.Fatalf("unexpected report:\n%s", stderr)
	}
	if _, _, err := cli(t, genesis, "encrypt", "-at", unlock.Format(time.RFC3339), "-in", in, "-out", dkc); err == nil {
		t.Fatal("overwrote an existing capsule")
	}

	stdout, _, err := cli(t, later, "inspect", "-in", dkc, "-json")
	if err != nil {
		t.Fatal(err)
	}
	var v inspectview.View
	if err := json.Unmarshal([]byte(stdout), &v); err != nil || !v.Valid || v.Round != 1000 || v.AccessPolicy != "time_and_key" {
		t.Fatalf("inspect: %+v %v", v, err)
	}
	for i, extra := range [][]string{{"-dkk", dkk}, {"-identity", key}} {
		out := filepath.Join(dir, fmt.Sprintf("out%d", i))
		args := append([]string{"decrypt", "-in", dkc, "-out", out, "-relay", relay(t)}, extra...)
		if _, stderr, err := cli(t, later, args...); err != nil {
			t.Fatalf("%v\n%s", err, stderr)
		}
		if b, _ := os.ReadFile(out); string(b) != "round trip through the CLI" {
			t.Fatal("plaintext differs")
		}
	}
}

func TestInspectReportsFailures(t *testing.T) {
	b, _ := os.ReadFile(filepath.Join(fixtures, "time_only.dkc"))
	b = bytes.Replace(b, []byte("-> tlock 1000 "), []byte("-> tlock 1001 "), 1)
	path := filepath.Join(t.TempDir(), "bad.dkc")
	os.WriteFile(path, b, 0o600)
	stdout, _, err := cli(t, later, "inspect", "-in", path)
	if !errors.Is(err, datekeys.ErrRoundMismatch) || !strings.Contains(stdout, "[FAIL] step  8") {
		t.Fatalf("%v\n%s", err, stdout)
	}
	stdout, _, err = cli(t, later, "inspect", "-in", filepath.Join(fixtures, "time_only.dkc"))
	if err != nil || !strings.Contains(stdout, "valid before unlock") {
		t.Fatalf("%v\n%s", err, stdout)
	}
}

// The frozen inspect outputs (testdata/fixtures/<name>.inspect.json) are
// exactly what "datekeys inspect -json -in <name>.dkc" prints in the fixture
// directory.
func TestInspectJSONGoldens(t *testing.T) {
	names, err := filepath.Glob(filepath.Join(fixtures, "*.inspect.json"))
	if err != nil {
		t.Fatal(err)
	}
	if len(names) != 5 {
		t.Fatalf("%d frozen inspect outputs, want one per official .dkc (5)", len(names))
	}
	t.Chdir(fixtures)
	for _, path := range names {
		name := strings.TrimSuffix(filepath.Base(path), ".inspect.json")
		t.Run(name, func(t *testing.T) {
			want, err := os.ReadFile(name + ".inspect.json")
			if err != nil {
				t.Fatal(err)
			}
			stdout, _, err := cli(t, later, "inspect", "-json", "-in", name+".dkc")
			if err != nil {
				t.Fatal(err)
			}
			if stdout != string(want) {
				t.Fatalf("output differs from %s.inspect.json:\n%s", name, stdout)
			}
		})
	}
}

func TestResolveAndProfile(t *testing.T) {
	stdout, _, err := cli(t, later, "datekey", "resolve", "-at", "2030-01-01T00:00:00Z")
	if err != nil || !strings.Contains(stdout, `"round":66884212`) || !strings.Contains(stdout, `"unlock_at":"2030-01-01T00:00:00Z"`) {
		t.Fatalf("%v %s", err, stdout)
	}
	if _, _, err := cli(t, later, "datekey", "resolve", "-at", "2030-01-01 00:00"); err == nil {
		t.Fatal("accepted a time without zone")
	}
	stdout, _, err = cli(t, later, "profile", "hash")
	if err != nil || !strings.Contains(stdout, profile.QuicknetProfileHash) || !strings.Contains(stdout, `"pinned":true`) {
		t.Fatalf("%v %s", err, stdout)
	}
	b, _ := profile.Quicknet().CanonicalCBOR()
	path := filepath.Join(t.TempDir(), "q.cbor")
	os.WriteFile(path, b, 0o600)
	if stdout, _, err = cli(t, later, "profile", "hash", "-in", path); err != nil || !strings.Contains(stdout, profile.QuicknetProfileHash) {
		t.Fatalf("%v %s", err, stdout)
	}
}

func TestUsage(t *testing.T) {
	for _, args := range [][]string{nil, {"nope"}, {"datekey"}, {"profile", "x"}, {"encrypt", "-bogus"}, {"inspect", "extra"}, {"version", "extra"}} {
		if _, _, err := cli(t, later, args...); err == nil {
			t.Errorf("%v accepted", args)
		}
	}
}

// The version command names the module version, the specification and the
// toolchain; in a test the module version is unknown.
func TestVersion(t *testing.T) {
	for _, arg := range []string{"version", "-version", "--version"} {
		out, _, err := cli(t, later, arg)
		if err != nil {
			t.Fatal(err)
		}
		want := "datekeys " + datekeys.Version() + "\nspecification " + datekeys.SpecVersion + "\n" + runtime.Version() + " " + runtime.GOOS + "/" + runtime.GOARCH + "\n"
		if out != want {
			t.Errorf("%s: %q, want %q", arg, out, want)
		}
	}
	if !strings.Contains(usage, "datekeys version") {
		t.Error("the usage does not list the version command")
	}
}

// Spec §53: long horizons get the harvest-now, decrypt-later warning.
func TestLongHorizonWarning(t *testing.T) {
	dir := t.TempDir()
	in := filepath.Join(dir, "in")
	os.WriteFile(in, []byte("x"), 0o600)
	for i, tc := range []struct {
		after time.Duration
		warn  bool
	}{{time.Hour, false}, {2 * 365 * 24 * time.Hour, true}} {
		out := filepath.Join(dir, fmt.Sprintf("%d.dkc", i))
		_, stderr, err := cli(t, later, "encrypt", "-at", later.Add(tc.after).Format(time.RFC3339), "-in", in, "-out", out)
		if err != nil || strings.Contains(stderr, "not post-quantum") != tc.warn {
			t.Fatalf("%s: %v: %s", tc.after, err, stderr)
		}
	}
}