package cli //nolint:testpackage // needs access to unexported emitStartupBanner

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/adrg/xdg"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// Command words and flags used to build argument vectors below. They are
// constants rather than repeated literals so that a rename shows up as a
// compile error in one place.
const (
	cmdSnapshot = "snapshot"
	cmdList     = "list"
	cmdCreate   = "create"
	cmdVerify   = "verify"
	cmdRemove   = "remove"
	cmdPrune    = "prune"
	cmdRemote   = "remote"
	cmdInfo     = "info"

	flagJSON  = "--json"
	flagQuiet = "--quiet"

	// someSnapshotID is any snapshot identifier: these tests never run
	// the command, so it only has to occupy the positional argument.
	someSnapshotID = "host_2026-01-01T00:00:00Z"
)

// placeholderJSONDocument stands in for whatever document a --json
// command writes to stdout. `snapshot list --json` with no snapshots
// prints exactly this; the other --json commands print an object rather
// than an array, but this test is not about their shape. It is about
// what is on stdout *before* them, which is the same for all of them
// because Entry prints the banner before cobra has parsed anything and
// therefore before it can know which command is running.
const placeholderJSONDocument = "[]\n"

// jsonArgumentVectors are the argument vectors of every --json
// invocation the CLI accepts, with the program name stripped exactly as
// Entry strips it. Each one must leave stdout untouched by the banner.
//
//nolint:gochecknoglobals // read-only test fixture shared by two tests
var jsonArgumentVectors = map[string][]string{
	"snapshot list":   {cmdSnapshot, cmdList, flagJSON},
	"snapshot verify": {cmdSnapshot, cmdVerify, someSnapshotID, flagJSON},
	"snapshot remove": {cmdSnapshot, cmdRemove, someSnapshotID, flagJSON},
	"prune":           {cmdPrune, flagJSON},
	"remote info":     {cmdRemote, cmdInfo, flagJSON},

	// --json before the subcommand, and with an explicit value: the
	// scan is positional, so both forms have to be recognized.
	"json first":      {flagJSON, cmdSnapshot, cmdList},
	"json with value": {cmdSnapshot, cmdList, flagJSON + "=true"},

	// A --json invocation that also carries a flag with a value, so the
	// scan cannot be fooled by an argument that consumes the next one.
	"json with config": {
		"--config", "/nonexistent/vaultik.yml", cmdSnapshot, cmdList, flagJSON,
	},
}

// TestJSONInvocationStdoutIsExactlyOneDocument is the CLI-layer
// regression guard for issue #106: `vaultik snapshot list --json | jq`
// must work with no other flags.
//
// internal/vaultik's TestListSnapshots_JSONStdoutIsOnlyTheDocument
// guards the same contract one layer down, but it calls the library
// function directly and so cannot see Entry, which is where the
// contamination was: the startup banner is written to stdout before
// cobra parses anything, and the suppression scan did not know about
// --json. The two banner lines and the blank line landed ahead of the
// document and `jq` refused the result.
//
// The document is a constant here because this test is about the
// argument vectors, one per --json command; the one that runs a real
// command end to end is TestEntryJSONStdoutIsExactlyOneDocument below.
func TestJSONInvocationStdoutIsExactlyOneDocument(t *testing.T) {
	t.Parallel()

	for name, argv := range jsonArgumentVectors {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			var stdout bytes.Buffer

			emitStartupBanner(argv, &stdout)

			require.Empty(t, stdout.String(),
				"nothing may reach stdout ahead of a --json document")

			_, err := stdout.WriteString(placeholderJSONDocument)
			require.NoError(t, err)

			requireExactlyOneJSONDocument(t, stdout.String())
		})
	}
}

// TestBannerStillPrintedWithoutSuppressingFlag pins the other half of
// the contract. Without it, deleting the banner outright would satisfy
// the test above, and the banner is wanted on interactive invocations.
func TestBannerStillPrintedWithoutSuppressingFlag(t *testing.T) {
	t.Parallel()

	for name, argv := range map[string][]string{
		"no flags": {cmdSnapshot, cmdList},
		"verbose":  {cmdSnapshot, cmdList, "--verbose"},
		"after the terminator": {
			cmdSnapshot, "restore", "--", flagJSON,
		},
	} {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			var stdout bytes.Buffer

			emitStartupBanner(argv, &stdout)

			assert.Contains(t, stdout.String(), "starting up at",
				"the banner belongs on invocations that did not opt out")
		})
	}
}

// TestBannerSuppressedInArgs covers the suppression scan directly,
// including the flags that suppressed the banner before --json joined
// them, so that adding --json cannot regress them.
func TestBannerSuppressedInArgs(t *testing.T) {
	t.Parallel()

	for name, testCase := range map[string]struct {
		args       []string
		suppressed bool
	}{
		"quiet long":     {[]string{cmdSnapshot, cmdCreate, flagQuiet}, true},
		"quiet short":    {[]string{cmdSnapshot, cmdCreate, "-q"}, true},
		"quiet combined": {[]string{cmdSnapshot, cmdCreate, "-qv"}, true},
		"cron":           {[]string{cmdSnapshot, cmdCreate, "--cron"}, true},
		"json":           {[]string{cmdSnapshot, cmdList, flagJSON}, true},
		"nothing":        {[]string{cmdSnapshot, cmdList}, false},
		"empty":          {nil, false},
		"json after dashes": {
			[]string{cmdSnapshot, cmdList, "--", flagJSON}, false,
		},
		"quiet after dashes": {
			[]string{cmdSnapshot, cmdCreate, "--", "-q"}, false,
		},
	} {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			assert.Equal(t, testCase.suppressed,
				bannerSuppressedInArgs(testCase.args))
		})
	}
}

// hermeticConfig is a complete, valid config that needs no network and
// no credentials: file:// storage is exempt from the S3 credential
// checks, and FileStorer over a directory that does not exist lists
// zero objects without erroring. Chunk, blob and compression settings
// are filled in by config.Load.
const hermeticConfig = `age_recipients:
  - age1278m9q7dp3chsh2dcy82qk27v047zywyvtxwnj4cvt0z65jw6a7q5dqhfj
snapshots:
  test:
    paths:
      - %s
storage_url: file://%s
index_path: %s
hostname: test-host
`

// TestEntryJSONStdoutIsExactlyOneDocument runs the real thing: Entry,
// with a real argument vector, over the process's real stdout file
// descriptor, all the way through cobra and the fx graph to the
// document. It is the assertion the issue asks for — `vaultik snapshot
// list --json | jq .` with no other flags — with the pipe replaced by a
// decoder.
//
// `snapshot list` is the command chosen because it is the only --json
// command that reaches its document without a populated destination
// store: it reads the local index, streams `metadata/` (empty here),
// and treats a barren destination as an empty list rather than a
// failure.
//
// Not parallel: it replaces os.Args, os.Stdout and the xdg globals.
func TestEntryJSONStdoutIsExactlyOneDocument(t *testing.T) {
	dir := t.TempDir()
	configPath := filepath.Join(dir, "config.yml")

	contents := fmt.Sprintf(hermeticConfig,
		filepath.Join(dir, "source"),
		filepath.Join(dir, "store"),
		filepath.Join(dir, "index.sqlite"))

	require.NoError(t,
		os.WriteFile(configPath, []byte(contents), configFileMode))

	// The PID lock lives under xdg.DataHome, which xdg resolves at
	// package init; point it at the temp dir so the test neither
	// touches nor collides with the real one.
	t.Setenv("XDG_DATA_HOME", filepath.Join(dir, "data"))
	xdg.Reload()
	t.Cleanup(xdg.Reload)

	previousArgs := os.Args

	t.Cleanup(func() {
		os.Args = previousArgs
		rootFlags = RootFlags{}
	})

	os.Args = []string{
		"vaultik", "--config", configPath, cmdSnapshot, cmdList, flagJSON,
	}

	stdout := captureProcessStdout(t, Entry)

	requireExactlyOneJSONDocument(t, stdout)

	var snapshots []any

	require.NoError(t, json.Unmarshal([]byte(stdout), &snapshots))
	assert.Empty(t, snapshots,
		"a destination store with no snapshots lists none")
}

// captureProcessStdout redirects the process's own stdout to a pipe for
// the duration of fn and returns what was written to it. The redirection
// has to be at the file-descriptor level rather than through an injected
// writer, because the banner and the JSON encoder reach os.Stdout
// independently and the point of the test is that both land in the same
// place.
//
// Not parallel-safe: os.Stdout is process-global.
func captureProcessStdout(t *testing.T, fn func()) string {
	t.Helper()

	reader, writer, err := os.Pipe()
	require.NoError(t, err)

	previous := os.Stdout
	os.Stdout = writer

	captured := make(chan string, 1)

	go func() {
		var buf bytes.Buffer

		_, _ = io.Copy(&buf, reader)
		captured <- buf.String()
	}()

	fn()

	os.Stdout = previous

	require.NoError(t, writer.Close())

	out := <-captured

	require.NoError(t, reader.Close())

	return out
}

// requireExactlyOneJSONDocument fails unless stdout decodes as a single
// JSON value with nothing before or after it — the property that makes
// `| jq` work.
func requireExactlyOneJSONDocument(t *testing.T, stdout string) {
	t.Helper()

	decoder := json.NewDecoder(strings.NewReader(stdout))

	var document any

	err := decoder.Decode(&document)
	require.NoError(t, err,
		"stdout must parse as JSON, got:\n%s", stdout)

	_, err = decoder.Token()
	require.ErrorIs(t, err, io.EOF,
		"stdout must hold exactly one JSON document, got:\n%s", stdout)
}