package claudewatcher

import (
	"context"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"

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

// recordingHandler captures log records so a test can assert that a file was
// never even attempted — the absence of a read error is the evidence.
type recordingHandler struct {
	mu      sync.Mutex
	records []string
}

func (h *recordingHandler) Enabled(context.Context, slog.Level) bool { return true }

func (h *recordingHandler) Handle(_ context.Context, r slog.Record) error {
	h.mu.Lock()
	defer h.mu.Unlock()
	var sb strings.Builder
	sb.WriteString(r.Message)
	r.Attrs(func(a slog.Attr) bool {
		sb.WriteString(" " + a.Key + "=" + a.Value.String())
		return true
	})
	h.records = append(h.records, sb.String())
	return nil
}

func (h *recordingHandler) WithAttrs([]slog.Attr) slog.Handler { return h }
func (h *recordingHandler) WithGroup(string) slog.Handler      { return h }

func (h *recordingHandler) contains(substr string) bool {
	h.mu.Lock()
	defer h.mu.Unlock()
	for _, r := range h.records {
		if strings.Contains(r, substr) {
			return true
		}
	}
	return false
}

func session(t *testing.T, root, project, id string) string {
	t.Helper()
	dir := filepath.Join(root, project)
	require.NoError(t, os.MkdirAll(dir, 0o755))
	return writeSession(t, dir, id, []string{
		`{"type":"user","sessionId":"` + id + `","message":"a prompt"}`,
		`{"type":"assistant","sessionId":"` + id + `","message":{"content":[{"type":"text","text":"an answer"}]}}`,
	})
}

// A named project is not ingested, and its neighbours still are.
func TestSkipProjects_skipsTheNamedProjectOnly(t *testing.T) {
	tmp := t.TempDir()
	session(t, tmp, "-home-mathias-dev-AGENTS-cobalt-dingo", "skipped")
	session(t, tmp, "-home-mathias-dev", "kept")

	sink := &memSink{}
	require.NoError(t, TickOnce(context.Background(), Config{
		SessionsDir:  tmp,
		Host:         "koala",
		Sink:         sink,
		SkipProjects: []string{"-home-mathias-dev-AGENTS-cobalt-dingo"},
	}))

	require.Len(t, sink.batches, 1)
	assert.Equal(t, "kept", sink.batches[0].SessionID)
	assert.Equal(t, "-home-mathias-dev", sink.batches[0].ProjectID)
}

// Globs are necessary, not a convenience. A project directory is derived from
// the session's WORKING DIRECTORY, so a git worktree produces an ephemeral
// name like "-home-mathias-dev--claude-worktrees-bridge-cse-017xoC...". An
// exact-match list could never keep up with those.
func TestSkipProjects_globMatchesEphemeralWorktreeNames(t *testing.T) {
	tmp := t.TempDir()
	session(t, tmp, "-home-mathias-dev--claude-worktrees-bridge-cse-017xoCEcrc35", "worktree")
	session(t, tmp, "-home-mathias-dev", "kept")

	sink := &memSink{}
	require.NoError(t, TickOnce(context.Background(), Config{
		SessionsDir:  tmp,
		Host:         "koala",
		Sink:         sink,
		SkipProjects: []string{"*claude-worktrees-bridge-cse*"},
	}))

	require.Len(t, sink.batches, 1)
	assert.Equal(t, "kept", sink.batches[0].SessionID)
}

// The point of skipping at the directory walk: the file is never OPENED, so
// its content never enters this process. Proven by making it unreadable — a
// skipped file produces no read error because nothing tried to read it, while
// the same file in a non-skipped project does.
func TestSkipProjects_theFileIsNeverOpened(t *testing.T) {
	tmp := t.TempDir()
	path := session(t, tmp, "-home-mathias-dev-AGENTS-cobalt-dingo", "unreadable")
	require.NoError(t, os.Chmod(path, 0o000))
	t.Cleanup(func() { _ = os.Chmod(path, 0o644) })

	rec := &recordingHandler{}
	sink := &memSink{}
	require.NoError(t, TickOnce(context.Background(), Config{
		SessionsDir:  tmp,
		Host:         "koala",
		Sink:         sink,
		Logger:       slog.New(rec),
		SkipProjects: []string{"*cobalt-dingo*"},
	}))

	assert.Empty(t, sink.batches)
	assert.False(t, rec.contains("file failed"),
		"a skipped file must not even be attempted")
}

// The control test for the one above: without the skip, the unreadable file IS
// attempted and fails. Otherwise the assertion above could pass for the wrong
// reason.
func TestSkipProjects_withoutTheSkipTheSameFileIsAttempted(t *testing.T) {
	tmp := t.TempDir()
	path := session(t, tmp, "-home-mathias-dev-AGENTS-cobalt-dingo", "unreadable")
	require.NoError(t, os.Chmod(path, 0o000))
	t.Cleanup(func() { _ = os.Chmod(path, 0o644) })

	rec := &recordingHandler{}
	require.NoError(t, TickOnce(context.Background(), Config{
		SessionsDir: tmp,
		Host:        "koala",
		Sink:        &memSink{},
		Logger:      slog.New(rec),
	}))

	assert.True(t, rec.contains("file failed"),
		"the unreadable file must fail when not skipped — otherwise the skip test proves nothing")
}

// Patterns match the project directory NAME, not the whole path. A temp
// directory or a home directory component must not accidentally match and
// silently disable ingestion.
func TestSkipProjects_matchesTheProjectNameNotTheFullPath(t *testing.T) {
	tmp := t.TempDir()
	session(t, tmp, "-home-mathias-dev", "kept")

	sink := &memSink{}
	require.NoError(t, TickOnce(context.Background(), Config{
		SessionsDir: tmp,
		Host:        "koala",
		Sink:        sink,
		// tmp is somewhere under /tmp; this must not match the project name.
		SkipProjects: []string{"*tmp*"},
	}))

	require.Len(t, sink.batches, 1, "a path component outside the project name must not match")
}

// An unparseable pattern must stop the watcher rather than be ignored. A
// silently dropped skip rule means ingesting what was meant to be excluded,
// which is the failure that cannot be noticed after the fact.
func TestSkipProjects_invalidPatternRefusesToRun(t *testing.T) {
	tmp := t.TempDir()
	session(t, tmp, "-home-mathias-dev", "kept")

	sink := &memSink{}
	err := TickOnce(context.Background(), Config{
		SessionsDir:  tmp,
		Host:         "koala",
		Sink:         sink,
		SkipProjects: []string{"[unclosed"},
	})

	require.Error(t, err)
	assert.Contains(t, err.Error(), "[unclosed")
	assert.Empty(t, sink.batches, "nothing may be ingested while a skip rule is broken")
}

func TestSkipProjects_emptyListChangesNothing(t *testing.T) {
	tmp := t.TempDir()
	session(t, tmp, "-home-mathias-dev", "kept")

	sink := &memSink{}
	require.NoError(t, TickOnce(context.Background(), Config{
		SessionsDir: tmp, Host: "koala", Sink: sink, SkipProjects: nil,
	}))

	require.Len(t, sink.batches, 1)
}

// The difference between SkipDir and filtering after the walk, made
// observable: an unreadable skipped directory must not disturb anything.
//
// Without SkipDir, WalkDir reads the directory's entries, gets a permission
// error, and that error aborts the ENTIRE walk — so one skipped project with
// awkward permissions would silently stop ingesting every other project.
// Returning SkipDir means its contents are never listed at all.
//
// Added after a mutation test showed the earlier assertions could not tell the
// two implementations apart.
func TestSkipProjects_anUnreadableSkippedDirDoesNotBreakTheWalk(t *testing.T) {
	tmp := t.TempDir()
	session(t, tmp, "-home-mathias-dev", "kept")

	blocked := filepath.Join(tmp, "-home-mathias-dev-AGENTS-cobalt-dingo")
	require.NoError(t, os.MkdirAll(blocked, 0o755))
	_ = writeSession(t, blocked, "secret", []string{
		`{"type":"user","sessionId":"secret","message":"should never be read"}`,
	})
	require.NoError(t, os.Chmod(blocked, 0o000))
	t.Cleanup(func() { _ = os.Chmod(blocked, 0o755) })

	sink := &memSink{}
	require.NoError(t, TickOnce(context.Background(), Config{
		SessionsDir:  tmp,
		Host:         "koala",
		Sink:         sink,
		SkipProjects: []string{"*cobalt-dingo*"},
	}))

	require.Len(t, sink.batches, 1, "an unreadable skipped directory must not abort the walk")
	assert.Equal(t, "kept", sink.batches[0].SessionID)
}