package process

import (
	"context"
	"os"
	"os/exec"
	"path/filepath"
	"testing"

	"github.com/kandev/kandev/internal/agentctl/server/config"
	"github.com/kandev/kandev/internal/agentctl/types"
	"github.com/kandev/kandev/internal/agentctl/types/streams"
	"github.com/kandev/kandev/internal/common/logger"
)

// TestRescanRepositories_TransitionsSingleToMultiRepo simulates the
// MCP add_branch flow: the agent launched as single-repo with WorkDir set
// to the primary worktree, then a sibling worktree appears at the task
// root. After RescanRepositories the manager must hold one bare root
// tracker + one per-repo tracker for each child.
func TestRescanRepositories_TransitionsSingleToMultiRepo(t *testing.T) {
	taskRoot := t.TempDir()
	primary := filepath.Join(taskRoot, "kandev")
	sibling := filepath.Join(taskRoot, "kandev-feature-x")
	initGitRepoAt(t, primary)
	initGitRepoAt(t, sibling)

	log, _ := logger.NewLogger(logger.LoggingConfig{Level: "error", Format: "json"})
	cfg := &config.InstanceConfig{WorkDir: primary}
	m := NewManager(cfg, log)

	if len(m.repoTrackers) != 0 {
		t.Fatalf("expected 0 repoTrackers in single-repo mode, got %d", len(m.repoTrackers))
	}

	m.RescanRepositories(context.Background(), taskRoot)

	if len(m.repoTrackers) != 2 {
		t.Fatalf("expected 2 repoTrackers after transition, got %d", len(m.repoTrackers))
	}
	names := map[string]bool{}
	for _, tr := range m.repoTrackers {
		names[tr.RepositoryName()] = true
	}
	if !names["kandev"] || !names["kandev-feature-x"] {
		t.Errorf("expected trackers for kandev + kandev-feature-x, got %v", names)
	}
	if m.cfg.WorkDir != taskRoot {
		t.Errorf("cfg.WorkDir = %q, want %q", m.cfg.WorkDir, taskRoot)
	}
	// Stop trackers so the goroutines don't outlive the test (parent
	// TestMain's goleak check would otherwise flag them).
	m.stopWorkspaceTrackers()
}

// TestRescanRepositories_AppendsNewRepoTrackerInMultiRepoMode covers the
// already-multi case: an extra sibling appears, the existing trackers
// remain, a new tracker is added for the new sibling.
func TestRescanRepositories_AppendsNewRepoTrackerInMultiRepoMode(t *testing.T) {
	taskRoot := t.TempDir()
	repoA := filepath.Join(taskRoot, "alpha")
	repoB := filepath.Join(taskRoot, "beta")
	initGitRepoAt(t, repoA)
	initGitRepoAt(t, repoB)

	log, _ := logger.NewLogger(logger.LoggingConfig{Level: "error", Format: "json"})
	cfg := &config.InstanceConfig{WorkDir: taskRoot}
	m := NewManager(cfg, log)

	if len(m.repoTrackers) != 2 {
		t.Fatalf("expected 2 repoTrackers from construct-time scan, got %d", len(m.repoTrackers))
	}

	// New sibling added after launch (e.g. via add_branch).
	repoC := filepath.Join(taskRoot, "gamma")
	initGitRepoAt(t, repoC)

	m.RescanRepositories(context.Background(), taskRoot)

	if len(m.repoTrackers) != 3 {
		t.Fatalf("expected 3 repoTrackers after append, got %d", len(m.repoTrackers))
	}
	names := map[string]bool{}
	for _, tr := range m.repoTrackers {
		names[tr.RepositoryName()] = true
	}
	for _, expected := range []string{"alpha", "beta", "gamma"} {
		if !names[expected] {
			t.Errorf("missing tracker for %q (got %v)", expected, names)
		}
	}
	m.stopWorkspaceTrackers()
}

// TestRescanRepositories_FileTreeReturnsTaskRootContentsAfterTransition
// covers the Files panel surface: after rescan flips a single-branch
// workspace to multi-repo mode, GetWorkspaceTracker().GetFileTree("", n)
// must list the sibling repo dirs (kandev/, kandev-feature-x/) instead of
// the contents of the original primary worktree. This is the bug the user
// hit where the Files panel still rendered .agents/.claude/apps/... from
// inside the primary worktree even though the task had become multi-branch.
func TestRescanRepositories_FileTreeReturnsTaskRootContentsAfterTransition(t *testing.T) {
	taskRoot := t.TempDir()
	primary := filepath.Join(taskRoot, "kandev")
	sibling := filepath.Join(taskRoot, "kandev-feature-x")
	initGitRepoAt(t, primary)
	initGitRepoAt(t, sibling)
	// Seed each worktree with a "marker" file so we can tell which one a
	// file-tree response is rooted at.
	if err := os.WriteFile(filepath.Join(primary, "primary-marker.txt"), []byte("p"), 0o644); err != nil {
		t.Fatalf("write primary marker: %v", err)
	}
	if err := os.WriteFile(filepath.Join(sibling, "sibling-marker.txt"), []byte("s"), 0o644); err != nil {
		t.Fatalf("write sibling marker: %v", err)
	}

	log, _ := logger.NewLogger(logger.LoggingConfig{Level: "error", Format: "json"})
	cfg := &config.InstanceConfig{WorkDir: primary}
	m := NewManager(cfg, log)
	defer m.stopWorkspaceTrackers()

	// Pre-rescan: workspaceTracker is bound to the primary, so the file
	// tree must include the primary's marker (and NOT the sibling's).
	preTree, err := m.workspaceTracker.GetFileTree("", 1)
	if err != nil {
		t.Fatalf("pre-rescan GetFileTree: %v", err)
	}
	preNames := fileTreeChildNames(preTree)
	if !preNames["primary-marker.txt"] {
		t.Errorf("pre-rescan tree missing primary marker: %v", preNames)
	}
	if preNames["sibling-marker.txt"] {
		t.Errorf("pre-rescan tree should not contain sibling marker yet: %v", preNames)
	}

	m.RescanRepositories(context.Background(), taskRoot)

	postTree, err := m.workspaceTracker.GetFileTree("", 1)
	if err != nil {
		t.Fatalf("post-rescan GetFileTree: %v", err)
	}
	postNames := fileTreeChildNames(postTree)
	if !postNames["kandev"] || !postNames["kandev-feature-x"] {
		t.Errorf("post-rescan tree should list sibling repo dirs, got %v", postNames)
	}
	if postNames["primary-marker.txt"] {
		t.Errorf("post-rescan tree should not include primary's inner files at root: %v", postNames)
	}
}

// fileTreeChildNames returns the set of top-level child names from a
// FileTreeNode. Returns an empty map for nil / leaf nodes so the caller can
// just index without nil checks.
func fileTreeChildNames(n *streams.FileTreeNode) map[string]bool {
	out := map[string]bool{}
	if n == nil {
		return out
	}
	for _, c := range n.Children {
		out[c.Name] = true
	}
	return out
}

// TestRescanRepositories_PropagatesSubscriberToNewTrackers locks in the
// subscriber-list invariant: any workspace-stream subscriber attached
// BEFORE the rescan must remain attached to the resulting tracker set so
// the Changes panel receives events from newly-discovered repos. Without
// this, the single→multi transition would silently drop the existing
// gateway subscriber when it stops the old workspaceTracker, and the UI
// would go quiet.
func TestRescanRepositories_PropagatesSubscriberToNewTrackers(t *testing.T) {
	taskRoot := t.TempDir()
	primary := filepath.Join(taskRoot, "kandev")
	sibling := filepath.Join(taskRoot, "kandev-branch-2")
	initGitRepoAt(t, primary)
	initGitRepoAt(t, sibling)

	log, _ := logger.NewLogger(logger.LoggingConfig{Level: "error", Format: "json"})
	cfg := &config.InstanceConfig{WorkDir: primary}
	m := NewManager(cfg, log)
	defer m.stopWorkspaceTrackers()

	sub := m.SubscribeWorkspaceStream()
	defer m.UnsubscribeWorkspaceStream(sub)
	// Drain the initial replay so the channel doesn't carry stale state
	// into our post-rescan assertions.
	drainChannel(sub)

	m.RescanRepositories(context.Background(), taskRoot)

	// After transition, every active tracker must hold the subscriber:
	// bare root + 2 per-repo trackers = 3 attach references. The exported
	// surface doesn't expose subscriber count directly, so we verify by
	// inspecting the trackers' internal subscriber maps via the same
	// concurrency primitives the tracker uses (read lock).
	checkTrackerHasSub := func(name string, tr *WorkspaceTracker) {
		tr.workspaceSubMu.RLock()
		defer tr.workspaceSubMu.RUnlock()
		if _, ok := tr.workspaceStreamSubscribers[sub]; !ok {
			t.Errorf("subscriber missing from %q tracker after rescan", name)
		}
	}
	checkTrackerHasSub("workspaceTracker (bare root)", m.workspaceTracker)
	for _, tr := range m.repoTrackers {
		checkTrackerHasSub("repoTracker "+tr.RepositoryName(), tr)
	}
}

// drainChannel non-blocking-empties a workspace-stream subscriber so test
// assertions about post-rescan messages aren't muddied by initial replays.
func drainChannel(ch types.WorkspaceStreamSubscriber) {
	for {
		select {
		case <-ch:
		default:
			return
		}
	}
}

// initGitRepoAt creates a git repo at dir with one commit so
// scanRepositorySubdirs (which gates on a valid `.git/index` file)
// recognizes it. git init alone leaves the index missing until the first
// add/commit.
func initGitRepoAt(t *testing.T, dir string) {
	t.Helper()
	if err := os.MkdirAll(dir, 0o755); err != nil {
		t.Fatalf("mkdir %s: %v", dir, err)
	}
	runIn := func(name string, args ...string) {
		cmd := exec.Command(name, args...)
		cmd.Dir = dir
		if out, err := cmd.CombinedOutput(); err != nil {
			t.Fatalf("%s %v in %s: %v\n%s", name, args, dir, err, out)
		}
	}
	runIn("git", "init", "-b", "main")
	runIn("git", "config", "user.email", "test@example.com")
	runIn("git", "config", "user.name", "Test User")
	runIn("git", "config", "commit.gpgsign", "false")
	runIn("git", "commit", "--allow-empty", "-m", "initial")
}