package admin

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"

	"thehouseoficarus/internal/world"
)

// newTestAdminServer builds an AdminServer wired to a temp data dir containing
// the given room bodies (map of id -> YAML body), with a live World, MobStore,
// and UndoStack. Only the fields the insert/remove handlers touch are set.
func newTestAdminServer(t *testing.T, rooms map[int]string) *AdminServer {
	t.Helper()
	dir := t.TempDir()
	roomsDir := filepath.Join(dir, "rooms")
	if err := os.MkdirAll(roomsDir, 0o755); err != nil {
		t.Fatal(err)
	}
	for id, body := range rooms {
		if err := os.WriteFile(filepath.Join(roomsDir, strconv.Itoa(id)+".yaml"), []byte(body), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	return &AdminServer{
		world:    world.New(dir),
		mobStore: world.NewMobStore(dir),
		dataDir:  dir,
		undoStack: NewUndoStack(dir),
	}
}

func writeRoomFile(t *testing.T, dir string, id int, body string) {
	t.Helper()
	roomsDir := filepath.Join(dir, "rooms")
	if err := os.MkdirAll(roomsDir, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(roomsDir, strconv.Itoa(id)+".yaml"), []byte(body), 0o644); err != nil {
		t.Fatal(err)
	}
}

func roomExists(s *AdminServer, id int) bool {
	_, err := s.world.LoadRoom(id)
	return err == nil
}

func roomExitTarget(s *AdminServer, id int, dir world.ExitDir) (int, bool) {
	r, err := s.world.LoadRoom(id)
	if err != nil {
		return 0, false
	}
	e, ok := r.Exits[dir]
	if !ok {
		return 0, false
	}
	return e.Room, true
}

// postInsert drives the insert endpoint with the given body and returns the
// decoded response alongside the response status code.
func postInsert(t *testing.T, s *AdminServer, body string) (map[string]any, int) {
	t.Helper()
	req := httptest.NewRequest(http.MethodPost, "/api/rooms/insert", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()
	s.handleRoomInsert(rr, req)
	var resp map[string]any
	_ = json.Unmarshal(rr.Body.Bytes(), &resp)
	return resp, rr.Code
}

func postRemove(t *testing.T, s *AdminServer, body string) (map[string]any, int) {
	t.Helper()
	req := httptest.NewRequest(http.MethodPost, "/api/rooms/remove", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()
	s.handleRoomRemove(rr, req)
	var resp map[string]any
	_ = json.Unmarshal(rr.Body.Bytes(), &resp)
	return resp, rr.Code
}

// TestInsertSuccess verifies a clean two-way insert creates the new room,
// rewires A and B onto it, and pushes an undo entry that restores everything.
func TestInsertSuccess(t *testing.T) {
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n",
		2: "name: B\nexits:\n  west: 1\n",
	})

	resp, code := postInsert(t, s, `{"from":1,"dir":"east","name":"Mid"}`)
	if code != http.StatusOK {
		t.Fatalf("insert: expected 200, got %d: %v", code, resp)
	}
	room := resp["room"].(map[string]any)
	newID := int(room["id"].(float64))
	if room["name"] != "Mid" {
		t.Errorf("insert: expected name Mid, got %v", room["name"])
	}

	// A→east→new, new→east→2, new→west→1, B→west→new.
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != newID {
		t.Errorf("A east: expected %d, got %d", newID, tgt)
	}
	if tgt, _ := roomExitTarget(s, newID, world.East); tgt != 2 {
		t.Errorf("new east: expected 2, got %d", tgt)
	}
	if tgt, _ := roomExitTarget(s, newID, world.West); tgt != 1 {
		t.Errorf("new west: expected 1, got %d", tgt)
	}
	if tgt, _ := roomExitTarget(s, 2, world.West); tgt != newID {
		t.Errorf("B west: expected %d, got %d", newID, tgt)
	}

	// Undo restores the original two-room world.
	change := s.undoStack.Undo()
	if change == nil {
		t.Fatal("undo: expected a change, got nil")
	}
	s.rebuildAfterUndo(change)
	if roomExists(s, newID) {
		t.Error("undo: new room file should be gone")
	}
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != 2 {
		t.Errorf("undo: A east should be 2, got %d", tgt)
	}
	if tgt, _ := roomExitTarget(s, 2, world.West); tgt != 1 {
		t.Errorf("undo: B west should be 1, got %d", tgt)
	}

	// Redo re-applies the insert.
	redoChange := s.undoStack.Redo()
	if redoChange == nil {
		t.Fatal("redo: expected a change, got nil")
	}
	s.rebuildAfterUndo(redoChange)
	if !roomExists(s, newID) {
		t.Error("redo: new room file should be back")
	}
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != newID {
		t.Errorf("redo: A east should be %d, got %d", newID, tgt)
	}
	if tgt, _ := roomExitTarget(s, 2, world.West); tgt != newID {
		t.Errorf("redo: B west should be %d, got %d", newID, tgt)
	}
}

// TestInsertDefaultName confirms an empty name falls back to "New Room".
func TestInsertDefaultName(t *testing.T) {
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n",
		2: "name: B\nexits:\n  west: 1\n",
	})
	resp, code := postInsert(t, s, `{"from":1,"dir":"east","name":""}`)
	if code != http.StatusOK {
		t.Fatalf("insert: expected 200, got %d: %v", code, resp)
	}
	if resp["room"].(map[string]any)["name"] != "New Room" {
		t.Errorf("insert: expected default name 'New Room', got %v", resp["room"].(map[string]any)["name"])
	}
}

// TestInsertGridConflict verifies a conflicting insert returns 409 with a
// human-readable message (not raw JSON, not the old generic string).
func TestInsertGridConflict(t *testing.T) {
	// 1→east→2→east→3 and 1→south→4→east→5→east→6→east→7→north→8 at (3,0,0).
	// Inserting between 1 and 2 pushes 3 to (3,0,0), colliding with 8.
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n  south: 4\n",
		2: "name: B\nexits:\n  east: 3\n  west: 1\n",
		3: "name: C\nexits:\n  west: 2\n",
		4: "name: D\nexits:\n  east: 5\n  north: 1\n",
		5: "name: E\nexits:\n  east: 6\n  west: 4\n",
		6: "name: F\nexits:\n  east: 7\n  west: 5\n",
		7: "name: G\nexits:\n  north: 8\n  west: 6\n",
		8: "name: H\nexits:\n  south: 7\n",
	})
	resp, code := postInsert(t, s, `{"from":1,"dir":"east","name":"X"}`)
	if code != http.StatusConflict {
		t.Fatalf("insert conflict: expected 409, got %d: %v", code, resp)
	}
	msg, _ := resp["error"].(string)
	if !strings.Contains(msg, "cannot insert:") {
		t.Errorf("insert conflict: expected 'cannot insert:' prefix, got %q", msg)
	}
	if !strings.Contains(msg, "collision") {
		t.Errorf("insert conflict: expected overlap wording, got %q", msg)
	}
	if !strings.Contains(msg, "#3") || !strings.Contains(msg, "#8") {
		t.Errorf("insert conflict: expected both colliding room ids (#3 and #8), got %q", msg)
	}
	// No partial writes: the world is unchanged.
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != 2 {
		t.Errorf("insert conflict: A east should still be 2, got %d", tgt)
	}
}

// TestRemoveSuccess verifies a clean remove deletes B, pulls C back to A, and
// undo/redo round-trip.
func TestRemoveSuccess(t *testing.T) {
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n",
		2: "name: B\nexits:\n  east: 3\n  west: 1\n",
		3: "name: C\nexits:\n  west: 2\n",
	})
	resp, code := postRemove(t, s, `{"from":1,"dir":"east"}`)
	if code != http.StatusOK {
		t.Fatalf("remove: expected 200, got %d: %v", code, resp)
	}
	if int(resp["removed"].(float64)) != 2 {
		t.Errorf("remove: expected removed=2, got %v", resp["removed"])
	}
	if int(resp["pulled_to"].(float64)) != 3 {
		t.Errorf("remove: expected pulled_to=3, got %v", resp["pulled_to"])
	}
	if roomExists(s, 2) {
		t.Error("remove: B file should be gone")
	}
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != 3 {
		t.Errorf("remove: A east should be 3, got %d", tgt)
	}
	if tgt, _ := roomExitTarget(s, 3, world.West); tgt != 1 {
		t.Errorf("remove: C west should be 1, got %d", tgt)
	}

	// Undo restores B and reverts A and C.
	change := s.undoStack.Undo()
	if change == nil {
		t.Fatal("undo: expected a change, got nil")
	}
	s.rebuildAfterUndo(change)
	if !roomExists(s, 2) {
		t.Error("undo: B file should be back")
	}
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != 2 {
		t.Errorf("undo: A east should be 2, got %d", tgt)
	}
	if tgt, _ := roomExitTarget(s, 3, world.West); tgt != 2 {
		t.Errorf("undo: C west should be 2, got %d", tgt)
	}
	if tgt, _ := roomExitTarget(s, 2, world.West); tgt != 1 {
		t.Errorf("undo: B west should be 1, got %d", tgt)
	}
	if tgt, _ := roomExitTarget(s, 2, world.East); tgt != 3 {
		t.Errorf("undo: B east should be 3, got %d", tgt)
	}

	// Redo re-deletes B and repulls C.
	redoChange := s.undoStack.Redo()
	if redoChange == nil {
		t.Fatal("redo: expected a change, got nil")
	}
	s.rebuildAfterUndo(redoChange)
	if roomExists(s, 2) {
		t.Error("redo: B file should be gone again")
	}
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != 3 {
		t.Errorf("redo: A east should be 3, got %d", tgt)
	}
}

// TestRemoveGuards exercises each structural guard, checking the 400 status and
// a human-readable, specific error message.
func TestRemoveGuards(t *testing.T) {
	tests := []struct {
		name  string
		rooms map[int]string
		body  string
		want  string
	}{
		{
			name: "no such exit",
			rooms: map[int]string{
				1: "name: A\nexits:\n  east: 2\n",
				2: "name: B\nexits:\n  west: 1\n",
			},
			body: `{"from":1,"dir":"north"}`,
			want: "has no north exit",
		},
		{
			name: "self loop",
			rooms: map[int]string{
				1: "name: A\nexits:\n  east: 1\n",
			},
			body: `{"from":1,"dir":"east"}`,
			want: "loops back",
		},
		{
			name: "not an insert chain (B does not lead back)",
			rooms: map[int]string{
				1: "name: A\nexits:\n  east: 2\n",
				2: "name: B\nexits:\n  east: 3\n",
				3: "name: C\nexits:\n  west: 2\n",
			},
			body: `{"from":1,"dir":"east"}`,
			want: "not an insert chain",
		},
		{
			name: "dead end (B has no forward exit)",
			rooms: map[int]string{
				1: "name: A\nexits:\n  east: 2\n",
				2: "name: B\nexits:\n  west: 1\n",
			},
			body: `{"from":1,"dir":"east"}`,
			want: "no room beyond",
		},
		{
			name: "B has extra exits",
			rooms: map[int]string{
				1: "name: A\nexits:\n  east: 2\n",
				2: "name: B\nexits:\n  east: 3\n  west: 1\n  north: 4\n",
				3: "name: C\nexits:\n  west: 2\n",
				4: "name: D\nexits:\n  south: 2\n",
			},
			body: `{"from":1,"dir":"east"}`,
			want: "other exits besides",
		},
		{
			name: "C does not lead back to B",
			rooms: map[int]string{
				1: "name: A\nexits:\n  east: 2\n",
				2: "name: B\nexits:\n  east: 3\n  west: 1\n",
				3: "name: C\nexits:\n  east: 4\n",
				4: "name: D\nexits:\n  west: 3\n",
			},
			body: `{"from":1,"dir":"east"}`,
			want: "does not lead back to",
		},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			s := newTestAdminServer(t, tc.rooms)
			resp, code := postRemove(t, s, tc.body)
			if code != http.StatusBadRequest {
				t.Fatalf("expected 400, got %d: %v", code, resp)
			}
			msg, _ := resp["error"].(string)
			if !strings.Contains(msg, tc.want) {
				t.Errorf("expected message containing %q, got %q", tc.want, msg)
			}
			if strings.HasPrefix(msg, "{") || strings.Contains(msg, `"error"`) {
				t.Errorf("error message looks like raw JSON: %q", msg)
			}
		})
	}
}

// TestRemoveGridConflict verifies a conflicting remove returns 409 with rich
// wording (overlap) instead of the old generic message.
func TestRemoveGridConflict(t *testing.T) {
	// 1→east→2→east→3 (3 has south→6), 1→south→4→east→5. Removing 2 pulls 3
	// to (1,0,0); 6 (at 3's old south neighbor (2,1,0)) follows to (1,1,0)? No
	// — the pull shifts the whole beyond-component; 6 lands on 5's cell (1,1,0).
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n  south: 4\n",
		2: "name: B\nexits:\n  east: 3\n  west: 1\n",
		3: "name: C\nexits:\n  south: 6\n  west: 2\n",
		4: "name: D\nexits:\n  east: 5\n  north: 1\n",
		5: "name: E\nexits:\n  west: 4\n",
		6: "name: F\nexits:\n  north: 3\n",
	})
	resp, code := postRemove(t, s, `{"from":1,"dir":"east"}`)
	if code != http.StatusConflict {
		t.Fatalf("remove conflict: expected 409, got %d: %v", code, resp)
	}
	msg, _ := resp["error"].(string)
	if !strings.Contains(msg, "cannot remove:") {
		t.Errorf("remove conflict: expected 'cannot remove:' prefix, got %q", msg)
	}
	if !strings.Contains(msg, "collision") {
		t.Errorf("remove conflict: expected overlap wording, got %q", msg)
	}
	// No partial writes: B is still there, A and C unchanged.
	if !roomExists(s, 2) {
		t.Error("remove conflict: B file should still exist")
	}
	if tgt, _ := roomExitTarget(s, 1, world.East); tgt != 2 {
		t.Errorf("remove conflict: A east should still be 2, got %d", tgt)
	}
}

// TestRemoveExtraInbound verifies the extra-inbound guard fires when a third
// room points into B, and that the message names the count.
func TestRemoveExtraInbound(t *testing.T) {
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n",
		2: "name: B\nexits:\n  east: 3\n  west: 1\n",
		3: "name: C\nexits:\n  west: 2\n",
		9: "name: X\nexits:\n  north: 2\n", // extra inbound edge into B
	})
	resp, code := postRemove(t, s, `{"from":1,"dir":"east"}`)
	if code != http.StatusBadRequest {
		t.Fatalf("expected 400, got %d: %v", code, resp)
	}
	msg, _ := resp["error"].(string)
	if !strings.Contains(msg, "other exit(s) point into") {
		t.Errorf("expected extra-inbound message, got %q", msg)
	}
}

// TestNextRoomIDNoCrossSubdirCollision confirms the allocator does not return an
// ID that already exists in a different subdirectory.
func TestNextRoomIDNoCrossSubdirCollision(t *testing.T) {
	dir := t.TempDir()
	roomsDir := filepath.Join(dir, "rooms")
	if err := os.MkdirAll(roomsDir, 0o755); err != nil {
		t.Fatal(err)
	}
	// Room 1 in root, room 2 in a subdirectory "zone".
	writeRoomFile(t, dir, 1, "name: A\nexits:\n  east: 2\n")
	zoneDir := filepath.Join(roomsDir, "zone")
	if err := os.MkdirAll(zoneDir, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(zoneDir, "2.yaml"), []byte("name: B\nexits:\n  west: 1\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	s := &AdminServer{
		world:    world.New(dir),
		mobStore: world.NewMobStore(dir),
		dataDir:  dir,
		undoStack: NewUndoStack(dir),
	}
	// Allocating near room 1 (root) must skip 2 (which lives in zone/).
	id, _, err := s.nextRoomID(1)
	if err != nil {
		t.Fatal(err)
	}
	if id == 2 {
		t.Fatalf("nextRoomID returned %d, which collides with the zone/ room", id)
	}
	if roomExists(s, id) {
		t.Errorf("nextRoomID returned an already-used id %d", id)
	}
}

// testMobDef returns a minimal mob def with enough HP that MobsInRoom (which
// filters HP > 0) reports it as present.
func testMobDef() *world.MobDef {
	return &world.MobDef{
		ID:   "testmob",
		Name: "Test",
		Combat: &world.MobCombat{
			Stats: world.MobCombatStats{HP: 10, MaxMeleeHit: 1},
		},
	}
}

// TestUndoInsertClearsMobs verifies that undoing an insert drops in-memory mob
// instances for the (now-deleted) new room, via rebuildAfterUndo's stat check.
func TestUndoInsertClearsMobs(t *testing.T) {
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n",
		2: "name: B\nexits:\n  west: 1\n",
	})
	resp, code := postInsert(t, s, `{"from":1,"dir":"east","name":"Mid"}`)
	if code != http.StatusOK {
		t.Fatalf("insert: expected 200, got %d: %v", code, resp)
	}
	newID := int(resp["room"].(map[string]any)["id"].(float64))

	// Spawn a transient mob in the new room so the store has something to clear.
	inst := s.mobStore.SpawnTransient(testMobDef(), &world.SpawnMobConfig{ID: "testmob"}, newID, "")
	if inst == nil {
		t.Fatal("SpawnTransient returned nil")
	}
	if got := len(s.mobStore.MobsInRoom(newID)); got != 1 {
		t.Fatalf("precondition: expected 1 mob in new room, got %d", got)
	}

	change := s.undoStack.Undo()
	if change == nil {
		t.Fatal("undo: expected a change, got nil")
	}
	s.rebuildAfterUndo(change)

	if got := len(s.mobStore.MobsInRoom(newID)); got != 0 {
		t.Errorf("undo: expected mobs for deleted room to be cleared, got %d", got)
	}
}

// TestRedoRemoveClearsMobs verifies that redoing a remove drops mob instances
// for the re-deleted room.
func TestRedoRemoveClearsMobs(t *testing.T) {
	s := newTestAdminServer(t, map[int]string{
		1: "name: A\nexits:\n  east: 2\n",
		2: "name: B\nexits:\n  east: 3\n  west: 1\n",
		3: "name: C\nexits:\n  west: 2\n",
	})
	if _, code := postRemove(t, s, `{"from":1,"dir":"east"}`); code != http.StatusOK {
		t.Fatal("remove failed")
	}
	// Undo to bring B back, then seed a mob in B before redoing.
	change := s.undoStack.Undo()
	if change == nil {
		t.Fatal("undo: expected a change, got nil")
	}
	s.rebuildAfterUndo(change)
	if !roomExists(s, 2) {
		t.Fatal("precondition: B should exist after undo")
	}
	s.mobStore.SpawnTransient(testMobDef(), &world.SpawnMobConfig{ID: "testmob"}, 2, "")
	if got := len(s.mobStore.MobsInRoom(2)); got != 1 {
		t.Fatalf("precondition: expected 1 mob in B, got %d", got)
	}

	redoChange := s.undoStack.Redo()
	if redoChange == nil {
		t.Fatal("redo: expected a change, got nil")
	}
	s.rebuildAfterUndo(redoChange)

	if got := len(s.mobStore.MobsInRoom(2)); got != 0 {
		t.Errorf("redo: expected mobs for re-deleted B to be cleared, got %d", got)
	}
}

// TestInsertInvalidBody confirms malformed input yields 400, not a panic.
func TestInsertInvalidBody(t *testing.T) {
	s := newTestAdminServer(t, map[int]string{1: "name: A\n"})
	for _, body := range []string{`{}`, `{"from":0,"dir":"east"}`, `{"from":1,"dir":""}`, `{"from":1,"dir":"sideways"}`} {
		resp, code := postInsert(t, s, body)
		if code != http.StatusBadRequest {
			t.Errorf("insert %q: expected 400, got %d: %v", body, code, resp)
		}
	}
}