package admin

import (
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"gopkg.in/yaml.v3"
)

var horizontalExitDirs = []string{
	"north", "south", "east", "west",
	"northeast", "northwest", "southeast", "southwest",
}

// coursesDir is the subdirectory under dataDir holding course YAML files.
func (s *AdminServer) coursesDir() string { return filepath.Join(s.dataDir, "courses") }

// courseFilePath returns the on-disk path for a course id. Course files live
// flat in data/courses/ (no subdirectories) per the existing layout.
func (s *AdminServer) courseFilePath(id string) string {
	return filepath.Join(s.coursesDir(), id+".yaml")
}

func (s *AdminServer) reloadCoursesIfWired() {
	if s.reloadCourses != nil {
		s.reloadCourses()
	}
}

func (s *AdminServer) listCourseIDs() ([]string, error) {
	entries, err := os.ReadDir(s.coursesDir())
	if err != nil {
		return nil, err
	}
	var ids []string
	for _, e := range entries {
		if e.IsDir() || !strings.HasSuffix(e.Name(), ".yaml") {
			continue
		}
		ids = append(ids, strings.TrimSuffix(e.Name(), ".yaml"))
	}
	return ids, nil
}

// loadCourseMap reads a course YAML file as a generic map (for both GET and
// internal manipulation). Returns nil if the file does not exist.
func (s *AdminServer) loadCourseMap(id string) (map[string]any, []byte, string, error) {
	path := s.courseFilePath(id)
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, nil, path, err
	}
	var m map[string]any
	if err := yaml.Unmarshal(data, &m); err != nil {
		return nil, data, path, err
	}
	return m, data, path, nil
}

// helpers -----------------------------------------------------------------

// asMapList coerces a yaml-decoded value into []map[string]any.
func asMapList(v any) []map[string]any {
	if list, ok := v.([]any); ok {
		out := make([]map[string]any, 0, len(list))
		for _, e := range list {
			if mm, ok := e.(map[string]any); ok {
				out = append(out, mm)
			} else {
				out = append(out, map[string]any{})
			}
		}
		return out
	}
	return nil
}

// obstacleRoomID extracts the room_id (int) from an obstacle map entry.
func obstacleRoomID(o map[string]any) int {
	switch v := o["room_id"].(type) {
	case int:
		return v
	case int64:
		return int(v)
	case float64:
		return int(v)
	}
	return 0
}

// toInt coerces yaml-decoded numbers to int.
func toInt(v any) int {
	switch x := v.(type) {
	case int:
		return x
	case int64:
		return int(x)
	case float64:
		return int(x)
	}
	return 0
}

// toFloat64 coerces yaml-decoded numbers to float64.
func toFloat64(v any) float64 {
	switch x := v.(type) {
	case int:
		return float64(x)
	case int64:
		return float64(x)
	case float64:
		return x
	}
	return 0
}

// indexOfObstacleForRoom returns the index of the obstacle whose room_id
// matches roomID, or -1 if none.
func indexOfObstacleForRoom(obstacles []map[string]any, roomID int) int {
	for i, o := range obstacles {
		if obstacleRoomID(o) == roomID {
			return i
		}
	}
	return -1
}

// Courses list / create ---------------------------------------------------

func (s *AdminServer) handleCourses(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		ids, err := s.listCourseIDs()
		if err != nil {
			writeJSON(w, map[string]any{"root": []string{}, "dirs": map[string][]string{}})
			return
		}
		writeJSON(w, map[string]any{"root": ids, "dirs": map[string][]string{}})

	case http.MethodPost:
		var body map[string]any
		if err := readJSON(r, &body); err != nil {
			writeJSON(w, map[string]any{"error": "invalid json"})
			return
		}
		id, _ := body["id"].(string)
		id = strings.TrimSpace(id)
		if id == "" {
			writeJSON(w, map[string]any{"error": "missing id"})
			return
		}
		delete(body, "id")
		path := s.courseFilePath(id)
		if _, err := os.Stat(path); err == nil {
			writeJSON(w, map[string]any{"error": "course already exists"})
			return
		}
		newContent, err := writeMapAsYAML(path, body)
		if err != nil {
			writeJSON(w, map[string]any{"error": "write error: " + err.Error()})
			return
		}
		s.undoStack.Push(ChangeDesc{
			Description: "Created course " + id,
			FilePath:    path,
			NewContent:  newContent,
			IsCreate:    true,
		})
		s.reloadCoursesIfWired()
		writeJSON(w, map[string]any{"ok": true, "id": id})

	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

// Course by id: get / put / delete ---------------------------------------

func (s *AdminServer) handleCourseByID(w http.ResponseWriter, r *http.Request) {
	id := strings.TrimPrefix(r.URL.Path, "/api/courses/")
	if id == "" {
		writeJSON(w, map[string]any{"error": "missing id"})
		return
	}
	path := s.courseFilePath(id)

	switch r.Method {
	case http.MethodGet:
		m, data, _, err := s.loadCourseMap(id)
		if err != nil {
			writeJSON(w, map[string]any{"error": "not found: " + id})
			return
		}
		m["id"] = id
		m["_raw"] = string(data)
		writeJSON(w, m)

	case http.MethodPost, http.MethodPut:
		var body map[string]any
		if err := readJSON(r, &body); err != nil {
			writeJSON(w, map[string]any{"error": "invalid JSON: " + err.Error()})
			return
		}
		delete(body, "id")
		delete(body, "_raw")
		delete(body, "_path")

		var oldContent []byte
		if existing, err := snapshotFile(path); err == nil {
			oldContent = existing
		}
		newContent, err := writeMapAsYAML(path, body)
		if err != nil {
			writeJSON(w, map[string]any{"error": "write error: " + err.Error()})
			return
		}
		isCreate := oldContent == nil
		desc := "Updated course " + id
		if isCreate {
			desc = "Created course " + id
		}
		s.undoStack.Push(ChangeDesc{
			Description: desc,
			FilePath:    path,
			OldContent:  oldContent,
			NewContent:  newContent,
			IsCreate:    isCreate,
		})
		warnings := s.reconcileCourseExits(body)
		s.reloadCoursesIfWired()
		resp := map[string]any{"ok": true, "id": id}
		if len(warnings) > 0 {
			resp["warnings"] = warnings
		}
		writeJSON(w, resp)

	case http.MethodDelete:
		oldContent, err := snapshotFile(path)
		if err != nil {
			writeJSON(w, map[string]any{"error": "not found: " + id})
			return
		}
		if err := os.Remove(path); err != nil {
			writeJSON(w, map[string]any{"error": "delete error: " + err.Error()})
			return
		}
		s.undoStack.Push(ChangeDesc{
			Description: "Deleted course " + id,
			FilePath:    path,
			OldContent:  oldContent,
			IsDelete:    true,
		})
		s.reloadCoursesIfWired()
		writeJSON(w, map[string]any{"ok": true, "id": id})

	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

// Room-course lookup ------------------------------------------------------

// handleRoomCourse returns the course this room belongs to (if any) along
// with the obstacle index and total obstacle count. Returns a JSON null
// body when the room is not part of any course.
func (s *AdminServer) handleRoomCourse(w http.ResponseWriter, r *http.Request, roomID int) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	ids, err := s.listCourseIDs()
	if err != nil {
		writeJSON(w, map[string]any{"error": err.Error()})
		return
	}
	for _, id := range ids {
		m, raw, _, err := s.loadCourseMap(id)
		if err != nil {
			continue
		}
		obstacles := asMapList(m["obstacles"])
		idx := indexOfObstacleForRoom(obstacles, roomID)
		if idx < 0 {
			continue
		}
		m["id"] = id
		delete(m, "_raw")
		writeJSON(w, map[string]any{
			"course":           m,
			"course_id":        id,
			"course_name":      m["name"],
			"obstacle_index":   idx,
			"total_obstacles":  len(obstacles),
			"obstacle":         obstacles[idx],
			"obstacles":        obstacles,
			"_raw":             string(raw),
			"room_id":          roomID,
		})
		return
	}
	writeJSON(w, nil)
}

// Attach a room to an existing course as a new obstacle -------------------

func (s *AdminServer) handleRoomAttachCourse(w http.ResponseWriter, r *http.Request, roomID int) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	var body struct {
		CourseID   string         `json:"course_id"`
		AfterIndex int            `json:"after_index"`
		Direction  string         `json:"direction"`
		Obstacle   map[string]any `json:"obstacle"`
	}
	if err := readJSON(r, &body); err != nil {
		writeJSON(w, map[string]any{"error": "invalid json"})
		return
	}
	if strings.TrimSpace(body.CourseID) == "" {
		writeJSON(w, map[string]any{"error": "missing course_id"})
		return
	}
	m, _, path, err := s.loadCourseMap(body.CourseID)
	if err != nil {
		writeJSON(w, map[string]any{"error": "course not found: " + body.CourseID})
		return
	}
	oldContent, _ := snapshotFile(path)

	obstacles := asMapList(m["obstacles"])
	for i, o := range obstacles {
		if obstacleRoomID(o) == roomID {
			writeJSON(w, map[string]any{"error": fmt.Sprintf("room %d is already step %d of course %s", roomID, i+1, body.CourseID)})
			return
		}
	}
	if body.Obstacle == nil {
		body.Obstacle = map[string]any{}
	}
	body.Obstacle["room_id"] = roomID
	if _, ok := body.Obstacle["verb"]; !ok {
		body.Obstacle["verb"] = "climb"
	}
	if _, ok := body.Obstacle["xp"]; !ok {
		body.Obstacle["xp"] = 0
	}
	if _, ok := body.Obstacle["fail_damage"]; !ok {
		body.Obstacle["fail_damage"] = []any{0, 0}
	}

	insertAt := body.AfterIndex + 1
	if insertAt < 0 {
		insertAt = 0
	}
	if insertAt > len(obstacles) {
		insertAt = len(obstacles)
	}
	newList := make([]map[string]any, 0, len(obstacles)+1)
	newList = append(newList, obstacles[:insertAt]...)
	newList = append(newList, body.Obstacle)
	newList = append(newList, obstacles[insertAt:]...)

	anyList := make([]any, len(newList))
	for i, o := range newList {
		anyList[i] = o
	}
	m["obstacles"] = anyList

	// --- course map exit management ---
	// Set exit_dir on the previous obstacle.
	// Append-only: the new obstacle is last so no new->next link is needed.
	if insertAt > 0 {
		prevIdx := insertAt - 1
		prevRoom := obstacleRoomID(newList[prevIdx])
		if prevRoom > 0 {
			dir := strings.TrimSpace(strings.ToLower(body.Direction))
			if dir == "auto" || dir == "" {
				dir = "north"
			}
			if !isHorizontalDir(dir) {
				writeJSON(w, map[string]any{"error": "invalid direction: " + dir})
				return
			}

			prevObstacle := newList[prevIdx]
			prevObstacle["exit_dir"] = dir
			newList[prevIdx] = prevObstacle
		}
	}
	anyList = make([]any, len(newList))
	for i, o := range newList {
		anyList[i] = o
	}
	m["obstacles"] = anyList

	newContent, err := writeMapAsYAML(path, m)
	if err != nil {
		writeJSON(w, map[string]any{"error": "write error: " + err.Error()})
		return
	}
	s.undoStack.Push(ChangeDesc{
		Description: fmt.Sprintf("attach room %d to course %s", roomID, body.CourseID),
		FilePath:    path,
		OldContent:  oldContent,
		NewContent:  newContent,
	})

	s.reloadCoursesIfWired()
	writeJSON(w, map[string]any{"ok": true, "course_id": body.CourseID, "obstacle_index": insertAt, "total_obstacles": len(newList)})
}

// Detach a room from its course; delete the course file if it becomes empty

// detachRoomFromCourse removes roomID from the course it belongs to, if any.
// Returns the course ID that was modified, or "" if none match.
func (s *AdminServer) detachRoomFromCourse(roomID int) (courseID string, deleted bool) {
	ids, err := s.listCourseIDs()
	if err != nil {
		return "", false
	}
	for _, id := range ids {
		m, _, path, err := s.loadCourseMap(id)
		if err != nil {
			continue
		}
		obstacles := asMapList(m["obstacles"])
		idx := indexOfObstacleForRoom(obstacles, roomID)
		if idx < 0 {
			continue
		}
		oldContent, _ := snapshotFile(path)

		if idx > 0 {
			delete(obstacles[idx-1], "exit_dir")
		}

		remaining := make([]map[string]any, 0, len(obstacles)-1)
		remaining = append(remaining, obstacles[:idx]...)
		remaining = append(remaining, obstacles[idx+1:]...)

		if len(remaining) == 0 {
			os.Remove(path)
			s.undoStack.Push(ChangeDesc{
				Description: fmt.Sprintf("delete course %s (last obstacle removed)", id),
				FilePath:    path,
				OldContent:  oldContent,
				IsDelete:    true,
			})
			s.reloadCoursesIfWired()
			return id, true
		}

		anyList := make([]any, len(remaining))
		for i, o := range remaining {
			anyList[i] = o
		}
		m["obstacles"] = anyList
		newContent, err := writeMapAsYAML(path, m)
		if err != nil {
			return "", false
		}
		s.undoStack.Push(ChangeDesc{
			Description: fmt.Sprintf("detach room %d from course %s", roomID, id),
			FilePath:    path,
			OldContent:  oldContent,
			NewContent:  newContent,
		})
		s.reloadCoursesIfWired()
		return id, false
	}
	return "", false
}

func (s *AdminServer) handleRoomDetachCourse(w http.ResponseWriter, r *http.Request, roomID int) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	courseID, deleted := s.detachRoomFromCourse(roomID)
	if courseID == "" && !deleted {
		writeJSON(w, map[string]any{"error": "room is not part of any course"})
		return
	}
	writeJSON(w, map[string]any{"ok": true, "course_id": courseID, "deleted": deleted})
}

// loadRoomMapByID reads a room YAML file as a generic map.
func (s *AdminServer) loadRoomMapByID(roomID int) (map[string]any, []byte, string, error) {
	path, ok := s.world.GetRoomPath(roomID)
	if !ok {
		return nil, nil, "", fmt.Errorf("room %d not found", roomID)
	}
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, nil, path, err
	}
	var m map[string]any
	if err := yaml.Unmarshal(data, &m); err != nil {
		return nil, data, path, err
	}
	return m, data, path, nil
}

// saveRoomMapByID writes a room map back to disk and pushes an undo entry.
func (s *AdminServer) saveRoomMapByID(roomID int, m map[string]any, desc string) error {
	path, ok := s.world.GetRoomPath(roomID)
	if !ok {
		return fmt.Errorf("room %d not found", roomID)
	}
	oldContent, _ := snapshotFile(path)
	newContent, err := writeMapAsYAML(path, m)
	if err != nil {
		return err
	}
	s.undoStack.Push(ChangeDesc{
		Description: desc,
		FilePath:    path,
		OldContent:  oldContent,
		NewContent:  newContent,
	})
	return nil
}

// removeExit deletes an exit by direction. Returns true if it existed.
func removeExit(m map[string]any, dir string) bool {
	ex, ok := m["exits"].(map[string]any)
	if !ok {
		return false
	}
	if _, exists := ex[dir]; exists {
		delete(ex, dir)
		return true
	}
	return false
}

// exitTargetRoom returns the target room ID of an exit value (scalar or map).
func exitTargetRoom(v any) int {
	switch x := v.(type) {
	case int:
		return x
	case int64:
		return int(x)
	case float64:
		return int(x)
	case map[string]any:
		return toInt(x["room"])
	}
	return 0
}

// exitIsAlwaysBlocked returns whether an exit value carries always_blocked: true.
func exitIsAlwaysBlocked(v any) bool {
	if mm, ok := v.(map[string]any); ok {
		if h, ok := mm["always_blocked"]; ok {
			return h == true
		}
	}
	return false
}



// isHorizontalDir returns whether d is one of the 8 horizontal directions.
func isHorizontalDir(d string) bool {
	for _, h := range horizontalExitDirs {
		if d == h {
			return true
		}
	}
	return false
}



// reconcileExitOnRoom validates that roomID has an exit in dir.
// If expectedTarget > 0, also checks the exit points to that room.
// Returns an error string or empty string on success.
func (s *AdminServer) validateExitDir(roomID int, dir string, expectedTarget int) string {
	m, _, _, err := s.loadRoomMapByID(roomID)
	if err != nil {
		return "cannot load room " + strconv.Itoa(roomID)
	}
	ex, _ := m["exits"].(map[string]any)

	existing := ex[dir]
	if existing == nil {
		return "room " + strconv.Itoa(roomID) + " has no exit in direction " + dir
	}
	if expectedTarget > 0 {
		target := exitTargetRoom(existing)
		if target != expectedTarget {
			return "direction " + dir + " on room " + strconv.Itoa(roomID) + " points to room " + strconv.Itoa(target) + ", expected " + strconv.Itoa(expectedTarget)
		}
	}
	return ""
}

// reconcileCourseExits validates every obstacle's exit_dir against the actual
// exits on the corresponding room. Returns warnings for any mismatches found.
func (s *AdminServer) reconcileCourseExits(m map[string]any) []string {
	var warnings []string
	obstacles := asMapList(m["obstacles"])

	for i, obs := range obstacles {
		roomID := obstacleRoomID(obs)
		dir, _ := obs["exit_dir"].(string)
		if dir == "" {
			continue
		}

		var nextRoom int
		if i < len(obstacles)-1 {
			nextRoom = obstacleRoomID(obstacles[i+1])
		}

		errMsg := s.validateExitDir(roomID, dir, nextRoom)
		if errMsg != "" {
			warnings = append(warnings, errMsg)
		}
	}

	return warnings
}