package admin

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

	"thehouseoficarus/internal/persistence"
)

// resolveDataPath resolves a request-supplied path inside the admin data
// directory, rejecting paths that would escape it via .. segments or a symlink.
// The returned path is always filepath.Join(dataDir, cleaned relative path).
func resolveDataPath(dataDir, relPath string) (string, error) {
	clean := filepath.Clean(strings.TrimPrefix(strings.TrimPrefix(relPath, "/"), "data/"))
	if clean == ".." || strings.HasPrefix(clean, ".."+string(filepath.Separator)) {
		return "", fmt.Errorf("path escapes the data directory: %s", relPath)
	}
	full := filepath.Join(dataDir, clean)
	// Defence in depth: a symlink inside data/ could redirect a read or write
	// outside it, so resolve the longest existing prefix and re-check
	// containment. The root is resolved too, since the data dir itself may be
	// a symlink (e.g. a mounted volume).
	resolved, err := evalExisting(full)
	if err != nil {
		return "", fmt.Errorf("resolve path %s: %w", relPath, err)
	}
	root := dataDir
	if r, err := filepath.EvalSymlinks(dataDir); err == nil {
		root = r
	}
	if !withinDir(root, resolved) {
		return "", fmt.Errorf("path escapes the data directory via a symlink: %s", relPath)
	}
	return full, nil
}

// evalExisting resolves symlinks on the longest existing prefix of path and
// re-appends the not-yet-existing suffix, so a create target is still checked.
func evalExisting(path string) (string, error) {
	p := path
	var suffix []string
	for {
		resolved, err := filepath.EvalSymlinks(p)
		if err == nil {
			for i := len(suffix) - 1; i >= 0; i-- {
				resolved = filepath.Join(resolved, suffix[i])
			}
			return resolved, nil
		}
		if !os.IsNotExist(err) {
			return "", err
		}
		parent := filepath.Dir(p)
		if parent == p {
			return path, nil
		}
		suffix = append(suffix, filepath.Base(p))
		p = parent
	}
}

// withinDir reports whether path lies inside dir.
func withinDir(dir, path string) bool {
	rel, err := filepath.Rel(dir, path)
	return err == nil && rel != ".." && !strings.HasPrefix(rel, ".."+string(filepath.Separator))
}

// canonicalDataRelPath normalizes a client-supplied data-relative path so that
// repeated leading "/" or "data/" prefixes cannot make the security
// classifiers (isPlayerDataFilePath / isAccountFilePath) disagree with the
// path resolveDataPath actually reads. Without this, "//players/..." resolved
// to the real player file while the classifiers saw a non-player path.
func canonicalDataRelPath(relPath string) string {
	clean := filepath.ToSlash(filepath.Clean("/" + strings.TrimPrefix(relPath, "/")))
	clean = strings.TrimPrefix(clean, "/")
	for strings.HasPrefix(clean, "data/") {
		clean = strings.TrimPrefix(clean, "data/")
	}
	return clean
}

// evictDeletedRoomFile drops cached room state and any cached in-room games
// when the raw file manager deletes a room YAML (rooms/<dir>/<id>.yaml).
// Best-effort: only numeric .yaml stems under rooms/ count as room files.
func (s *AdminServer) evictDeletedRoomFile(relPath string) {
	dir, base := filepath.Split(relPath)
	idStr, ok := strings.CutSuffix(base, ".yaml")
	if !ok || idStr == "" {
		return
	}
	dir = strings.TrimSuffix(dir, "/")
	if dir == "rooms" || strings.HasPrefix(dir, "rooms"+string(filepath.Separator)) {
		id, err := strconv.Atoi(idStr)
		if err != nil {
			return
		}
		s.world.RebuildRoomIndex(s.dataDir)
		s.world.ClearRoomState(id)
		if s.mobStore != nil {
			s.mobStore.RemoveMobsInRoom(id)
		}
		if s.evictRoom != nil {
			s.evictRoom(id)
		}
	}
}

func (s *AdminServer) handleFileRename(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	var body struct {
		Path    string `json:"path"`
		NewName string `json:"new_name"`
	}
	if err := readJSON(r, &body); err != nil || body.Path == "" || body.NewName == "" {
		failJSON(w, "missing path or new_name")
		return
	}

	newName := strings.TrimSpace(body.NewName)
	if newName == "" || newName == "." || newName == ".." || strings.ContainsAny(newName, "/\\") {
		failJSON(w, "invalid file name")
		return
	}
	for _, c := range newName {
		if c < 32 || c == 127 {
			failJSON(w, "file name contains invalid characters")
			return
		}
	}

	relPath := canonicalDataRelPath(body.Path)
	oldAbs, err := resolveDataPath(s.dataDir, relPath)
	if err != nil {
		failJSON(w, err.Error())
		return
	}
	if isPlayerDataFilePath(relPath) && s.playerFileOnline(relPath) {
		failJSON(w, "cannot rename a player/account file while it is online; log the character out first")
		return
	}

	oldContent, err := snapshotFile(oldAbs)
	if err != nil {
		failJSON(w, "file not found: "+relPath)
		return
	}

	newAbs := filepath.Join(filepath.Dir(oldAbs), newName)
	if _, err := os.Stat(newAbs); err == nil {
		failJSON(w, "a file named "+newName+" already exists")
		return
	}

	if err := writeFilePreservingMode(newAbs, oldContent); err != nil {
		failJSON(w, "write error: "+err.Error())
		return
	}
	if err := os.Remove(oldAbs); err != nil {
		failJSON(w, "remove error: "+err.Error())
		return
	}

	// A raw rename changes the ID-bearing filename. Rebuild the room index
	// and drop the old room's cached state (mirroring the DELETE path), and
	// refresh item/mob/drop caches, or the old ID resolves to a deleted file
	// and the new one resolves to nothing until a restart.
	s.evictDeletedRoomFile(relPath)
	s.invalidateEntityCacheForPath(newAbs)
	// Hazards and courses have their own runtime caches that a raw rename
	// must refresh (the undo path does the same). Techs and triggers keep the
	// documented in-game `reload` requirement.
	if pathUnderDir(s.dataDir, "hazards", newAbs) {
		s.world.ClearHazardCache()
	}
	if pathUnderDir(s.dataDir, "courses", newAbs) {
		s.reloadCoursesIfWired()
	}

	newRelPath := filepath.Join(filepath.Dir(relPath), newName)
	if filepath.Dir(relPath) == "." {
		newRelPath = newName
	}
	s.undoStack.Push(ChangeDesc{
		Description: "Renamed file " + relPath + " to " + newRelPath,
		FilePath:    oldAbs,
		NewFilePath: newAbs,
		OldContent:  oldContent,
		NewContent:  oldContent,
	})
	writeJSON(w, map[string]any{"ok": true, "path": newRelPath})
}

// handleFiles is only reachable through ownerMiddleware (see server.go), so
// every player/account mutation below executes on the game owner and cannot
// interleave with a live save. This is the same single-owner guarantee the
// lifecycle transactions rely on. Additionally, a file whose character/account
// is currently online is refused: overwriting it would clobber the in-memory
// player the game will later save.
func (s *AdminServer) handleFiles(w http.ResponseWriter, r *http.Request) {
	relPath := canonicalDataRelPath(r.URL.Query().Get("path"))
	fullPath, pathErr := resolveDataPath(s.dataDir, relPath)
	if pathErr != nil {
		failJSON(w, pathErr.Error())
		return
	}

	switch r.Method {
	case http.MethodGet:
		if relPath == "" {
			entries, err := os.ReadDir(fullPath)
			if err != nil {
				failJSON(w, err.Error())
				return
			}
			var files []map[string]any
			for _, e := range entries {
				files = append(files, map[string]any{
					"name": e.Name(),
					"dir":  e.IsDir(),
				})
			}
			writeJSON(w, files)
			return
		}

		info, err := os.Stat(fullPath)
		if err != nil {
			failJSON(w, "not found: "+relPath)
			return
		}

		if info.IsDir() {
			entries, err := os.ReadDir(fullPath)
			if err != nil {
				failJSON(w, err.Error())
				return
			}
			var files []map[string]any
			for _, e := range entries {
				files = append(files, map[string]any{
					"name": e.Name(),
					"dir":  e.IsDir(),
				})
			}
			writeJSON(w, files)
			return
		}

		data, err := os.ReadFile(fullPath)
		if err != nil {
			failJSON(w, "read error: "+err.Error())
			return
		}
		data = redactAccountContent(relPath, data)
		writeJSON(w, map[string]any{
			"name":    info.Name(),
			"content": string(data),
			"path":    relPath,
		})

	case http.MethodPut, http.MethodPost:
		if relPath == "" {
			failJSON(w, "missing path")
			return
		}
		if isPlayerDataFilePath(relPath) && s.playerFileOnline(relPath) {
			failJSON(w, "cannot edit a player/account file while it is online; log the character out first")
			return
		}
		body, err := io.ReadAll(r.Body)
		if err != nil {
			failJSON(w, "read body: "+err.Error())
			return
		}
		// A redacted account hash is restored from the file on disk before
		// writing, so the raw editor can never disclose or overwrite it. A
		// non-mapping body is refused rather than blanking the hash.
		body, err = restoreAccountSecret(relPath, fullPath, body)
		if err != nil {
			failJSON(w, err.Error())
			return
		}

		oldContent, existed, err := snapshotBefore(fullPath)
		if err != nil {
			failJSON(w, "read existing file: "+err.Error())
			return
		}

		dir := filepath.Dir(fullPath)
		if err := os.MkdirAll(dir, 0755); err != nil {
			failJSON(w, "mkdir: "+err.Error())
			return
		}

		if err := writeFilePreservingMode(fullPath, body); err != nil {
			failJSON(w, "write error: "+err.Error())
			return
		}

		isCreate := !existed
		desc := "Updated file " + relPath
		if isCreate {
			desc = "Created file " + relPath
		}
		s.undoStack.Push(ChangeDesc{
			Description: desc,
			FilePath:    fullPath,
			OldContent:  oldContent,
			NewContent:  body,
			IsCreate:    isCreate,
		})
		writeJSON(w, map[string]any{"ok": true, "path": relPath})

	case http.MethodDelete:
		if relPath == "" {
			failJSON(w, "missing path")
			return
		}
		if isPlayerDataFilePath(relPath) && s.playerFileOnline(relPath) {
			failJSON(w, "cannot delete a player/account file while it is online; log the character out first")
			return
		}
		oldContent, _ := snapshotFile(fullPath)
		if err := os.Remove(fullPath); err != nil {
			failJSON(w, "delete error: "+err.Error())
			return
		}
		s.evictDeletedRoomFile(relPath)
		s.undoStack.Push(ChangeDesc{
			Description: "Deleted file " + relPath,
			FilePath:    fullPath,
			OldContent:  oldContent,
			IsDelete:    true,
		})
		writeJSON(w, map[string]any{"ok": true, "path": relPath})

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

// writeFilePreservingMode writes data atomically without widening an existing
// file's permissions (persistence.WriteFile preserves the current mode and
// uses the caller's perm for a new file). Player/account files are treated as
// owner-only: they carry password hashes and live player state, so a newly
// created file is 0600 and an existing wider mode is tightened.
func writeFilePreservingMode(path string, data []byte) error {
	perm := os.FileMode(0644)
	if isPlayerDataAbsPath(path) {
		perm = 0600
	}
	if err := persistence.WriteFile(path, data, perm); err != nil {
		return err
	}
	if perm == 0600 {
		return os.Chmod(path, 0600)
	}
	return nil
}

// isPlayerDataFilePath reports whether a data-relative path is a player or
// account YAML file (password hash / live character state).
func isPlayerDataFilePath(relPath string) bool {
	clean := filepath.ToSlash(filepath.Clean(relPath))
	return strings.HasPrefix(clean, "players/accounts/") || strings.HasPrefix(clean, "players/characters/")
}

// isPlayerDataAbsPath is the absolute-path form of isPlayerDataFilePath: it
// matches .../players/accounts/<name>.yaml and .../players/characters/<name>.yaml.
func isPlayerDataAbsPath(path string) bool {
	parent := filepath.Base(filepath.Dir(path))
	if parent != "accounts" && parent != "characters" {
		return false
	}
	return filepath.Base(filepath.Dir(filepath.Dir(path))) == "players"
}

// playerFileOnline reports whether the character/account addressed by a
// data-relative player file path has a live session. The game wires this via
// SetPlayerFileOnlineCheck; nil (unwired) disables the refusal.
func (s *AdminServer) playerFileOnline(relPath string) bool {
	if s.playerFileOnlineCheck == nil {
		return false
	}
	return s.playerFileOnlineCheck(relPath)
}

// isAccountFilePath reports whether a data-relative path is an account file
// whose password hash must not be exposed or overwritten through the raw file
// editor.
func isAccountFilePath(relPath string) bool {
	clean := filepath.ToSlash(filepath.Clean(relPath))
	return strings.HasPrefix(clean, "players/accounts/")
}

const redactedAccountHash = "[redacted]"

// redactAccountContent replaces the password hash with a placeholder for GET
// responses. The placeholder round-trips through restoreAccountSecret on save.
func redactAccountContent(relPath string, data []byte) []byte {
	if !isAccountFilePath(relPath) {
		return data
	}
	m, err := yamlToMap(data)
	if err != nil {
		return data
	}
	if _, ok := m["password_hash"]; !ok {
		return data
	}
	m["password_hash"] = redactedAccountHash
	out, err := marshalMapYAML(m)
	if err != nil {
		return data
	}
	return out
}

// restoreAccountSecret copies the on-disk password hash back into a submitted
// account file, so a redacted value (or any client-supplied value) can never
// change or blank an existing hash through the raw file editor. It returns an
// error when the existing hash cannot be preserved (for example a non-mapping
// body), so the caller refuses the write instead of blanking the hash.
func restoreAccountSecret(relPath, fullPath string, body []byte) ([]byte, error) {
	if !isAccountFilePath(relPath) {
		return body, nil
	}
	existing, err := os.ReadFile(fullPath)
	if err != nil {
		// A missing account file is a create; nothing to preserve.
		return body, nil
	}
	em, err := yamlToMap(existing)
	if err != nil {
		return nil, fmt.Errorf("existing account file is not a YAML mapping: %w", err)
	}
	hash, ok := em["password_hash"]
	if !ok {
		return body, nil
	}
	bm, err := yamlToMap(body)
	if err != nil {
		return nil, fmt.Errorf("submitted account file is not a YAML mapping; refusing to blank the password hash")
	}
	bm["password_hash"] = hash
	out, err := marshalMapYAML(bm)
	if err != nil {
		return nil, fmt.Errorf("marshal account file: %w", err)
	}
	return out, nil
}