feat: file viewer added

webui/backend/app/services/file_ops_service.py

@@ -3,10 +3,27 @@ from __future__ import annotations
 from pathlib import Path
 
 from backend.app.api.errors import AppError
-from backend.app.api.schemas import DeleteResponse, MkdirResponse, RenameResponse
+from backend.app.api.schemas import DeleteResponse, MkdirResponse, RenameResponse, ViewResponse
 from backend.app.fs.filesystem_adapter import FilesystemAdapter
 from backend.app.security.path_guard import PathGuard
 
+TEXT_PREVIEW_MAX_BYTES = 256 * 1024
+TEXT_CONTENT_TYPES = {
+    ".txt": "text/plain",
+    ".log": "text/plain",
+    ".md": "text/markdown",
+    ".yml": "text/yaml",
+    ".yaml": "text/yaml",
+    ".json": "application/json",
+    ".js": "text/javascript",
+    ".css": "text/css",
+    ".html": "text/html",
+}
+SPECIAL_TEXT_FILENAMES = {
+    "dockerfile": "text/plain",
+    "containerfile": "text/plain",
+}
+
 
 class FileOpsService:
     def __init__(self, path_guard: PathGuard, filesystem: FilesystemAdapter):
@@ -129,6 +146,64 @@ class FileOpsService:
 
         return DeleteResponse(path=resolved_target.relative)
 
+    def view(self, path: str) -> ViewResponse:
+        resolved_target = self._path_guard.resolve_existing_path(path)
+
+        if resolved_target.absolute.is_dir():
+            raise AppError(
+                code="type_conflict",
+                message="Source must be a file",
+                status_code=409,
+                details={"path": resolved_target.relative},
+            )
+        if not resolved_target.absolute.is_file():
+            raise AppError(
+                code="type_conflict",
+                message="Unsupported path type for view",
+                status_code=409,
+                details={"path": resolved_target.relative},
+            )
+
+        content_type = self._content_type_for(resolved_target.absolute)
+        if content_type is None:
+            raise AppError(
+                code="unsupported_type",
+                message="File type is not supported for preview",
+                status_code=409,
+                details={"path": resolved_target.relative},
+            )
+
+        try:
+            preview = self._filesystem.read_text_preview(
+                resolved_target.absolute,
+                max_bytes=TEXT_PREVIEW_MAX_BYTES,
+                encoding="utf-8",
+            )
+        except OSError as exc:
+            raise AppError(
+                code="io_error",
+                message="Filesystem operation failed",
+                status_code=500,
+                details={"reason": str(exc)},
+            )
+
+        return ViewResponse(
+            path=resolved_target.relative,
+            name=resolved_target.absolute.name,
+            content_type=content_type,
+            encoding="utf-8",
+            truncated=preview["truncated"],
+            size=preview["size"],
+            content=preview["content"],
+        )
+
     @staticmethod
     def _join_relative(base: str, name: str) -> str:
         return f"{base}/{name}" if base else name
+
+    @staticmethod
+    def _content_type_for(path: Path) -> str | None:
+        special_name = SPECIAL_TEXT_FILENAMES.get(path.name.lower())
+        if special_name:
+            return special_name
+        return TEXT_CONTENT_TYPES.get(path.suffix.lower())