import shutil
from pathlib import Path

from fastapi import HTTPException

from editor_app import config
from editor_app.models import FileInfo

LIB_DIR_NAME = "lib"
WRITABLE_ROOTS = {"code", "demos"}


def _workspace_root(workspace_root: Path | None = None) -> Path:
    return (workspace_root or config.WORKSPACE_ROOT).resolve()


def _shared_lib_root() -> Path:
    """Shared MicroPython stubs ship in the repo `lib/` directory and are read directly.

    Treating the bundle as the single source of truth means there is no on-disk
    `workspace/lib/` cache to keep in sync — updates to e.g. `machine.py` flow
    straight through to Pyodide and the file tree.
    """
    return (config.PROJECT_ROOT / LIB_DIR_NAME).resolve()


def normalize_relative_path(relative_path: str) -> str:
    cleaned = (relative_path or "").strip().lstrip("/")
    if not cleaned:
        return ""

    parts = [segment for segment in cleaned.split("/") if segment]
    if len(parts) >= 2 and parts[0] == "code":
        while len(parts) >= 2 and parts[0] == parts[1] == "code":
            parts.pop(1)
    if len(parts) >= 2 and parts[0] == "demos":
        while len(parts) >= 2 and parts[0] == parts[1] == "demos":
            parts.pop(1)
    return "/".join(parts)


def resolve_workspace_path(relative_path: str, workspace_root: Path | None = None) -> Path:
    relative_path = normalize_relative_path(relative_path)
    root = _workspace_root(workspace_root)
    if relative_path == LIB_DIR_NAME or relative_path.startswith(f"{LIB_DIR_NAME}/"):
        suffix = relative_path[len(LIB_DIR_NAME) :].lstrip("/")
        target_path = (_shared_lib_root() / suffix).resolve()
        try:
            target_path.relative_to(_shared_lib_root())
        except ValueError as exc:
            raise HTTPException(status_code=400, detail="Path escapes shared lib") from exc
        return target_path
    target_path = (root / relative_path).resolve()
    try:
        target_path.relative_to(root)
    except ValueError as exc:
        raise HTTPException(status_code=400, detail="Path escapes workspace") from exc
    return target_path


def _is_path_in_lib(target_path: Path, workspace_root: Path | None = None) -> bool:
    try:
        target_path.resolve().relative_to(_shared_lib_root())
        return True
    except ValueError:
        return False


def _ensure_not_lib_path(target_path: Path, workspace_root: Path | None = None) -> None:
    if _is_path_in_lib(target_path, workspace_root):
        raise HTTPException(status_code=403, detail="lib is read-only")


def _is_writable_path(target_path: Path, workspace_root: Path | None = None) -> bool:
    workspace = _workspace_root(workspace_root)
    resolved = target_path.resolve()
    try:
        relative = resolved.relative_to(workspace)
    except ValueError:
        return False
    if not relative.parts:
        return False
    return relative.parts[0] in WRITABLE_ROOTS


def _ensure_writable_path(target_path: Path, workspace_root: Path | None = None) -> None:
    if not _is_writable_path(target_path, workspace_root):
        raise HTTPException(
            status_code=403,
            detail="Only code/ and demos/ are writable (lib is read-only)",
        )


def list_files(path: str = "", workspace_root: Path | None = None) -> list[FileInfo]:
    path = normalize_relative_path(path)
    root = _workspace_root(workspace_root)
    target_path = resolve_workspace_path(path, root) if path else root
    if not target_path.exists() or not target_path.is_dir():
        raise HTTPException(status_code=404, detail="Directory not found")

    files = []
    for item in sorted(target_path.iterdir()):
        if item.name.startswith("."):
            continue
        if not path and item.name == "users":
            continue
        files.append(
            FileInfo(
                name=item.name,
                is_directory=item.is_dir(),
                size=item.stat().st_size if item.is_file() else None,
            )
        )
    if not path:
        shared_lib = _shared_lib_root()
        if shared_lib.exists() and not any(f.name == LIB_DIR_NAME for f in files):
            files.append(FileInfo(name=LIB_DIR_NAME, is_directory=True, size=None))
    return files


def read_text_file(file_path: str, workspace_root: Path | None = None) -> tuple[str, str]:
    target_path = resolve_workspace_path(file_path, workspace_root)
    if not target_path.exists():
        raise HTTPException(status_code=404, detail="File not found")
    if target_path.is_dir():
        raise HTTPException(status_code=400, detail="Path is a directory")
    try:
        content = target_path.read_text(encoding="utf-8")
    except UnicodeDecodeError as exc:
        raise HTTPException(status_code=400, detail="File is not a text file") from exc
    return content, target_path.name


def save_text_file(file_path: str, content: str, workspace_root: Path | None = None) -> str:
    target_path = resolve_workspace_path(file_path, workspace_root)
    _ensure_not_lib_path(target_path, workspace_root)
    _ensure_writable_path(target_path, workspace_root)
    target_path.parent.mkdir(parents=True, exist_ok=True)
    target_path.write_text(content, encoding="utf-8")
    return target_path.name


def delete_file(file_path: str, workspace_root: Path | None = None) -> None:
    target_path = resolve_workspace_path(file_path, workspace_root)
    _ensure_not_lib_path(target_path, workspace_root)
    _ensure_writable_path(target_path, workspace_root)
    if not target_path.exists():
        raise HTTPException(status_code=404, detail="File not found")
    if target_path.is_dir():
        raise HTTPException(status_code=400, detail="Cannot delete directories")
    target_path.unlink()


def move_path(source_path: str, destination_folder: str, workspace_root: Path | None = None) -> tuple[str, str]:
    root = _workspace_root(workspace_root)
    source = resolve_workspace_path(source_path, root)
    _ensure_not_lib_path(source, root)
    _ensure_writable_path(source, root)
    if not source.exists():
        raise HTTPException(status_code=404, detail="Source path not found")

    destination_dir = (
        resolve_workspace_path(destination_folder, root)
        if destination_folder
        else root
    )
    _ensure_not_lib_path(destination_dir, root)
    _ensure_writable_path(destination_dir, root)
    if not destination_dir.exists() or not destination_dir.is_dir():
        raise HTTPException(status_code=404, detail="Destination folder not found")

    destination = destination_dir / source.name
    source_resolved = source.resolve()
    destination_resolved = destination.resolve()
    if destination_resolved == source_resolved:
        raise HTTPException(status_code=400, detail="Path is already in that folder")
    if source.is_dir():
        source_prefix = str(source_resolved) + "/"
        if str(destination_dir.resolve()).startswith(source_prefix):
            raise HTTPException(
                status_code=400, detail="Cannot move a folder into itself or its child"
            )
    if destination.exists():
        raise HTTPException(
            status_code=409,
            detail="A path with that name already exists in destination",
        )

    destination.parent.mkdir(parents=True, exist_ok=True)
    source.rename(destination)
    moved_type = "folder" if destination.is_dir() else "file"
    return str(destination.relative_to(root)), moved_type


def create_folder(folder_path: str, workspace_root: Path | None = None) -> str:
    target_path = resolve_workspace_path(folder_path, workspace_root)
    _ensure_not_lib_path(target_path, workspace_root)
    _ensure_writable_path(target_path, workspace_root)
    if target_path.exists():
        raise HTTPException(status_code=400, detail="Folder already exists")
    target_path.mkdir(parents=True, exist_ok=False)
    return target_path.name


def delete_folder(folder_path: str, workspace_root: Path | None = None) -> None:
    target_path = resolve_workspace_path(folder_path, workspace_root)
    _ensure_not_lib_path(target_path, workspace_root)
    _ensure_writable_path(target_path, workspace_root)
    if not target_path.exists():
        raise HTTPException(status_code=404, detail="Folder not found")
    if not target_path.is_dir():
        raise HTTPException(status_code=400, detail="Path is not a directory")
    shutil.rmtree(target_path)


def collect_python_sources(workspace_root: Path | None = None) -> dict[str, str]:
    """Return UTF-8 `.py` under the scoped workspace plus shared stubs from `WORKSPACE_ROOT/lib/` (bundled Micropython mocks for Jedi/completion and Pyodide)."""
    result: dict[str, str] = {}
    workspace = _workspace_root(workspace_root)
    if workspace.exists():
        for path in workspace.rglob("*.py"):
            try:
                rel = path.relative_to(workspace)
            except ValueError:
                continue
            if any(part.startswith(".") for part in rel.parts):
                continue
            try:
                key = str(rel).replace("\\", "/")
                result[key] = path.read_text(encoding="utf-8")
            except (UnicodeDecodeError, OSError):
                continue
    shared_lib = _shared_lib_root()
    if shared_lib.is_dir():
        for path in shared_lib.rglob("*.py"):
            try:
                rel = path.relative_to(shared_lib)
            except ValueError:
                continue
            if any(part.startswith(".") for part in rel.parts):
                continue
            try:
                key = str(Path(LIB_DIR_NAME) / rel).replace("\\", "/")
                result[key] = path.read_text(encoding="utf-8")
            except (UnicodeDecodeError, OSError):
                continue
    return result