from __future__ import annotations

import json
import os
import shutil
import stat
from datetime import datetime
from typing import Annotated, Optional
import re

import gradio as gr

from app import _log_call_end, _log_call_start, _truncate_for_log
from ._docstrings import autodoc


TOOL_SUMMARY = (
    "Browse and manage files within a safe root. "
    "Actions: list, read, write, append, mkdir, move, copy, delete, info, help. "
    "Fill other fields as needed. "
    "Use paths like `.` because all paths are relative to the root (`/`). "
    "Use 'help' to see action-specific required fields and examples."
)

HELP_TEXT = (
    "File System — actions and usage\n\n"
    "Root: paths resolve under Nymbo-Tools/Filesystem by default (or NYMBO_TOOLS_ROOT if set). "
    "Absolute paths are disabled unless UNSAFE_ALLOW_ABS_PATHS=1.\n\n"
    "Actions and fields:\n"
    "- list: path='.' (default), recursive=false, show_hidden=false, max_entries=200\n"
    "- read: path, offset=0, max_chars=4000 (shows next_cursor when truncated)\n"
    "- write: path, content (UTF-8), create_dirs=true\n"
    "- append: path, content (UTF-8), create_dirs=true\n"
    "- mkdir: path (directory), exist_ok=true\n"
    "- move: path (src), dest_path (dst), overwrite=false\n"
    "- copy: path (src), dest_path (dst), overwrite=false\n"
    "- delete: path, recursive=true (required for directories)\n"
    "- info: path\n"
    "- help: show this guide\n\n"
    "Errors are returned as JSON with fields: {status:'error', code, message, path?, hint?, data?}.\n\n"
    "Examples:\n"
    "- list current: action=list, path='.'\n"
    "- make folder: action=mkdir, path='notes'\n"
    "- write file: action=write, path='notes/todo.txt', content='hello'\n"
    "- read file: action=read, path='notes/todo.txt', max_chars=200\n"
    "- move file: action=move, path='notes/todo.txt', dest_path='notes/todo-old.txt', overwrite=true\n"
    "- delete dir: action=delete, path='notes', recursive=true\n"
)


def _default_root() -> str:
    # Prefer explicit root via env var
    root = os.getenv("NYMBO_TOOLS_ROOT")
    if root and root.strip():
        return os.path.abspath(os.path.expanduser(root.strip()))
    # Default to "Nymbo-Tools/Filesystem" alongside this module package
    try:
        here = os.path.abspath(__file__)
        tools_dir = os.path.dirname(os.path.dirname(here))  # .../Nymbo-Tools
        default_root = os.path.abspath(os.path.join(tools_dir, "Filesystem"))
        return default_root
    except Exception:
        # Final fallback
        return os.path.abspath(os.getcwd())


ROOT_DIR = _default_root()
# Ensure the default root directory exists to make listing/writing more convenient
try:
    os.makedirs(ROOT_DIR, exist_ok=True)
except Exception:
    pass
ALLOW_ABS = bool(int(os.getenv("UNSAFE_ALLOW_ABS_PATHS", "0")))

def _safe_err(exc: Exception | str) -> str:
    """Return an error string with any absolute root replaced by '/' and slashes normalized.
    This handles variants like backslashes and duplicate slashes in OS messages.
    """
    s = str(exc)
    # Normalize to forward slashes for comparison
    s_norm = s.replace("\\", "/")
    root_fwd = ROOT_DIR.replace("\\", "/")
    # Collapse duplicate slashes in root representation
    root_variants = {ROOT_DIR, root_fwd, re.sub(r"/+", "/", root_fwd)}
    for variant in root_variants:
        if variant:
            s_norm = s_norm.replace(variant, "/")
    # Collapse duplicate slashes in final output
    s_norm = re.sub(r"/+", "/", s_norm)
    return s_norm


def _err(code: str, message: str, *, path: Optional[str] = None, hint: Optional[str] = None, data: Optional[dict] = None) -> str:
    """Return a structured error JSON string.
    Fields: status='error', code, message, path?, hint?, data?, root='/'
    """
    payload = {
        "status": "error",
        "code": code,
        "message": message,
        "root": "/",
    }
    if path is not None and path != "":
        payload["path"] = path
    if hint:
        payload["hint"] = hint
    if data:
        payload["data"] = data
    return json.dumps(payload, ensure_ascii=False)


def _resolve_path(path: str) -> tuple[str, str]:
    """
    Resolve a user-provided path to an absolute, normalized path constrained to ROOT_DIR
    (unless UNSAFE_ALLOW_ABS_PATHS=1). Returns (abs_path, error_message). error_message is empty when ok.
    """
    try:
        user_input = (path or ".").strip()
        raw = os.path.expanduser(user_input)
        if os.path.isabs(raw):
            if not ALLOW_ABS:
                # Absolute paths are not allowed in safe mode
                return "", _err(
                    "absolute_path_disabled",
                    "Absolute paths are disabled in safe mode.",
                    path=raw.replace("\\", "/"),
                    hint="Use a path relative to / (e.g., notes/todo.txt)."
                )
            abs_path = os.path.abspath(raw)
        else:
            abs_path = os.path.abspath(os.path.join(ROOT_DIR, raw))
        # Constrain to ROOT when not unsafe mode
        if not ALLOW_ABS:
            try:
                common = os.path.commonpath([os.path.normpath(ROOT_DIR), os.path.normpath(abs_path)])
            except Exception:
                # Fallback to simple check
                root_cmp = os.path.normcase(os.path.normpath(ROOT_DIR))
                abs_cmp = os.path.normcase(os.path.normpath(abs_path))
                if not abs_cmp.startswith(root_cmp):
                    return "", _err(
                        "path_outside_root",
                        "Path not allowed outside root.",
                        path=user_input.replace("\\", "/"),
                        hint="Use a path under / (the tool's root)."
                    )
            else:
                root_cmp = os.path.normcase(os.path.normpath(ROOT_DIR))
                common_cmp = os.path.normcase(os.path.normpath(common))
                if common_cmp != root_cmp:
                    return "", _err(
                        "path_outside_root",
                        "Path not allowed outside root.",
                        path=user_input.replace("\\", "/"),
                        hint="Use a path under / (the tool's root)."
                    )
        return abs_path, ""
    except Exception as exc:
        return "", _err(
            "resolve_path_failed",
            "Failed to resolve path.",
            path=(path or ""),
            data={"error": _safe_err(exc)}
        )


def _fmt_size(num_bytes: int) -> str:
    units = ["B", "KB", "MB", "GB", "TB"]
    size = float(num_bytes)
    for unit in units:
        if size < 1024.0:
            return f"{size:.1f} {unit}"
        size /= 1024.0
    return f"{size:.1f} PB"


def _display_path(abs_path: str) -> str:
    """Return a user-friendly path relative to ROOT_DIR using forward slashes.
    Example: ROOT_DIR -> '/', a file under it -> '/sub/dir/file.txt'."""
    try:
        norm_root = os.path.normpath(ROOT_DIR)
        norm_abs = os.path.normpath(abs_path)
        common = os.path.commonpath([norm_root, norm_abs])
        if os.path.normcase(common) == os.path.normcase(norm_root):
            rel = os.path.relpath(norm_abs, norm_root)
            if rel == ".":
                return "/"
            return "/" + rel.replace("\\", "/")
    except Exception:
        pass
    # Fallback to original absolute path
    return abs_path.replace("\\", "/")


def _list_dir(abs_path: str, *, show_hidden: bool, recursive: bool, max_entries: int) -> str:
    lines: list[str] = []
    total = 0
    root_display = "/"
    listing_display = _display_path(abs_path)
    for root, dirs, files in os.walk(abs_path):
        # filter hidden
        if not show_hidden:
            dirs[:] = [d for d in dirs if not d.startswith('.')]
            files = [f for f in files if not f.startswith('.')]
        try:
            rel_root = os.path.relpath(root, ROOT_DIR)
        except Exception:
            rel_root = root
        rel_root_disp = "/" if rel_root == "." else "/" + rel_root.replace("\\", "/")
        lines.append(f"\n📂 {rel_root_disp}")
        # sort
        dirs.sort()
        files.sort()
        for d in dirs:
            p = os.path.join(root, d)
            try:
                mtime = datetime.fromtimestamp(os.path.getmtime(p)).isoformat(sep=' ', timespec='seconds')
            except Exception:
                mtime = "?"
            lines.append(f"  • [DIR] {d}    (modified {mtime})")
            total += 1
            if total >= max_entries:
                lines.append(f"\n… Truncated at {max_entries} entries.")
                return "\n".join(lines).strip()
        for f in files:
            p = os.path.join(root, f)
            try:
                size = _fmt_size(os.path.getsize(p))
                mtime = datetime.fromtimestamp(os.path.getmtime(p)).isoformat(sep=' ', timespec='seconds')
            except Exception:
                size, mtime = "?", "?"
            lines.append(f"  • {f}    ({size}, modified {mtime})")
            total += 1
            if total >= max_entries:
                lines.append(f"\n… Truncated at {max_entries} entries.")
                return "\n".join(lines).strip()
        if not recursive:
            break
    header = f"Listing of {listing_display}\nRoot: {root_display}\nEntries: {total}"
    return (header + "\n" + "\n".join(lines)).strip()


def _read_file(abs_path: str, *, offset: int, max_chars: int) -> str:
    if not os.path.exists(abs_path):
        return _err("file_not_found", f"File not found: {_display_path(abs_path)}", path=_display_path(abs_path))
    if os.path.isdir(abs_path):
        return _err("is_directory", f"Path is a directory, not a file: {_display_path(abs_path)}", path=_display_path(abs_path), hint="Provide a file path.")
    try:
        with open(abs_path, 'r', encoding='utf-8', errors='replace') as f:
            data = f.read()
    except Exception as exc:
        return _err("read_failed", "Failed to read file.", path=_display_path(abs_path), data={"error": _safe_err(exc)})
    total = len(data)
    start = max(0, min(offset, total))
    if max_chars > 0:
        end = min(total, start + max_chars)
    else:
        end = total
    chunk = data[start:end]
    next_cursor = end if end < total else None
    meta = {
        "offset": start,
        "returned": len(chunk),
        "total": total,
        "next_cursor": next_cursor,
        "path": _display_path(abs_path),
    }
    header = (
        f"Reading {_display_path(abs_path)}\n"
        f"Offset {start}, returned {len(chunk)} of {total}."
        + (f"\nNext cursor: {next_cursor}" if next_cursor is not None else "")
    )
    sep = "\n\n---\n\n"
    return header + sep + chunk


def _ensure_parent(abs_path: str, create_dirs: bool) -> None:
    parent = os.path.dirname(abs_path)
    if parent and not os.path.exists(parent):
        if create_dirs:
            os.makedirs(parent, exist_ok=True)
        else:
            raise FileNotFoundError(f"Parent directory does not exist: {_display_path(parent)}")


def _write_file(abs_path: str, content: str, *, append: bool, create_dirs: bool) -> str:
    try:
        _ensure_parent(abs_path, create_dirs)
        mode = 'a' if append else 'w'
        with open(abs_path, mode, encoding='utf-8') as f:
            f.write(content or "")
        return f"{'Appended to' if append else 'Wrote'} file: {_display_path(abs_path)} (chars={len(content or '')})"
    except Exception as exc:
        return _err("write_failed", "Failed to write file.", path=_display_path(abs_path), data={"error": _safe_err(exc)})


def _mkdir(abs_path: str, exist_ok: bool) -> str:
    try:
        os.makedirs(abs_path, exist_ok=exist_ok)
        return f"Created directory: {_display_path(abs_path)}"
    except Exception as exc:
        return _err("mkdir_failed", "Failed to create directory.", path=_display_path(abs_path), data={"error": _safe_err(exc)})


def _move_copy(action: str, src: str, dst: str, *, overwrite: bool) -> str:
    try:
        if not os.path.exists(src):
            return _err("source_not_found", f"Source not found: {_display_path(src)}", path=_display_path(src))
        if os.path.isdir(dst):
            # allow moving into an existing directory
            dst_path = os.path.join(dst, os.path.basename(src))
        else:
            dst_path = dst
        if os.path.exists(dst_path):
            if overwrite:
                if os.path.isdir(dst_path):
                    shutil.rmtree(dst_path)
                else:
                    os.remove(dst_path)
            else:
                return _err(
                    "destination_exists",
                    f"Destination already exists: {_display_path(dst_path)}",
                    path=_display_path(dst_path),
                    hint="Set overwrite=True to replace the destination."
                )
        if action == 'move':
            shutil.move(src, dst_path)
        else:
            if os.path.isdir(src):
                shutil.copytree(src, dst_path)
            else:
                shutil.copy2(src, dst_path)
        return f"{action.capitalize()}d: {_display_path(src)} -> {_display_path(dst_path)}"
    except Exception as exc:
        return _err(f"{action}_failed", f"Failed to {action}.", path=_display_path(src), data={"error": _safe_err(exc), "destination": _display_path(dst)})


def _delete(abs_path: str, *, recursive: bool) -> str:
    try:
        if not os.path.exists(abs_path):
            return _err("path_not_found", f"Path not found: {_display_path(abs_path)}", path=_display_path(abs_path))
        if os.path.isdir(abs_path):
            if not recursive:
                # Refuse to delete a dir unless recursive=True
                return _err("requires_recursive", "Refusing to delete a directory without recursive=True", path=_display_path(abs_path), hint="Pass recursive=True to delete a directory.")
            shutil.rmtree(abs_path)
        else:
            os.remove(abs_path)
        return f"Deleted: {_display_path(abs_path)}"
    except Exception as exc:
        return _err("delete_failed", "Failed to delete path.", path=_display_path(abs_path), data={"error": _safe_err(exc)})


def _info(abs_path: str) -> str:
    try:
        st = os.stat(abs_path)
    except Exception as exc:
        return _err("stat_failed", "Failed to stat path.", path=_display_path(abs_path), data={"error": _safe_err(exc)})
    info = {
        "path": _display_path(abs_path),
        "type": "directory" if stat.S_ISDIR(st.st_mode) else "file",
        "size": st.st_size,
        "modified": datetime.fromtimestamp(st.st_mtime).isoformat(sep=' ', timespec='seconds'),
        "created": datetime.fromtimestamp(st.st_ctime).isoformat(sep=' ', timespec='seconds'),
        "mode": oct(st.st_mode),
        "root": "/",
    }
    return json.dumps(info, indent=2)


@autodoc(summary=TOOL_SUMMARY)
def File_System(
    action: Annotated[str, "Operation to perform: 'list', 'read', 'write', 'append', 'mkdir', 'move', 'copy', 'delete', 'info'."],
    path: Annotated[str, "Target path, relative to root unless UNSAFE_ALLOW_ABS_PATHS=1."] = ".",
    content: Annotated[Optional[str], "Content for write/append actions (UTF-8)."] = None,
    dest_path: Annotated[Optional[str], "Destination for move/copy (relative to root unless unsafe absolute allowed)."] = None,
    recursive: Annotated[bool, "For list (recurse into subfolders) and delete (required for directories)."] = False,
    show_hidden: Annotated[bool, "Include hidden files (dotfiles)."] = False,
    max_entries: Annotated[int, "Max entries to list (for list)."] = 200,
    offset: Annotated[int, "Start offset for reading files (for read)."] = 0,
    max_chars: Annotated[int, "Max characters to return when reading (0 = full file)."] = 4000,
    create_dirs: Annotated[bool, "Create parent directories for write/append if missing."] = True,
    overwrite: Annotated[bool, "Allow overwrite for move/copy destinations."] = False,
) -> str:
    _log_call_start(
        "File_System",
        action=action,
        path=path,
        dest_path=dest_path,
        recursive=recursive,
        show_hidden=show_hidden,
        max_entries=max_entries,
        offset=offset,
        max_chars=max_chars,
        create_dirs=create_dirs,
        overwrite=overwrite,
    )
    action = (action or "").strip().lower()
    if action not in {"list", "read", "write", "append", "mkdir", "move", "copy", "delete", "info", "help"}:
        result = _err(
            "invalid_action",
            "Invalid action.",
            hint="Choose from: list, read, write, append, mkdir, move, copy, delete, info, help."
        )
        _log_call_end("File_System", _truncate_for_log(result))
        return result

    abs_path, err = _resolve_path(path)
    if err:
        _log_call_end("File_System", _truncate_for_log(err))
        return err

    try:
        if action == "help":
            result = HELP_TEXT
        elif action == "list":
            if not os.path.exists(abs_path):
                result = _err("path_not_found", f"Path not found: {_display_path(abs_path)}", path=_display_path(abs_path))
            else:
                result = _list_dir(abs_path, show_hidden=show_hidden, recursive=recursive, max_entries=max_entries)
        elif action == "read":
            result = _read_file(abs_path, offset=offset, max_chars=max_chars)
        elif action in {"write", "append"}:
            # Prevent attempts to write to root or any directory
            if _display_path(abs_path) == "/" or os.path.isdir(abs_path):
                result = _err(
                    "invalid_write_path",
                    "Invalid path for write/append.",
                    path=_display_path(abs_path),
                    hint="Provide a file path under / (e.g., /notes/todo.txt)."
                )
            else:
                result = _write_file(abs_path, content or "", append=(action == "append"), create_dirs=create_dirs)
        elif action == "mkdir":
            result = _mkdir(abs_path, exist_ok=True)
        elif action in {"move", "copy"}:
            if not dest_path:
                result = _err("missing_dest_path", "dest_path is required for move/copy (ignored for other actions).")
            else:
                abs_dst, err2 = _resolve_path(dest_path)
                if err2:
                    result = err2
                else:
                    result = _move_copy(action, abs_path, abs_dst, overwrite=overwrite)
        elif action == "delete":
            result = _delete(abs_path, recursive=recursive)
        else:  # info
            result = _info(abs_path)
    except Exception as exc:
        result = _err("exception", "Unhandled error during operation.", data={"error": _safe_err(exc)})

    _log_call_end("File_System", _truncate_for_log(result))
    return result


def build_interface() -> gr.Interface:
    return gr.Interface(
        fn=File_System,
        inputs=[
            gr.Radio(
                label="Action",
                choices=["list", "read", "write", "append", "mkdir", "move", "copy", "delete", "info", "help"],
                value="help",
            ),
            gr.Textbox(label="Path", placeholder=". or src/file.txt", max_lines=1, value="."),
            gr.Textbox(label="Content (for write/append)", lines=6, placeholder="Text to write..."),
            gr.Textbox(label="Destination (for move/copy)", max_lines=1),
            gr.Checkbox(label="Recursive (list/delete)", value=False),
            gr.Checkbox(label="Show hidden (list)", value=False),
            gr.Slider(minimum=10, maximum=5000, step=10, value=200, label="Max entries (list)"),
            gr.Slider(minimum=0, maximum=1_000_000, step=100, value=0, label="Offset (read)"),
            gr.Slider(minimum=0, maximum=100_000, step=500, value=4000, label="Max chars (read, 0=all)"),
            gr.Checkbox(label="Create parent dirs (write)", value=True),
            gr.Checkbox(label="Overwrite destination (move/copy)", value=False),
        ],
        outputs=gr.Textbox(label="Result", lines=20),
        title="File System",
        description=(
            "<div id=\"fs-desc\" style=\"text-align:center; overflow:hidden;\">Browse and interact with a filesystem. "
            "Actions are required, fill other fields as needed." 
            "</div>"
        ),
        api_description=TOOL_SUMMARY,
        flagging_mode="never",
        submit_btn="Run",
        css=(
            """
/* Hide scrollbars/arrows that can appear on the description block in some browsers */
article.prose, .prose, .gr-prose {
  overflow: visible !important;
  max-height: none !important;
  -ms-overflow-style: none !important; /* IE/Edge */
  scrollbar-width: none !important;    /* Firefox */
}
article.prose::-webkit-scrollbar,
.prose::-webkit-scrollbar,
.gr-prose::-webkit-scrollbar {
  display: none !important;            /* Chrome/Safari */
}
            """
        ),
    )


__all__ = ["File_System", "build_interface"]