"""Tool for creating and evolving custom skills."""

from __future__ import annotations

import asyncio
import logging
from typing import Any
from weakref import WeakValueDictionary

from langchain.tools import ToolRuntime, tool
from langgraph.typing import ContextT

from deerflow.agents.lead_agent.prompt import refresh_skills_system_prompt_cache_async
from deerflow.agents.thread_state import ThreadState
from deerflow.mcp.tools import _make_sync_tool_wrapper
from deerflow.persistence.skills import SkillStore
from deerflow.runtime.user_context import get_effective_user_id
from deerflow.skills.security_scanner import scan_skill_content
from deerflow.skills.storage import get_or_new_skill_storage
from deerflow.skills.storage.skill_storage import SkillStorage
from deerflow.skills.types import SKILL_MD_FILE

logger = logging.getLogger(__name__)

_skill_locks: WeakValueDictionary[str, asyncio.Lock] = WeakValueDictionary()


def _get_lock(name: str) -> asyncio.Lock:
    lock = _skill_locks.get(name)
    if lock is None:
        lock = asyncio.Lock()
        _skill_locks[name] = lock
    return lock


def _get_thread_id(runtime: ToolRuntime[ContextT, ThreadState] | None) -> str | None:
    if runtime is None:
        return None
    if runtime.context and runtime.context.get("thread_id"):
        return runtime.context.get("thread_id")
    return runtime.config.get("configurable", {}).get("thread_id")


def _history_record(*, action: str, file_path: str, prev_content: str | None, new_content: str | None, thread_id: str | None, scanner: dict[str, Any]) -> dict[str, Any]:
    return {
        "action": action,
        "author": "agent",
        "thread_id": thread_id,
        "file_path": file_path,
        "prev_content": prev_content,
        "new_content": new_content,
        "scanner": scanner,
    }


async def _scan_or_raise(content: str, *, executable: bool, location: str) -> dict[str, str]:
    result = await scan_skill_content(content, executable=executable, location=location)
    if result.decision == "block":
        raise ValueError(f"Security scan blocked the write: {result.reason}")
    if executable and result.decision != "allow":
        raise ValueError(f"Security scan rejected executable content: {result.reason}")
    return {"decision": result.decision, "reason": result.reason}


async def _to_thread(func, /, *args, **kwargs):
    return await asyncio.to_thread(func, *args, **kwargs)


async def _bump_patch_best_effort(name: str) -> None:
    """记一次技能维护活动(patch / edit)。

    刷新 ``.usage.json`` 的 ``patch_count`` 与 ``last_patched_at``,让 curator 的
    年龄流转把"Agent 正在主动维护的技能"算作活跃,而不是误判为闲置后归档。
    best-effort:埋点失败只记 DEBUG 日志,绝不影响技能写入主流程。
    """
    try:
        from deerflow.skills.usage import bump_patch

        await _to_thread(bump_patch, name)
    except Exception:
        logger.debug("Failed to bump patch count for %r", name, exc_info=True)


async def _ensure_skill_db_registered(store: SkillStore, name: str, user_id: str) -> None:
    """Idempotently record an agent-created skill's ownership in the DB.

    Mirrors the ``/api/skills/install-upload`` path so agent-created skills
    show up in the Web UI listing (which filters custom skills by DB
    ownership). ``ensure_legacy`` is idempotent — it never overwrites an
    existing owner — so re-running the create flow on an already-owned skill
    is a no-op. Failures are swallowed so DB outages can never break the
    agent's create flow itself.
    """
    try:
        await store.ensure_legacy(
            {"name": name, "owner_user_id": user_id, "published": False}
        )
    except Exception:
        logger.debug("Failed to register skill ownership for %r", name, exc_info=True)


def _default_skill_store() -> SkillStore | None:
    """Build a ``SkillStore`` backed by the global session factory.

    Returns ``None`` if no DB session factory is configured (e.g. ephemeral
    test environments), letting the caller skip the registration step
    silently.
    """
    try:
        from deerflow.persistence.engine import get_session_factory
        from deerflow.persistence.skills import make_skill_store

        factory = get_session_factory()
        if factory is None:
            return None
        return make_skill_store(factory)
    except Exception:
        logger.debug("Failed to build default skill store", exc_info=True)
        return None


def _default_agent_store() -> Any | None:
    """Build an ``AgentStore`` backed by the global session factory."""
    try:
        from deerflow.persistence.agents import make_agent_store
        from deerflow.persistence.engine import get_session_factory

        factory = get_session_factory()
        if factory is None:
            return None
        return make_agent_store(factory)
    except Exception:
        logger.debug("Failed to build default agent store", exc_info=True)
        return None


async def _assert_skill_is_agent_authored(name: str) -> None:
    """Refuse to modify skills authored by a human (UI upload / adopt / legacy).

    Even when ownership lines up, we draw a hard line at content the *human*
    curated through the Web UI: uploads, adopted orphan skills, and legacy
    skills with no usage entry (which default to ``source='upload'``).
    Those represent reviewed content the user has explicitly endorsed —
    letting the agent rewrite them risks silent drift away from what was
    approved. Only skills marked ``source='agent'`` (set by
    ``mark_agent_created`` in the ``create`` flow) remain editable so the
    evolution loop can keep refining them.

    Raises ``ValueError`` (mapped to a tool error visible to the LLM) on
    refusal.
    """
    from deerflow.skills.usage import get_entry

    entry = await _to_thread(get_entry, name)
    if entry.get("source") != "agent":
        raise ValueError(
            f"Refused: skill '{name}' was authored by a human via the Web UI "
            f"and cannot be modified by an agent. Ask the owner to edit it "
            f"through the Web UI, or have the user duplicate it to a new "
            f"agent-owned skill first."
        )


async def _assert_agent_may_modify(store: SkillStore, name: str, user_id: str) -> dict[str, Any]:
    """Pre-flight ownership check before an agent-driven write touches a custom skill.

    LocalSkillStorage operates by name only — patch/edit/write_file/remove_file
    and delete all resolve a name to a directory without knowing who owns it.
    Without this guard a malicious or hallucinating agent could overwrite or
    destroy another user's skill (including UI-uploaded skills) just by
    knowing the name. We refuse unless the DB confirms ``user_id`` owns the
    skill outright.

    Returns the DB record so callers that need owner info (e.g. delete
    cascade) can reuse it. Raises ``ValueError`` (mapped to a tool error
    visible to the LLM) on refusal.
    """
    record = await store.get_any(name)
    if record is None:
        # No DB row — could be a legacy/orphan skill. Refuse rather than
        # touch blindly; users should adopt it via /api/skills/reconcile-custom
        # or an admin can clean it up via the Web UI.
        raise ValueError(
            f"Refused: skill '{name}' has no ownership record. Ask a human to adopt or manage it via the Web UI."
        )
    owner = record.get("owner_user_id")
    if owner is None:
        raise ValueError(f"Refused: skill '{name}' is built-in and cannot be modified by an agent.")
    if owner != user_id:
        raise ValueError(f"Refused: skill '{name}' is owned by another user.")
    return record


async def _skill_manage_impl(
    runtime: ToolRuntime[ContextT, ThreadState],
    action: str,
    name: str,
    content: str | None = None,
    path: str | None = None,
    find: str | None = None,
    replace: str | None = None,
    expected_count: int | None = None,
) -> str:
    """Manage custom skills under skills/custom/.

    Args:
        action: One of create, patch, edit, delete, write_file, remove_file.
                For listing or viewing skills, prefer the dedicated
                ``skill_list`` / ``skill_view`` tools — but ``action='list'``
                and ``action='view'`` are accepted here as convenience
                aliases that delegate to those tools.
        name: Skill name in hyphen-case.
        content: New file content for create, edit, or write_file.
        path: Supporting file path for write_file or remove_file.
        find: Existing text to replace for patch.
        replace: Replacement text for patch.
        expected_count: Optional expected number of replacements for patch.
    """
    # Read-only aliases — delegate to the dedicated tools so a model that
    # over-uses skill_manage doesn't trip on Unsupported action errors.
    # Pass the active agent_id through so a custom agent's skill whitelist
    # is enforced on these aliases just like on skill_list/skill_view.
    if action == "list":
        from deerflow.tools.builtins.skill_tools import _resolve_active_agent_id, skill_list_impl

        return await _to_thread(skill_list_impl, _resolve_active_agent_id(runtime))
    if action == "view":
        from deerflow.tools.builtins.skill_tools import _resolve_active_agent_id, skill_view_impl

        return await _to_thread(skill_view_impl, name, _resolve_active_agent_id(runtime))

    name = SkillStorage.validate_skill_name(name)
    lock = _get_lock(name)
    thread_id = _get_thread_id(runtime)
    skill_storage = get_or_new_skill_storage()
    # Resolved up-front so ownership checks in the write-action branches stay
    # one-liners. Cheap when the DB is unconfigured (returns None).
    user_id = get_effective_user_id()
    skill_store = _default_skill_store()

    async with lock:
        if action == "create":
            if await _to_thread(skill_storage.custom_skill_exists, name):
                raise ValueError(f"Custom skill '{name}' already exists.")
            if content is None:
                raise ValueError("content is required for create.")
            await _to_thread(skill_storage.validate_skill_markdown_content, name, content)
            scan = await _scan_or_raise(content, executable=False, location=f"{name}/{SKILL_MD_FILE}")
            await _to_thread(skill_storage.write_custom_skill, name, SKILL_MD_FILE, content)
            await _to_thread(
                skill_storage.append_history,
                name,
                _history_record(action="create", file_path=SKILL_MD_FILE, prev_content=None, new_content=content, thread_id=thread_id, scanner=scan),
            )
            try:
                from deerflow.skills.usage import mark_agent_created
                await _to_thread(mark_agent_created, name)
            except Exception:
                pass
            # Register the new skill in the DB so the web UI listing actually
            # surfaces it (custom skills without a DB row are filtered out by
            # ``GET /api/skills``). Resolve the user_id *here* on the main
            # async stack — contextvars don't propagate into ``to_thread``.
            if skill_store is not None:
                await _ensure_skill_db_registered(skill_store, name, user_id)
            await refresh_skills_system_prompt_cache_async()
            return f"Created custom skill '{name}'."

        if action == "edit":
            await _to_thread(skill_storage.ensure_custom_skill_is_editable, name)
            if skill_store is not None:
                await _assert_agent_may_modify(skill_store, name, user_id)
            await _assert_skill_is_agent_authored(name)
            if content is None:
                raise ValueError("content is required for edit.")
            await _to_thread(skill_storage.validate_skill_markdown_content, name, content)
            scan = await _scan_or_raise(content, executable=False, location=f"{name}/{SKILL_MD_FILE}")
            skill_file = skill_storage.get_custom_skill_file(name)
            prev_content = await _to_thread(skill_file.read_text, encoding="utf-8")
            await _to_thread(skill_storage.write_custom_skill, name, SKILL_MD_FILE, content)
            await _to_thread(
                skill_storage.append_history,
                name,
                _history_record(action="edit", file_path=SKILL_MD_FILE, prev_content=prev_content, new_content=content, thread_id=thread_id, scanner=scan),
            )
            await _bump_patch_best_effort(name)
            await refresh_skills_system_prompt_cache_async()
            return f"Updated custom skill '{name}'."

        if action == "patch":
            await _to_thread(skill_storage.ensure_custom_skill_is_editable, name)
            if skill_store is not None:
                await _assert_agent_may_modify(skill_store, name, user_id)
            await _assert_skill_is_agent_authored(name)
            if find is None or replace is None:
                raise ValueError("find and replace are required for patch.")
            skill_file = skill_storage.get_custom_skill_file(name)
            prev_content = await _to_thread(skill_file.read_text, encoding="utf-8")
            occurrences = prev_content.count(find)
            if occurrences == 0:
                raise ValueError("Patch target not found in SKILL.md.")
            if expected_count is not None and occurrences != expected_count:
                raise ValueError(f"Expected {expected_count} replacements but found {occurrences}.")
            replacement_count = expected_count if expected_count is not None else 1
            new_content = prev_content.replace(find, replace, replacement_count)
            await _to_thread(skill_storage.validate_skill_markdown_content, name, new_content)
            scan = await _scan_or_raise(new_content, executable=False, location=f"{name}/{SKILL_MD_FILE}")
            await _to_thread(skill_storage.write_custom_skill, name, SKILL_MD_FILE, new_content)
            await _to_thread(
                skill_storage.append_history,
                name,
                _history_record(action="patch", file_path=SKILL_MD_FILE, prev_content=prev_content, new_content=new_content, thread_id=thread_id, scanner=scan),
            )
            await _bump_patch_best_effort(name)
            await refresh_skills_system_prompt_cache_async()
            return f"Patched custom skill '{name}' ({replacement_count} replacement(s) applied, {occurrences} match(es) found)."

        if action == "delete":
            # Ownership pre-check: LocalSkillStorage deletes purely by name,
            # so without this an agent could blow away another user's skill
            # just by knowing the name. Raise BEFORE touching the filesystem.
            record: dict[str, Any] | None = None
            if skill_store is not None:
                record = await _assert_agent_may_modify(skill_store, name, user_id)
            await _assert_skill_is_agent_authored(name)

            await _to_thread(
                skill_storage.delete_custom_skill,
                name,
                history_meta=_history_record(
                    action="delete",
                    file_path=SKILL_MD_FILE,
                    prev_content=None,
                    new_content=None,
                    thread_id=thread_id,
                    scanner={"decision": "allow", "reason": "Deletion requested."},
                ),
            )
            # Mirror what ``DELETE /api/skills/custom/{name}`` does: drop the
            # ``.usage.json`` entry and the DB ownership row, then cascade
            # the removal to every agent that referenced this skill so
            # ``config.yaml`` doesn't end up with a dangling reference.
            # Failures are best-effort — the on-disk delete already happened
            # and is authoritative.
            try:
                from deerflow.skills.usage import forget
                await _to_thread(forget, name)
            except Exception:
                logger.debug("Failed to forget usage entry for %r", name, exc_info=True)
            if skill_store is not None:
                try:
                    await skill_store.delete(name, user_id)
                except Exception:
                    logger.debug("Failed to delete DB row for %r", name, exc_info=True)
            agent_store = _default_agent_store()
            if agent_store is not None:
                try:
                    from deerflow.skills.cascade import cascade_skill_unpublished_or_deleted

                    await cascade_skill_unpublished_or_deleted(
                        name,
                        actor_user_id=user_id,
                        operation="delete",
                        skill_owner_user_id=(record.get("owner_user_id") if record else user_id),
                        agent_store=agent_store,
                    )
                except Exception:
                    logger.debug("Cascade failed for deleted skill %r", name, exc_info=True)
            await refresh_skills_system_prompt_cache_async()
            return f"Deleted custom skill '{name}'."

        if action == "write_file":
            await _to_thread(skill_storage.ensure_custom_skill_is_editable, name)
            if skill_store is not None:
                await _assert_agent_may_modify(skill_store, name, user_id)
            await _assert_skill_is_agent_authored(name)
            if path is None or content is None:
                raise ValueError("path and content are required for write_file.")
            target = await _to_thread(skill_storage.ensure_safe_support_path, name, path)
            exists = await _to_thread(target.exists)
            prev_content = await _to_thread(target.read_text, encoding="utf-8") if exists else None
            executable = "scripts/" in path or path.startswith("scripts/")
            scan = await _scan_or_raise(content, executable=executable, location=f"{name}/{path}")
            await _to_thread(skill_storage.write_custom_skill, name, path, content)
            await _to_thread(
                skill_storage.append_history,
                name,
                _history_record(action="write_file", file_path=path, prev_content=prev_content, new_content=content, thread_id=thread_id, scanner=scan),
            )
            return f"Wrote '{path}' for custom skill '{name}'."

        if action == "remove_file":
            await _to_thread(skill_storage.ensure_custom_skill_is_editable, name)
            if skill_store is not None:
                await _assert_agent_may_modify(skill_store, name, user_id)
            await _assert_skill_is_agent_authored(name)
            if path is None:
                raise ValueError("path is required for remove_file.")
            target = await _to_thread(skill_storage.ensure_safe_support_path, name, path)
            if not await _to_thread(target.exists):
                raise FileNotFoundError(f"Supporting file '{path}' not found for skill '{name}'.")
            prev_content = await _to_thread(target.read_text, encoding="utf-8")
            await _to_thread(target.unlink)
            await _to_thread(
                skill_storage.append_history,
                name,
                _history_record(action="remove_file", file_path=path, prev_content=prev_content, new_content=None, thread_id=thread_id, scanner={"decision": "allow", "reason": "Deletion requested."}),
            )
            return f"Removed '{path}' from custom skill '{name}'."

        if await _to_thread(skill_storage.public_skill_exists, name):
            raise ValueError(f"'{name}' is a built-in skill. To customise it, create a new skill with the same name under skills/custom/.")
        raise ValueError(f"Unsupported action '{action}'.")


@tool("skill_manage", parse_docstring=True)
async def skill_manage_tool(
    runtime: ToolRuntime[ContextT, ThreadState],
    action: str,
    name: str,
    content: str | None = None,
    path: str | None = None,
    find: str | None = None,
    replace: str | None = None,
    expected_count: int | None = None,
) -> str:
    """Manage custom skills under skills/custom/.

    Args:
        action: One of create, patch, edit, delete, write_file, remove_file.
        name: Skill name in hyphen-case.
        content: New file content for create, edit, or write_file.
        path: Supporting file path for write_file or remove_file.
        find: Existing text to replace for patch.
        replace: Replacement text for patch.
        expected_count: Optional expected number of replacements for patch.
    """
    return await _skill_manage_impl(
        runtime=runtime,
        action=action,
        name=name,
        content=content,
        path=path,
        find=find,
        replace=replace,
        expected_count=expected_count,
    )


skill_manage_tool.func = _make_sync_tool_wrapper(_skill_manage_impl, "skill_manage")