#!/usr/bin/env python3
"""Shared handlers for the /memory and /skills write-approval subcommands.

Both the interactive CLI (``cli.py``) and the gateway (``gateway/run.py``) call
into this module so the pending-review UX (list / approve / reject / diff /
mode) lives in one place. Each caller owns only its surface concerns:
formatting the returned text and, for the gateway, persisting config + evicting
the cached agent on a mode change.

Every public handler returns a plain text string suitable for both a terminal
and a chat message. Skill diffs are intentionally NOT inlined here — the
``diff`` handler returns the full diff for the CLI pager, but on a messaging
platform the gateway truncates it and points the user at the dashboard / file.
"""

from __future__ import annotations

import json
from typing import List, Optional

from tools import write_approval as wa

_VALID_MODES = (wa.MODE_ON, wa.MODE_OFF, wa.MODE_APPROVE)


# ---------------------------------------------------------------------------
# Formatting helpers
# ---------------------------------------------------------------------------

def _fmt_pending_list(subsystem: str) -> str:
    records = wa.list_pending(subsystem)
    if not records:
        return f"No pending {subsystem} writes."
    lines = [f"Pending {subsystem} writes ({len(records)}):"]
    for r in records:
        origin = r.get("origin", "foreground")
        tag = " [auto]" if origin == "background_review" else ""
        lines.append(f"  {r['id']}{tag}  {r.get('summary', '')}")
    where = "/{s} approve <id>".format(s=subsystem)
    lines.append("")
    lines.append(f"Apply: {where}   Reject: /{subsystem} reject <id>")
    if subsystem == wa.SKILLS:
        lines.append("Review full diff: /skills diff <id>")
    return "\n".join(lines)


# ---------------------------------------------------------------------------
# Subcommand dispatch
# ---------------------------------------------------------------------------

def handle_pending_subcommand(
    subsystem: str,
    args: List[str],
    *,
    memory_store=None,
    set_mode_fn=None,
) -> Optional[str]:
    """Dispatch a /memory or /skills subcommand.

    Args:
        subsystem: ``memory`` or ``skills``.
        args: tokens after the slash command (e.g. ``["approve", "a1b2"]``).
        memory_store: live MemoryStore for applying approved memory writes
            (CLI passes ``self.agent._memory_store``; gateway applies against a
            freshly loaded store).
        set_mode_fn: optional callable ``(mode: str) -> None`` that persists the
            new write_mode to config (gateway provides this; CLI uses its own
            ``save_config_value`` and passes a closure).

    Returns a text string to show the user. Returns None when the args are not
    a write-approval subcommand (caller falls through to its other handling,
    e.g. /skills search).
    """
    if not args:
        # Bare /memory or /skills with no sub → show pending + current mode.
        mode = wa.get_write_mode(subsystem)
        return f"{subsystem}.write_mode = {mode}\n\n" + _fmt_pending_list(subsystem)

    sub = args[0].lower()
    rest = args[1:]

    if sub == "pending":
        return _fmt_pending_list(subsystem)

    if sub in {"approve", "apply"}:
        return _approve(subsystem, rest, memory_store)

    if sub in {"reject", "deny", "drop"}:
        return _reject(subsystem, rest)

    if sub == "diff" and subsystem == wa.SKILLS:
        return _diff(rest)

    if sub == "mode":
        return _set_mode(subsystem, rest, set_mode_fn)

    return None  # not ours — caller handles


def _resolve_one(subsystem: str, rest: List[str]):
    if not rest:
        return None, f"Usage: /{subsystem} approve|reject <id>  (or 'all')"
    return rest[0], None


def _approve(subsystem: str, rest: List[str], memory_store) -> str:
    target, err = _resolve_one(subsystem, rest)
    if err or target is None:
        return err or f"Usage: /{subsystem} approve <id>"

    records = wa.list_pending(subsystem)
    if not records:
        return f"No pending {subsystem} writes."

    if target.lower() == "all":
        targets = list(records)
    else:
        rec = wa.get_pending(subsystem, target)
        if not rec:
            return f"No pending {subsystem} write with id '{target}'."
        targets = [rec]

    applied, failed = 0, []
    for rec in targets:
        ok, msg = _apply_one(subsystem, rec, memory_store)
        if ok:
            wa.discard_pending(subsystem, rec["id"])
            applied += 1
        else:
            failed.append(f"{rec['id']}: {msg}")

    out = [f"Approved {applied} {subsystem} write(s)."]
    if failed:
        out.append("Failed:")
        out.extend(f"  {f}" for f in failed)
    return "\n".join(out)


def _apply_one(subsystem: str, rec, memory_store):
    payload = rec.get("payload", {})
    try:
        if subsystem == wa.MEMORY:
            if memory_store is None:
                return False, "memory store unavailable"
            from tools.memory_tool import apply_memory_pending
            result = apply_memory_pending(payload, memory_store)
            return bool(result.get("success")), result.get("error", "")
        else:
            from tools.skill_manager_tool import apply_skill_pending
            result = json.loads(apply_skill_pending(payload))
            return bool(result.get("success")), result.get("error", "")
    except Exception as e:
        return False, str(e)


def _reject(subsystem: str, rest: List[str]) -> str:
    target, err = _resolve_one(subsystem, rest)
    if err or target is None:
        return err or f"Usage: /{subsystem} reject <id>"
    if target.lower() == "all":
        n = 0
        for rec in wa.list_pending(subsystem):
            if wa.discard_pending(subsystem, rec["id"]):
                n += 1
        return f"Rejected {n} pending {subsystem} write(s)."
    if wa.discard_pending(subsystem, target):
        return f"Rejected pending {subsystem} write '{target}'."
    return f"No pending {subsystem} write with id '{target}'."


def _diff(rest: List[str]) -> str:
    if not rest:
        return "Usage: /skills diff <id>"
    rec = wa.get_pending(wa.SKILLS, rest[0])
    if not rec:
        return f"No pending skill write with id '{rest[0]}'."
    diff = wa.skill_pending_diff(rec)
    header = f"# Pending skill write {rec['id']}: {rec.get('summary', '')}\n"
    return header + "\n" + diff


def _set_mode(subsystem: str, rest: List[str], set_mode_fn) -> str:
    if not rest:
        cur = wa.get_write_mode(subsystem)
        return (f"{subsystem}.write_mode = {cur}\n"
                f"Set with: /{subsystem} mode <on|off|approve>")
    mode = rest[0].lower()
    if mode not in _VALID_MODES:
        return f"Invalid mode '{mode}'. Use: on, off, approve."
    if set_mode_fn is None:
        return (f"To change {subsystem} write mode, run:\n"
                f"  hermes config set {subsystem}.write_mode {mode}")
    try:
        set_mode_fn(mode)
    except Exception as e:
        return f"Failed to set {subsystem}.write_mode: {e}"
    return f"{subsystem}.write_mode set to '{mode}'."