"""
Account settings router.

Routes:
  GET  /settings               → show account settings page (requires auth)
  POST /settings/password      → change password
  POST /settings/username      → rename the user account (forces re-login)
  POST /settings/persona/rename → rename a persona directory
"""

import logging
import re
from pathlib import Path

import jwt
from fastapi import APIRouter, Form, Request
from fastapi.responses import HTMLResponse, RedirectResponse

from auth_utils import COOKIE_NAME, decode_token, check_credentials, set_password, _read_auth, _write_auth
from persona import list_user_personas
from config import settings as app_settings

_SLUG_RE = re.compile(r"^[a-z_][a-z0-9_-]{0,31}$")

logger = logging.getLogger(__name__)
router = APIRouter()

_STATIC = Path(__file__).parent.parent / "static"


def _get_session_user(request: Request) -> str | None:
    token = request.cookies.get(COOKIE_NAME)
    if not token:
        return None
    try:
        return decode_token(token)
    except jwt.InvalidTokenError:
        return None


def _settings_page(username: str, personas: list[str], success: str = "", error: str = "") -> str:
    html = (_STATIC / "settings.html").read_text()
    html = html.replace("{{ username }}", username)

    # Connected Google account
    auth_data    = _read_auth(username)
    google_email = auth_data.get("google_email") or ""
    html = html.replace("{{ google_email }}", google_email)

    # Gemini API key — show masked hint only, never the full key
    gemini_key = auth_data.get("gemini_api_key") or ""
    if gemini_key:
        hint = f"Saved (…{gemini_key[-4:]})"
    else:
        hint = "Using server key"
    html = html.replace("{{ gemini_key_hint }}", hint)
    html = html.replace("{{ gemini_key_set }}", "true" if gemini_key else "false")

    persona_items = "\n".join(
        f'''<li>
          <a href="/{username}/{p}" class="persona-link">{p}</a>
          <button class="persona-rename-toggle" data-persona="{p}" title="Rename">✏</button>
          <form class="persona-rename-form" data-persona="{p}"
                method="POST" action="/settings/persona/rename" style="display:none">
            <input type="hidden" name="old_name" value="{p}">
            <input type="text" name="new_name" value="{p}"
                   pattern="[a-z_][a-z0-9_\\-]{{0,31}}" required>
            <button type="submit">Save</button>
            <button type="button" class="persona-rename-cancel">Cancel</button>
          </form>
        </li>''' for p in personas
    )
    html = html.replace("{{ persona_items }}", persona_items or "<li><em>No personas yet.</em></li>")
    back_persona = personas[0] if personas else ""
    html = html.replace("{{ back_href }}", f"/{username}/{back_persona}" if back_persona else "/")
    html = html.replace("{{ help_href }}", f"/help?persona={back_persona}" if back_persona else "/help")
    if success:
        html = html.replace("<!-- SUCCESS -->", f'<p class="success">{success}</p>')
    if error:
        html = html.replace("<!-- ERROR -->", f'<p class="error">{error}</p>')
    return html


@router.get("/settings", include_in_schema=False)
async def settings_page(request: Request):
    username = _get_session_user(request)
    if not username:
        return RedirectResponse("/login", status_code=302)
    personas = list_user_personas(username)
    return HTMLResponse(_settings_page(username, personas))


@router.post("/settings/password", include_in_schema=False)
async def change_password(
    request: Request,
    current_password: str = Form(...),
    new_password: str = Form(...),
    confirm_password: str = Form(...),
):
    username = _get_session_user(request)
    if not username:
        return RedirectResponse("/login", status_code=302)

    personas = list_user_personas(username)

    if not check_credentials(username, current_password):
        return HTMLResponse(_settings_page(username, personas, error="Current password is incorrect."))

    if len(new_password) < 8:
        return HTMLResponse(_settings_page(username, personas, error="New password must be at least 8 characters."))

    if new_password != confirm_password:
        return HTMLResponse(_settings_page(username, personas, error="New passwords do not match."))

    set_password(username, new_password)
    logger.info("password changed: %s", username)
    return HTMLResponse(_settings_page(username, personas, success="Password updated successfully."))


@router.post("/settings/username", include_in_schema=False)
async def rename_username(
    request: Request,
    new_username: str = Form(...),
):
    username = _get_session_user(request)
    if not username:
        return RedirectResponse("/login", status_code=302)

    personas = list_user_personas(username)
    new_username = new_username.strip().lower()

    if not _SLUG_RE.match(new_username):
        return HTMLResponse(_settings_page(
            username, personas,
            error="Invalid username. Use lowercase letters, digits, _ or - only."))

    if new_username == username:
        return RedirectResponse("/settings", status_code=302)

    home_root = app_settings.home_root()
    old_dir = home_root / username
    new_dir = home_root / new_username

    if new_dir.exists():
        return HTMLResponse(_settings_page(
            username, personas,
            error=f"Username '{new_username}' is already taken."))

    old_dir.rename(new_dir)
    logger.info("user renamed: %s → %s", username, new_username)

    # Clear the auth cookie — old JWT now refers to a non-existent user
    resp = RedirectResponse("/login?msg=username_changed", status_code=302)
    resp.delete_cookie(COOKIE_NAME)
    return resp


@router.post("/settings/gemini-key", include_in_schema=False)
async def save_gemini_key(
    request: Request,
    gemini_api_key: str = Form(...),
):
    username = _get_session_user(request)
    if not username:
        return RedirectResponse("/login", status_code=302)

    personas = list_user_personas(username)
    gemini_api_key = gemini_api_key.strip()

    data = _read_auth(username)
    if gemini_api_key:
        data["gemini_api_key"] = gemini_api_key
        msg = "Gemini API key saved."
    else:
        data.pop("gemini_api_key", None)
        msg = "Gemini API key removed — using server key."
    _write_auth(username, data)
    logger.info("gemini key updated: %s", username)
    return HTMLResponse(_settings_page(username, personas, success=msg))


@router.post("/settings/persona/rename", include_in_schema=False)
async def rename_persona(
    request: Request,
    old_name: str = Form(...),
    new_name: str = Form(...),
):
    username = _get_session_user(request)
    if not username:
        return RedirectResponse("/login", status_code=302)

    personas = list_user_personas(username)
    new_name = new_name.strip().lower()

    if not _SLUG_RE.match(new_name):
        return HTMLResponse(_settings_page(
            username, personas,
            error="Invalid name. Use lowercase letters, digits, _ or - only."))

    if new_name == old_name:
        return RedirectResponse("/settings", status_code=302)

    persona_root = app_settings.home_root() / username / "persona"
    old_dir = persona_root / old_name
    new_dir = persona_root / new_name

    if not old_dir.exists():
        return HTMLResponse(_settings_page(username, personas, error=f"Persona '{old_name}' not found."))

    if new_dir.exists():
        return HTMLResponse(_settings_page(
            username, personas,
            error=f"A persona named '{new_name}' already exists."))

    old_dir.rename(new_dir)
    logger.info("persona renamed: %s/%s → %s", username, old_name, new_name)
    return RedirectResponse("/settings", status_code=302)