"""YouTube community post flow.

    1. navigate youtube.com
    2. click button[aria-label="Create"]
    3. click "Create post" in the dropdown
    4. wait for the redirect to the channel posts page
    5. type into #contenteditable-root
    6. click Post
    7. the editor emptying / the post appearing = success

Community posts require a channel that has them enabled. Video upload
(post_youtube_video in the proposal) is NOT built here — the brief scoped this
module to the community post.
"""

import asyncio

from ..cdp import CDPError, human_delay
from . import guard, require_text, validate_media
from ..selectors import YOUTUBE as S

PLATFORM = "yt"


async def post(cdp_client, text, media_path=None, options=None):
    options = options or {}
    require_text(PLATFORM, text)
    validate_media(media_path)
    if media_path:
        # Community posts do take images, but that flow is unmapped. Refuse
        # rather than drop the media on the floor.
        raise CDPError(
            "yt: media on community posts is not implemented (the image-attach "
            "flow has not been mapped live). Post text-only, or use a platform "
            "whose media flow is built."
        )

    tab, reused = await cdp_client.get_or_open_tab(S["url"], "youtube.com")
    if reused:
        await tab.eval("window.onbeforeunload = null")
        await tab.navigate(S["url"])
    return await guard(PLATFORM, tab, _flow(tab, text))


async def _flow(tab, text):
    await tab.wait_for(S["create_button"])
    await human_delay()
    await tab.click(S["create_button"])

    # TODO: VALIDATE LIVE — the dropdown item text and element type.
    await _wait_for_js(tab, S["create_post_item_js"], "the 'Create post' menu item")
    await tab.click_js(S["create_post_item_js"])

    # Step 4: YouTube navigates to the channel's posts page.
    await tab.wait_for_load(timeout=30.0)
    await tab.wait_for(S["editor"], timeout=30.0)

    # #contenteditable-root is a YouTube custom editor: it listens to real key
    # events, so type per-char rather than insertText.
    # TODO: VALIDATE LIVE — whether insertText alone enables the Post button.
    await tab.type_text(S["editor"], text, per_char=True)

    if await tab.exists(S["post_button"]):
        await tab.click(S["post_button"])
    else:
        await tab.click_js(S["post_button_js"])

    # TODO: VALIDATE LIVE — success marker. The editor going empty is the
    # cheapest observable signal; the proposal says "post appears".
    await _wait_for_editor_empty(tab)


async def _wait_for_js(tab, expression, what, timeout=20.0):
    deadline = asyncio.get_running_loop().time() + timeout
    while asyncio.get_running_loop().time() < deadline:
        if await tab.eval("!!(%s)" % expression):
            return
        await asyncio.sleep(0.25)
    raise CDPError(f"yt: {what} did not appear within {timeout}s")


async def _wait_for_editor_empty(tab, timeout=30.0):
    deadline = asyncio.get_running_loop().time() + timeout
    while asyncio.get_running_loop().time() < deadline:
        text = await tab.eval(
            "(() => { const e = document.querySelector('%s');"
            " return e ? e.innerText.trim() : null; })()" % S["editor"]
        )
        if text == "":
            return
        await asyncio.sleep(0.5)
    raise CDPError("yt: editor still holds text 30s after clicking Post")


async def check_login(cdp_client):
    tab, reused = await cdp_client.get_or_open_tab(S["url"], "youtube.com")
    if reused:
        await tab.eval("window.onbeforeunload = null")
        await tab.navigate(S["url"])
    await asyncio.sleep(5)
    if await tab.exists(S["login_marker"]):
        return False
    return await tab.eval(
        "!!document.querySelector('#avatar-btn, button#avatar-btn,"
        " ytd-topbar-menu-button-renderer #avatar-btn')"
    )