"""Google Sheets integration - read/write member data via gspread.

Public network-hitting functions are async and delegate the blocking gspread
work to `asyncio.to_thread` so the discord.py event loop is not stalled
(stalled loops drop gateway heartbeats and can disconnect the bot).
Pure-cache helpers (get_cache, find_*) remain sync.
"""

import asyncio
import logging
import re
from dataclasses import dataclass, field

import gspread
from google.oauth2.service_account import Credentials

import config

log = logging.getLogger(__name__)

# Scopes needed: read + write to Sheets
SCOPES = [
    "https://www.googleapis.com/auth/spreadsheets",
    "https://www.googleapis.com/auth/drive",
]

# ---------------------------------------------------------------------------
# Expected sheet columns (header row):
#   Nimi | Organisatsioon | Meil | Discord | User ID | Sünnipäev |
#   Telefon | Valdkond | Roll | Discordis synced? | Groupi lisatud?
#
# - Nimi              : member's real name (used as Discord nickname)
# - Organisatsioon    : organisation value - maps to a Discord role
# - Meil              : email address (read-only for bot)
# - Discord           : Discord username for initial matching
# - User ID           : numeric Discord user ID (bot can populate this)
# - Sünnipäev         : birthday date string (YYYY-MM-DD or MM-DD)
# - Telefon           : phone number (read-only for bot)
# - Valdkond          : field/area value - maps to a Discord role
# - Roll              : role value - maps to a Discord role
# - Discordis synced? : TRUE/FALSE - bot writes this after confirming sync
# - Groupi lisatud?   : group membership flag (managed externally)
# ---------------------------------------------------------------------------

EXPECTED_HEADERS = [
    "Nimi",
    "Organisatsioon",
    "Meil",
    "Discord",
    "User ID",
    "Sünnipäev",
    "Telefon",
    "Valdkond",
    "Roll",
    "Discordis synced?",
    "Groupi lisatud?",
]

_client: gspread.Client | None = None
_worksheet: gspread.Worksheet | None = None

# In-memory cache: list of dicts (one per row)
_cache: list[dict] = []


def _get_worksheet() -> gspread.Worksheet:
    """Authenticate and return the first worksheet of the configured sheet."""
    global _client, _worksheet
    creds = Credentials.from_service_account_file(config.GOOGLE_CREDS_PATH, scopes=SCOPES)
    _client = gspread.authorize(creds)
    spreadsheet = _client.open_by_key(config.SHEET_ID)
    _worksheet = spreadsheet.sheet1
    return _worksheet


def _ensure_headers(ws: gspread.Worksheet) -> None:
    """Verify the header row matches what we expect.

    The production sheet is owner-managed and its header row (row 1) is a
    protected range, so the bot must NOT write to it — attempting to do so
    raises `APIError [400]: You are trying to edit a protected cell or object`
    and aborts the whole refresh. We only log a mismatch so it can be fixed
    by hand; column lookups still work as long as the headers we rely on exist.
    """
    existing = ws.row_values(1)
    if existing != EXPECTED_HEADERS:
        missing = [h for h in EXPECTED_HEADERS if h not in existing]
        log.warning(
            "Sheet header row does not match EXPECTED_HEADERS "
            "(missing/renamed: %s). Expected %s, found %s. "
            "Not writing to the (protected) header row; fix it manually if needed.",
            missing or "none — order/whitespace differs",
            EXPECTED_HEADERS,
            existing,
        )


def _refresh_sync() -> list[dict]:
    global _cache
    ws = _get_worksheet()
    _ensure_headers(ws)
    # head=1: row 1 is the header; row 2 is a formula/stats row - skip it
    records = ws.get_all_records(head=1)
    _cache = records[1:]  # drop the formula row (row 2) from the cache
    return _cache


async def refresh() -> list[dict]:
    """Pull all rows from the sheet into the in-memory cache (non-blocking)."""
    return await asyncio.to_thread(_refresh_sync)


def get_cache() -> list[dict]:
    """Return the current in-memory cache without re-querying."""
    return _cache


def find_member_by_id(discord_id: int) -> dict | None:
    """Look up a member row by Discord user ID."""
    for row in _cache:
        raw = row.get("User ID", "")
        if str(raw).strip() == str(discord_id):
            return row
    return None


def find_member_by_username(username: str) -> dict | None:
    """Look up a member row by Discord username (case-insensitive)."""
    for row in _cache:
        if str(row.get("Discord", "")).strip().lower() == username.lower():
            return row
    return None


def find_member(discord_id: int, username: str) -> dict | None:
    """Try ID first, fall back to username."""
    return find_member_by_id(discord_id) or find_member_by_username(username)


# ---- Write helpers --------------------------------------------------------

def _row_index_for_member(discord_id: int | None = None, username: str | None = None) -> int | None:
    """Return the 1-based sheet row index for a member (header = row 2, data from row 3)."""
    for idx, row in enumerate(_cache):
        if discord_id and str(row.get("User ID", "")).strip() == str(discord_id):
            return idx + 3  # +3 because header is row 2, data starts row 3, idx is 0-based
        if username and str(row.get("Discord", "")).strip().lower() == username.lower():
            return idx + 3
    return None


def _update_cell_for_member_sync(
    discord_id: int | None,
    username: str | None,
    column_name: str,
    value: str,
) -> bool:
    ws = _worksheet or _get_worksheet()
    row_idx = _row_index_for_member(discord_id=discord_id, username=username)
    if row_idx is None:
        return False

    try:
        col_idx = EXPECTED_HEADERS.index(column_name) + 1
    except ValueError:
        return False

    ws.update([[value]], gspread.utils.rowcol_to_a1(row_idx, col_idx),
               value_input_option="USER_ENTERED")

    cache_idx = row_idx - 3
    if 0 <= cache_idx < len(_cache):
        _cache[cache_idx][column_name] = value

    return True


async def update_cell_for_member(
    discord_id: int | None,
    username: str | None,
    column_name: str,
    value: str,
) -> bool:
    """Write a value to a specific column for a member row (non-blocking)."""
    return await asyncio.to_thread(
        _update_cell_for_member_sync, discord_id, username, column_name, value
    )


def _batch_set_synced_sync(updates: list[tuple[int, bool]]) -> None:
    ws = _worksheet or _get_worksheet()
    col_idx = EXPECTED_HEADERS.index("Discordis synced?") + 1
    cells = []
    for discord_id, synced in updates:
        row_idx = _row_index_for_member(discord_id=discord_id)
        if row_idx is None:
            continue
        cells.append(gspread.Cell(row_idx, col_idx, "TRUE" if synced else "FALSE"))
        cache_idx = row_idx - 3
        if 0 <= cache_idx < len(_cache):
            _cache[cache_idx]["Discordis synced?"] = "TRUE" if synced else "FALSE"
    if cells:
        ws.update_cells(cells, value_input_option="USER_ENTERED")


async def batch_set_synced(updates: list[tuple[int, bool]]) -> None:
    """Batch-write 'Discordis synced?' for multiple members (non-blocking)."""
    await asyncio.to_thread(_batch_set_synced_sync, updates)


async def set_user_id(username: str, discord_id: int) -> bool:
    """Write a Discord user ID for a row matched by Discord username."""
    return await update_cell_for_member(
        discord_id=None,
        username=username,
        column_name="User ID",
        value=str(discord_id),
    )


async def set_synced(discord_id: int, synced: bool) -> bool:
    """Mark a member as synced (TRUE) or not (FALSE)."""
    return await update_cell_for_member(
        discord_id=discord_id,
        username=None,
        column_name="Discordis synced?",
        value="TRUE" if synced else "FALSE",
    )


async def update_username(discord_id: int, new_username: str) -> bool:
    """Update the Discord column for a member (keeps sheet in sync with Discord)."""
    return await update_cell_for_member(
        discord_id=discord_id,
        username=None,
        column_name="Discord",
        value=new_username,
    )


def _add_new_member_row_sync(username: str, discord_id: int) -> None:
    ws = _worksheet or _get_worksheet()
    row = [""] * len(EXPECTED_HEADERS)
    row[EXPECTED_HEADERS.index("Discord")] = username
    row[EXPECTED_HEADERS.index("User ID")] = str(discord_id)
    row[EXPECTED_HEADERS.index("Discordis synced?")] = "FALSE"
    ws.append_row(row, value_input_option="USER_ENTERED")
    new_entry = {h: row[i] for i, h in enumerate(EXPECTED_HEADERS)}
    _cache.append(new_entry)


async def add_new_member_row(username: str, discord_id: int) -> None:
    """Append a new row pre-filled with Discord username and User ID (non-blocking)."""
    await asyncio.to_thread(_add_new_member_row_sync, username, discord_id)


# ===========================================================================
# Team registration sheet (a SEPARATE spreadsheet, config.TEAM_SHEET_ID)
# ---------------------------------------------------------------------------
# Unlike the member roster this sheet is NOT a single clean table: it stacks
# several game sections (CS2, LoL, ...) - each with merged title/description
# rows, its own header row, and a block of team rows - across one or more tabs.
# So we read raw cell values (get_all_values) and scan for header rows rather
# than relying on get_all_records, which requires one rectangular table.
#
# Each team's players live in one "Lineup" cell, comma-joined, every nickname
# suffixed with a citizenship marker like "(EST)". Those nicknames ARE the
# players' Discord usernames; the citizenship is used only as a delimiter
# (a nickname may itself contain commas) and then discarded.
# ===========================================================================

# Matches a citizenship marker such as "(EST)" / "(LAT)". Used to split a
# lineup cell into individual players, then thrown away.
_CITIZENSHIP_RE = re.compile(r"\(\s*[A-Za-z]{2,4}\s*\)")

_TEAM_NAME_HEADER = "team name"
_LINEUP_HEADER_PREFIX = "lineup"

# Team-sheet caches (mirrors the member-roster cache above)
_team_roster: dict[str, list[str]] = {}   # team name -> [Discord username, ...]
_team_by_username: dict[str, str] = {}     # normalized username -> team name
_team_names: set[str] = set()              # universe of all team names
_team_divider: dict[str, int] = {}         # team name -> divider role ID


@dataclass(frozen=True)
class TeamSection:
    """One game's block of teams within a tab, plus the title row above it.

    The title ("TipiLAN 2026 CS2 Registration Log") is the only thing that says
    which game and year a block belongs to - the header and team rows below it
    carry neither - so it is what :func:`resolve_divider` matches against.
    """
    title: str = ""
    rosters: dict[str, list[str]] = field(default_factory=dict)


def parse_lineup(cell: str) -> list[str]:
    """Split one 'Lineup' cell into player nicknames (Discord usernames).

    Players are delimited by their trailing citizenship marker, e.g.
        'TFT (EST), nqmm (EST), sn1rk (EST)' -> ['TFT', 'nqmm', 'sn1rk']
    Splitting on the marker (not on commas) keeps nicknames that themselves
    contain commas or semicolons intact. Falls back to comma-splitting when a
    cell carries no citizenship markers at all.
    """
    cell = str(cell).strip()
    if not cell:
        return []
    names: list[str] = []
    last = 0
    matched = False
    for m in _CITIZENSHIP_RE.finditer(cell):
        matched = True
        chunk = cell[last:m.start()].strip().strip(",;").strip()
        if chunk:
            names.append(chunk)
        last = m.end()
    if not matched:
        return [p.strip() for p in cell.split(",") if p.strip()]
    tail = cell[last:].strip().strip(",;").strip()  # stray name after last marker
    if tail:
        names.append(tail)
    return names


def _find_col(row: list, matches) -> int | None:
    for idx, cell in enumerate(row):
        if matches(str(cell)):
            return idx
    return None


def _cell(row: list, idx: int) -> str:
    return str(row[idx]) if 0 <= idx < len(row) else ""


def _merged_title(row: list) -> str | None:
    """Return a row's lone non-empty cell - a merged section title - else None.

    A fully blank row returns None rather than "", so blank separators between
    sections do not wipe the title we are holding for the next header row.
    """
    values = [str(c).strip() for c in row if str(c).strip()]
    return values[0] if len(values) == 1 else None


def parse_team_sections(rows: list[list]) -> list[TeamSection]:
    """Extract each game's block of teams from a tab's raw rows, with its title.

    Scans for every header row that has both a 'Team Name' and a 'Lineup...'
    column, then reads the rows beneath it (using that section's own column
    positions) until the team-name column goes blank or a new header appears.
    Handles multiple stacked sections with differing layouts in one tab, and
    tags each with the most recent merged title row seen above it.
    """
    sections: list[TeamSection] = []
    title = ""
    i, n = 0, len(rows)
    while i < n:
        name_col = _find_col(rows[i], lambda c: c.strip().lower() == _TEAM_NAME_HEADER)
        lineup_col = _find_col(rows[i], lambda c: c.strip().lower().startswith(_LINEUP_HEADER_PREFIX))
        if name_col is None or lineup_col is None:
            if (text := _merged_title(rows[i])) is not None:
                title = text
            i += 1
            continue
        rosters: dict[str, list[str]] = {}
        i += 1  # move past the header into the data block
        while i < n:
            team = _cell(rows[i], name_col).strip()
            if not team or team.lower() == _TEAM_NAME_HEADER:
                break  # blank team-name (or a new header) ends this section
            players = parse_lineup(_cell(rows[i], lineup_col))
            if players:
                rosters.setdefault(team, []).extend(players)
            i += 1
        if rosters:
            sections.append(TeamSection(title=title, rosters=rosters))
        title = ""  # consumed - do not leak it onto the next section
    return sections


def parse_team_rosters(rows: list[list]) -> dict[str, list[str]]:
    """Flatten every section in a tab into {team_name: [nickname, ...]}."""
    rosters: dict[str, list[str]] = {}
    for section in parse_team_sections(rows):
        for team, players in section.rosters.items():
            rosters.setdefault(team, []).extend(players)
    return rosters


def resolve_divider(title: str, dividers: dict[str, int] | None = None) -> int | None:
    """Return the divider role ID configured for a section title, if any.

    A ``TEAM_DIVIDER_<SUFFIX>`` entry matches when every underscore-separated
    part of its suffix appears as a whole word in the title, so ``CS2`` matches
    a CS2 section from any year while ``CS2_2026`` matches only the 2026 one.
    The most specific match (most parts) wins, which lets a year-scoped entry
    override a general one for the same game.
    """
    if dividers is None:
        dividers = config.TEAM_DIVIDERS
    haystack = title.lower()
    best_id: int | None = None
    best_parts = 0
    for suffix, role_id in dividers.items():
        parts = [p for p in suffix.split("_") if p]
        if not parts or len(parts) <= best_parts:
            continue
        if all(re.search(rf"\b{re.escape(p)}\b", haystack) for p in parts):
            best_id, best_parts = role_id, len(parts)
    return best_id


def build_username_index(rosters: dict[str, list[str]]) -> dict[str, str]:
    """Invert {team: [usernames]} into {normalized username: team}.

    If the same username appears on two teams the last one wins and a warning
    is logged (a person is expected to be on exactly one team).
    """
    index: dict[str, str] = {}
    for team, players in rosters.items():
        for player in players:
            key = player.strip().lower()
            if not key:
                continue
            if key in index and index[key] != team:
                log.warning(
                    "Player %r appears on both %r and %r; using %r",
                    player, index[key], team, team,
                )
            index[key] = team
    return index


def _refresh_teams_sync() -> dict[str, list[str]]:
    global _team_roster, _team_by_username, _team_names, _team_divider
    creds = Credentials.from_service_account_file(config.GOOGLE_CREDS_PATH, scopes=SCOPES)
    client = gspread.authorize(creds)
    spreadsheet = client.open_by_key(config.TEAM_SHEET_ID)

    rosters: dict[str, list[str]] = {}
    dividers: dict[str, int] = {}
    for ws in spreadsheet.worksheets():
        for section in parse_team_sections(ws.get_all_values()):
            divider = resolve_divider(section.title)
            for team, players in section.rosters.items():
                rosters.setdefault(team, []).extend(players)
                if divider:
                    dividers[team] = divider

    _team_roster = rosters
    _team_by_username = build_username_index(rosters)
    _team_names = set(rosters)
    _team_divider = dividers
    return rosters


async def refresh_teams() -> dict[str, list[str]]:
    """Reload the team registration sheet into the in-memory team caches.

    No-op returning {} when TEAM_SHEET_ID is not configured, so the whole
    feature can be left switched off without touching sync behaviour.
    """
    if not config.TEAM_SHEET_ID:
        return {}
    return await asyncio.to_thread(_refresh_teams_sync)


def get_team_for_username(username: str) -> str | None:
    """Return the team a Discord username is registered on, or None."""
    return _team_by_username.get(str(username).strip().lower())


def all_team_names() -> set[str]:
    """Every team name known from the registration sheet (the role universe)."""
    return set(_team_names)


def get_team_rosters() -> dict[str, list[str]]:
    """Current {team: [usernames]} cache (mainly for diagnostics/tests)."""
    return _team_roster


def get_team_dividers() -> dict[str, int]:
    """Current {team: divider role ID} cache.

    Only teams whose section title matched a configured TEAM_DIVIDER_* entry
    appear here, so an empty dict means positioning is switched off.
    """
    return dict(_team_divider)