"""Login identifiers, address verification, and one-time reset links."""
from __future__ import annotations

import hashlib
import os
import re
import secrets
import uuid
from datetime import datetime, timedelta

from fastapi import HTTPException

from auth import hash_password
from db import row_to_dict

USERNAME_RE = re.compile(r"^[a-z0-9._]{3,32}$")
PUBLIC_COLUMNS = (
    "id",
    "email",
    "name",
    "role",
    "status",
    "tier_id",
    "created",
    "username",
    "secondary_email",
    "email_verified_at",
    "secondary_email_verified_at",
    "pending_email",
    "pending_secondary_email",
)
FORGOT_MESSAGE = (
    "Wenn ein Konto zu dieser Angabe existiert, wurde ein Link an die verifizierten Adressen gesendet."
)
RESET_MINUTES = 60
VERIFY_HOURS = 24
LINK_LIMIT = 3


def utc_stamp(moment: datetime | None = None) -> str:
    current = moment or datetime.utcnow()
    return current.strftime("%Y-%m-%d %H:%M:%S")


def hash_token(token: str) -> str:
    return hashlib.sha256(token.encode()).hexdigest()


def app_base_url() -> str:
    return (os.environ.get("APP_URL") or "http://localhost:5188").rstrip("/")


def profile_view(row: dict | None) -> dict | None:
    if not row:
        return None
    data = {key: row.get(key) for key in PUBLIC_COLUMNS}
    data["email_verified"] = bool(row.get("email_verified_at"))
    data["secondary_email_verified"] = bool(row.get("secondary_email_verified_at"))
    return data


def normalize_email(value: str) -> str:
    email = (value or "").strip().lower()
    if "@" not in email or email.startswith("@") or email.endswith("@") or " " in email or email.count("@") != 1:
        raise HTTPException(400, "E-Mail-Adresse ist ungültig")
    local, domain = email.split("@", 1)
    if not local or "." not in domain:
        raise HTTPException(400, "E-Mail-Adresse ist ungültig")
    return email


def normalize_username(value: str) -> str:
    username = (value or "").strip().lower()
    if not USERNAME_RE.match(username):
        raise HTTPException(400, "Benutzername: 3–32 Zeichen, Buchstaben, Ziffern, Punkt oder Unterstrich")
    return username


def find_by_login(conn, identifier: str) -> dict | None:
    key = (identifier or "").strip().lower()
    if not key:
        return None
    return row_to_dict(
        conn.execute(
            """
            SELECT * FROM profiles
            WHERE lower(email) = ? OR lower(COALESCE(username, '')) = ?
            """,
            (key, key),
        ).fetchone()
    )


def _owner_of_address(conn, email: str, exclude_id: str | None) -> dict | None:
    return row_to_dict(
        conn.execute(
            """
            SELECT id FROM profiles
            WHERE (
                lower(email) = ?
                OR lower(COALESCE(secondary_email, '')) = ?
                OR lower(COALESCE(pending_email, '')) = ?
                OR lower(COALESCE(pending_secondary_email, '')) = ?
            )
            AND id != COALESCE(?, '')
            """,
            (email, email, email, email, exclude_id or ""),
        ).fetchone()
    )


def assert_address_free(conn, email: str, exclude_id: str | None) -> None:
    if _owner_of_address(conn, email, exclude_id):
        raise HTTPException(409, "E-Mail ist bereits vergeben")


def assert_username_free(conn, username: str, exclude_id: str | None) -> None:
    row = conn.execute(
        """
        SELECT id FROM profiles
        WHERE lower(COALESCE(username, '')) = ? AND id != COALESCE(?, '')
        """,
        (username, exclude_id or ""),
    ).fetchone()
    if row:
        raise HTTPException(409, "Benutzername ist bereits vergeben")


def _recent_count(conn, table: str, profile_id: str) -> int:
    cutoff = utc_stamp(datetime.utcnow() - timedelta(hours=1))
    if table not in {"password_reset_tokens", "email_verification_tokens"}:
        raise HTTPException(500, "Unbekannte Token-Tabelle")
    row = conn.execute(
        f"SELECT COUNT(*) AS n FROM {table} WHERE profile_id = ? AND created > ?",
        (profile_id, cutoff),
    ).fetchone()
    return int(row["n"])


def issue_password_reset(conn, profile_id: str) -> str | None:
    if _recent_count(conn, "password_reset_tokens", profile_id) >= LINK_LIMIT:
        return None
    raw = secrets.token_urlsafe(32)
    now = datetime.utcnow()
    conn.execute(
        """
        INSERT INTO password_reset_tokens (id, profile_id, token_hash, expires_at, created)
        VALUES (?, ?, ?, ?, ?)
        """,
        (
            str(uuid.uuid4()),
            profile_id,
            hash_token(raw),
            utc_stamp(now + timedelta(minutes=RESET_MINUTES)),
            utc_stamp(now),
        ),
    )
    return raw


def issue_verification(conn, profile_id: str, purpose: str, email: str) -> str | None:
    if purpose not in {"primary", "secondary"}:
        raise HTTPException(400, "Unbekannter Verifikationszweck")
    if _recent_count(conn, "email_verification_tokens", profile_id) >= LINK_LIMIT:
        return None
    raw = secrets.token_urlsafe(32)
    now = datetime.utcnow()
    conn.execute(
        """
        INSERT INTO email_verification_tokens
            (id, profile_id, purpose, email, token_hash, expires_at, created)
        VALUES (?, ?, ?, ?, ?, ?, ?)
        """,
        (
            str(uuid.uuid4()),
            profile_id,
            purpose,
            email,
            hash_token(raw),
            utc_stamp(now + timedelta(hours=VERIFY_HOURS)),
            utc_stamp(now),
        ),
    )
    return raw


def reset_link(token: str) -> str:
    return f"{app_base_url()}/reset-password?token={token}"


def verify_link(token: str) -> str:
    return f"{app_base_url()}/verify-email?token={token}"


def reset_message(token: str) -> tuple[str, str]:
    body = (
        "Über diesen Link setzt du das Passwort für Kanshō zurück.\n\n"
        f"{reset_link(token)}\n\n"
        "Der Link gilt 60 Minuten und kann nur einmal verwendet werden. "
        "Wenn du das nicht angefordert hast, ignoriere diese Nachricht."
    )
    return "Kanshō – Passwort zurücksetzen", body


def verify_message(token: str) -> tuple[str, str]:
    body = (
        "Über diesen Link bestätigst du eine E-Mail-Adresse für Kanshō.\n\n"
        f"{verify_link(token)}\n\n"
        "Der Link gilt 24 Stunden und kann nur einmal verwendet werden."
    )
    return "Kanshō – E-Mail-Adresse bestätigen", body


def change_notice() -> tuple[str, str]:
    body = (
        "Für dieses Kanshō-Konto wurde eine Änderung der E-Mail-Adresse angefordert. "
        "Wenn du das nicht warst, setze das Passwort zurück."
    )
    return "Kanshō – Änderung der E-Mail-Adresse", body


def verified_reset_recipients(profile: dict) -> list[str]:
    recipients: list[str] = []
    if profile.get("email_verified_at") and profile.get("email"):
        recipients.append(profile["email"])
    if profile.get("secondary_email_verified_at") and profile.get("secondary_email"):
        recipients.append(profile["secondary_email"])
    return recipients


def admin_reset_recipients(profile: dict) -> list[str]:
    recipients: list[str] = []
    if profile.get("email"):
        recipients.append(profile["email"])
    if profile.get("secondary_email_verified_at") and profile.get("secondary_email"):
        recipients.append(profile["secondary_email"])
    return recipients


def notice_recipients(profile: dict) -> list[str]:
    return verified_reset_recipients(profile)


def load_profile(conn, profile_id: str) -> dict | None:
    return row_to_dict(conn.execute("SELECT * FROM profiles WHERE id = ?", (profile_id,)).fetchone())


def consume_password_reset(conn, token: str, password: str) -> None:
    if len(password or "") < 4:
        raise HTTPException(400, "Passwort muss mind. 4 Zeichen haben")
    now = utc_stamp()
    row = row_to_dict(
        conn.execute(
            """
            SELECT * FROM password_reset_tokens
            WHERE token_hash = ? AND used_at IS NULL AND expires_at > ?
            """,
            (hash_token(token.strip()), now),
        ).fetchone()
    )
    if not row:
        raise HTTPException(400, "Ungültiger oder abgelaufener Link")
    conn.execute(
        "UPDATE profiles SET password_hash = ? WHERE id = ?",
        (hash_password(password), row["profile_id"]),
    )
    conn.execute(
        "UPDATE password_reset_tokens SET used_at = ? WHERE id = ?",
        (now, row["id"]),
    )
    conn.execute("DELETE FROM sessions WHERE profile_id = ?", (row["profile_id"],))


def consume_verification(conn, token: str) -> dict:
    now = utc_stamp()
    row = row_to_dict(
        conn.execute(
            """
            SELECT * FROM email_verification_tokens
            WHERE token_hash = ? AND used_at IS NULL AND expires_at > ?
            """,
            (hash_token(token.strip()), now),
        ).fetchone()
    )
    if not row:
        raise HTTPException(400, "Ungültiger oder abgelaufener Link")
    profile = load_profile(conn, row["profile_id"])
    if not profile:
        raise HTTPException(400, "Ungültiger oder abgelaufener Link")
    purpose = row["purpose"]
    address = row["email"]
    if purpose == "primary":
        pending = (profile.get("pending_email") or "").strip().lower()
        current = (profile.get("email") or "").strip().lower()
        if pending:
            if address != pending:
                raise HTTPException(400, "Ungültiger oder abgelaufener Link")
            assert_address_free(conn, address, profile["id"])
            conn.execute(
                """
                UPDATE profiles
                SET email = ?, email_verified_at = ?, pending_email = NULL
                WHERE id = ?
                """,
                (address, now, profile["id"]),
            )
            conn.execute("DELETE FROM sessions WHERE profile_id = ?", (profile["id"],))
        elif address == current:
            conn.execute(
                "UPDATE profiles SET email_verified_at = ? WHERE id = ?",
                (now, profile["id"]),
            )
        else:
            raise HTTPException(400, "Ungültiger oder abgelaufener Link")
    elif purpose == "secondary":
        pending = (profile.get("pending_secondary_email") or "").strip().lower()
        current = (profile.get("secondary_email") or "").strip().lower()
        if pending:
            if address != pending:
                raise HTTPException(400, "Ungültiger oder abgelaufener Link")
            assert_address_free(conn, address, profile["id"])
            conn.execute(
                """
                UPDATE profiles
                SET secondary_email = ?, secondary_email_verified_at = ?, pending_secondary_email = NULL
                WHERE id = ?
                """,
                (address, now, profile["id"]),
            )
        elif current and address == current:
            conn.execute(
                "UPDATE profiles SET secondary_email_verified_at = ? WHERE id = ?",
                (now, profile["id"]),
            )
        else:
            raise HTTPException(400, "Ungültiger oder abgelaufener Link")
    else:
        raise HTTPException(400, "Ungültiger oder abgelaufener Link")
    conn.execute(
        "UPDATE email_verification_tokens SET used_at = ? WHERE id = ?",
        (now, row["id"]),
    )
    updated = load_profile(conn, profile["id"])
    viewed = profile_view(updated)
    if viewed is None:
        raise HTTPException(400, "Ungültiger oder abgelaufener Link")
    return viewed


def _queue_verification(conn, profile: dict, purpose: str, address: str) -> tuple[str, str] | None:
    raw = issue_verification(conn, profile["id"], purpose, address)
    if not raw:
        return None
    return verify_message(raw)


def apply_identifier_edits(
    conn,
    profile: dict,
    *,
    username: str | None = None,
    email: str | None = None,
    secondary_email: str | None = None,
    username_set: bool = False,
    email_set: bool = False,
    secondary_set: bool = False,
) -> list[tuple[list[str], str, str]]:
    """Apply username and address edits. Returns mails as (recipients, subject, body)."""
    jobs: list[tuple[list[str], str, str]] = []
    if username_set:
        if username is None or username.strip() == "":
            conn.execute("UPDATE profiles SET username = NULL WHERE id = ?", (profile["id"],))
        else:
            cleaned = normalize_username(username)
            assert_username_free(conn, cleaned, profile["id"])
            conn.execute("UPDATE profiles SET username = ? WHERE id = ?", (cleaned, profile["id"]))
        profile = load_profile(conn, profile["id"]) or profile
    if email_set and email is not None:
        cleaned = normalize_email(email)
        current = (profile.get("email") or "").strip().lower()
        secondary = (profile.get("secondary_email") or "").strip().lower()
        pending_secondary = (profile.get("pending_secondary_email") or "").strip().lower()
        if cleaned == current:
            pass
        else:
            if cleaned == secondary or cleaned == pending_secondary:
                raise HTTPException(409, "E-Mail ist bereits vergeben")
            assert_address_free(conn, cleaned, profile["id"])
            conn.execute("UPDATE profiles SET pending_email = ? WHERE id = ?", (cleaned, profile["id"]))
            queued = _queue_verification(conn, profile, "primary", cleaned)
            if queued:
                subject, body = queued
                jobs.append(([cleaned], subject, body))
                notice = notice_recipients(profile)
                notice = [item for item in notice if item != cleaned]
                if notice:
                    jobs.append((notice, *change_notice()))
            else:
                raise HTTPException(429, "Zu viele Bestätigungslinks. Bitte später erneut versuchen.")
        profile = load_profile(conn, profile["id"]) or profile
    if secondary_set:
        if secondary_email is None or secondary_email.strip() == "":
            conn.execute(
                """
                UPDATE profiles
                SET secondary_email = NULL,
                    secondary_email_verified_at = NULL,
                    pending_secondary_email = NULL
                WHERE id = ?
                """,
                (profile["id"],),
            )
        else:
            cleaned = normalize_email(secondary_email)
            current_primary = (profile.get("email") or "").strip().lower()
            pending_primary = (profile.get("pending_email") or "").strip().lower()
            current_secondary = (profile.get("secondary_email") or "").strip().lower()
            if cleaned == current_primary or cleaned == pending_primary:
                raise HTTPException(409, "E-Mail ist bereits vergeben")
            if cleaned == current_secondary and profile.get("secondary_email_verified_at") and not profile.get("pending_secondary_email"):
                pass
            else:
                assert_address_free(conn, cleaned, profile["id"])
                conn.execute(
                    "UPDATE profiles SET pending_secondary_email = ? WHERE id = ?",
                    (cleaned, profile["id"]),
                )
                queued = _queue_verification(conn, profile, "secondary", cleaned)
                if queued:
                    subject, body = queued
                    jobs.append(([cleaned], subject, body))
                    notice = [item for item in notice_recipients(profile) if item != cleaned]
                    if notice:
                        jobs.append((notice, *change_notice()))
                else:
                    raise HTTPException(429, "Zu viele Bestätigungslinks. Bitte später erneut versuchen.")
    return jobs


def deliver_jobs(jobs: list[tuple[list[str], str, str]]) -> None:
    from mailer import send_mail

    for recipients, subject, body in jobs:
        send_mail(recipients, subject, body)


def resend_verification(conn, profile: dict, purpose: str) -> tuple[list[str], str, str]:
    if purpose == "primary":
        target = (profile.get("pending_email") or "").strip().lower()
        if not target and not profile.get("email_verified_at"):
            target = (profile.get("email") or "").strip().lower()
        if not target or (profile.get("email_verified_at") and not profile.get("pending_email")):
            raise HTTPException(400, "Keine offene Bestätigung für die primäre E-Mail")
    elif purpose == "secondary":
        target = (profile.get("pending_secondary_email") or "").strip().lower()
        if not target and profile.get("secondary_email") and not profile.get("secondary_email_verified_at"):
            target = profile["secondary_email"].strip().lower()
        if not target or (
            profile.get("secondary_email_verified_at") and not profile.get("pending_secondary_email")
        ):
            raise HTTPException(400, "Keine offene Bestätigung für die zweite E-Mail")
    else:
        raise HTTPException(400, "Unbekannter Verifikationszweck")
    queued = _queue_verification(conn, profile, purpose, target)
    if not queued:
        raise HTTPException(429, "Zu viele Bestätigungslinks. Bitte später erneut versuchen.")
    subject, body = queued
    return [target], subject, body