from __future__ import annotations

import re
import urllib.parse
from pathlib import Path

from pydantic import BaseModel, ConfigDict, Field, field_validator

_RESERVED_PUBLIC_PATHS = {
    "/admin.css",
    "/admin-tables.js",
    "/api",
    "/app.js",
    "/clipboard.js",
    "/docs",
    "/favicon.ico",
    "/healthz",
    "/install.sh",
    "/llms.txt",
    "/bootstrap-subset.css",
    "/logo.png",
    "/logo-nav.webp",
    "/logo.webp",
    "/m",
    "/openapi.json",
    "/privacy",
    "/redoc",
    "/robots.txt",
    "/sitemap.xml",
    "/site.webmanifest",
    "/social-preview.png",
    "/social-preview.webp",
    "/theme.js",
    "/uninstall.sh",
    "/visitor-ip.js",
}


class DdnsSettings(BaseModel):
    model_config = ConfigDict(extra="forbid")

    database_path: Path = Field(default=Path("ddns.sqlite3"))
    admin_password: str = Field(default="")
    admin_path: str = Field(default="/admin")
    public_base_url: str = Field(default="http://localhost:8080")
    trusted_hosts: set[str] = Field(default_factory=set)
    hostname_suffix: str = Field(default="")
    rate_limit_per_minute: int = Field(default=60, ge=1, le=10_000)
    admin_rate_limit_per_minute: int = Field(default=20, ge=1, le=10_000)
    max_request_body_bytes: int = Field(default=16_384, ge=1024, le=1_048_576)
    trusted_proxy_ips: set[str] = Field(default_factory=set)
    trust_private_proxy_headers: bool = Field(default=True)
    rfc2136_server: str | None = None
    rfc2136_zone: str | None = None
    rfc2136_key_name: str | None = None
    rfc2136_key_secret: str | None = None
    dns_provider: str = Field(default="")
    dns_zones: set[str] = Field(default_factory=set)
    require_dns_provider: bool = Field(default=False)
    cloudflare_api_token: str = Field(default="")
    cloudflare_zone_id: str = Field(default="")
    cleanup_pending_account_hours: int = Field(default=24, ge=1, le=24 * 30)
    cleanup_unused_account_hours: int = Field(default=1080, ge=1, le=24 * 365)
    cleanup_event_history_hours: int = Field(default=24 * 180, ge=1, le=24 * 3650)
    cleanup_interval_seconds: int = Field(default=3600, ge=1, le=24 * 60 * 60)
    dashboard_unlock_seconds: int = Field(default=24 * 60 * 60, ge=60, le=30 * 24 * 60 * 60)
    dashboard_stay_unlocked_seconds: int = Field(default=30 * 24 * 60 * 60, ge=60, le=30 * 24 * 60 * 60)
    dashboard_cookie_secret: str = Field(default="")
    redacted_access_log: bool = Field(default=False)
    ttl: int = Field(default=60, ge=60, le=86400)

    @field_validator("public_base_url")
    @classmethod
    def validate_public_base_url(_cls, value: str) -> str:
        if not value.startswith(("http://", "https://")):
            raise ValueError("public_base_url must start with http:// or https://")
        return value.rstrip("/")

    @field_validator("trusted_hosts")
    @classmethod
    def validate_trusted_hosts(_cls, value: set[str]) -> set[str]:
        return {host.strip().lower() for host in value if host.strip()}

    @field_validator("admin_path")
    @classmethod
    def validate_admin_path(_cls, value: str) -> str:
        path = value.strip()
        if not _has_valid_admin_path_shape(path):
            raise ValueError("admin_path must start with / and must not be / or end with /")
        if not _has_url_safe_path_chars(path):
            raise ValueError("admin_path may only contain URL-safe path characters")
        if _is_reserved_admin_path(path):
            raise ValueError("admin_path must not conflict with a public route")
        return path

    @property
    def effective_trusted_hosts(self) -> list[str]:
        hosts = set(self.trusted_hosts)
        public_host = urllib.parse.urlparse(self.public_base_url).hostname
        if public_host:
            hosts.add(public_host.lower())
        if not self.require_dns_provider:
            hosts.update({"testserver", "localhost", "127.0.0.1", "::1"})
        return sorted(hosts)

    def validate_launch_ready(self) -> None:
        from .dns import validate_dns_provider_settings

        validate_dns_provider_settings(self)
        if not self.require_dns_provider:
            return
        _validate_launch_secrets(self.admin_password, self.dashboard_cookie_secret)
        _validate_launch_hostname_suffix(self.hostname_suffix)
        _validate_launch_trusted_hosts(self.effective_trusted_hosts)

    @classmethod
    def from_env(_cls) -> DdnsSettings:
        from .config import settings_from_env

        return settings_from_env()


def _has_valid_admin_path_shape(path: str) -> bool:
    return path.startswith("/") and path != "/" and not path.endswith("/")


def _has_url_safe_path_chars(path: str) -> bool:
    return re.fullmatch(r"/[A-Za-z0-9._~/-]+", path) is not None


def _is_reserved_admin_path(path: str) -> bool:
    return any(path == reserved or path.startswith(f"{reserved}/") for reserved in _RESERVED_PUBLIC_PATHS)


def _validate_launch_secrets(admin_password: str, dashboard_cookie_secret: str) -> None:
    if len(admin_password) < 16:
        raise RuntimeError("DDNS_ADMIN_PASSWORD must be at least 16 characters when DDNS_REQUIRE_DNS_PROVIDER=1")
    if len(dashboard_cookie_secret or admin_password) < 32:
        raise RuntimeError(
            "DDNS_DASHBOARD_COOKIE_SECRET or DDNS_ADMIN_PASSWORD must be at least 32 characters "
            "for dashboard cookie signing when DDNS_REQUIRE_DNS_PROVIDER=1"
        )


def _validate_launch_hostname_suffix(hostname_suffix: str) -> None:
    if not hostname_suffix:
        raise RuntimeError("DDNS_HOSTNAME_SUFFIX is required when DDNS_REQUIRE_DNS_PROVIDER=1")


def _validate_launch_trusted_hosts(effective_trusted_hosts: list[str]) -> None:
    if not effective_trusted_hosts:
        raise RuntimeError("At least one trusted host is required for production")