"""Blocklist parser and validator component.

Parses blocklist text content and validates individual entries as IP addresses
or CIDR networks. Separates valid IPs from invalid/CIDR entries.
"""

from __future__ import annotations

import structlog

from app.utils.ip_utils import is_valid_ip, is_valid_network, normalise_ip

log: structlog.stdlib.BoundLogger = structlog.get_logger()


class ParsedBlocklist:
    """Result of parsing a blocklist text."""

    def __init__(
        self,
        valid_ips: list[str],
        skipped_entries: int,
    ) -> None:
        """Initialize parsed result.

        Args:
            valid_ips: List of valid individual IP addresses.
            skipped_entries: Count of skipped/invalid entries (comments, CIDRs, malformed).
        """
        self.valid_ips = valid_ips
        self.skipped_entries = skipped_entries

    @property
    def total_entries(self) -> int:
        """Total number of entries processed."""
        return len(self.valid_ips) + self.skipped_entries


class BlocklistParser:
    """Parses and validates blocklist text content."""

    @staticmethod
    def parse(content: str) -> ParsedBlocklist:
        """Parse blocklist text and extract valid individual IP addresses.

        Lines starting with '#' are treated as comments and skipped.
        Empty lines are skipped. CIDR ranges and malformed entries are skipped
        but counted. Only individual IPv4/IPv6 addresses are extracted.

        Args:
            content: Raw blocklist text content.

        Returns:
            :class:`ParsedBlocklist` with valid IPs and skip count.
        """
        valid_ips: list[str] = []
        skipped = 0

        for line in content.splitlines():
            stripped = line.strip()

            # Skip empty lines and comments
            if not stripped or stripped.startswith("#"):
                continue

            # Accept only individual IP addresses, skip CIDRs and malformed
            if is_valid_ip(stripped):
                valid_ips.append(normalise_ip(stripped))
            else:
                skipped += 1

        return ParsedBlocklist(valid_ips=valid_ips, skipped_entries=skipped)

    @staticmethod
    def parse_with_stats(
        content: str,
        *,
        sample_lines: int = 20,
    ) -> tuple[list[str], dict[str, int]]:
        """Parse blocklist and return sample of valid IPs with statistics.

        Used by preview functionality to show sample entries and counts.

        Args:
            content: Raw blocklist text content.
            sample_lines: Maximum number of sample entries to return.

        Returns:
            Tuple of (sample IPs list, stats dict with keys: total_lines,
            valid_count, skipped_count).
        """
        lines = content.splitlines()
        entries: list[str] = []
        valid = 0
        skipped = 0

        for line in lines:
            stripped = line.strip()
            if not stripped or stripped.startswith("#"):
                continue
            if is_valid_ip(stripped) or is_valid_network(stripped):
                valid += 1
                if len(entries) < sample_lines:
                    # Normalise individual IPs; keep networks as-is
                    entries.append(normalise_ip(stripped) if is_valid_ip(stripped) else stripped)
            else:
                skipped += 1

        return entries, {
            "total_lines": len(lines),
            "valid_count": valid,
            "skipped_count": skipped,
        }