from __future__ import annotations

from pathlib import Path
import re

import yaml

from app.config import get_settings
from app.models import ClientConfig, ResolvedProfile, RuleConfig

_CIDR_PATTERN = re.compile(r"^[0-9a-fA-F:.]+/\d+$")


def resolve_policy(policy: str, client: ClientConfig) -> str:
    return (
        policy.replace("{{ main_policy }}", client.main_policy)
        .replace("{{main_policy}}", client.main_policy)
        .replace("{{ direct_policy }}", client.direct_policy)
        .replace("{{direct_policy}}", client.direct_policy)
    )


def load_rule_text(path: Path) -> str:
    return path.read_text(encoding="utf-8")


def load_rule_payload(path: Path) -> list[str]:
    if path.suffix.lower() in {".yaml", ".yml"}:
        data = yaml.safe_load(path.read_text(encoding="utf-8")) or {}
        payload = data.get("payload", [])
        if not isinstance(payload, list):
            raise ValueError(f"Rule file {path.name} must contain a list field named 'payload'")
        return [str(item).strip() for item in payload if str(item).strip()]

    lines: list[str] = []
    for line in path.read_text(encoding="utf-8").splitlines():
        stripped = line.strip()
        if not stripped or stripped.startswith("#"):
            continue
        lines.append(stripped)
    return lines


def _render_payload_line(payload_line: str, behavior: str) -> str:
    if "," in payload_line:
        return payload_line
    if behavior == "classical":
        if _CIDR_PATTERN.fullmatch(payload_line):
            prefix = "IP-CIDR6" if ":" in payload_line else "IP-CIDR"
            return f"{prefix},{payload_line}"
        return f"DOMAIN-SUFFIX,{payload_line}"
    if behavior == "ipcidr":
        return f"IP-CIDR,{payload_line}"
    if behavior == "domain":
        return f"DOMAIN-SUFFIX,{payload_line}"
    return payload_line


def _attach_policy(rendered_line: str, target: str, append_no_resolve: bool) -> str:
    parts = [part.strip() for part in rendered_line.split(",")]
    if parts and parts[-1] == "no-resolve":
        parts.insert(len(parts) - 1, target)
        return ",".join(parts)
    line = f"{rendered_line},{target}"
    if append_no_resolve:
        line += ",no-resolve"
    return line


def iter_resolved_rule_lines(
    *,
    resolved_profile: ResolvedProfile,
    include_rule_set_references: bool,
    inline_file_payloads: bool,
) -> list[str]:
    settings = get_settings()
    lines: list[str] = []

    for rule_name, rule in resolved_profile.rules.items():
        target = resolve_policy(rule.policy, resolved_profile.client)
        for payload_line in rule.payload:
            lines.append(_attach_policy(_render_payload_line(payload_line, rule.behavior), target, rule.no_resolve))

        if not rule.file:
            continue

        if include_rule_set_references:
            ref_line = f"RULE-SET,{rule_name},{target}"
            if rule.no_resolve:
                ref_line += ",no-resolve"
            lines.append(ref_line)

        if not inline_file_payloads:
            continue

        path = (settings.rules_dir / rule.file).resolve()
        if not path.is_file() or settings.rules_dir.resolve() not in path.parents:
            raise FileNotFoundError(f"Rule file missing: {rule.file}")
        for payload_line in load_rule_payload(path):
            lines.append(_attach_policy(_render_payload_line(payload_line, rule.behavior), target, rule.no_resolve))

    lines.append(f"MATCH,{resolved_profile.client.main_policy}")
    return lines


def build_rule_provider_entries(
    *,
    resolved_profile: ResolvedProfile,
    base_url: str,
    public_path: str,
) -> dict[str, dict]:
    providers: dict[str, dict] = {}
    for name, rule in resolved_profile.rules.items():
        if not rule.file:
            continue
        providers[name] = {
            "behavior": rule.behavior,
            "format": rule.format,
            "url": f"{base_url}/{public_path}/rules/{name}.yaml",
            "interval": rule.interval,
        }
    return providers