import json
import re
from typing import Any, Dict, Optional

from .models import ExtractRule


def extract_jsonpath(payload: Any, path: str) -> Optional[str]:
    if not path.startswith("$."):
        return None
    current = payload
    for part in path[2:].split("."):
        if isinstance(current, list):
            if not part.isdigit():
                return None
            index = int(part)
            if index >= len(current):
                return None
            current = current[index]
            continue
        if not isinstance(current, dict):
            return None
        if part not in current:
            return None
        current = current[part]
    return None if current is None else str(current)


def extract_version(
    body: str,
    rule: ExtractRule,
    headers: Optional[Dict[str, str]] = None,
) -> Optional[str]:
    if rule.type == "jsonpath":
        try:
            return extract_jsonpath(json.loads(body), rule.value)
        except json.JSONDecodeError:
            return None

    if rule.type == "jsonpath_join":
        try:
            payload = json.loads(body)
        except json.JSONDecodeError:
            return None
        parts = []
        for path in rule.value.split(","):
            value = extract_jsonpath(payload, path.strip())
            if value is None:
                return None
            parts.append(value)
        return ".".join(parts)

    if rule.type == "header":
        return headers.get(rule.value.lower()) if headers else None

    if rule.type == "regex":
        match = re.search(rule.value, body)
        if not match:
            return None
        return match.group(1) if match.lastindex else match.group(0)

    if rule.type == "text":
        return rule.value if rule.value in body else None

    return None


def build_upstream_fallback(url: Optional[str]) -> Optional[Dict[str, Any]]:
    if not url:
        return None
    for host in ("api.github.com/repos/", "codeberg.org/api/v1/repos/"):
        if host in url and url.endswith("/releases/latest"):
            return {
                "url": url.replace("/releases/latest", "/tags"),
                "extract": ExtractRule(type="jsonpath", value="$.0.name"),
            }
    return None