"""Parse terraform/tofu/terragrunt plan output for resource actions."""
from __future__ import annotations

import re
from dataclasses import dataclass


@dataclass(frozen=True)
class ParsedResource:
    address: str
    type: str
    action: str


_HEADER_RE = re.compile(
    r"^\s*#\s+(?P<addr>\S+)\s+(?:"
    r"(?P<create>will be created)|"
    r"(?P<update>will be updated in-place)|"
    r"(?P<delete>will be destroyed)|"
    r"(?P<replace>must be replaced|will be replaced)|"
    r"(?P<read>will be read during apply)"
    r")\s*$"
)


def _action_from_match(m: re.Match) -> str:
    for k in ("create", "update", "delete", "replace", "read"):
        if m.group(k):
            return k
    return "unknown"


def _type_from_address(address: str) -> str:
    """Strip module prefixes and any index suffix; return the resource type."""
    parts = address.split(".")
    i = 0
    while i + 1 < len(parts) and parts[i].startswith("module"):
        i += 2
    if i < len(parts) and parts[i] == "data":
        i += 1
    if i >= len(parts):
        return ""
    type_token = parts[i]
    return re.sub(r"\[.*\]$", "", type_token)


def parse_plan_resources(plan_stdout: str) -> list[ParsedResource]:
    out: list[ParsedResource] = []
    for line in plan_stdout.splitlines():
        m = _HEADER_RE.match(line)
        if not m:
            continue
        addr = m.group("addr")
        out.append(ParsedResource(
            address=addr,
            type=_type_from_address(addr),
            action=_action_from_match(m),
        ))
    return out