"""Response validation for FormFav payloads.

Guards against shape drift / missing fields. Never fabricates missing data —
it records what was present so the scoring model can degrade gracefully.
"""
from __future__ import annotations

from typing import Any


class ValidationIssue:
    def __init__(self, level: str, field: str, message: str) -> None:
        self.level = level  # 'error' | 'warn'
        self.field = field
        self.message = message

    def __repr__(self) -> str:
        return f"[{self.level}] {self.field}: {self.message}"


def validate_meetings(payload: Any) -> list[ValidationIssue]:
    issues: list[ValidationIssue] = []
    if not isinstance(payload, dict):
        return [ValidationIssue("error", "payload", "meetings payload is not an object")]
    meetings = payload.get("meetings")
    if not isinstance(meetings, list):
        issues.append(ValidationIssue("error", "meetings", "missing 'meetings' array"))
        return issues
    for i, m in enumerate(meetings):
        if not isinstance(m, dict):
            issues.append(ValidationIssue("error", f"meetings[{i}]", "meeting is not an object"))
            continue
        if "slug" not in m and "track" not in m:
            issues.append(ValidationIssue("warn", f"meetings[{i}]", "no slug/track"))
        if "races" not in m:
            issues.append(ValidationIssue("warn", f"meetings[{i}]", "no 'races' array"))
    return issues


def validate_race_form(payload: Any) -> list[ValidationIssue]:
    issues: list[ValidationIssue] = []
    if not isinstance(payload, dict):
        return [ValidationIssue("error", "payload", "race form payload is not an object")]
    if "runners" not in payload:
        issues.append(ValidationIssue("error", "runners", "missing 'runners' array"))
    else:
        runners = payload["runners"]
        if not isinstance(runners, list):
            issues.append(ValidationIssue("error", "runners", "'runners' is not a list"))
        else:
            for i, r in enumerate(runners):
                if not isinstance(r, dict):
                    issues.append(ValidationIssue("error", f"runners[{i}]", "runner not an object"))
                    continue
                if "number" not in r and "barrier" not in r:
                    issues.append(ValidationIssue("warn", f"runners[{i}]", "runner missing number/barrier"))
    return issues