"""Validation failure history verifier for reviewer reports (#396).

A reviewer run that observes a validation failure and later reruns to green
must report the failure, its investigation, and why the eventual pass is
trustworthy. A later pass never erases the duty to report the earlier
failure. This verifier fails closed when known failures are omitted, when
failure entries lack the required investigation fields, when a rerun-pass
claim lacks a what-changed explanation, or when an unexplained transient
failure is reported as a bare pass.
"""

from __future__ import annotations

import re
from typing import Any

# Issue #396 criterion 4: required status wording when the cause is unknown.
TRANSIENT_INVESTIGATION_STATUS = "passed after transient failure investigation"

_HISTORY_SECTION_RE = re.compile(
    r"(?:^#+\s*validation failure history\b|validation failure history\s*:)",
    re.IGNORECASE | re.MULTILINE,
)
_FAILURE_ENTRY_FIELDS = (
    ("command", re.compile(r"command\s*:", re.IGNORECASE)),
    ("failing test or error", re.compile(r"(?:failing test|error)\s*:", re.IGNORECASE)),
    ("suspected cause", re.compile(r"suspected cause\s*:", re.IGNORECASE)),
    ("reproduced status", re.compile(r"reproduced\s*:", re.IGNORECASE)),
    ("baseline master status", re.compile(r"baseline(?:\s+master)?\s*:", re.IGNORECASE)),
    ("PR-caused evidence", re.compile(r"(?:pr-caused|not pr-caused|evidence)", re.IGNORECASE)),
)
_RERUN_PASS_RE = re.compile(
    r"(?:passed on rerun|rerun[^.\n]*passed|later (?:run|rerun) passed)",
    re.IGNORECASE,
)
_WHAT_CHANGED_RE = re.compile(r"what changed", re.IGNORECASE)
_ENV_STATE_RE = re.compile(
    r"(?:environmental state|/tmp/|state (?:was )?cleaned|none cleaned)",
    re.IGNORECASE,
)
_TRUST_RE = re.compile(r"(?:trustworthy|trust the pass|why the pass)", re.IGNORECASE)
_UNKNOWN_CAUSE_RE = re.compile(r"suspected cause\s*:\s*unknown", re.IGNORECASE)
_BARE_PASSED_STATUS_RE = re.compile(
    r"validation status\s*:\s*passed\s*$",
    re.IGNORECASE | re.MULTILINE,
)


def assess_validation_failure_history_report(
    report_text: str,
    *,
    observed_failures: list[dict] | None = None,
) -> dict[str, Any]:
    """Require complete failure-history reporting for observed failures (#396)."""
    text = report_text or ""
    reasons: list[str] = []
    has_history = bool(_HISTORY_SECTION_RE.search(text))

    if observed_failures and not has_history:
        reasons.append(
            "validation failures were observed this session but the report has "
            "no Validation failure history section"
        )

    if observed_failures and has_history:
        for entry in observed_failures:
            failure = str(entry.get("failure") or "").strip()
            if failure and failure not in text:
                reasons.append(
                    f"observed validation failure omitted from history: {failure}"
                )

        missing_fields = [
            name for name, pattern in _FAILURE_ENTRY_FIELDS if not pattern.search(text)
        ]
        for name in missing_fields:
            reasons.append(f"failure history entry missing required field: {name}")

    if has_history and _RERUN_PASS_RE.search(text):
        if not _WHAT_CHANGED_RE.search(text):
            reasons.append(
                "rerun-pass claim does not explain what changed between runs"
            )
        if not _ENV_STATE_RE.search(text):
            reasons.append(
                "rerun-pass claim does not state whether environmental state "
                "was cleaned"
            )
        if not _TRUST_RE.search(text):
            reasons.append(
                "rerun-pass claim does not explain why the pass is trustworthy"
            )

    if (
        observed_failures
        and _UNKNOWN_CAUSE_RE.search(text)
        and _BARE_PASSED_STATUS_RE.search(text)
    ):
        reasons.append(
            "unexplained transient failure cannot be reported as a bare pass; "
            f"use '{TRANSIENT_INVESTIGATION_STATUS}'"
        )

    return {
        "proven": not reasons,
        "block": bool(reasons),
        "reasons": reasons,
        "history_section_present": has_history,
    }