from __future__ import annotations

from pathlib import Path
import json


DETAILS_DIR_NAME = "details"
LEGACY_DETAILS_DIR_NAME = "advanced"
DETAILS_SUMMARY_FILENAME = "details_summary.json"
LEGACY_DETAILS_SUMMARY_FILENAME = "advanced_summary.json"


def preferred_details_dir(output_dir: str | Path) -> Path:
    return Path(output_dir) / DETAILS_DIR_NAME


def legacy_details_dir(output_dir: str | Path) -> Path:
    return Path(output_dir) / LEGACY_DETAILS_DIR_NAME


def resolve_existing_details_dir(output_dir: str | Path) -> Path | None:
    preferred = preferred_details_dir(output_dir)
    if _details_dir_has_outputs(preferred):
        return preferred
    legacy = legacy_details_dir(output_dir)
    if _details_dir_has_outputs(legacy):
        return legacy
    if preferred.exists():
        return preferred
    if legacy.exists():
        return legacy
    return None


def resolve_details_dir(output_dir: str | Path) -> Path:
    existing = resolve_existing_details_dir(output_dir)
    if existing is not None:
        return existing
    return preferred_details_dir(output_dir)


def resolve_details_summary_path(output_dir: str | Path) -> Path | None:
    for details_dir in [preferred_details_dir(output_dir), legacy_details_dir(output_dir)]:
        for filename in [DETAILS_SUMMARY_FILENAME, LEGACY_DETAILS_SUMMARY_FILENAME]:
            path = details_dir / filename
            if path.exists():
                return path
    return None


def details_outputs_exist(output_dir: str | Path) -> bool:
    return _details_dir_has_outputs(preferred_details_dir(output_dir)) or _details_dir_has_outputs(
        legacy_details_dir(output_dir)
    )


def _details_dir_has_outputs(details_dir: Path) -> bool:
    if not details_dir.exists():
        return False
    required_files = [
        details_dir / "request_metrics.csv",
        details_dir / "theoretical_block_reuse_gaps.csv",
        details_dir / "theoretical_block_lifetimes.csv",
        details_dir / "theoretical_alive_block_timeline.csv",
        details_dir / "session_bucket_boundary_miss.csv",
    ]
    if not all(path.exists() for path in required_files):
        return False
    summary_path = details_dir / DETAILS_SUMMARY_FILENAME
    if not summary_path.exists():
        return False
    try:
        payload = json.loads(summary_path.read_text(encoding="utf-8"))
    except Exception:
        return False
    return int(payload.get("schema_version", 0) or 0) >= 3