from __future__ import annotations

import sys
import time
from typing import Iterable

from . import __version__
from .config import Config, ConfigError, load_config
from .logging_setup import (
    configure_json_logging,
    log_error,
    log_run_summary,
    log_startup,
)
from .state import load_posted, save_posted


def _iter_candidates(config: Config) -> Iterable[str]:
    """Yield candidate post identifiers.

    This is the extension seam for the future blog-clone + matching
    pipeline. Job 1083 leaves it empty so the silent-on-no-matches
    contract is the default behaviour.
    """
    return []


def _run_once(config: Config) -> tuple[int, int, int, int, list[str]]:
    """Execute one pipeline pass and return the summary counters.

    Returns ``(scanned, matched, posted, skipped, posted_ids)``.
    """
    already_posted = set(load_posted(config.data_dir).keys())

    scanned = 0
    matched = 0
    posted = 0
    skipped = 0
    posted_ids: list[str] = []

    state = load_posted(config.data_dir)

    for candidate_id in _iter_candidates(config):
        scanned += 1
        matched += 1
        if candidate_id in already_posted:
            skipped += 1
            continue
        posted_ids.append(candidate_id)
        state[candidate_id] = {"posted_at": _now_iso()}
        posted += 1

    if posted_ids:
        save_posted(config.data_dir, state)

    return scanned, matched, posted, skipped, posted_ids


def _now_iso() -> str:
    from datetime import datetime, timezone

    return datetime.now(tz=timezone.utc).isoformat()


def _run_with_retry(config: Config) -> tuple[int, int, int, int, list[str]] | None:
    """Execute the pipeline with retries. Returns the summary counters on
    success or ``None`` when the retry budget is exhausted."""
    attempts = max(1, config.max_retries + 1)
    last_exc: BaseException | None = None
    for attempt in range(1, attempts + 1):
        try:
            return _run_once(config)
        except Exception as exc:  # noqa: BLE001 — broad on purpose
            last_exc = exc
            log_error(
                "pipeline_error",
                exc=exc,
                attempt=attempt,
                max_attempts=attempts,
            )
            if attempt < attempts:
                time.sleep(0)
    assert last_exc is not None
    log_error("pipeline_failed", exc=last_exc, attempts=attempts)
    return None


def main() -> int:
    configure_json_logging()

    try:
        config = load_config()
    except ConfigError as exc:
        log_error("configuration_error", exc=exc)
        return 2

    config.data_dir.mkdir(parents=True, exist_ok=True)

    log_startup(
        version=__version__,
        site_url=config.site_url,
        run_at=config.run_at,
        tz=config.tz,
        hashtags=config.hashtags,
        throwback_prefix=config.throwback_prefix,
    )

    result = _run_with_retry(config)
    if result is None:
        return 1

    scanned, matched, posted, skipped, posted_ids = result
    log_run_summary(scanned, matched, posted, skipped, posted_ids)
    return 0


if __name__ == "__main__":
    sys.exit(main())