import os
import redis

# ---------------------------------------------------------
# Redis connection
# ---------------------------------------------------------
REDIS_URL = os.getenv("REDIS_URL", "redis://redis:6379/0")
r = redis.Redis.from_url(REDIS_URL, decode_responses=True)


# =========================================================
#  ABORT FLAG
# =========================================================


def set_abort(book_id: str):
    """
    Enable abort mode for this book.
    All download tasks that haven't started yet will immediately exit.
    """
    r.set(f"abort:{book_id}", "1")


def clear_abort(book_id: str):
    """
    Clear abort flag so future runs are unaffected.
    """
    r.delete(f"abort:{book_id}")


def abort_requested(book_id: str) -> bool:
    """
    True if abort flag is set for this book.
    """
    return r.exists(f"abort:{book_id}") == 1


# =========================================================
#  PER-CHAPTER STATE
# =========================================================
# We mark a chapter "started" once its download task begins.
# If abort is activated AFTER download start:
#   → download must complete
#   → parse must complete
#   → save must complete
# All subsequent chapters will skip.


def mark_chapter_started(book_id: str, chapter_num: int):
    """
    Mark this chapter as started. Parse/save will always run after this,
    even if abort has been activated afterwards.
    """
    key = f"started:{book_id}:{chapter_num}"
    r.set(key, "1")


def chapter_started(book_id: str, chapter_num: int) -> bool:
    """
    Return True if this chapter has already started downloading.
    """
    key = f"started:{book_id}:{chapter_num}"
    return r.exists(key) == 1


# =========================================================
#  UTILITY: RESET FOR A BOOK
# =========================================================


def reset_book_state(book_id: str):
    """
    Optional utility: remove abort flag and all started-chapter markers.
    Useful during testing or manual cleanup.
    """
    # Remove abort flag
    r.delete(f"abort:{book_id}")

    # Remove all "started:*" keys for this book
    pattern = f"started:{book_id}:*"
    for key in r.scan_iter(pattern):
        r.delete(key)