# ============================================
# File: scraper/ui_log.py
# Purpose: Central UI log buffer for WebGUI
# Single global buffer. No book_id.
# ============================================

import redis
import os
from datetime import datetime

REDIS_URL = os.getenv("REDIS_BROKER", "redis://redis:6379/0")
LOG_BUFFER_SIZE = int(os.getenv("LOG_BUFFER_SIZE", "1000"))

r = redis.Redis.from_url(REDIS_URL, decode_responses=True)

UI_LOG_KEY = "logs:ui"


def push_ui(message: str):
    """Push a message into the global UI log (no book_id)."""
    if not message or not message.strip():
        return

    ts = datetime.now().strftime("%H:%M:%S")
    entry = f"[{ts}] {message}"

    r.rpush(UI_LOG_KEY, entry)
    r.ltrim(UI_LOG_KEY, -LOG_BUFFER_SIZE, -1)


def get_ui_logs(limit: int = None):
    """Return last N global UI log lines."""
    if limit is None:
        limit = LOG_BUFFER_SIZE

    return r.lrange(UI_LOG_KEY, -limit, -1)


def reset_ui_logs():
    """
    Clear the entire UI log buffer.
    Used by:
      - Clear button in GUI
      - Auto-clear when new book scraping starts
    """
    r.delete(UI_LOG_KEY)


# ============================================================
# Delta-based log retrieval using Redis indexes
# ============================================================


def get_ui_logs_delta(last_index: int):
    """
    Returns (new_lines, total_count).
    Only returns log lines AFTER last_index.

    Example:
        last_index = 10 → returns logs with Redis indexes 11..end
    """
    total = r.llen(UI_LOG_KEY)

    if total == 0:
        return [], 0

    # First load OR index invalid → send entire buffer
    if last_index < 0 or last_index >= total:
        logs = r.lrange(UI_LOG_KEY, 0, -1)
        return logs, total

    # Only new logs
    new_lines = r.lrange(UI_LOG_KEY, last_index + 1, -1)
    return new_lines, total