# -*- coding: utf-8 -*-
"""Helpers for deduplicating ranked retrieval results by document content."""
import re


_WHITESPACE_RE = re.compile(r"\s+")


def normalized_content(text):
    """Normalize content for exact duplicate detection."""
    if text is None:
        return ""
    return _WHITESPACE_RE.sub(" ", str(text).strip())


def content_dedup_key(doc):
    """Build a stable dedup key, preferring normalized page content."""
    content = normalized_content(getattr(doc, "page_content", ""))
    if content:
        return ("content", content)
    return ("object", id(doc))


def deduplicate_ranked_results(results, k=None):
    """
    Deduplicate ``(doc, score)`` retrieval results by content.

    The highest scoring duplicate wins. Ties keep the earlier result. Final
    output is sorted by score descending, with original order as the tie-breaker.
    """
    if k is not None and k <= 0:
        return []

    best_by_key = {}
    for order, (doc, score) in enumerate(results or []):
        key = content_dedup_key(doc)
        score = float(score)
        current = best_by_key.get(key)
        if current is None or score > current[2]:
            best_by_key[key] = (order, doc, score)

    ranked = sorted(best_by_key.values(), key=lambda item: (-item[2], item[0]))
    deduped = [(doc, score) for _, doc, score in ranked]
    if k is None:
        return deduped
    return deduped[:k]