"""Skills 榜单：同 source 合并为一条（企微 Top N）。"""

from __future__ import annotations

from typing import Any


def skill_id(item: dict[str, Any]) -> str:
    return str(item.get("id") or f"{item.get('source')}/{item.get('title')}")


def format_installs(n: int | float) -> str:
    if n >= 1_000_000:
        return f"{n / 1_000_000:.1f}M"
    if n >= 1_000:
        return f"{n / 1_000:.1f}K"
    return str(int(n))


def _installs_range(items: list[dict[str, Any]]) -> tuple[int, int, str]:
    values = [int(item.get("installs") or 0) for item in items]
    lo, hi = min(values), max(values)
    if lo == hi:
        return lo, hi, format_installs(hi)
    return lo, hi, f"{format_installs(lo)}–{format_installs(hi)}"


def _best_description(items: list[dict[str, Any]]) -> str:
    for item in items:
        desc = (item.get("description") or "").strip()
        if desc:
            return desc
    return ""


def _cluster_skill(items: list[dict[str, Any]]) -> dict[str, Any]:
    ranked = sorted(items, key=lambda x: int(x.get("installs") or 0), reverse=True)
    top = ranked[0]
    _lo, _hi, installs_fmt = _installs_range(ranked)
    titles = [str(x.get("title") or "") for x in ranked if x.get("title")]
    sample = ", ".join(titles[:4])
    if len(titles) > 4:
        sample = f"{sample}…"
    return {
        "id": skill_id(top),
        "title": top.get("title", ""),
        "source": top.get("source", ""),
        "installs": int(top.get("installs") or 0),
        "installs_min": _lo,
        "installs_max": _hi,
        "installs_fmt": installs_fmt,
        "link": top.get("link", ""),
        "description": _best_description(ranked),
        "cluster": True,
        "cluster_count": len(ranked),
        "cluster_skills": titles,
        "cluster_titles": sample,
    }


def _single_skill(item: dict[str, Any]) -> dict[str, Any]:
    installs = int(item.get("installs") or 0)
    return {
        "id": skill_id(item),
        "title": item.get("title", ""),
        "source": item.get("source", ""),
        "installs": installs,
        "installs_fmt": format_installs(installs),
        "link": item.get("link", ""),
        "description": item.get("description", ""),
        "cluster": False,
    }


def group_skills_by_source(
    items: list[dict[str, Any]],
    *,
    limit: int = 10,
    pool_size: int = 50,
) -> list[dict[str, Any]]:
    """按 source 去重合并；保留各 source 在榜内的最佳名次顺序。"""
    if not items or limit <= 0:
        return []

    pool = items[: max(pool_size, limit)]
    by_source: dict[str, list[dict[str, Any]]] = {}
    first_rank: dict[str, int] = {}
    for rank, item in enumerate(pool, 1):
        source = (item.get("source") or "?").strip() or "?"
        by_source.setdefault(source, []).append(item)
        first_rank.setdefault(source, rank)

    ordered_sources = sorted(by_source.keys(), key=lambda s: first_rank[s])
    result: list[dict[str, Any]] = []
    for source in ordered_sources:
        group = by_source[source]
        if len(group) == 1:
            result.append(_single_skill(group[0]))
        else:
            result.append(_cluster_skill(group))
        if len(result) >= limit:
            break
    return result