"""三层去重模块的数据模型。"""

from __future__ import annotations

from datetime import datetime
from enum import StrEnum
from typing import Literal

from pydantic import BaseModel, Field


class DedupLayer(StrEnum):
    """命中去重的层。"""

    URL = "url"          # L1: 完全相同 URL
    CONTENT = "content"  # L2: 标准化后 content 完全一致
    SIMHASH = "simhash"  # L3: SimHash 汉明距离 <= 阈值


class Fingerprint(BaseModel):
    """单篇文章的指纹记录,持久化到 SQLite。"""

    url_hash: str = Field(..., description="主键,与 Article.url_hash 一致")
    content_hash: str = Field(..., description="标准化 content 的 SHA1[:16]")
    simhash: int = Field(..., description="64 位 SimHash 整数(无符号)")
    source_id: str
    url: str
    title: str
    publish_date: str | None = Field(default=None, description="YYYY-MM-DD,用于时间窗口")
    ingested_at: datetime = Field(default_factory=datetime.now)


class DedupResult(BaseModel):
    """对单篇文章的判重结果。"""

    url_hash: str
    is_duplicate: bool
    matched_layer: DedupLayer | None = None
    matched_url_hash: str | None = None
    matched_url: str | None = None
    matched_title: str | None = None
    hamming_distance: int | None = Field(
        default=None, description="仅 SimHash 层有值"
    )

    def short_summary(self) -> str:
        if not self.is_duplicate:
            return f"[UNIQUE] {self.url_hash}"
        layer = self.matched_layer.value if self.matched_layer else "?"
        extra = f" hd={self.hamming_distance}" if self.hamming_distance is not None else ""
        return f"[DUP/{layer}] {self.url_hash} ~ {self.matched_url_hash}{extra}"


class DedupStats(BaseModel):
    """指纹库统计。"""

    total: int = 0
    by_source: dict[str, int] = Field(default_factory=dict)
    earliest: str | None = None
    latest: str | None = None


# 类型别名,便于在批处理日志中归类
DedupVerdict = Literal["unique", "duplicate"]