"""论文对比页路由 — 多篇论文结构化字段并排对比。"""

from __future__ import annotations

from fastapi import APIRouter, Depends, Query, Request
from sqlalchemy import select
from sqlalchemy.orm import Session, joinedload

from app.database import get_db
from app.models import PAPER_DEFAULT_LOAD, Paper
from app.utils import templates

router = APIRouter()


@router.get("/compare")
def compare_page(
    request: Request,
    ids: str = Query(default="", description="逗号分隔的 arxiv_id，最多 5 篇"),
    db: Session = Depends(get_db),
):
    """论文对比页面。GET /compare?ids=id1,id2,id3"""
    if not ids:
        return templates.TemplateResponse(
            request,
            "compare.html",
            {
                "page_title": "论文对比",
                "papers": [],
                "error": None,
            },
        )

    arxiv_ids = [i.strip() for i in ids.split(",") if i.strip()]

    # 最多 5 篇
    if len(arxiv_ids) > 5:
        arxiv_ids = arxiv_ids[:5]

    if not arxiv_ids:
        return templates.TemplateResponse(
            request,
            "compare.html",
            {
                "page_title": "论文对比",
                "papers": [],
                "error": "请提供有效的论文 ID",
            },
        )

    papers = (
        db.execute(
            select(Paper)
            .where(Paper.arxiv_id.in_(arxiv_ids))
            .options(
                joinedload(Paper.summary),
                *PAPER_DEFAULT_LOAD,
            )
        )
        .unique()
        .scalars()
        .all()
    )

    # 按请求顺序排列
    id_order = {aid: idx for idx, aid in enumerate(arxiv_ids)}
    papers.sort(key=lambda p: id_order.get(p.arxiv_id, 999))

    # 构建对比数据
    compare_fields = [
        ("title_zh", "中文标题"),
        ("title_en", "英文标题"),
        ("one_line", "一句话摘要"),
        ("difficulty", "难度"),
        ("motivation_problem", "研究问题"),
        ("motivation_goal", "研究目标"),
        ("motivation_gap", "研究差距"),
        ("method_overview", "方法概述"),
        ("method_key_idea", "关键思路"),
        ("method_novelty", "新颖性"),
        ("results", "实验结果"),
        ("limitations", "局限与改进"),
    ]

    rows = []
    for field_key, field_label in compare_fields:
        cells = []
        for paper in papers:
            if field_key in ("title_zh", "title_en"):
                val = getattr(paper, field_key, None) or ""
            elif paper.summary:
                val = getattr(paper.summary, field_key, None) or ""
                # JSON 字段直接展示
                if field_key == "results" and not val:
                    val = paper.summary.results_main_json or ""
                if field_key == "limitations" and not val:
                    val = paper.summary.limitations_json or ""
            else:
                val = ""
            cells.append(val)
        rows.append({"key": field_key, "label": field_label, "cells": cells})

    return templates.TemplateResponse(
        request,
        "compare.html",
        {
            "page_title": "论文对比",
            "papers": papers,
            "rows": rows,
            "ids_param": ids,
            "error": None,
        },
    )