import csv
import io
import json
import re

from sqlalchemy import select
from sqlalchemy.orm import Session

from app.models import Comment, ContentItem, Hotspot, Report


def labels_to_text(labels_json: str | None) -> str:
    try:
        labels = json.loads(labels_json or "[]")
    except json.JSONDecodeError:
        return ""
    return "，".join(str(label) for label in labels) if isinstance(labels, list) else ""


def safe_csv_field(value) -> str:
    text = "" if value is None else str(value)
    text = text.replace("\r\n", " ").replace("\n", " ").replace("\r", " ")
    if text.startswith(("=", "+", "-", "@")):
        return f"'{text}"
    return text


def safe_filename(platform: str, task_id: str, hotspot_keyword: str, *, extension: str = "csv") -> str:
    keyword = hotspot_keyword[:20] + ("..." if len(hotspot_keyword) > 20 else "")
    name = f"{platform}_{task_id}_{keyword}"
    name = re.sub(r'[/\\:*?"<>|]+', "_", name)
    name = re.sub(r"_+", "_", name).strip("_")
    return f"{name}.{extension}"


def export_item_comments_csv(session: Session, item_id: str) -> tuple[bytes, str]:
    item = session.get(ContentItem, item_id)
    if item is None:
        raise ValueError("content item not found")
    hotspot = session.get(Hotspot, item.hotspot_id)
    comments = list(session.scalars(select(Comment).where(Comment.content_item_id == item.id)))
    output = io.StringIO()
    writer = csv.writer(output)
    writer.writerow(["平台", "任务 ID", "热点 ID", "热点标题", "内容条目 ID", "内容条目标题", "评论 ID", "评论内容", "情绪倾向", "方向标签", "点赞数", "评论时间"])
    for comment in comments:
        writer.writerow(
            [
                item.platform,
                item.task_id,
                hotspot.id if hotspot else "",
                hotspot.title if hotspot else "",
                item.id,
                item.title or "",
                comment.source_comment_id or "",
                safe_csv_field(comment.content),
                comment.sentiment,
                labels_to_text(comment.labels),
                comment.like_count or 0,
                comment.comment_time or "",
            ]
        )
    filename = safe_filename(item.platform, item.task_id, hotspot.title if hotspot else item.title or "comments")
    return output.getvalue().encode("utf-8-sig"), filename


def export_hotspot_comments_csv(session: Session, hotspot_id: str) -> tuple[bytes, str]:
    hotspot = session.get(Hotspot, hotspot_id)
    if hotspot is None:
        raise ValueError("hotspot not found")
    comments = list(session.scalars(select(Comment).where(Comment.hotspot_id == hotspot.id)))
    output = io.StringIO()
    writer = csv.writer(output)
    writer.writerow(["平台", "任务 ID", "热点 ID", "热点标题", "内容条目 ID", "内容条目标题", "评论 ID", "评论内容", "情绪倾向", "方向标签", "点赞数", "评论时间"])
    for comment in comments:
        item = session.get(ContentItem, comment.content_item_id)
        writer.writerow(
            [
                comment.platform,
                comment.task_id,
                hotspot.id,
                hotspot.title,
                item.id if item else "",
                item.title if item else "",
                comment.source_comment_id or "",
                safe_csv_field(comment.content),
                comment.sentiment,
                labels_to_text(comment.labels),
                comment.like_count or 0,
                comment.comment_time or "",
            ]
        )
    return output.getvalue().encode("utf-8-sig"), safe_filename(hotspot.platform, hotspot.task_id, hotspot.title)


def export_report_markdown(session: Session, *, report_type: str, hotspot_id: str | None = None, item_id: str | None = None) -> tuple[str, str]:
    query = select(Report).where(Report.report_type == report_type)
    if hotspot_id:
        query = query.where(Report.hotspot_id == hotspot_id)
    if item_id:
        query = query.where(Report.content_item_id == item_id)
    report = session.scalar(query)
    if report is None:
        raise ValueError("report not found")
    return report.markdown_content or report.markdown, safe_filename("report", report.task_id, report.title, extension="md")