import os
import re
import asyncio
import threading
import nest_asyncio
nest_asyncio.apply()
import captcha_state
from invoice_fetcher import main as fetch_main
from dotenv import load_dotenv
from fastapi import FastAPI, Request, HTTPException
from linebot.v3 import WebhookHandler
from linebot.v3.messaging import (
    Configuration,
    ApiClient,
    MessagingApi,
    ReplyMessageRequest,
    TextMessage,
)
from linebot.v3.webhooks import MessageEvent, TextMessageContent, FollowEvent
from linebot.v3.exceptions import InvalidSignatureError
from sqlalchemy import create_engine, Column, Integer, String, Numeric, Date, DateTime, BigInteger, text
from sqlalchemy.orm import declarative_base, sessionmaker
from datetime import datetime, date

load_dotenv()

app = FastAPI()

# LINE 設定
configuration = Configuration(access_token=os.getenv("LINE_CHANNEL_ACCESS_TOKEN"))
handler = WebhookHandler(os.getenv("LINE_CHANNEL_SECRET"))

# DB 設定
DATABASE_URL = os.getenv("DATABASE_URL")
engine = create_engine(DATABASE_URL)
SessionLocal = sessionmaker(bind=engine)
Base = declarative_base()

# Models
class User(Base):
    __tablename__ = "users"
    id = Column(BigInteger, primary_key=True)
    name = Column(String)
    email = Column(String, unique=True)

class LineUser(Base):
    __tablename__ = "line_users"
    id = Column(BigInteger, primary_key=True)
    line_user_id = Column(String, unique=True)
    user_id = Column(BigInteger)
    created_at = Column(DateTime, default=datetime.now)

class Category(Base):
    __tablename__ = "categories"
    id = Column(BigInteger, primary_key=True)
    user_id = Column(BigInteger)
    parent_id = Column(BigInteger, nullable=True)
    name = Column(String)
    color = Column(String, default='#3B82F6')
    icon = Column(String, nullable=True)

class CategoryRule(Base):
    __tablename__ = "category_rules"
    id = Column(BigInteger, primary_key=True)
    user_id = Column(BigInteger)
    category_id = Column(BigInteger)
    keyword = Column(String)

class Expense(Base):
    __tablename__ = "expenses"
    id = Column(BigInteger, primary_key=True)
    user_id = Column(BigInteger)
    category_id = Column(BigInteger, nullable=True)
    amount = Column(Numeric(10, 2))
    note = Column(String, nullable=True)
    invoice_number = Column(String, nullable=True)
    seller_name = Column(String, nullable=True)
    item_name = Column(String, nullable=True)
    date = Column(Date)
    created_at = Column(DateTime, default=datetime.now)
    updated_at = Column(DateTime, default=datetime.now)

# 記帳模板
EXPENSE_TEMPLATE = (
    "請填寫以下記帳資料後傳回：\n\n"
    "品項: \n"
    "類別: \n"
    "金額: \n"
    "店家: \n"
    "備註: "
)

def get_or_create_user(db, line_user_id: str) -> int:
    line_user = db.query(LineUser).filter(
        LineUser.line_user_id == line_user_id
    ).first()
    if line_user:
        return line_user.user_id

    new_user = User(
        name="LINE用戶",
        email=f"{line_user_id}@line.user"
    )
    db.add(new_user)
    db.flush()

    default_categories = [
        ("餐飲", "#F97316", "🍽"),
        ("交通", "#3B82F6", "🚗"),
        ("購物", "#8B5CF6", "🛍"),
        ("娛樂", "#EC4899", "🎮"),
        ("醫療", "#10B981", "🏥"),
        ("其他", "#6B7280", "📦"),
    ]
    parent_ids = {}
    for name, color, icon in default_categories:
        cat = Category(user_id=new_user.id, name=name, color=color, icon=icon)
        db.add(cat)
        db.flush()
        parent_ids[name] = cat.id

    default_rules = {
        "餐飲": ["早餐", "午餐", "晚餐", "飲料", "便當", "餐飲"],
        "交通": ["捷運", "公車", "計程車", "油錢", "停車", "交通"],
        "購物": ["衣服", "3C", "日用品", "購物"],
        "娛樂": ["電影", "遊戲", "旅遊", "娛樂"],
        "醫療": ["藥局", "診所", "醫院", "醫療"],
    }
    for cat_name, keywords in default_rules.items():
        for kw in keywords:
            db.add(CategoryRule(
                user_id=new_user.id,
                category_id=parent_ids[cat_name],
                keyword=kw
            ))

    db.add(LineUser(line_user_id=line_user_id, user_id=new_user.id))
    db.commit()
    return new_user.id

def resolve_category(db, user_id: int, category_input: str) -> tuple[int, int | None]:
    """
    回傳 (category_id, subcategory_id)
    先查 category_rules keyword
    找不到就新增 subcategory 到「其他」
    """
    # 查 rule
    rule = db.query(CategoryRule).filter(
        CategoryRule.user_id == user_id,
        CategoryRule.keyword == category_input
    ).first()
    if rule:
        return rule.category_id, None

    # 查是否是大類名稱
    parent = db.query(Category).filter(
        Category.user_id == user_id,
        Category.name == category_input,
        Category.parent_id == None
    ).first()
    if parent:
        return parent.id, None

    # 查是否是已存在的小類
    sub = db.query(Category).filter(
        Category.user_id == user_id,
        Category.name == category_input,
        Category.parent_id != None
    ).first()
    if sub:
        return sub.parent_id, sub.id

    # 找不到 → 新增 subcategory 到「其他」
    other = db.query(Category).filter(
        Category.user_id == user_id,
        Category.name == "其他",
        Category.parent_id == None
    ).first()
    parent_id = other.id if other else None

    new_sub = Category(
        user_id=user_id,
        parent_id=parent_id,
        name=category_input,
        color="#6B7280",
    )
    db.add(new_sub)
    db.flush()

    db.add(CategoryRule(
        user_id=user_id,
        category_id=new_sub.id,
        keyword=category_input
    ))

    return parent_id, new_sub.id

def parse_multiline_expense(text: str) -> dict | None:
    """解析多行記帳格式，欄位不限順序"""
    fields = {}
    field_map = {
        "品項": "item_name",
        "類別": "category",
        "金額": "amount",
        "店家": "seller_name",
        "備註": "note",
    }
    for line in text.strip().splitlines():
        for key, field in field_map.items():
            if line.startswith(f"{key}:") or line.startswith(f"{key}："):
                value = re.split(r"[:：]", line, 1)[-1].strip()
                if value:
                    fields[field] = value
                break

    required = ["item_name", "category", "amount"]
    if not all(k in fields for k in required):
        return None

    try:
        fields["amount"] = float(re.sub(r"[^\d.]", "", fields["amount"]))
    except ValueError:
        return None

    return fields

# Webhook endpoint
@app.post("/webhook")
async def webhook(request: Request):
    signature = request.headers.get("X-Line-Signature", "")
    body = await request.body()
    try:
        handler.handle(body.decode(), signature)
    except InvalidSignatureError:
        raise HTTPException(status_code=400, detail="Invalid signature")
    return "OK"

def run_fetch_in_thread():
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    try:
        loop.run_until_complete(fetch_main())
    finally:
        loop.close()

@app.get("/fetch")
async def fetch_invoices():
    print("🚀 開始抓取發票...")
    thread = threading.Thread(target=run_fetch_in_thread)
    thread.start()
    return {"status": "started"}

@handler.add(MessageEvent, message=TextMessageContent)
def handle_message(event):
    line_user_id = event.source.user_id
    msg = event.message.text.strip()

    if msg.isdigit() and len(msg) == 5 and captcha_state.captcha_event and not captcha_state.captcha_event.is_set():
        captcha_state.captcha_answer = msg
        captcha_state.captcha_event.set()
        reply = "✅ 驗證碼已送出！"
    else:
        reply = handle_text(line_user_id, msg)

    with ApiClient(configuration) as api_client:
        line_bot_api = MessagingApi(api_client)
        line_bot_api.reply_message(
            ReplyMessageRequest(
                reply_token=event.reply_token,
                messages=[TextMessage(text=reply)]
            )
        )

@handler.add(FollowEvent)
def handle_follow(event):
    with ApiClient(configuration) as api_client:
        line_bot_api = MessagingApi(api_client)
        line_bot_api.reply_message(
            ReplyMessageRequest(
                reply_token=event.reply_token,
                messages=[TextMessage(text=(
                    "👋 歡迎使用 Myfinance 記帳 Bot！\n\n"
                    "📝 點下方「記帳」開始記帳\n"
                    "📊 點「查今天」或「查本月」查詢\n\n"
                    "開始記帳吧！💪"
                ))]
            )
        )

def handle_text(line_user_id: str, text: str) -> str:
    if text == "查今天":
        return query_today(line_user_id)
    if text == "查本月":
        return query_month(line_user_id)
    if text in ("記帳", "記帳說明"):
        return EXPENSE_TEMPLATE
    if text.startswith("刪除 "):
        return delete_expense(line_user_id, text[3:].strip())

    # 多行記帳格式
    if "\n" in text:
        fields = parse_multiline_expense(text)
        if fields:
            return save_expense(line_user_id, fields)
        return (
            "格式不正確 😅\n\n"
            "必填欄位：品項、類別、金額\n"
            "點下方「記帳」取得模板！"
        )

    return (
        "點下方「記帳」取得記帳模板\n"
        "或輸入「查今天」/「查本月」查詢"
    )

def save_expense(line_user_id: str, fields: dict) -> str:
    db = SessionLocal()
    try:
        user_id = get_or_create_user(db, line_user_id)
        category_id, subcategory_id = resolve_category(db, user_id, fields["category"])

        db.add(Expense(
            user_id=user_id,
            category_id=subcategory_id or category_id,
            amount=fields["amount"],
            note=fields.get("note"),
            seller_name=fields.get("seller_name"),
            item_name=fields["item_name"],
            date=date.today(),
        ))
        db.commit()

        reply = (
            f"✅ 已記錄！\n"
            f"品項：{fields['item_name']}\n"
            f"類別：{fields['category']}\n"
            f"金額：${fields['amount']:.0f}\n"
        )
        if fields.get("seller_name"):
            reply += f"店家：{fields['seller_name']}\n"
        if fields.get("note"):
            reply += f"備註：{fields['note']}\n"
        return reply.strip()
    except Exception as e:
        db.rollback()
        print("❌ 儲存失敗:", e)
        return "儲存失敗，請稍後再試"
    finally:
        db.close()

def delete_expense(line_user_id: str, target: str) -> str:
    db = SessionLocal()
    try:
        user_id = get_or_create_user(db, line_user_id)
        rows = db.query(Expense).filter(
            Expense.user_id == user_id,
            text("DATE(date) = :today")
        ).params(today=date.today()).all()

        if not rows:
            return "今天還沒有記錄 📭"

        if target.isdigit():
            idx = int(target) - 1
            if idx < 0 or idx >= len(rows):
                return f"沒有第 {target} 筆記錄，請先輸入「查今天」確認編號"
            row = rows[idx]
            db.delete(row)
            db.commit()
            return f"✅ 已刪除：{row.item_name} ${float(row.amount):.0f}"

        matched = [r for r in rows if r.item_name == target]
        if not matched:
            return f"今天沒有「{target}」的記錄"
        row = matched[-1]
        db.delete(row)
        db.commit()
        return f"✅ 已刪除：{row.item_name} ${float(row.amount):.0f}"
    except Exception as e:
        db.rollback()
        print("❌ 刪除失敗:", e)
        return "刪除失敗，請稍後再試"
    finally:
        db.close()

def query_today(line_user_id: str) -> str:
    db = SessionLocal()
    try:
        user_id = get_or_create_user(db, line_user_id)
        rows = db.query(Expense).filter(
            Expense.user_id == user_id,
            text("DATE(date) = :today")
        ).params(today=date.today()).all()

        if not rows:
            return "今天還沒有記錄 📭"

        total = sum(float(r.amount) for r in rows)
        lines = [
            f"{i+1}. {r.item_name} ${float(r.amount):.0f}" + (f"（{r.note}）" if r.note else "")
            for i, r in enumerate(rows)
        ]
        return "📋 今日記錄：\n" + "\n".join(lines) + f"\n\n💰 合計：${total:.0f}\n\n🗑 刪除請輸入：刪除 編號\n例如：刪除 1"
    except Exception as e:
        print("❌ 查詢失敗:", e)
        return "查詢失敗，請稍後再試"
    finally:
        db.close()

def query_month(line_user_id: str) -> str:
    db = SessionLocal()
    try:
        user_id = get_or_create_user(db, line_user_id)
        now = datetime.now()
        rows = db.query(Expense).filter(
            Expense.user_id == user_id,
            text("EXTRACT(YEAR FROM date) = :year AND EXTRACT(MONTH FROM date) = :month")
        ).params(year=now.year, month=now.month).all()

        if not rows:
            return "本月還沒有記錄 📭"

        total = sum(float(r.amount) for r in rows)
        summary = {}
        for r in rows:
            key = r.item_name or "其他"
            summary[key] = summary.get(key, 0) + float(r.amount)
        lines = [f"{cat}：${amt:.0f}" for cat, amt in sorted(summary.items(), key=lambda x: -x[1])]
        return f"📊 本月統計（{now.month}月）：\n" + "\n".join(lines) + f"\n\n💰 總計：${total:.0f}"
    except Exception as e:
        print("❌ 查詢失敗:", e)
        return "查詢失敗，請稍後再試"
    finally:
        db.close()