"""数据库操作层 — 封装所有 SQLite 操作。"""

import sqlite3
import os
from datetime import datetime

DB_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)), "books.db")


def _connect():
    conn = sqlite3.connect(DB_PATH)
    conn.row_factory = sqlite3.Row
    conn.execute("PRAGMA journal_mode=WAL")
    return conn


def init_db():
    """初始化数据库和表结构。"""
    conn = _connect()
    conn.execute("""
        CREATE TABLE IF NOT EXISTS books (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            title TEXT NOT NULL,
            author TEXT,
            translator TEXT,
            publisher TEXT,
            pub_date TEXT,
            cover_url TEXT,
            format TEXT DEFAULT 'paper',
            status TEXT DEFAULT 'to-read',
            rating INTEGER,
            douban_score REAL,
            goodreads_score REAL,
            tags TEXT DEFAULT '',
            notes TEXT,
            start_date TEXT,
            finish_date TEXT,
            created_at TEXT DEFAULT (datetime('now', 'localtime')),
            updated_at TEXT DEFAULT (datetime('now', 'localtime'))
        )
    """)
    conn.commit()
    conn.close()


def add_book(title, *, author=None, translator=None, publisher=None,
             pub_date=None, cover_url=None, format="paper", status="to-read",
             rating=None, douban_score=None, goodreads_score=None,
             tags="", notes=None, start_date=None, finish_date=None):
    """添加一本书，返回新书 ID。"""
    conn = _connect()
    cur = conn.execute("""
        INSERT INTO books (title, author, translator, publisher, pub_date,
                           cover_url, format, status, rating, douban_score,
                           goodreads_score, tags, notes, start_date, finish_date)
        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
    """, (title, author, translator, publisher, pub_date, cover_url,
          format, status, rating, douban_score, goodreads_score,
          tags, notes, start_date, finish_date))
    conn.commit()
    book_id = cur.lastrowid
    conn.close()
    return book_id


def update_book(book_id, **kwargs):
    """更新书目字段。只更新传入的字段。"""
    if not kwargs:
        return
    allowed = {
        "title", "author", "translator", "publisher", "pub_date",
        "cover_url", "format", "status", "rating", "douban_score",
        "goodreads_score", "tags", "notes", "start_date", "finish_date",
    }
    fields = {k: v for k, v in kwargs.items() if k in allowed}
    if not fields:
        return
    fields["updated_at"] = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    set_clause = ", ".join(f"{k} = ?" for k in fields)
    values = list(fields.values()) + [book_id]
    conn = _connect()
    conn.execute(f"UPDATE books SET {set_clause} WHERE id = ?", values)
    conn.commit()
    conn.close()


def delete_book(book_id):
    """删除一本书。"""
    conn = _connect()
    conn.execute("DELETE FROM books WHERE id = ?", (book_id,))
    conn.commit()
    conn.close()


def get_book(book_id):
    """获取单本书详情，返回 dict 或 None。"""
    conn = _connect()
    row = conn.execute("SELECT * FROM books WHERE id = ?", (book_id,)).fetchone()
    conn.close()
    return dict(row) if row else None


def list_books(*, status=None, format=None, tag=None):
    """查询书目列表，支持按状态/格式/标签过滤。"""
    conn = _connect()
    query = "SELECT * FROM books WHERE 1=1"
    params = []
    if status:
        query += " AND status = ?"
        params.append(status)
    if format:
        query += " AND format = ?"
        params.append(format)
    if tag:
        # 逗号分隔的 tags 字段中模糊匹配
        query += " AND (',' || tags || ',' LIKE ?)"
        params.append(f"%,{tag},%")
    query += " ORDER BY updated_at DESC"
    rows = conn.execute(query, params).fetchall()
    conn.close()
    return [dict(r) for r in rows]


def get_stats():
    """获取统计数据。"""
    conn = _connect()
    total = conn.execute("SELECT COUNT(*) FROM books").fetchone()[0]
    by_status = {}
    for row in conn.execute("SELECT status, COUNT(*) as cnt FROM books GROUP BY status"):
        by_status[row["status"]] = row["cnt"]
    by_format = {}
    for row in conn.execute("SELECT format, COUNT(*) as cnt FROM books GROUP BY format"):
        by_format[row["format"]] = row["cnt"]
    conn.close()
    return {
        "total": total,
        "by_status": by_status,
        "by_format": by_format,
    }


def get_all_tags():
    """获取所有不重复的标签列表。"""
    conn = _connect()
    rows = conn.execute("SELECT tags FROM books WHERE tags != ''").fetchall()
    conn.close()
    tag_set = set()
    for row in rows:
        for t in row["tags"].split(","):
            t = t.strip()
            if t:
                tag_set.add(t)
    return sorted(tag_set)