#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import psycopg2
import os
import sys
from dotenv import load_dotenv


load_dotenv("../../.env", override=True)
DB_CONFIG = {
    "host": os.getenv("ROOT_DB_HOST", "localhost"),
    "port": os.getenv("ROOT_DB_PORT", "5432"),
    "dbname": os.getenv("ROOT_DB_NAME", "mydb"),
    "user": os.getenv("ROOT_DB_USER", "postgres"),
    "password": os.getenv("ROOT_DB_PASSWD", "postgres"),
}


def fetch_nodes():
    conn = psycopg2.connect(**DB_CONFIG)
    cur = conn.cursor()
    cur.execute("SELECT id, name, parent_id FROM fst")
    rows = cur.fetchall()
    cur.close()
    conn.close()
    return rows


def build_tree(rows):
    nodes = {}
    for id_, name, parent_id in rows:
        nodes[id_] = {"id": id_, "name": name, "parent_id": parent_id, "children": []}
    roots = []
    for n in nodes.values():
        if n["parent_id"] is None or n["parent_id"] not in nodes:
            roots.append(n)
        else:
            nodes[n["parent_id"]]["children"].append(n)

    def sort_rec(n):
        n["children"].sort(key=lambda x: x["name"])
        for c in n["children"]:
            sort_rec(c)

    for r in roots:
        sort_rec(r)
    return roots


def print_subtree(node, prefix="", is_last=True, depth=0):
    # depth==0: 根节点；depth>=1: 各层子节点
    if depth == 0:
        # 根直接打印名字
        print(node["name"])
    else:
        # 非根：打印前置 prefix + 连接符 + 名字
        connector = "└── " if is_last else "├── "
        print(prefix + connector + node["name"])
    # 计算传给下一层孩子的前缀
    if depth == 0:
        # 第一层孩子不缩进，prefix 仍然空
        child_prefix = ""
    else:
        # depth>=1：如果我是本层最后一个，用空格填充，否则保留竖线
        child_prefix = prefix + ("    " if is_last else "│   ")
    # 递归打印子节点
    cnt = len(node["children"])
    for idx, child in enumerate(node["children"]):
        last = idx == cnt - 1
        print_subtree(child, child_prefix, last, depth + 1)


def main():
    rows = fetch_nodes()
    if not rows:
        print("fst 表中没有数据。", file=sys.stderr)
        sys.exit(1)
    roots = build_tree(rows)
    for idx, r in enumerate(roots):
        last_root = idx == len(roots) - 1
        print_subtree(r, prefix="", is_last=last_root, depth=0)


if __name__ == "__main__":
    main()