'use strict';

/**
 * 校区地图 · 学校数据（JSON 静态存储）
 * ----------------------------------------------------------------------------
 * 两份文件合并成一份视图：
 *   server/schools.seed.json  随版本发布的内置学校（只读，可被运行时覆盖 enabled/坐标）
 *   data/schools.json         运行时新增/修改（gitignore；由 SCHOOLS_FILE 可覆盖，测试用）
 *
 * 合并规则：以 name 为唯一键，运行时同名字段覆盖种子；种子的 seed 标记始终保留。
 */

const fs = require('fs');
const path = require('path');

const ROOT_DIR = __dirname;
const SEED_FILE = process.env.SCHOOLS_SEED_FILE
  ? path.resolve(process.env.SCHOOLS_SEED_FILE)
  : path.join(ROOT_DIR, 'server', 'schools.seed.json');
const RUNTIME_FILE = process.env.SCHOOLS_FILE
  ? path.resolve(process.env.SCHOOLS_FILE)
  : path.join(ROOT_DIR, 'data', 'schools.json');

function readJson(file, fallback) {
  try {
    return JSON.parse(fs.readFileSync(file, 'utf8'));
  } catch (e) {
    if (e.code !== 'ENOENT') console.warn(`[schools] 读取失败 ${file}: ${e.message}`);
    return fallback;
  }
}

function normalizeEntry(raw) {
  if (!raw || !raw.name) return null;
  const name = String(raw.name).trim();
  if (!name) return null;
  const lng = Number(raw.lng);
  const lat = Number(raw.lat);
  const hasPoint = Number.isFinite(lng) && Number.isFinite(lat)
    && lng > 73 && lng < 136 && lat > 3 && lat < 54;
  return {
    id: raw.id || `sch_${Buffer.from(name).toString('base64url').slice(0, 10)}`,
    name,
    aliases: Array.isArray(raw.aliases) ? raw.aliases.map(String) : [],
    province: raw.province || '',
    city: raw.city || '',
    county: raw.county || '',
    lng: hasPoint ? lng : null,
    lat: hasPoint ? lat : null,
    source: raw.source || 'local',
    seed: raw.seed === true,
    enabled: raw.enabled !== false,
    created_at: raw.created_at || '',
    updated_at: raw.updated_at || '',
  };
}

/** 读原始条目（不补默认值）：合并时才能区分「显式给了空值」和「没给」 */
function readRawList(file) {
  const data = readJson(file, null);
  if (!data || !Array.isArray(data.schools)) return [];
  return data.schools.filter((item) => item && typeof item === 'object' && String(item.name || '').trim());
}

/** 合并后的学校列表（种子 + 运行时），按省份、名称排序 */
function loadSchools() {
  const merged = new Map();
  for (const raw of readRawList(SEED_FILE)) {
    const name = String(raw.name).trim();
    merged.set(name, { ...raw, name, seed: true });
  }
  for (const raw of readRawList(RUNTIME_FILE)) {
    const name = String(raw.name).trim();
    const base = merged.get(name);
    merged.set(name, {
      // 只覆盖运行时显式给出的字段
      ...(base || {}),
      ...raw,
      name,
      // 种子标记不可被运行时文件伪造/清除
      seed: !!(base && base.seed),
    });
  }
  return [...merged.values()].map(normalizeEntry).filter(Boolean).sort((a, b) => {
    const p = String(a.province).localeCompare(String(b.province), 'zh-Hans-CN');
    return p !== 0 ? p : String(a.name).localeCompare(String(b.name), 'zh-Hans-CN');
  });
}

function runtimeFile() {
  return RUNTIME_FILE;
}

function seedFile() {
  return SEED_FILE;
}

module.exports = { loadSchools, normalizeEntry, runtimeFile, seedFile };