'use strict';

/**
 * 分析编排：候选发现 → 天气 → 空气质量 → 公路 → 铁路 → 综合评分 → 备选清单
 * progress(stage, pct, text) 用于 SSE 进度推送。
 */

const U = require('./util');
const S = require('./sources');
const { aqiLabel } = S;

/** 小时数 → 人类可读时长（0.07h 读起来毫无意义，转成 4分钟） */
function humanHours(h) {
  if (h == null || !Number.isFinite(h)) return '—';
  const total = Math.round(h * 60);
  const hh = Math.floor(total / 60);
  const mm = total % 60;
  return hh ? `${hh}小时${mm ? mm + '分' : ''}` : `${mm}分钟`;
}

function validate(input) {
  const start = String(input.startDate || '');
  const end = String(input.endDate || '');
  if (!U.isValidISO(start) || !U.isValidISO(end)) throw new Error('请提供合法的出行起止日期（YYYY-MM-DD）');
  const days = U.diffDays(start, end) + 1;
  if (days < 1) throw new Error('结束日期不能早于开始日期');
  if (days > 31) throw new Error('单次分析最多支持 31 天，请缩小时间范围');
  const maxOneWayHours = U.clamp(Number(input.maxOneWayHours) || 2.5, 0.5, 8);
  const radiusKm = U.clamp(Number(input.radiusKm) || 150, 20, 300);
  // 排除同城：填了高德 Key 后 POI 会带回大量本市城区点位，和「周边出行」的定位冲突。
  // 默认开启；localKm 不超过搜索半径的六成，避免小半径时把清单清空。
  const excludeLocal = input.excludeLocal !== false;
  const localKm = Math.min(
    U.clamp(Number(input.localKm) || 30, 10, 80),
    Math.max(8, Math.round(radiusKm * 0.5)),
  );
  const o = input.origin || {};
  if (!o.lat || !o.lon) {
    if (!String(o.name || '').trim()) throw new Error('请填写出发地或允许网页定位');
  }
  return {
    start, end, days, maxOneWayHours, radiusKm, excludeLocal, localKm,
    transportPrefs: Array.isArray(input.transportPrefs) ? input.transportPrefs : [],
    interests: Array.isArray(input.interests) ? input.interests : [],
    origin: {
      name: o.name || '当前位置',
      label: o.label || o.name || '当前位置',
      lat: Number(o.lat), lon: Number(o.lon),
      admin1: o.admin1 || '', country: o.country || '',
    },
  };
}

function travelOptions(c, road, rail, prefs) {
  const allowAll = prefs.length === 0 || prefs.includes('不限');
  const allowRoad = allowAll || prefs.includes('自驾');
  const allowRail = allowAll || prefs.some((p) => /铁路|高铁|火车/.test(p));
  const allowTransit = allowAll || prefs.includes('公共交通');
  const options = [];
  if (allowRoad && Number.isFinite(road?.durationMinutes)) {
    options.push({ mode: '自驾', hours: U.round(road.durationMinutes / 60, 2), source: road.source, estimate: road.source === '估算' });
  }
  if (allowRail && rail?.available && Number.isFinite(rail.durationMinutes)) {
    options.push({ mode: '铁路/高铁', hours: U.round(rail.durationMinutes / 60, 2), source: rail.source, estimate: rail.source === '估算' });
  }
  if (allowTransit && Number.isFinite(road?.durationMinutes)) {
    options.push({ mode: '公共交通', hours: U.round((road.durationMinutes * 1.28) / 60, 2), source: '估算', estimate: true });
  }
  options.sort((a, b) => a.hours - b.hours);
  const best = options[0] || null;
  return { options, bestHours: best ? best.hours : null, bestMode: best ? best.mode : null };
}

function scoreOne(c, ctx) {
  const { weather, aqi, road, rail, constraints, days } = ctx;
  const s = weather?.summary || null;
  const travel = travelOptions(c, road, rail, constraints.transportPrefs);

  // 1) 天气舒适度 0~40
  let weatherScore = 20;
  if (s) {
    const tempPenalty = U.clamp(Math.max(0, 12 - s.avgLow) * 0.9 + Math.max(0, s.avgHigh - 28) * 1.1, 0, 16);
    const precipPenalty = U.clamp(s.totalPrecip * 1.1 + s.maxPrecipProb * 0.09, 0, 16);
    const windPenalty = U.clamp(Math.max(0, s.maxWind - 25) * 0.22, 0, 7);
    const severePenalty = U.clamp(s.badDays * 3, 0, 10);
    weatherScore = U.clamp(40 - tempPenalty - precipPenalty - windPenalty - severePenalty, 0, 40);
  }

  // 2) 时间适配 0~26
  let timeScore = 2;
  let overLimit = false;
  if (travel.bestHours != null) {
    if (travel.bestHours > constraints.maxOneWayHours) {
      timeScore = 4;
      overLimit = true;
    } else {
      timeScore = U.clamp(
        26 - (travel.bestHours / constraints.maxOneWayHours) * 15 - (travel.bestHours > 3 ? 4 : 0) + (days >= 2 && travel.bestHours <= 1.5 ? 2 : 0),
        0, 26,
      );
    }
  }

  // 3) 距离 0~7（不鼓励「越近越好」，只做轻微惩罚）
  const distanceScore = U.clamp(7 - (c.distanceKm / constraints.radiusKm) * 4.5, 2.5, 7);

  // 4) 兴趣匹配 0~14
  let interestScore = 8;
  const matched = constraints.interests.filter((i) => c.tags.includes(i));
  if (constraints.interests.length) interestScore = U.clamp(4 + matched.length * 4, 0, 14);

  // 5) 空气质量 0~6
  let aqiScore = 3;
  if (aqi != null) aqiScore = aqi <= 50 ? 6 : aqi <= 100 ? 4 : aqi <= 150 ? 2 : 0;

  // 6) 目的地辨识度 0~8（知名景区 > 小众精选 > OSM 无名点位）
  const qualityScore = U.clamp(
    (c.featured ? 6 : 0)
      + (c.hasExtent ? 1 : 0)
      + (/高德/.test(c.source || '') ? 1 : 0)
      + (c.niche ? 1 : 0),
    0, 8,
  );

  const score = U.round(weatherScore + timeScore + distanceScore + interestScore + aqiScore + qualityScore, 0);
  const breakdown = {
    weather: U.round(weatherScore, 1), time: U.round(timeScore, 1),
    distance: U.round(distanceScore, 1), interest: U.round(interestScore, 1),
    aqi: U.round(aqiScore, 1), quality: U.round(qualityScore, 1),
  };

  let verdict = score >= 74 ? '强烈推荐' : score >= 60 ? '推荐' : score >= 45 ? '可考虑' : '不推荐';
  // 天气硬门槛：整段行程都是坏天气时，不因交通/距离优势给出「推荐」
  if (s && s.badDays >= s.days && verdict === '强烈推荐') verdict = '推荐';
  if (s && s.badDays >= s.days && verdict === '推荐') verdict = '可考虑';
  return { score, breakdown, verdict, travel, overLimit, matched };
}

function buildReasons(c, ctx, scored) {
  const { weather, aqi, road, rail, constraints, days, weatherMode } = ctx;
  const s = weather?.summary;
  const reasons = [];
  const warnings = [];

  if (s) {
    if (s.badDays === 0 && s.maxPrecipProb < 40) {
      reasons.push(`${s.days} 天以${s.dominant.label}为主，平均 ${s.avgLow}~${s.avgHigh}℃，降水概率最高 ${s.maxPrecipProb}%，天气窗口友好`);
    } else {
      reasons.push(`${s.days} 天内有 ${s.badDays} 天需注意天气（最差：${s.dominant.label}），累计降水 ${s.totalPrecip}mm、最大风速 ${s.maxWind}km/h`);
      warnings.push('期间有明显降水/大风，建议准备室内备选');
    }
    if (s.avgHigh >= 30) warnings.push('高温，注意防晒补水并避开正午户外');
    if (s.avgLow <= 3) warnings.push('气温偏低，需保暖并留意路面结冰');
  } else {
    warnings.push('未取到该地天气数据，天气维度按中性计分');
  }

  const optionsText = scored.travel.options
    .slice(0, 2)
    .map((o) => `${o.mode} ${humanHours(o.hours)}${o.estimate ? '(估算)' : ''}`)
    .join(' / ');
  if (optionsText) reasons.push(`${optionsText}；公路里程约 ${road.distanceKm}km`);
  if (scored.travel.bestHours == null) warnings.push('按所选交通方式无可达方案');
  else if (scored.overLimit) warnings.push(`最快单程 ${humanHours(scored.travel.bestHours)}，超出你设定的 ${constraints.maxOneWayHours} 小时`);
  else reasons.push(`最快单程约 ${humanHours(scored.travel.bestHours)}（${scored.travel.bestMode}），${days} 天行程节奏${days >= 2 && scored.travel.bestHours <= 1.5 ? '宽松' : '适中'}`);

  if (scored.matched.length) reasons.push(`匹配你的兴趣：${scored.matched.join('、')}`);
  if (aqi != null) {
    const a = aqiLabel(aqi);
    reasons.push(`空气质量${a.label}（AQI ${aqi}）`);
    if (a.level === 'bad') warnings.push('空气质量较差，敏感人群减少户外停留');
  }

  if (road.source === '估算') warnings.push('公路耗时为路网兜底估算，请出发前用地图复核');
  if (rail.source === '估算') warnings.push('铁路耗时/票价为估算，车次与余票需在 12306 核对');
  if (weatherMode === 'climatology') warnings.push('超出 16 天预报范围，天气为去年同期历史气候参考，非实时预报');

  return { reasons: reasons.slice(0, 5), warnings: warnings.slice(0, 4) };
}

async function analyze(input, cfg, progress = () => {}) {
  const c = validate(input);
  const t0 = Date.now();

  // ---- 0. 解析出发地
  progress('origin', 6, '解析出发地坐标');
  let origin = { ...c.origin };
  if (!Number.isFinite(origin.lat) || !Number.isFinite(origin.lon)) {
    const hits = await S.geocode(origin.name, cfg, 1);
    if (!hits.length) throw new Error(`没找到「${origin.name}」，换个地名试试`);
    origin = { ...hits[0], name: origin.name, label: hits[0].label };
  }
  origin.lat = U.round(origin.lat, 5);
  origin.lon = U.round(origin.lon, 5);

  // 出发地的行政区信息（省/市/区县）。
  // 用途：① 高德 place/text 检索时限定在同一个省；② 「排除同城」按**区县**判定——
  // 同市下辖的其它县（融水、三江、鹿寨…）是真正的周边目的地，不该被排除。
  if (!origin.district || !origin.province) {
    try {
      const rev = await S.reverseGeocode(origin.lat, origin.lon, cfg);
      origin.province = origin.province || (rev.admin1 || '');
      origin.city = origin.city || rev.name || '';
      origin.district = origin.district || (rev.label || '').split(' · ').pop() || '';
    } catch { /* 拿不到就退回距离判定 */ }
  }
  // 高德检索限定在同一个省（周边出行通常不出省）
  const searchCfg = origin.province ? { ...cfg, AMAP_PROVINCE: origin.province.replace(/省$/, '') } : cfg;

  // ---- 1. 周边候选
  progress('discover', 18, `检索 ${c.radiusKm}km 内的景点、公园、博物馆与邻近城市`);
  const { candidates, stats } = await S.discoverCandidates(origin, c.radiusKm, searchCfg, {
    excludeLocal: c.excludeLocal,
    localKm: c.localKm,
    homeDistrict: origin.district || '',
    homeCity: origin.city || '',
  });
  if (!candidates.length) {
    throw new Error('这个范围内没有检索到可用目的地，试试调大搜索半径');
  }

  // ---- 2. 天气 + 空气质量（并行）
  progress('weather', 42, `获取 ${candidates.length} 个候选地的逐日天气与空气质量`);
  const [weatherRes, aqiRes] = await Promise.all([
    S.fetchWeather(candidates, c.start, c.end, cfg),
    S.fetchAQI(candidates, c.start, c.end, cfg),
  ]);

  // ---- 3. 公路 + 铁路（并行）
  progress('traffic', 66, '计算公路路网耗时与铁路可达性');
  const [roadRes, railRes] = await Promise.all([
    S.roadMatrix(origin, candidates, cfg),
    S.railMatrix(origin, candidates, c.start, cfg),
  ]);

  // ---- 4. 评分
  progress('score', 86, '综合天气、交通、距离与偏好评分');
  const ctxBase = { constraints: c, days: c.days, weatherMode: weatherRes.mode };
  const scored = candidates.map((cd, i) => {
    const ctx = {
      ...ctxBase,
      weather: weatherRes.series[i],
      aqi: aqiRes.values[i],
      road: roadRes.matrix[i],
      rail: railRes[i],
    };
    const s = scoreOne(cd, ctx);
    const { reasons, warnings } = buildReasons(cd, ctx, s);
    return {
      ...cd,
      score: s.score,
      breakdown: s.breakdown,
      verdict: s.verdict,
      travel: s.travel,
      weather: ctx.weather ? {
        summary: ctx.weather.summary,
        daily: ctx.weather.daily,
      } : null,
      aqi: ctx.aqi,
      aqiInfo: aqiLabel(ctx.aqi),
      road: ctx.road,
      rail: ctx.rail,
      reasons,
      warnings,
    };
  });
  scored.sort((a, b) => b.score - a.score || a.distanceKm - b.distanceKm);
  scored.forEach((x, i) => { x.rank = i + 1; });

  // ---- 5. 汇总
  const withWeather = scored.filter((x) => x.weather?.summary);
  const avgHigh = withWeather.length
    ? U.round(withWeather.reduce((s, x) => s + x.weather.summary.avgHigh, 0) / withWeather.length, 1) : null;
  const rainy = withWeather.filter((x) => x.weather.summary.badDays > 0).length;
  const weatherAlert = withWeather.length > 0 && rainy / withWeather.length >= 0.7
    ? '所选时间窗口内多数候选地有降水/大风等不利天气，建议关注逐日天气并准备室内备选'
    : null;

  const dataNotes = [
    `周边目的地：Photon / OpenStreetMap（成功 ${stats.categoryHits}/${stats.requested} 类）` +
      `${stats.amapCount ? ` + 高德周边 ${stats.amapCount} 条` : ''}` +
      ` + 内置知名景区 ${stats.curatedCount} 个 + 内置城市 ${stats.cityCount} 个 + 内置小众地点 ${stats.nicheCount} 个` +
      `${stats.fallbackOnly ? '；⚠️ 实时 POI 服务不可用，本次清单完全来自内置地名库（坐标为近似值）' : ''}` +
      `${c.excludeLocal && stats.localExcluded ? `；已排除出发地所在城区的同城点位 ${stats.localExcluded} 个（同市下辖的其它县保留为周边目的地）` : ''}`,
    `天气：${weatherRes.note}`,
    `空气质量：${aqiRes.note}`,
    `公路：${roadRes.provider === '估算' ? '路网服务不可用，全部为里程-速度估算' : roadRes.provider === '高德' ? '高德 Web 服务驾车路径（WGS-84→GCJ-02）' : 'OSRM 公开路网矩阵'}`,
    `铁路：${cfg.RAIL_API_URL ? '优先调用配置的铁路接口，失败时降级估算' : '未配置铁路接口，高铁/城际耗时与票价均为估算'}`,
    '所有标注「估算」的数据不得视为实时信息；车次、票价、门票、营业时间需临近出发前在官方渠道核对',
  ];

  const result = {
    origin,
    timeRange: {
      start: c.start, end: c.end, days: c.days,
      weekdayHint: `${U.weekdayCN(c.start)} ~ ${U.weekdayCN(c.end)}`,
    },
    constraints: {
      maxOneWayHours: c.maxOneWayHours,
      radiusKm: c.radiusKm,
      excludeLocal: c.excludeLocal,
      localKm: c.localKm,
      transportPrefs: c.transportPrefs,
      interests: c.interests,
    },
    summary: {
      total: scored.length,
      recommended: scored.filter((x) => x.score >= 60).length,
      avgScore: U.round(scored.reduce((s, x) => s + x.score, 0) / scored.length, 1),
      avgHigh,
      rainyCount: rainy,
      weatherAlert,
      weatherMode: weatherRes.mode,
      weatherNote: weatherRes.note,
      roadProvider: roadRes.provider,
      elapsedMs: Date.now() - t0,
    },
    candidates: scored,
    dataNotes,
    stats,
  };
  progress('done', 100, '分析完成');
  return result;
}

module.exports = { analyze, validate };