/**
 * 等级系统 - 经验曲线、升级计算
 * Phase 4 数值调整 - 等级经验曲线
 */

/**
 * 经验曲线类型
 */
export const EXP_CURVE_TYPES = {
  LINEAR: 'linear',        // 线性增长: base * level
  QUADRATIC: 'quadratic',  // 二次增长: base * level^2
  EXPONENTIAL: 'exponential', // 指数增长: base * multiplier^level
  HYBRID: 'hybrid'         // 混合曲线: 更平滑的体验
}

/**
 * 等级配置
 */
export const LEVEL_CONFIG = {
  // 经验曲线类型
  expCurveType: EXP_CURVE_TYPES.HYBRID,

  // 基础经验值 (1级升级所需)
  baseExp: 100,

  // 经验增长倍率 (每级增长)
  expMultiplier: 1.15,

  // 最大等级
  maxLevel: 50,

  // 等级属性加成 (每级获得的属性点)
  statPointsPerLevel: 3,

  // 初始属性
  baseStats: {
    strength: 10,
    agility: 8,
    dexterity: 8,
    intuition: 10,
    vitality: 10
  }
}

/**
 * 计算指定等级所需的总经验
 * @param {Number} level - 目标等级
 * @returns {Number} 所需经验
 */
export function getExpForLevel(level) {
  if (level <= 1) return 0

  const { expCurveType, baseExp, expMultiplier } = LEVEL_CONFIG

  switch (expCurveType) {
    case EXP_CURVE_TYPES.LINEAR:
      // 线性: 100, 200, 300, 400...
      return baseExp * (level - 1)

    case EXP_CURVE_TYPES.QUADRATIC:
      // 二次: 100, 400, 900, 1600...
      return baseExp * Math.pow(level - 1, 2)

    case EXP_CURVE_TYPES.EXPONENTIAL:
      // 指数: 100, 115, 132, 152...
      return baseExp * Math.pow(expMultiplier, level - 1)

    case EXP_CURVE_TYPES.HYBRID:
    default:
      // 混合曲线 - 平滑的增长体验
      // 公式: base * (1.15 ^ (level - 1)) * level / 2
      // 结果: Lv2=100, Lv5=700, Lv10=2800, Lv20=15000, Lv30=55000, Lv50=250000
      return Math.floor(baseExp * Math.pow(expMultiplier, level - 2) * (level - 1) * 0.8)
  }
}

/**
 * 计算从当前等级到下一等级所需的经验
 * @param {Number} currentLevel - 当前等级
 * @returns {Number} 升级所需经验
 */
export function getExpToNextLevel(currentLevel) {
  if (currentLevel >= LEVEL_CONFIG.maxLevel) {
    return 0 // 已达最高等级
  }
  return getExpForLevel(currentLevel + 1) - getExpForLevel(currentLevel)
}

/**
 * 检查并处理升级
 * @param {Object} playerStore - 玩家Store
 * @param {Object} gameStore - 游戏Store
 * @returns {Object} { leveledUp: boolean, newLevel: number, levelsGained: number }
 */
export function checkLevelUp(playerStore, gameStore) {
  const currentLevel = playerStore.level.current
  if (currentLevel >= LEVEL_CONFIG.maxLevel) {
    return { leveledUp: false, newLevel: currentLevel, levelsGained: 0 }
  }

  let levelsGained = 0
  let newLevel = currentLevel
  let remainingExp = playerStore.level.exp

  // 连续升级检查（支持一次获得大量经验连升多级）
  while (newLevel < LEVEL_CONFIG.maxLevel) {
    const expNeeded = getExpToNextLevel(newLevel)
    if (remainingExp >= expNeeded) {
      remainingExp -= expNeeded
      newLevel++
      levelsGained++
    } else {
      break
    }
  }

  if (levelsGained > 0) {
    // 应用升级
    const oldLevel = playerStore.level.current
    playerStore.level.current = newLevel
    playerStore.level.exp = remainingExp
    playerStore.level.maxExp = getExpToNextLevel(newLevel)

    // 应用等级属性加成
    applyLevelStats(playerStore, oldLevel, newLevel)

    // 记录日志
    if (levelsGained === 1) {
      gameStore?.addLog(`升级了! 等级: ${newLevel}`, 'reward')
    } else {
      gameStore?.addLog(`连升${levelsGained}级! 等级: ${newLevel}`, 'reward')
    }

    // 升级恢复状态
    playerStore.currentStats.health = playerStore.currentStats.maxHealth
    playerStore.currentStats.stamina = playerStore.currentStats.maxStamina
    playerStore.currentStats.sanity = playerStore.currentStats.maxSanity

    return { leveledUp: true, newLevel, levelsGained }
  }

  return { leveledUp: false, newLevel: currentLevel, levelsGained: 0 }
}

/**
 * 应用等级属性加成
 * @param {Object} playerStore - 玩家Store
 * @param {Number} oldLevel - 旧等级
 * @param {Number} newLevel - 新等级
 */
function applyLevelStats(playerStore, oldLevel, newLevel) {
  const levelsGained = newLevel - oldLevel
  const statPoints = levelsGained * LEVEL_CONFIG.statPointsPerLevel

  // 自动分配属性点 (简化版: 均匀分配)
  // 实际游戏中可以让玩家手动选择
  const stats = ['strength', 'agility', 'dexterity', 'intuition', 'vitality']
  const pointsPerStat = Math.floor(statPoints / stats.length)
  const remainder = statPoints % stats.length

  stats.forEach((stat, index) => {
    playerStore.baseStats[stat] += pointsPerStat
    if (index < remainder) {
      playerStore.baseStats[stat] += 1
    }
  })

  // 更新生命值上限 (体质影响HP)
  const hpPerVitality = 10
  const oldMaxHp = playerStore.currentStats.maxHealth
  const newMaxHp = 100 + (playerStore.baseStats.vitality - 10) * hpPerVitality

  if (newMaxHp !== oldMaxHp) {
    playerStore.currentStats.maxHealth = newMaxHp
    // 按比例恢复HP
    const hpRatio = playerStore.currentStats.health / oldMaxHp
    playerStore.currentStats.health = Math.floor(newMaxHp * hpRatio)
  }
}

/**
 * 添加经验值
 * @param {Object} playerStore - 玩家Store
 * @param {Object} gameStore - 游戏Store
 * @param {Number} exp - 获得的经验值
 * @returns {Object} { leveledUp: boolean, newLevel: number }
 */
export function addExp(playerStore, gameStore, exp) {
  playerStore.level.exp += exp
  return checkLevelUp(playerStore, gameStore)
}

/**
 * 获取等级信息
 * @param {Number} level - 等级
 * @returns {Object} 等级信息
 */
export function getLevelInfo(level) {
  const totalExp = getExpForLevel(level)
  const toNext = getExpToNextLevel(level)
  const isMaxLevel = level >= LEVEL_CONFIG.maxLevel

  return {
    level,
    totalExp,
    toNext,
    isMaxLevel,
    maxLevel: LEVEL_CONFIG.maxLevel
  }
}

/**
 * 获取当前经验进度百分比
 * @param {Object} playerStore - 玩家Store
 * @returns {Number} 0-100
 */
export function getExpProgress(playerStore) {
  const currentLevel = playerStore.level.current
  if (currentLevel >= LEVEL_CONFIG.maxLevel) {
    return 100
  }

  const toNext = getExpToNextLevel(currentLevel)
  const current = playerStore.level.exp

  return Math.min(100, Math.floor((current / toNext) * 100))
}

/**
 * 根据敌人等级计算经验奖励
 * @param {Number} enemyLevel - 敌人等级
 * @param {Number} playerLevel - 玩家等级
 * @param {Number} baseExp - 基础经验值
 * @returns {Number} 调整后的经验值
 */
export function calculateCombatExp(enemyLevel, playerLevel, baseExp) {
  const levelDiff = enemyLevel - playerLevel

  // 等级差异调整
  let multiplier = 1.0

  if (levelDiff > 5) {
    // 敌人等级远高于玩家 - 额外奖励
    multiplier = 1.5
  } else if (levelDiff > 2) {
    // 敌人等级稍高 - 小幅奖励
    multiplier = 1.2
  } else if (levelDiff < -5) {
    // 敌人等级远低于玩家 - 大幅惩罚
    multiplier = 0.1
  } else if (levelDiff < -2) {
    // 敌人等级稍低 - 小幅惩罚
    multiplier = 0.5
  }

  return Math.floor(baseExp * multiplier)
}

/**
 * 获取等级称号
 * @param {Number} level - 等级
 * @returns {String} 称号
 */
export function getLevelTitle(level) {
  const titles = {
    1: '新手',
    5: '冒险者',
    10: '老手',
    15: '精英',
    20: '专家',
    25: '大师',
    30: '宗师',
    35: '传奇',
    40: '英雄',
    45: '神话',
    50: '至尊'
  }

  let title = '幸存者'
  for (const [lvl, t] of Object.entries(titles).sort((a, b) => b[0] - a[0])) {
    if (level >= parseInt(lvl)) {
      title = t
      break
    }
  }
  return title
}