/**
 * 技能系统 - 技能经验、升级、里程碑、父技能同步
 * Phase 6 核心系统实现
 */

import { SKILL_CONFIG } from '@/config/skills.js'
import { GAME_CONSTANTS } from '@/config/constants.js'

/**
 * 添加技能经验
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 技能ID
 * @param {Number} amount - 经验值
 * @param {Object} options - 选项 { partialSuccess: boolean }
 * @returns {Object} { leveledUp: boolean, newLevel: number, milestoneReached: number|null }
 */
export function addSkillExp(playerStore, skillId, amount, options = {}) {
  const { partialSuccess = false } = options

  // 检查技能是否存在且已解锁
  if (!playerStore.skills || !playerStore.skills[skillId]) {
    return { leveledUp: false, newLevel: 0, milestoneReached: null }
  }

  const skill = playerStore.skills[skillId]
  if (!skill.unlocked) {
    return { leveledUp: false, newLevel: 0, milestoneReached: null }
  }

  // 部分成功时经验减半
  const finalAmount = partialSuccess ? Math.floor(amount * GAME_CONSTANTS.EXP_PARTIAL_SUCCESS) : amount

  // 检查玩家等级限制
  const maxSkillLevel = playerStore.level ? playerStore.level.current * 2 : 2
  if (skill.level >= maxSkillLevel) {
    return { leveledUp: false, newLevel: skill.level, milestoneReached: null, capped: true }
  }

  // 获取技能配置
  const config = SKILL_CONFIG[skillId]
  if (!config) {
    return { leveledUp: false, newLevel: 0, milestoneReached: null }
  }

  // 计算有效等级上限（取技能上限和玩家限制的最小值）
  const effectiveMaxLevel = Math.min(config.maxLevel, maxSkillLevel)

  // 添加经验
  skill.exp += finalAmount

  let leveledUp = false
  let milestoneReached = null

  // 检查升级（可能连续升级）
  while (skill.level < effectiveMaxLevel && skill.exp >= getNextLevelExp(skillId, skill.level)) {
    const result = levelUpSkill(playerStore, skillId, skill.level)
    leveledUp = true
    if (result.milestone) {
      milestoneReached = result.milestone
    }
  }

  return {
    leveledUp,
    newLevel: skill.level,
    milestoneReached,
    capped: skill.level >= effectiveMaxLevel
  }
}

/**
 * 获取下一级所需经验
 * @param {String} skillId - 技能ID
 * @param {Number} currentLevel - 当前等级
 * @returns {Number} 所需经验值
 */
export function getNextLevelExp(skillId, currentLevel) {
  const config = SKILL_CONFIG[skillId]
  if (!config) return 100

  // 使用配置中的经验公式，默认为 level * 100
  if (typeof config.expPerLevel === 'function') {
    return config.expPerLevel(currentLevel + 1)
  }
  return (currentLevel + 1) * 100
}

/**
 * 技能升级
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 技能ID
 * @param {Number} currentLevel - 当前等级
 * @returns {Object} { milestone: number|null, effects: Object }
 */
export function levelUpSkill(playerStore, skillId, currentLevel) {
  const skill = playerStore.skills[skillId]
  const config = SKILL_CONFIG[skillId]
  if (!skill || !config) {
    return { milestone: null, effects: {} }
  }

  // 增加等级
  skill.level++
  const requiredExp = getNextLevelExp(skillId, currentLevel)
  skill.exp -= requiredExp

  // 检查里程碑奖励
  let milestone = null
  let effects = {}

  if (config.milestones && config.milestones[skill.level]) {
    milestone = skill.level
    effects = applyMilestoneBonus(playerStore, skillId, skill.level)
  }

  // 更新父技能等级
  updateParentSkill(playerStore, skillId)

  return { milestone, effects }
}

/**
 * 应用里程碑奖励
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 技能ID
 * @param {Number} level - 里程碑等级
 * @returns {Object} 应用的效果
 */
export function applyMilestoneBonus(playerStore, skillId, level) {
  const config = SKILL_CONFIG[skillId]
  if (!config || !config.milestones || !config.milestones[level]) {
    return {}
  }

  const milestone = config.milestones[level]
  const effects = { ...milestone.effect }

  // 初始化里程碑奖励存储
  if (!playerStore.milestoneBonuses) {
    playerStore.milestoneBonuses = {}
  }

  const bonusKey = `${skillId}_${level}`

  // 如果已经应用过，跳过
  if (playerStore.milestoneBonuses[bonusKey]) {
    return effects
  }

  // 标记里程碑已应用
  playerStore.milestoneBonuses[bonusKey] = {
    skillId,
    level,
    desc: milestone.desc,
    effect: effects,
    appliedAt: Date.now()
  }

  // 应用全局属性加成
  if (!playerStore.globalBonus) {
    playerStore.globalBonus = {
      critRate: 0,
      attackBonus: 0,
      expRate: 1,
      critMult: 0,
      darkPenaltyReduce: 0,
      globalExpRate: 0,
      readingSpeed: 1
    }
  }

  // 应用具体效果
  if (effects.critRate) {
    playerStore.globalBonus.critRate += effects.critRate
  }
  if (effects.attackBonus) {
    playerStore.globalBonus.attackBonus += effects.attackBonus
  }
  if (effects.expRate) {
    playerStore.globalBonus.expRate *= effects.expRate
  }
  if (effects.critMult) {
    playerStore.globalBonus.critMult += effects.critMult
  }
  if (effects.darkPenaltyReduce) {
    playerStore.globalBonus.darkPenaltyReduce += effects.darkPenaltyReduce
  }
  if (effects.globalExpRate) {
    playerStore.globalBonus.globalExpRate += effects.globalExpRate
  }
  if (effects.readingSpeed) {
    playerStore.globalBonus.readingSpeed *= effects.readingSpeed
  }

  return effects
}

/**
 * 更新父技能等级
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 子技能ID
 */
export function updateParentSkill(playerStore, skillId) {
  const config = SKILL_CONFIG[skillId]
  if (!config || !config.parentSkill) {
    return
  }

  const parentSkillId = config.parentSkill

  // 查找所有子技能的最高等级
  const childSkills = Object.keys(SKILL_CONFIG).filter(id =>
    SKILL_CONFIG[id].parentSkill === parentSkillId
  )

  let maxChildLevel = 0
  for (const childId of childSkills) {
    const childSkill = playerStore.skills[childId]
    if (childSkill && childSkill.unlocked) {
      maxChildLevel = Math.max(maxChildLevel, childSkill.level)
    }
  }

  // 更新父技能等级
  if (!playerStore.skills[parentSkillId]) {
    playerStore.skills[parentSkillId] = {
      level: 0,
      exp: 0,
      unlocked: true
    }
  }

  playerStore.skills[parentSkillId].level = maxChildLevel
}

/**
 * 解锁技能
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 技能ID
 * @returns {boolean} 是否成功解锁
 */
export function unlockSkill(playerStore, skillId) {
  if (!playerStore.skills) {
    playerStore.skills = {}
  }

  const config = SKILL_CONFIG[skillId]
  if (!config) {
    return false
  }

  // 检查是否已解锁
  if (playerStore.skills[skillId] && playerStore.skills[skillId].unlocked) {
    return true
  }

  // 初始化技能数据
  playerStore.skills[skillId] = {
    level: 0,
    exp: 0,
    unlocked: true,
    maxExp: getNextLevelExp(skillId, 0)
  }

  return true
}

/**
 * 检查技能是否可解锁
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 技能ID
 * @returns {Object} { canUnlock: boolean, reason: string }
 */
export function canUnlockSkill(playerStore, skillId) {
  const config = SKILL_CONFIG[skillId]
  if (!config) {
    return { canUnlock: false, reason: '技能不存在' }
  }

  // 已解锁
  if (playerStore.skills[skillId] && playerStore.skills[skillId].unlocked) {
    return { canUnlock: true, reason: '已解锁' }
  }

  // 检查解锁条件
  if (config.unlockCondition) {
    const condition = config.unlockCondition

    // 物品条件
    if (condition.type === 'item') {
      const hasItem = playerStore.inventory?.some(i => i.id === condition.item)
      if (!hasItem) {
        return { canUnlock: false, reason: '需要特定物品' }
      }
    }

    // 位置条件
    if (condition.location) {
      if (playerStore.currentLocation !== condition.location) {
        return { canUnlock: false, reason: '需要在特定位置解锁' }
      }
    }

    // 技能等级条件
    if (condition.skillLevel) {
      const requiredSkill = playerStore.skills[condition.skillId]
      if (!requiredSkill || requiredSkill.level < condition.skillLevel) {
        return { canUnlock: false, reason: '需要前置技能达到特定等级' }
      }
    }
  }

  return { canUnlock: true, reason: '' }
}

/**
 * 获取技能经验倍率（含父技能加成）
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 技能ID
 * @returns {Number} 经验倍率
 */
export function getSkillExpRate(playerStore, skillId) {
  let rate = 1.0

  // 全局经验加成
  if (playerStore.globalBonus && playerStore.globalBonus.globalExpRate) {
    rate *= (1 + playerStore.globalBonus.globalExpRate / 100)
  }

  // 父技能加成
  const config = SKILL_CONFIG[skillId]
  if (config && config.parentSkill) {
    const parentSkill = playerStore.skills[config.parentSkill]
    if (parentSkill && parentSkill.unlocked) {
      const parentConfig = SKILL_CONFIG[config.parentSkill]
      if (parentConfig && parentConfig.milestones) {
        // 检查父技能里程碑奖励
        for (const [level, milestone] of Object.entries(parentConfig.milestones)) {
          if (parentSkill.level >= parseInt(level) && milestone.effect?.expRate) {
            rate *= milestone.effect.expRate
          }
        }
      }

      // 如果子技能等级低于父技能，提供额外加成
      if (parentSkill.level > 0 && playerStore.skills[skillId]) {
        const childLevel = playerStore.skills[skillId].level
        if (childLevel < parentSkill.level) {
          rate *= 1.5  // 父技能倍率加成
        }
      }
    }
  }

  return rate
}

/**
 * 获取技能显示信息
 * @param {Object} playerStore - 玩家Store
 * @param {String} skillId - 技能ID
 * @returns {Object|null} 技能显示信息
 */
export function getSkillDisplayInfo(playerStore, skillId) {
  const config = SKILL_CONFIG[skillId]
  if (!config) {
    return null
  }

  const skillData = playerStore.skills[skillId] || {
    level: 0,
    exp: 0,
    unlocked: false
  }

  const maxExp = getNextLevelExp(skillId, skillData.level)
  const progress = skillData.level >= config.maxLevel ? 1 : skillData.exp / maxExp

  // 获取已达到的里程碑
  const reachedMilestones = []
  if (config.milestones && playerStore.milestoneBonuses) {
    for (const [level, milestone] of Object.entries(config.milestones)) {
      const bonusKey = `${skillId}_${level}`
      if (playerStore.milestoneBonuses[bonusKey]) {
        reachedMilestones.push({
          level: parseInt(level),
          desc: milestone.desc
        })
      }
    }
  }

  return {
    id: skillId,
    name: config.name,
    type: config.type,
    category: config.category,
    icon: config.icon,
    level: skillData.level,
    maxLevel: config.maxLevel,
    exp: skillData.exp,
    maxExp,
    progress,
    unlocked: skillData.unlocked,
    reachedMilestones,
    nextMilestone: getNextMilestone(config, skillData.level)
  }
}

/**
 * 获取下一个里程碑
 * @param {Object} config - 技能配置
 * @param {Number} currentLevel - 当前等级
 * @returns {Object|null} 下一个里程碑
 */
function getNextMilestone(config, currentLevel) {
  if (!config.milestones) {
    return null
  }

  for (const [level, milestone] of Object.entries(config.milestones)) {
    if (parseInt(level) > currentLevel) {
      return {
        level: parseInt(level),
        desc: milestone.desc
      }
    }
  }

  return null
}

/**
 * 重置技能系统（用于新游戏）
 * @param {Object} playerStore - 玩家Store
 */
export function resetSkillSystem(playerStore) {
  playerStore.skills = {}
  playerStore.milestoneBonuses = {}
  playerStore.globalBonus = {
    critRate: 0,
    attackBonus: 0,
    expRate: 1,
    critMult: 0,
    darkPenaltyReduce: 0,
    globalExpRate: 0,
    readingSpeed: 1
  }
}