import { Solar } from 'lunar-typescript'
import { ElementScore } from '../services/request'

type ElementName = '木' | '火' | '土' | '金' | '水'

export type FiveElementReport = {
  scores: ElementScore[]
  favorable: string
  unfavorable: string
  dayMaster: string
}

const stemElements: Record<string, ElementName> = {
  甲: '木', 乙: '木', 丙: '火', 丁: '火', 戊: '土', 己: '土', 庚: '金', 辛: '金', 壬: '水', 癸: '水'
}

const branchElements: Record<string, ElementName> = {
  子: '水', 丑: '土', 寅: '木', 卯: '木', 辰: '土', 巳: '火', 午: '火', 未: '土', 申: '金', 酉: '金', 戌: '土', 亥: '水'
}

const elementMeta: Record<ElementName, { color: string }> = {
  木: { color: '#36b85b' },
  火: { color: '#ef5a58' },
  土: { color: '#b46a18' },
  金: { color: '#d59a05' },
  水: { color: '#35bfe8' }
}

const scoreOrder: ElementName[] = ['土', '金', '水', '木', '火']
const generationOrder: ElementName[] = ['木', '火', '土', '金', '水']

const hourFromBirthHour = (birthHour: string) => {
  const numericHour = Number.parseInt(birthHour, 10)
  if (Number.isFinite(numericHour)) return Math.max(0, Math.min(23, numericHour))

  const branchHours: Record<string, number> = {
    子: 23, 丑: 1, 寅: 3, 卯: 5, 辰: 7, 巳: 9,
    午: 11, 未: 13, 申: 15, 酉: 17, 戌: 19, 亥: 21
  }
  return branchHours[birthHour.slice(0, 1)] ?? 12
}

export function calculateFiveElements(birthday: string, birthHour: string): FiveElementReport {
  const date = new Date(`${birthday}T00:00:00`)
  if (Number.isNaN(date.getTime())) {
    return {
      scores: scoreOrder.map((name) => ({ name, color: elementMeta[name].color, value: 20 })),
      favorable: '金水',
      unfavorable: '木火土',
      dayMaster: '壬'
    }
  }

  const solar = Solar.fromYmdHms(
    date.getFullYear(),
    date.getMonth() + 1,
    date.getDate(),
    hourFromBirthHour(birthHour),
    0,
    0
  )
  const eightChar = solar.getLunar().getEightChar()
  const pillars = [eightChar.getYear(), eightChar.getMonth(), eightChar.getDay(), eightChar.getTime()]
  const weights: Record<ElementName, number> = { 木: 0, 火: 0, 土: 0, 金: 0, 水: 0 }

  pillars.forEach((pillar) => {
    const [stem, branch] = pillar
    if (stemElements[stem]) weights[stemElements[stem]] += 2
    if (branchElements[branch]) weights[branchElements[branch]] += 1
  })

  const total = Object.values(weights).reduce((sum, value) => sum + value, 0)
  const scores = scoreOrder.map((name) => ({
    name,
    color: elementMeta[name].color,
    value: Math.round((weights[name] / total) * 100)
  }))
  const dayMaster = eightChar.getDay().slice(0, 1)
  const masterElement = stemElements[dayMaster] || '水'
  const masterIndex = generationOrder.indexOf(masterElement)
  const resourceElement = generationOrder[(masterIndex + generationOrder.length - 1) % generationOrder.length]
  const unfavorable = generationOrder.filter((element) => element !== resourceElement && element !== masterElement).join('')

  return {
    scores,
    favorable: `${resourceElement}${masterElement}`,
    unfavorable,
    dayMaster
  }
}