export type TimeRange = '1D' | '5D' | '1M' | '3M' | '6M' | 'YTD' | '1Y' | '3Y' | '5Y'

export interface RawHistoricalLinePoint {
  timestamp: string
  price: number | null
  volume: number | null
}

export interface ChartPoint {
  index: number
  timestamp: string // ISO 8601 UTC
  price: number | null
  volume: number | null
  percentChange: number | null
}

export interface TimeRangeConfig {
  label: TimeRange
  duration: string
  barSize: string
  tickInterval: (data: ChartPoint[]) => number[]
  formatLabel: (timestamp: string) => string
}

function formatInLocalTime(
  timestamp: string,
  opts: Intl.DateTimeFormatOptions
): string {
  const date = new Date(timestamp)
  if (Number.isNaN(date.getTime())) return ''

  return new Intl.DateTimeFormat(undefined, opts).format(date)
}

/**
 * Get the trading day key for a timestamp based on US Eastern time
 * (NYSE operates in Eastern time, so trading days should be determined by ET, not UTC)
 */
function getTradingDayKey(timestamp: string) {
  const d = new Date(timestamp)
  if (Number.isNaN(d.getTime())) return ''
  
  // Format in US Eastern time to get the correct trading day
  return d.toLocaleDateString('en-CA', { timeZone: 'America/New_York' }) // 'en-CA' gives YYYY-MM-DD format
}

function sortByTimestamp<T extends { timestamp: string }>(rows: T[]) {
  return [...rows].sort(
    (a, b) => new Date(a.timestamp).getTime() - new Date(b.timestamp).getTime()
  )
}

function keepLatestTradingDay<T extends { timestamp: string }>(rows: T[]) {
  const sorted = sortByTimestamp(rows)
  const distinctDays = [...new Set(sorted.map((r) => getTradingDayKey(r.timestamp)).filter(Boolean))]
  if (!distinctDays.length) return sorted

  const latest = distinctDays[distinctDays.length - 1]
  return sorted.filter((r) => getTradingDayKey(r.timestamp) === latest)
}

function keepLatestNTradingDays<T extends { timestamp: string }>(rows: T[], n: number) {
  const sorted = sortByTimestamp(rows)
  const distinctDays = [...new Set(sorted.map((r) => getTradingDayKey(r.timestamp)).filter(Boolean))]
  const keep = new Set(distinctDays.slice(-n))
  return sorted.filter((r) => keep.has(getTradingDayKey(r.timestamp)))
}

function normalizeRawRows(input: unknown[]): RawHistoricalLinePoint[] {
  return input
    .map((row): RawHistoricalLinePoint | null => {
      if (!row || typeof row !== 'object') return null

      const r = row as Record<string, unknown>
      const timestamp = typeof r.timestamp === 'string' ? r.timestamp : null
      const price =
        typeof r.price === 'number'
          ? r.price
          : typeof r.price === 'string'
            ? Number(r.price)
            : null
      const volume =
        typeof r.volume === 'number'
          ? r.volume
          : typeof r.volume === 'string'
            ? Number(r.volume)
            : null

      if (!timestamp) return null

      const parsed = new Date(timestamp)
      if (Number.isNaN(parsed.getTime())) return null

      return {
        timestamp: parsed.toISOString(),
        price: price !== null && Number.isFinite(price) ? price : null,
        volume: volume !== null && Number.isFinite(volume) ? volume : null,
      }
    })
    .filter((row): row is RawHistoricalLinePoint => row !== null)
}

export function buildChartData(input: unknown[], range: TimeRange): ChartPoint[] {
  let rows = normalizeRawRows(input)
  rows = sortByTimestamp(rows)

  if (range === '1D') {
    rows = keepLatestTradingDay(rows)
  } else if (range === '5D') {
    rows = keepLatestNTradingDays(rows, 5)
  }

  const firstValid = rows.find((r) => r.price !== null)
  const openPrice = firstValid?.price ?? null

  return rows.map((row, index) => {
    const percentChange =
      row.price !== null && openPrice !== null && openPrice !== 0
        ? ((row.price - openPrice) / openPrice) * 100
        : null

    return {
      index,
      timestamp: row.timestamp,
      price: row.price,
      volume: row.volume,
      percentChange,
    }
  })
}

function tickEveryN(data: ChartPoint[], count: number) {
  if (data.length <= 1) return [0]
  const step = Math.max(1, Math.floor((data.length - 1) / count))
  const indices: number[] = []

  for (let i = 0; i < data.length; i += step) {
    indices.push(i)
  }

  if (indices[indices.length - 1] !== data.length - 1) {
    indices.push(data.length - 1)
  }

  return [...new Set(indices)]
}

function tickByDistinctLocalDays(data: ChartPoint[]) {
  const out: number[] = []
  let lastDay = ''

  for (let i = 0; i < data.length; i++) {
    const label = formatInLocalTime(data[i].timestamp, {
      year: 'numeric',
      month: '2-digit',
      day: '2-digit',
    })

    if (label !== lastDay) {
      out.push(i)
      lastDay = label
    }
  }

  return out
}

export const TIME_RANGE_CONFIGS: TimeRangeConfig[] = [
  {
    label: '1D',
    duration: '1 D',
    barSize: 'FiveMins',
    tickInterval: (data) => tickEveryN(data, 4),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        hour: '2-digit',
        minute: '2-digit',
        hour12: false,
      }),
  },
  {
    label: '5D',
    duration: '5 D',
    barSize: 'FiveMins',
    tickInterval: (data) => tickByDistinctLocalDays(data),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        month: 'short',
        day: 'numeric',
      }),
  },
  {
    label: '1M',
    duration: '1 M',
    barSize: 'OneHour',
    tickInterval: (data) => tickEveryN(data, 5),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        month: 'short',
        day: 'numeric',
      }),
  },
  {
    label: '3M',
    duration: '3 M',
    barSize: 'OneDay',
    tickInterval: (data) => tickEveryN(data, 5),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        month: 'short',
        day: 'numeric',
      }),
  },
  {
    label: '6M',
    duration: '6 M',
    barSize: 'OneDay',
    tickInterval: (data) => tickEveryN(data, 5),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        month: 'short',
        day: 'numeric',
      }),
  },
  {
    label: 'YTD',
    duration: '1 Y',
    barSize: 'OneDay',
    tickInterval: (data) => tickEveryN(data, 5),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        month: 'short',
      }),
  },
  {
    label: '1Y',
    duration: '1 Y',
    barSize: 'OneDay',
    tickInterval: (data) => tickEveryN(data, 5),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        month: 'short',
      }),
  },
  {
    label: '3Y',
    duration: '3 Y',
    barSize: 'OneWeek',
    tickInterval: (data) => tickEveryN(data, 5),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        month: 'short',
        year: '2-digit',
      }),
  },
  {
    label: '5Y',
    duration: '5 Y',
    barSize: 'OneMonth',
    tickInterval: (data) => tickEveryN(data, 5),
    formatLabel: (timestamp) =>
      formatInLocalTime(timestamp, {
        year: '2-digit',
      }),
  },
]