import { useEffect, useMemo, useState } from 'react'
import { Card } from '@/libs/frontend-ui-primitives'
import Link from 'next/link'
import { explorerFeaturePages } from '@/data/explorerOperations'
import { blocksApi, type Block } from '@/services/api/blocks'
import {
  missionControlApi,
  type MissionControlBridgeStatusResponse,
  type MissionControlChainStatus,
} from '@/services/api/missionControl'
import {
  statsApi,
  type ExplorerRecentActivitySnapshot,
  type ExplorerStats,
  type ExplorerTransactionTrendPoint,
} from '@/services/api/stats'
import { transactionsApi, type Transaction } from '@/services/api/transactions'
import { formatWeiAsEth } from '@/utils/format'
import { summarizeChainActivity } from '@/utils/activityContext'
import ActivityContextPanel from '@/components/common/ActivityContextPanel'
import FreshnessTrustNote from '@/components/common/FreshnessTrustNote'
import SubsystemPosturePanel from '@/components/common/SubsystemPosturePanel'
import { resolveEffectiveFreshness, shouldExplainEmptyHeadBlocks } from '@/utils/explorerFreshness'
import OperationsPageShell, {
  MetricCard,
  StatusBadge,
  formatNumber,
  relativeAge,
  truncateMiddle,
} from './OperationsPageShell'

interface AnalyticsOperationsPageProps {
  initialStats?: ExplorerStats | null
  initialTransactionTrend?: ExplorerTransactionTrendPoint[]
  initialActivitySnapshot?: ExplorerRecentActivitySnapshot | null
  initialBlocks?: Block[]
  initialTransactions?: Transaction[]
  initialBridgeStatus?: MissionControlBridgeStatusResponse | null
}

function getChainStatus(bridgeStatus: MissionControlBridgeStatusResponse | null): MissionControlChainStatus | null {
  const chains = bridgeStatus?.data?.chains
  if (!chains) return null
  const [firstChain] = Object.values(chains)
  return firstChain || null
}

export default function AnalyticsOperationsPage({
  initialStats = null,
  initialTransactionTrend = [],
  initialActivitySnapshot = null,
  initialBlocks = [],
  initialTransactions = [],
  initialBridgeStatus = null,
}: AnalyticsOperationsPageProps) {
  const [stats, setStats] = useState<ExplorerStats | null>(initialStats)
  const [transactionTrend, setTransactionTrend] = useState<ExplorerTransactionTrendPoint[]>(initialTransactionTrend)
  const [activitySnapshot, setActivitySnapshot] = useState<ExplorerRecentActivitySnapshot | null>(initialActivitySnapshot)
  const [blocks, setBlocks] = useState<Block[]>(initialBlocks)
  const [transactions, setTransactions] = useState<Transaction[]>(initialTransactions)
  const [bridgeStatus, setBridgeStatus] = useState<MissionControlBridgeStatusResponse | null>(initialBridgeStatus)
  const [loadingError, setLoadingError] = useState<string | null>(null)
  const page = explorerFeaturePages.analytics

  useEffect(() => {
    let cancelled = false

    const load = async () => {
      const [statsResult, trendResult, snapshotResult, blocksResult, transactionsResult, bridgeResult] = await Promise.allSettled([
        statsApi.get(),
        statsApi.getTransactionTrend(),
        statsApi.getRecentActivitySnapshot(),
        blocksApi.list({ chain_id: 138, page: 1, page_size: 5 }),
        transactionsApi.list(138, 1, 5),
        missionControlApi.getBridgeStatus(),
      ])

      if (cancelled) return

      if (statsResult.status === 'fulfilled') setStats(statsResult.value)
      if (trendResult.status === 'fulfilled') setTransactionTrend(trendResult.value)
      if (snapshotResult.status === 'fulfilled') setActivitySnapshot(snapshotResult.value)
      if (blocksResult.status === 'fulfilled') setBlocks(blocksResult.value.data)
      if (transactionsResult.status === 'fulfilled') setTransactions(transactionsResult.value.data)
      if (bridgeResult.status === 'fulfilled') setBridgeStatus(bridgeResult.value)

      const failedCount = [statsResult, trendResult, snapshotResult, blocksResult, transactionsResult, bridgeResult].filter(
        (result) => result.status === 'rejected'
      ).length

      if (failedCount === 6) {
        setLoadingError('Analytics data is temporarily unavailable from the public explorer APIs.')
      }
    }

    load().catch((error) => {
      if (!cancelled) {
        setLoadingError(error instanceof Error ? error.message : 'Analytics data is temporarily unavailable from the public explorer APIs.')
      }
    })

    return () => {
      cancelled = true
    }
  }, [])

  const chainStatus = useMemo(() => getChainStatus(bridgeStatus), [bridgeStatus])
  const trailingWindow = useMemo(() => transactionTrend.slice(0, 7), [transactionTrend])
  const sevenDayAverage = useMemo(() => {
    if (trailingWindow.length === 0) return 0
    const total = trailingWindow.reduce((sum, point) => sum + point.transaction_count, 0)
    return total / trailingWindow.length
  }, [trailingWindow])
  const topDay = useMemo(() => {
    if (trailingWindow.length === 0) return null
    return trailingWindow.reduce((best, point) => (point.transaction_count > best.transaction_count ? point : best))
  }, [trailingWindow])
  const averageGasUtilization = useMemo(() => {
    if (blocks.length === 0) return 0
    return blocks.reduce((sum, block) => {
      const ratio = block.gas_limit > 0 ? block.gas_used / block.gas_limit : 0
      return sum + ratio
    }, 0) / blocks.length
  }, [blocks])
  const trendPeak = useMemo(
    () => trailingWindow.reduce((max, point) => Math.max(max, point.transaction_count), 0),
    [trailingWindow],
  )
  const activityContext = useMemo(
    () =>
      summarizeChainActivity({
        blocks,
        transactions,
        latestBlockNumber: stats?.latest_block ?? blocks[0]?.number ?? null,
        latestBlockTimestamp: blocks[0]?.timestamp ?? null,
        freshness: resolveEffectiveFreshness(stats, bridgeStatus),
        diagnostics: stats?.diagnostics ?? bridgeStatus?.data?.diagnostics ?? null,
      }),
    [blocks, bridgeStatus, stats, transactions],
  )

  return (
    <OperationsPageShell page={page}>
      {loadingError ? (
        <Card className="mb-6 border border-red-200 bg-red-50/70 dark:border-red-900/50 dark:bg-red-950/20">
          <p className="text-sm leading-6 text-red-900 dark:text-red-100">{loadingError}</p>
        </Card>
      ) : null}

      <div className="mb-6">
        <ActivityContextPanel context={activityContext} title="Analytics Freshness Context" />
        <FreshnessTrustNote
          className="mt-3"
          context={activityContext}
          stats={stats}
          bridgeStatus={bridgeStatus}
          scopeLabel="This page combines public stats, recent block samples, and indexed transactions."
        />
        <SubsystemPosturePanel
          className="mt-3"
          subsystems={bridgeStatus?.data?.subsystems}
          title="Analytics Subsystem Posture"
          preferredKeys={['rpc_head', 'tx_index', 'stats_summary', 'freshness_queries']}
          scopeLabel="These subsystem signals explain whether sparse analytics reflect quiet-chain conditions, partial transaction indexing, or stale summary generation."
        />
      </div>

      <div className="mb-6 grid gap-4 md:grid-cols-2 xl:grid-cols-4">
        <MetricCard
          title="Total Blocks"
          value={formatNumber(stats?.total_blocks)}
          description="Current block count from the public Blockscout stats endpoint."
          className="border border-sky-200 bg-sky-50/70 dark:border-sky-900/50 dark:bg-sky-950/20"
        />
        <MetricCard
          title="Transactions"
          value={formatNumber(stats?.total_transactions)}
          description="Total transactions currently indexed by the public explorer."
          className="border border-emerald-200 bg-emerald-50/70 dark:border-emerald-900/50 dark:bg-emerald-950/20"
        />
        <MetricCard
          title="Addresses"
          value={formatNumber(stats?.total_addresses)}
          description="Known addresses from the public stats surface."
        />
        <MetricCard
          title="Chain Head"
          value={chainStatus?.head_age_sec != null ? `${Math.round(chainStatus.head_age_sec)}s` : 'Unknown'}
          description={
            chainStatus?.latency_ms != null
              ? `RPC latency ${Math.round(chainStatus.latency_ms)}ms on Chain 138.`
              : 'Latest public RPC head age from mission control.'
          }
        />
        <MetricCard
          title="7d Avg Tx"
          value={formatNumber(Math.round(sevenDayAverage))}
          description="Average daily transactions over the latest seven charted days."
          className="border border-violet-200 bg-violet-50/70 dark:border-violet-900/50 dark:bg-violet-950/20"
        />
        <MetricCard
          title="Recent Success Rate"
          value={activitySnapshot ? `${Math.round(activitySnapshot.success_rate * 100)}%` : 'Unknown'}
          description="Success rate across the public main-page transaction sample."
        />
        <MetricCard
          title="Failure Rate"
          value={activitySnapshot ? `${Math.round(activitySnapshot.failure_rate * 100)}%` : 'Unknown'}
          description="The complement to the recent success rate in the visible sample."
          className="border border-rose-200 bg-rose-50/70 dark:border-rose-900/50 dark:bg-rose-950/20"
        />
        <MetricCard
          title="Avg Gas Used"
          value={activitySnapshot ? formatNumber(Math.round(activitySnapshot.average_gas_used)) : 'Unknown'}
          description="Average gas used in the recent sampled transactions."
        />
        <MetricCard
          title="Avg Block Gas"
          value={`${Math.round(averageGasUtilization * 100)}%`}
          description="Average gas utilization across the latest visible blocks."
          className="border border-amber-200 bg-amber-50/70 dark:border-amber-900/50 dark:bg-amber-950/20"
        />
      </div>

      <div className="mb-8 grid gap-6 lg:grid-cols-[1fr_1fr]">
        <Card title="Activity Trend">
          <div className="space-y-4">
            <div className="grid gap-4 sm:grid-cols-3">
              <div className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40">
                <div className="text-xs font-semibold uppercase tracking-wide text-gray-500 dark:text-gray-400">Peak Day</div>
                <div className="mt-2 text-xl font-semibold text-gray-900 dark:text-white">
                  {topDay ? formatNumber(topDay.transaction_count) : 'Unknown'}
                </div>
                <div className="mt-1 text-sm text-gray-600 dark:text-gray-400">{topDay?.date || 'No trend data yet'}</div>
              </div>
              <div className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40">
                <div className="text-xs font-semibold uppercase tracking-wide text-gray-500 dark:text-gray-400">Contract Creations</div>
                <div className="mt-2 text-xl font-semibold text-gray-900 dark:text-white">
                  {formatNumber(activitySnapshot?.contract_creations)}
                </div>
                <div className="mt-1 text-sm text-gray-600 dark:text-gray-400">Within the sampled recent transaction feed.</div>
              </div>
              <div className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40">
                <div className="text-xs font-semibold uppercase tracking-wide text-gray-500 dark:text-gray-400">Avg Sample Fee</div>
                <div className="mt-2 text-xl font-semibold text-gray-900 dark:text-white">
                  {activitySnapshot ? formatWeiAsEth(Math.round(activitySnapshot.average_fee_wei).toString(), 6) : 'Unknown'}
                </div>
                <div className="mt-1 text-sm text-gray-600 dark:text-gray-400">Average fee from the recent public transaction sample.</div>
              </div>
            </div>

            {activitySnapshot ? (
              <div className="grid gap-3 sm:grid-cols-3">
                <div className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40">
                  <div className="text-xs font-semibold uppercase tracking-wide text-gray-500 dark:text-gray-400">Token Transfer Share</div>
                  <div className="mt-2 text-xl font-semibold text-gray-900 dark:text-white">
                    {Math.round(activitySnapshot.token_transfer_share * 100)}%
                  </div>
                  <div className="mt-1 text-sm text-gray-600 dark:text-gray-400">Sampled transactions involving token transfers.</div>
                </div>
                <div className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40">
                  <div className="text-xs font-semibold uppercase tracking-wide text-gray-500 dark:text-gray-400">Contract Call Share</div>
                  <div className="mt-2 text-xl font-semibold text-gray-900 dark:text-white">
                    {Math.round(activitySnapshot.contract_call_share * 100)}%
                  </div>
                  <div className="mt-1 text-sm text-gray-600 dark:text-gray-400">Sampled transactions calling contracts.</div>
                </div>
                <div className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40">
                  <div className="text-xs font-semibold uppercase tracking-wide text-gray-500 dark:text-gray-400">Creation Share</div>
                  <div className="mt-2 text-xl font-semibold text-gray-900 dark:text-white">
                    {Math.round(activitySnapshot.contract_creation_share * 100)}%
                  </div>
                  <div className="mt-1 text-sm text-gray-600 dark:text-gray-400">Sampled transactions deploying contracts.</div>
                </div>
              </div>
            ) : null}

            <div className="space-y-3">
              {trailingWindow.map((point) => {
                const width = trendPeak > 0 ? Math.max(8, Math.round((point.transaction_count / trendPeak) * 100)) : 0
                return (
                  <div key={point.date}>
                    <div className="mb-1 flex items-center justify-between text-sm text-gray-600 dark:text-gray-400">
                      <span>{point.date}</span>
                      <span>{formatNumber(point.transaction_count)} tx</span>
                    </div>
                    <div className="h-2 rounded-full bg-gray-200 dark:bg-gray-800">
                      <div className="h-2 rounded-full bg-primary-600" style={{ width: `${width}%` }} />
                    </div>
                  </div>
                )
              })}
              {trailingWindow.length === 0 ? (
                <p className="text-sm text-gray-600 dark:text-gray-400">Trend data is temporarily unavailable.</p>
              ) : null}
            </div>
          </div>
        </Card>

        <Card title="Recent Blocks">
          <div className="space-y-4">
            {shouldExplainEmptyHeadBlocks(blocks, activityContext) ? (
              <p className="rounded-xl border border-amber-200 bg-amber-50/70 px-3 py-2 text-sm text-amber-900 dark:border-amber-900/40 dark:bg-amber-950/20 dark:text-amber-100">
                Recent head blocks are currently empty; use the latest transaction block for recent visible activity.
              </p>
            ) : null}
            {blocks.map((block) => (
              <div
                key={block.hash}
                className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40"
              >
                <div className="flex flex-col gap-3 sm:flex-row sm:items-start sm:justify-between">
                  <div>
                    <Link href={`/blocks/${block.number}`} className="text-base font-semibold text-primary-600 hover:underline">
                      Block {formatNumber(block.number)}
                    </Link>
                    <div className="mt-1 text-xs text-gray-500 dark:text-gray-400">
                      {truncateMiddle(block.hash)} · miner{' '}
                      <Link href={`/addresses/${block.miner}`} className="text-primary-600 hover:underline">
                        {truncateMiddle(block.miner)}
                      </Link>
                    </div>
                  </div>
                  <div className="text-sm text-gray-600 dark:text-gray-400">
                    {formatNumber(block.transaction_count)} tx · {Math.round((block.gas_limit > 0 ? block.gas_used / block.gas_limit : 0) * 100)}% gas · {relativeAge(block.timestamp)}
                  </div>
                </div>
              </div>
            ))}
            {blocks.length === 0 ? (
              <p className="text-sm text-gray-600 dark:text-gray-400">No recent block data available.</p>
            ) : null}
          </div>
        </Card>

        <Card title="Recent Transactions">
          <div className="space-y-4">
            {transactions.map((transaction) => (
              <div
                key={transaction.hash}
                className="rounded-2xl border border-gray-200 bg-gray-50 p-4 dark:border-gray-700 dark:bg-gray-900/40"
              >
                <div className="flex flex-col gap-3 sm:flex-row sm:items-start sm:justify-between">
                  <div>
                    <Link href={`/transactions/${transaction.hash}`} className="text-base font-semibold text-primary-600 hover:underline">
                      {truncateMiddle(transaction.hash, 12, 10)}
                    </Link>
                    <div className="mt-1 text-xs text-gray-500 dark:text-gray-400">
                      Block{' '}
                      <Link href={`/blocks/${transaction.block_number}`} className="text-primary-600 hover:underline">
                        {formatNumber(transaction.block_number)}
                      </Link>
                      {' '}· from{' '}
                      <Link href={`/addresses/${transaction.from_address}`} className="text-primary-600 hover:underline">
                        {truncateMiddle(transaction.from_address)}
                      </Link>
                      {transaction.to_address ? (
                        <>
                          {' '}· to{' '}
                          <Link href={`/addresses/${transaction.to_address}`} className="text-primary-600 hover:underline">
                            {truncateMiddle(transaction.to_address)}
                          </Link>
                        </>
                      ) : null}
                    </div>
                  </div>
                  <div className="flex items-center gap-3">
                    <StatusBadge
                      status={transaction.status === 1 ? 'success' : 'failed'}
                      tone={transaction.status === 1 ? 'normal' : 'danger'}
                    />
                    <div className="text-sm text-gray-600 dark:text-gray-400">
                      {relativeAge(transaction.created_at)}
                    </div>
                  </div>
                </div>
                <div className="mt-3 flex flex-wrap gap-2 text-xs">
                  {transaction.method ? <StatusBadge status={transaction.method} tone="warning" /> : null}
                  {transaction.contract_address ? <StatusBadge status="contract creation" tone="warning" /> : null}
                  {transaction.token_transfers && transaction.token_transfers.length > 0 ? (
                    <StatusBadge status={`${transaction.token_transfers.length} token transfer${transaction.token_transfers.length === 1 ? '' : 's'}`} />
                  ) : null}
                </div>
              </div>
            ))}
            {transactions.length === 0 ? (
              <p className="text-sm text-gray-600 dark:text-gray-400">No recent transaction data available.</p>
            ) : null}
          </div>
        </Card>
      </div>
    </OperationsPageShell>
  )
}
