import { ref, readonly, computed } from 'vue'
import { useNostr } from './useNostr.js'
import { finalizeEvent } from 'nostr-tools'
import * as nip04 from 'nostr-tools/nip04'
import * as nip44 from 'nostr-tools/nip44'
import { hexToBytes, bytesToHex } from 'nostr-tools/utils'
import { authFetch } from '../lib/nostr-auth'

type WalletMethod = 'nwc' | 'lnaddress' | null
type PaymentStatus = 'idle' | 'invoiced' | 'paying' | 'confirmed' | 'failed'

// Persist wallet method across navigations
function loadStored<T>(key: string): T | null {
  try {
    const raw = localStorage.getItem(key)
    return raw ? JSON.parse(raw) : null
  } catch { return null }
}
function store(key: string, value: unknown) {
  try {
    if (value == null) localStorage.removeItem(key)
    else localStorage.setItem(key, JSON.stringify(value))
  } catch { /* Safari private browsing quota exception */ }
}

const isWalletConnected = ref(!!loadStored<string>('bf_wallet_method'))
const walletMethod = ref<WalletMethod>(loadStored<WalletMethod>('bf_wallet_method'))
const paymentStatus = ref<PaymentStatus>('idle')
const pendingPayment = ref<{ paymentId: string; bolt11: string } | null>(null)

interface NwcConfig {
  pubkey: string
  relay: string
  secret: Uint8Array
}

function parseNwcUrl(url: string): NwcConfig {
  const withoutScheme = url.replace('nostr+walletconnect://', '')
  const [pubkey, queryString] = withoutScheme.split('?')
  const params = new URLSearchParams(queryString)
  const relay = params.get('relay')
  const secret = params.get('secret')
  if (!pubkey || !relay || !secret) {
    throw new Error('Invalid NWC URL: missing pubkey, relay, or secret')
  }
  // Validate hex before parsing — must be even-length hex string
  const trimmed = secret.trim()
  if (trimmed.length === 0 || trimmed.length % 2 !== 0 || !/^[0-9a-fA-F]+$/.test(trimmed)) {
    throw new Error('Invalid NWC URL: secret is not valid hex (must be even-length hex string)')
  }
  return { pubkey, relay, secret: hexToBytes(trimmed) }
}

export function useWallet() {
  const { pubkey, bot } = useNostr()

  async function connectNWC(connectionString: string): Promise<void> {
    if (!pubkey.value) throw new Error('Not logged in')

    // Validate the NWC URL format
    parseNwcUrl(connectionString)

    const res = await authFetch('/api/payments/connect-wallet', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        pubkey: pubkey.value,
        method: 'nwc',
        connectionData: connectionString,
      }),
    })

    if (!res.ok) {
      const data = await res.json()
      throw new Error(data.error || 'Failed to connect wallet')
    }

    // Store NWC string locally for client-side payment sending
    try { localStorage.setItem('bf_nwc_url', connectionString) } catch { /* quota */ }
    walletMethod.value = 'nwc'
    isWalletConnected.value = true
    store('bf_wallet_method', 'nwc')
  }

  async function connectLightningAddress(address: string): Promise<void> {
    if (!pubkey.value) throw new Error('Not logged in')

    if (!address.includes('@')) {
      throw new Error('Invalid Lightning Address format')
    }

    const res = await authFetch('/api/payments/connect-wallet', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        pubkey: pubkey.value,
        method: 'lnaddress',
        connectionData: address,
      }),
    })

    if (!res.ok) {
      const data = await res.json()
      throw new Error(data.error || 'Failed to connect wallet')
    }

    walletMethod.value = 'lnaddress'
    isWalletConnected.value = true
    store('bf_wallet_method', 'lnaddress')
  }

  async function disconnectWallet(): Promise<void> {
    if (!pubkey.value) return

    await authFetch('/api/payments/disconnect-wallet', {
      method: 'DELETE',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ pubkey: pubkey.value }),
    })

    walletMethod.value = null
    isWalletConnected.value = false
    paymentStatus.value = 'idle'
    pendingPayment.value = null
    store('bf_wallet_method', null)
    try { localStorage.removeItem('bf_nwc_url') } catch { /* quota */ }
  }

  async function checkWalletStatus(): Promise<void> {
    if (!pubkey.value) return

    const res = await authFetch(`/api/payments/wallet-status?pubkey=${pubkey.value}`)
    if (res.ok) {
      const data = await res.json()
      isWalletConnected.value = data.connected
      walletMethod.value = data.method || null
      if (data.connected) {
        store('bf_wallet_method', data.method)
      }
    }
  }

  async function payEntryFee(botId: string): Promise<string> {
    paymentStatus.value = 'invoiced'

    try {
      // Create invoice
      const invoiceRes = await authFetch('/api/payments/create-invoice', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ botId, pubkey: pubkey.value }),
      })

      if (!invoiceRes.ok) {
        const err = await invoiceRes.json()
        throw new Error(err.error || 'Failed to create invoice')
      }

      const { bolt11, paymentId } = await invoiceRes.json()
      pendingPayment.value = { paymentId, bolt11 }

      // Dev mode: server auto-confirmed, skip payment
      if (bolt11 === 'dev_auto_confirmed') {
        paymentStatus.value = 'confirmed'
        return paymentId
      }

      // If NWC connected, auto-pay via NWC and confirm directly
      const nwcUrl = localStorage.getItem('bf_nwc_url')
      let nwcValid = false
      if (nwcUrl) {
        try { parseNwcUrl(nwcUrl); nwcValid = true } catch { /* bad stored URL — fall through to poll */ }
      }
      if (nwcUrl && nwcValid) {
        paymentStatus.value = 'paying'
        try {
          const preimage = await payViaNWC(nwcUrl, bolt11)
          if (preimage) {
            await authFetch(`/api/payments/confirm/${paymentId}`, {
              method: 'POST',
              headers: { 'Content-Type': 'application/json' },
              body: JSON.stringify({ preimage, pubkey: pubkey.value }),
            })
            paymentStatus.value = 'confirmed'
            return paymentId
          }
        } catch (err) {
          console.warn('[Wallet] NWC payment failed, falling back to polling:', err)
        }
        // NWC failed or returned no preimage — fall through to polling
        paymentStatus.value = 'pending'
      }

      // No NWC — poll for confirmation (manual payment / QR code flow)
      for (let i = 0; i < 30; i++) {
        await new Promise(r => setTimeout(r, 2000))
        const checkRes = await authFetch(`/api/payments/check/${paymentId}`)
        if (checkRes.ok) {
          const { status } = await checkRes.json()
          if (status === 'confirmed') {
            paymentStatus.value = 'confirmed'
            return paymentId
          }
          if (status === 'failed') {
            paymentStatus.value = 'failed'
            throw new Error('Payment failed')
          }
        }
      }

      paymentStatus.value = 'failed'
      throw new Error('Payment timed out')
    } catch (err) {
      if (paymentStatus.value !== 'confirmed') {
        paymentStatus.value = 'failed'
      }
      throw err
    }
  }

  async function submitCashuToken(botId: string, token: string): Promise<string> {
    const res = await authFetch('/api/payments/submit-cashu', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ botId, token }),
    })

    if (!res.ok) {
      const err = await res.json()
      throw new Error(err.error || 'Cashu redemption failed')
    }

    const data = await res.json()
    if (data.status !== 'confirmed') {
      throw new Error('Invalid or spent Cashu token')
    }

    paymentStatus.value = 'confirmed'
    return data.paymentId
  }

  return {
    isWalletConnected: readonly(isWalletConnected),
    walletMethod: readonly(walletMethod),
    paymentStatus: readonly(paymentStatus),
    pendingPayment: readonly(pendingPayment),
    connectNWC,
    connectLightningAddress,
    disconnectWallet,
    checkWalletStatus,
    payEntryFee,
    submitCashuToken,
  }
}

/** Send a pay_invoice request via NWC WebSocket */
async function payViaNWC(nwcUrl: string, bolt11: string): Promise<string | undefined> {
  const nwc = parseNwcUrl(nwcUrl)
  const secretHex = bytesToHex(nwc.secret)

  // Use NIP-04 encryption (BTCPay/LND compatibility)
  const content = await nip04.encrypt(secretHex, nwc.pubkey,
    JSON.stringify({ method: 'pay_invoice', params: { invoice: bolt11 } }),
  )

  const event = finalizeEvent({
    kind: 23194,
    created_at: Math.floor(Date.now() / 1000),
    tags: [['p', nwc.pubkey]],
    content,
  }, nwc.secret)

  return new Promise((resolve, reject) => {
    const ws = new WebSocket(nwc.relay)
    const timeout = setTimeout(() => {
      ws.close()
      reject(new Error('NWC payment timed out'))
    }, 30_000)

    ws.onopen = () => {
      const subId = Math.random().toString(36).slice(2, 10)
      ws.send(JSON.stringify(['REQ', subId, {
        kinds: [23195],
        authors: [nwc.pubkey],
        '#e': [event.id],
      }]))
      ws.send(JSON.stringify(['EVENT', event]))
    }

    ws.onmessage = async (msg) => {
      try {
        const data = JSON.parse(msg.data)
        if (data[0] === 'EVENT' && data[2]?.kind === 23195) {
          clearTimeout(timeout)
          ws.close()
          // Decrypt response — try NIP-04 first, fall back to NIP-44
          let decrypted: string
          try {
            decrypted = await nip04.decrypt(secretHex, nwc.pubkey, data[2].content)
          } catch {
            const convKey = nip44.v2.utils.getConversationKey(nwc.secret, nwc.pubkey)
            decrypted = nip44.v2.decrypt(data[2].content, convKey)
          }
          const result = JSON.parse(decrypted)
          if (result.error) {
            reject(new Error(result.error.message || 'NWC payment failed'))
          } else {
            resolve(result.result?.preimage)
          }
        }
      } catch {
        // ignore parse errors
      }
    }

    ws.onerror = () => {
      clearTimeout(timeout)
      reject(new Error('NWC WebSocket error'))
    }
  })
}