/**
 * Flow Service API Client for rFunds.online
 *
 * Connects the visual TBFF editor to the flow-service backend.
 * Handles type conversion between frontend visual nodes and backend flow types.
 */

import type { FlowNode, FunnelNodeData, OutcomeNodeData } from '../types'

// ─── Backend API Types ──────────────────────────────────────

export interface BackendFlow {
  id: string
  name: string
  description?: string
  funnels: BackendFunnel[]
  outcomes: BackendOutcome[]
  token: string
  chainId: number
  ownerAddress: string
  adminAddresses: string[]
  automationEnabled: boolean
  checkIntervalMs: number
  status: 'draft' | 'active' | 'paused' | 'archived'
  createdAt: number
  updatedAt: number
}

export interface BackendFunnel {
  id: string
  flowId: string
  name: string
  description?: string
  minThreshold: string
  maxThreshold: string
  balance: string
  walletAddress: string
  overflowAllocations: BackendAllocation[]
  spendingAllocations: BackendAllocation[]
  inflowRate?: string
  spendingRate?: string
  createdAt: number
  updatedAt: number
}

export interface BackendOutcome {
  id: string
  flowId: string
  name: string
  description?: string
  targetAmount: string
  currentAmount: string
  walletAddress: string
  ownerAddress: string
  status: 'active' | 'funded' | 'completed' | 'cancelled'
  createdAt: number
  updatedAt: number
}

export interface BackendAllocation {
  targetId: string
  targetType: 'funnel' | 'outcome' | 'wallet'
  targetAddress: string
  percentage: number
  label: string
}

export interface BackendTransaction {
  id: string
  flowId: string
  type: 'deposit' | 'overflow' | 'spending' | 'withdrawal'
  amount: string
  status: 'pending' | 'committed' | 'settled' | 'failed'
  triggeredBy: 'user' | 'threshold' | 'schedule'
  createdAt: number
}

interface ApiResponse<T = unknown> {
  success: boolean
  error?: string
  flow?: T
  flows?: T[]
  funnel?: BackendFunnel
  outcome?: BackendOutcome
  transaction?: BackendTransaction
  transactions?: BackendTransaction[]
  session?: { sessionId: string; widgetUrl?: string }
}

// ─── Configuration ──────────────────────────────────────────

const USDC_DECIMALS = 6
const DEFAULT_TOKEN = '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913' // USDC on Base
const DEFAULT_CHAIN_ID = 84532 // Base Sepolia

// Use relative URL — Traefik routes rfunds.online/api/flows to flow-service
const API_BASE = '/api/flows'

// ─── Unit Conversion ────────────────────────────────────────

/** Convert human-readable amount (e.g., 1000) to smallest unit string (e.g., "1000000000") */
export function toSmallestUnit(amount: number, decimals = USDC_DECIMALS): string {
  return Math.round(amount * Math.pow(10, decimals)).toString()
}

/** Convert smallest unit string (e.g., "1000000000") to human-readable number (e.g., 1000) */
export function fromSmallestUnit(amount: string, decimals = USDC_DECIMALS): number {
  return parseInt(amount, 10) / Math.pow(10, decimals)
}

// ─── API Helpers ────────────────────────────────────────────

async function api<T = BackendFlow>(
  path: string,
  options?: RequestInit & { ownerAddress?: string }
): Promise<ApiResponse<T>> {
  const { ownerAddress, ...fetchOpts } = options || {}
  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    ...(ownerAddress ? { 'X-Owner-Address': ownerAddress } : {}),
    ...((fetchOpts.headers as Record<string, string>) || {}),
  }

  const res = await fetch(`${API_BASE}${path}`, {
    ...fetchOpts,
    headers,
  })

  if (!res.ok) {
    const body = await res.json().catch(() => ({ error: res.statusText }))
    throw new Error(body.error || `API error ${res.status}`)
  }

  return res.json()
}

// ─── CRUD Operations ────────────────────────────────────────

export async function listFlows(ownerAddress: string): Promise<BackendFlow[]> {
  const res = await api<BackendFlow>('', { ownerAddress })
  return (res.flows || []) as BackendFlow[]
}

export async function getFlow(flowId: string): Promise<BackendFlow> {
  const res = await api<BackendFlow>(`/${flowId}`)
  return res.flow as BackendFlow
}

export async function createFlow(
  name: string,
  ownerAddress: string,
  description?: string
): Promise<BackendFlow> {
  const res = await api<BackendFlow>('', {
    method: 'POST',
    ownerAddress,
    body: JSON.stringify({
      name,
      description,
      token: DEFAULT_TOKEN,
      chainId: DEFAULT_CHAIN_ID,
      automationEnabled: true,
      checkIntervalMs: 30000,
    }),
  })
  return res.flow as BackendFlow
}

export async function activateFlow(flowId: string): Promise<BackendFlow> {
  const res = await api<BackendFlow>(`/${flowId}/activate`, { method: 'POST' })
  return res.flow as BackendFlow
}

export async function pauseFlow(flowId: string): Promise<BackendFlow> {
  const res = await api<BackendFlow>(`/${flowId}/pause`, { method: 'POST' })
  return res.flow as BackendFlow
}

// ─── Funnel & Outcome Operations ────────────────────────────

export async function addFunnel(
  flowId: string,
  name: string,
  minThreshold: number,
  maxThreshold: number,
  overflowAllocations: BackendAllocation[],
  spendingAllocations: BackendAllocation[],
  description?: string
): Promise<BackendFunnel> {
  const res = await api(`/${flowId}/funnels`, {
    method: 'POST',
    body: JSON.stringify({
      name,
      description,
      minThreshold: toSmallestUnit(minThreshold),
      maxThreshold: toSmallestUnit(maxThreshold),
      overflowAllocations,
      spendingAllocations,
    }),
  })
  return res.funnel as BackendFunnel
}

export async function addOutcome(
  flowId: string,
  name: string,
  targetAmount: number,
  ownerAddress: string,
  description?: string
): Promise<BackendOutcome> {
  const res = await api(`/${flowId}/outcomes`, {
    method: 'POST',
    body: JSON.stringify({
      name,
      description,
      targetAmount: toSmallestUnit(targetAmount),
      ownerAddress,
    }),
  })
  return res.outcome as BackendOutcome
}

// ─── Deposit / Withdraw ─────────────────────────────────────

export async function deposit(
  flowId: string,
  funnelId: string,
  amount: number,
  source: 'wallet' | 'card' | 'bank' = 'wallet'
): Promise<BackendTransaction> {
  const res = await api(`/${flowId}/deposit`, {
    method: 'POST',
    body: JSON.stringify({
      funnelId,
      amount: toSmallestUnit(amount),
      source,
    }),
  })
  return res.transaction as BackendTransaction
}

export async function withdraw(
  flowId: string,
  sourceType: 'funnel' | 'outcome',
  sourceId: string,
  amount: number,
  externalAddress: string
): Promise<BackendTransaction> {
  const res = await api(`/${flowId}/withdraw`, {
    method: 'POST',
    body: JSON.stringify({
      sourceType,
      sourceId,
      amount: toSmallestUnit(amount),
      destination: 'external',
      externalAddress,
    }),
  })
  return res.transaction as BackendTransaction
}

export async function getTransactions(flowId: string): Promise<BackendTransaction[]> {
  const res = await api(`/${flowId}/transactions`)
  return (res.transactions || []) as BackendTransaction[]
}

// ─── On-Ramp ────────────────────────────────────────────────

export async function initiateOnRamp(
  flowId: string,
  funnelId: string,
  fiatAmount: number,
  fiatCurrency = 'USD'
): Promise<{ widgetUrl?: string; sessionId: string }> {
  const res = await api(`/${flowId}/onramp`, {
    method: 'POST',
    body: JSON.stringify({
      funnelId,
      fiatAmount,
      fiatCurrency,
      provider: 'transak',
      paymentMethod: 'card',
    }),
  })
  return res.session as { widgetUrl?: string; sessionId: string }
}

// ─── Deploy: Convert Visual Nodes → Backend Flow ────────────

/** Node ID → Backend ID mapping (returned after deploy) */
export interface DeployResult {
  flow: BackendFlow
  idMap: Record<string, string> // frontend nodeId → backend id
}

/**
 * Deploy visual nodes to the backend as a live Flow.
 *
 * 1. Creates the Flow
 * 2. Creates all Outcomes first (so funnel allocations can reference them)
 * 3. Creates all Funnels with resolved allocation targets
 * 4. Activates the flow
 */
export async function deployNodes(
  name: string,
  ownerAddress: string,
  nodes: FlowNode[]
): Promise<DeployResult> {
  const idMap: Record<string, string> = {}

  // 1. Create flow
  const flow = await createFlow(name, ownerAddress, `Deployed from rFunds.online editor`)

  // 2. Create outcomes first
  const outcomeNodes = nodes.filter(n => n.type === 'outcome')
  for (const node of outcomeNodes) {
    const data = node.data as OutcomeNodeData
    const outcome = await addOutcome(
      flow.id,
      data.label,
      data.fundingTarget,
      ownerAddress,
      data.description
    )
    idMap[node.id] = outcome.id
  }

  // 3. Create funnels (resolve allocation targetIds to backend IDs)
  const funnelNodes = nodes.filter(n => n.type === 'funnel')
  for (const node of funnelNodes) {
    const data = node.data as FunnelNodeData

    const resolveAllocations = (
      allocs: { targetId: string; percentage: number }[],
      type: 'overflow' | 'spending'
    ): BackendAllocation[] => {
      return allocs
        .filter(a => idMap[a.targetId] || nodes.find(n => n.id === a.targetId))
        .map((a, i) => {
          const targetNode = nodes.find(n => n.id === a.targetId)
          const isOutcome = targetNode?.type === 'outcome'
          return {
            targetId: idMap[a.targetId] || a.targetId,
            targetType: (isOutcome ? 'outcome' : 'funnel') as 'funnel' | 'outcome' | 'wallet',
            targetAddress: '0x0000000000000000000000000000000000000000', // backend assigns real addresses
            percentage: a.percentage,
            label: `${type} #${i + 1} (${a.percentage}%)`,
          }
        })
    }

    const funnel = await addFunnel(
      flow.id,
      data.label,
      data.minThreshold,
      data.maxThreshold,
      resolveAllocations(data.overflowAllocations, 'overflow'),
      resolveAllocations(data.spendingAllocations, 'spending'),
    )
    idMap[node.id] = funnel.id
  }

  // 4. Activate
  const activeFlow = await activateFlow(flow.id)

  return { flow: activeFlow, idMap }
}

// ─── Sync: Update Visual Nodes from Backend ─────────────────

/**
 * Update visual node data with live balances from the backend.
 * Returns updated nodes with real balance/funding data.
 */
export function syncNodesToBackend(
  nodes: FlowNode[],
  flow: BackendFlow,
  idMap: Record<string, string>
): FlowNode[] {
  // Build reverse map: backend id → frontend node id
  const reverseMap: Record<string, string> = {}
  for (const [frontendId, backendId] of Object.entries(idMap)) {
    reverseMap[backendId] = frontendId
  }

  return nodes.map((node) => {
    if (node.type === 'funnel') {
      const backendId = idMap[node.id]
      const backendFunnel = flow.funnels.find(f => f.id === backendId)
      if (!backendFunnel) return node

      const data = node.data as FunnelNodeData
      return {
        ...node,
        data: {
          ...data,
          currentValue: fromSmallestUnit(backendFunnel.balance),
          minThreshold: fromSmallestUnit(backendFunnel.minThreshold),
          maxThreshold: fromSmallestUnit(backendFunnel.maxThreshold),
        },
      }
    }

    if (node.type === 'outcome') {
      const backendId = idMap[node.id]
      const backendOutcome = flow.outcomes.find(o => o.id === backendId)
      if (!backendOutcome) return node

      const data = node.data as OutcomeNodeData
      return {
        ...node,
        data: {
          ...data,
          fundingReceived: fromSmallestUnit(backendOutcome.currentAmount),
          fundingTarget: fromSmallestUnit(backendOutcome.targetAmount),
          status: backendOutcome.status === 'completed' ? 'completed' :
                  backendOutcome.status === 'funded' ? 'completed' :
                  fromSmallestUnit(backendOutcome.currentAmount) > 0 ? 'in-progress' : 'not-started',
        },
      }
    }

    return node
  })
}