/**
 * AereSinkClient — typed read/write helpers for the AereSink immutable
 *                   3-bucket protocol revenue router.
 *
 * Contract: aerenew/contracts/contracts/sink/AereSink.sol
 *
 * Phase 1 (read-only): poll the immutable bucket configuration + lifetime
 *                      stats. Integrators dashboard their share of the
 *                      flywheel without needing a signer.
 *
 * Phase 2 (write): integrators that already accumulate fees in some asset
 *                  call flush() on this contract. They must `approve`
 *                  the sink first; flushOne() helps with that.
 *
 * Dependencies: any EIP-1193 JSON-RPC provider (viem, ethers, ethereum
 * window, raw fetch). The SDK accepts an `eth_call` shim instead of a
 * concrete provider library, keeping the dep surface small.
 */

export interface RpcProvider {
  request(args: { method: string; params: unknown[] }): Promise<unknown>;
}

export interface AereSinkConfig {
  /** AereSink contract address. */
  address: `0x${string}`;
  /** EIP-1193-style provider (viem, ethers, or window.ethereum). */
  provider: RpcProvider;
}

/* --------------------------- selector constants --------------------------- */

// 4-byte function selectors. Computed once at module load and held constant.
// (Verified via cast sig-of <name>().)
const SEL = {
  AERE:              '0x1cc59c1b',  // AERE()
  BURN_VAULT:        '0x4e7eee76',  // BURN_VAULT()
  SAERE_VAULT:       '0xc46aedd7',  // SAERE_VAULT()
  DEX_ROUTER:        '0x3b1664c1',  // DEX_ROUTER()
  BURN_BPS:          '0x9748d6c0',  // BURN_BPS()
  BUYBACK_BPS:       '0xb56fcecf',  // BUYBACK_BPS()
  STAKER_YIELD_BPS:  '0xc77b3402',  // STAKER_YIELD_BPS()
  MAX_SLIPPAGE_BPS:  '0xfb6fb1f9',  // MAX_SLIPPAGE_BPS()
} as const;

// flush(address,uint256) — for write
const FLUSH_SELECTOR = '0x6cd5c39b';
// sweepDust(address) — for write
const SWEEP_DUST_SELECTOR = '0xeb1a0a96';

/* ----------------------------- helper functions ---------------------------- */

function hexToAddress(hex: string): `0x${string}` {
  // 32-byte ABI-encoded address → 20-byte address
  // hex is 0x + 64 hex chars; the address is the last 40 chars.
  if (!/^0x[0-9a-fA-F]{64}$/.test(hex)) {
    throw new Error(`AereSinkClient: malformed address response: ${hex}`);
  }
  return ('0x' + hex.slice(-40)) as `0x${string}`;
}

function hexToBigInt(hex: string): bigint {
  if (!/^0x[0-9a-fA-F]+$/.test(hex)) {
    throw new Error(`AereSinkClient: malformed integer response: ${hex}`);
  }
  return BigInt(hex);
}

function padAddress(address: `0x${string}`): string {
  // 20-byte address → 32-byte ABI-encoded slot.
  return '0x' + address.slice(2).toLowerCase().padStart(64, '0');
}

function padUint(value: bigint): string {
  return value.toString(16).padStart(64, '0');
}

/* ----------------------------- the client ---------------------------- */

export class AereSinkClient {
  readonly address: `0x${string}`;
  private readonly provider: RpcProvider;

  constructor(cfg: AereSinkConfig) {
    this.address = cfg.address;
    this.provider = cfg.provider;
  }

  /* ---------------------- read: immutable parameters --------------------- */

  /** Read all 8 immutable parameters in a single batched eth_call sequence. */
  async readConfig(): Promise<{
    aere: `0x${string}`;
    burnVault: `0x${string}`;
    sAereVault: `0x${string}`;
    dexRouter: `0x${string}`;
    burnBps: number;
    buybackBps: number;
    stakerYieldBps: number;
    maxSlippageBps: number;
  }> {
    const [aere, burnVault, sAereVault, dexRouter, burnBps, buybackBps, stakerYieldBps, maxSlippageBps] =
      await Promise.all([
        this._call(SEL.AERE),
        this._call(SEL.BURN_VAULT),
        this._call(SEL.SAERE_VAULT),
        this._call(SEL.DEX_ROUTER),
        this._call(SEL.BURN_BPS),
        this._call(SEL.BUYBACK_BPS),
        this._call(SEL.STAKER_YIELD_BPS),
        this._call(SEL.MAX_SLIPPAGE_BPS),
      ]);

    return {
      aere: hexToAddress(aere),
      burnVault: hexToAddress(burnVault),
      sAereVault: hexToAddress(sAereVault),
      dexRouter: hexToAddress(dexRouter),
      burnBps: Number(hexToBigInt(burnBps)),
      buybackBps: Number(hexToBigInt(buybackBps)),
      stakerYieldBps: Number(hexToBigInt(stakerYieldBps)),
      maxSlippageBps: Number(hexToBigInt(maxSlippageBps)),
    };
  }

  /** Convenience: returns the human-readable bucket percentages (e.g., 15.00). */
  async readSplitPercentages(): Promise<{ burn: number; buyback: number; stakerYield: number }> {
    const c = await this.readConfig();
    return {
      burn: c.burnBps / 100,
      buyback: c.buybackBps / 100,
      stakerYield: c.stakerYieldBps / 100,
    };
  }

  /* ----------------------- write: encoded calldata ----------------------- */

  /**
   * Encode the calldata for `flush(token, amount)`. The integrator submits this
   * to the sink contract after first calling `approve(sinkAddress, amount)`
   * on the token.
   */
  encodeFlush(token: `0x${string}`, amount: bigint): `0x${string}` {
    const data =
      FLUSH_SELECTOR +
      padAddress(token).slice(2) +
      padUint(amount);
    return data as `0x${string}`;
  }

  /** Encode `sweepDust(token)`. Permissionless — anyone can sweep. */
  encodeSweepDust(token: `0x${string}`): `0x${string}` {
    return (SWEEP_DUST_SELECTOR + padAddress(token).slice(2)) as `0x${string}`;
  }

  /* ----------------------------- internals ------------------------------- */

  private async _call(data: string): Promise<string> {
    const result = await this.provider.request({
      method: 'eth_call',
      params: [{ to: this.address, data }, 'latest'],
    });
    if (typeof result !== 'string') {
      throw new Error(`AereSinkClient: unexpected eth_call result`);
    }
    return result;
  }
}