// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

import "@openzeppelin/contracts/access/AccessControl.sol";
import "./interfaces/IPolicyManager.sol";
import "./interfaces/IComplianceRegistry.sol";
import "./interfaces/IDebtRegistry.sol";
import "./libraries/ReasonCodes.sol";
import "./errors/RegistryErrors.sol";

/**
 * @title PolicyManager
 * @notice Central rule engine for transfer authorization across all eMoney tokens
 * @dev Consults ComplianceRegistry and DebtRegistry to make transfer decisions.
 * Manages per-token configuration including pause state, bridge-only mode, and lien modes.
 * Lien enforcement is performed by eMoneyToken based on the lien mode returned here.
 */
contract PolicyManager is IPolicyManager, AccessControl {
    bytes32 public constant POLICY_OPERATOR_ROLE = keccak256("POLICY_OPERATOR_ROLE");

    struct TokenConfig {
        bool paused;
        bool bridgeOnly;
        address bridge;
        uint8 lienMode; // 0 = off, 1 = hard freeze, 2 = encumbered
    }

    IComplianceRegistry public immutable complianceRegistry;
    IDebtRegistry public immutable debtRegistry;

    mapping(address => TokenConfig) private _tokenConfigs;
    mapping(address => mapping(address => bool)) private _tokenFreezes; // token => account => frozen

    /**
     * @notice Initializes PolicyManager with registry addresses
     * @param admin Address that will receive DEFAULT_ADMIN_ROLE
     * @param compliance Address of ComplianceRegistry contract
     * @param debt Address of DebtRegistry contract
     */
    constructor(address admin, address compliance, address debt) {
        _grantRole(DEFAULT_ADMIN_ROLE, admin);
        complianceRegistry = IComplianceRegistry(compliance);
        debtRegistry = IDebtRegistry(debt);
    }

    /**
     * @notice Returns whether a token is paused
     * @param token Token address to check
     * @return true if token is paused, false otherwise
     */
    function isPaused(address token) external view override returns (bool) {
        return _tokenConfigs[token].paused;
    }

    /**
     * @notice Returns whether a token is in bridge-only mode
     * @param token Token address to check
     * @return true if token only allows transfers to/from bridge, false otherwise
     */
    function bridgeOnly(address token) external view override returns (bool) {
        return _tokenConfigs[token].bridgeOnly;
    }

    /**
     * @notice Returns the bridge address for a token
     * @param token Token address to check
     * @return Bridge address (zero address if not set)
     */
    function bridge(address token) external view override returns (address) {
        return _tokenConfigs[token].bridge;
    }

    /**
     * @notice Returns the lien mode for a token
     * @param token Token address to check
     * @return Lien mode: 0 = off, 1 = hard freeze, 2 = encumbered
     */
    function lienMode(address token) external view override returns (uint8) {
        return _tokenConfigs[token].lienMode;
    }

    /**
     * @notice Returns whether an account is frozen for a specific token
     * @param token Token address to check
     * @param account Address to check
     * @return true if account is frozen for this token, false otherwise
     */
    function isTokenFrozen(address token, address account) external view override returns (bool) {
        return _tokenFreezes[token][account];
    }

    /**
     * @notice Determines if a transfer should be allowed
     * @dev Checks in order: paused, token freezes, compliance freezes, compliance allowed status, bridge-only mode.
     * Lien checks are performed by eMoneyToken based on lien mode.
     * @param token Token address
     * @param from Sender address
     * @param to Recipient address
     * @param amount Transfer amount (unused but required for interface)
     * @return allowed true if transfer should be allowed, false otherwise
     * @return reasonCode bytes32 reason code (ReasonCodes.OK if allowed, otherwise the blocking reason)
     */
    function canTransfer(
        address token,
        address from,
        address to,
        uint256 amount
    ) external view override returns (bool allowed, bytes32 reasonCode) {
        TokenConfig memory config = _tokenConfigs[token];

        // Check paused
        if (config.paused) {
            return (false, ReasonCodes.PAUSED);
        }

        // Check token-specific freezes
        if (_tokenFreezes[token][from]) {
            return (false, ReasonCodes.FROM_FROZEN);
        }
        if (_tokenFreezes[token][to]) {
            return (false, ReasonCodes.TO_FROZEN);
        }

        // Check compliance registry freezes
        if (complianceRegistry.isFrozen(from)) {
            return (false, ReasonCodes.FROM_FROZEN);
        }
        if (complianceRegistry.isFrozen(to)) {
            return (false, ReasonCodes.TO_FROZEN);
        }

        // Check compliance allowed status
        if (!complianceRegistry.isAllowed(from)) {
            return (false, ReasonCodes.FROM_NOT_COMPLIANT);
        }
        if (!complianceRegistry.isAllowed(to)) {
            return (false, ReasonCodes.TO_NOT_COMPLIANT);
        }

        // Check bridgeOnly mode
        if (config.bridgeOnly) {
            if (from != config.bridge && to != config.bridge) {
                return (false, ReasonCodes.BRIDGE_ONLY);
            }
        }

        // Lien mode checks are handled in eMoneyToken._update
        // PolicyManager only provides the lien mode, not the enforcement

        return (true, ReasonCodes.OK);
    }

    /**
     * @notice Check if transfer is allowed with additional context
     * @param token Token address
     * @param from Sender address
     * @param to Recipient address
     * @param amount Transfer amount
     * @param context Additional context data (unused but required by interface)
     * @return allowed True if transfer is allowed
     * @return reasonCode Reason code if not allowed
     */
    function canTransferWithContext(
        address token,
        address from,
        address to,
        uint256 amount,
        bytes memory context
    ) external view override returns (bool allowed, bytes32 reasonCode) {
        // For now, context is unused - use same logic as canTransfer
        TokenConfig memory config = _tokenConfigs[token];

        // Check paused
        if (config.paused) {
            return (false, ReasonCodes.PAUSED);
        }

        // Check token-specific freezes
        if (_tokenFreezes[token][from]) {
            return (false, ReasonCodes.FROM_FROZEN);
        }
        if (_tokenFreezes[token][to]) {
            return (false, ReasonCodes.TO_FROZEN);
        }

        // Check compliance registry freezes
        if (complianceRegistry.isFrozen(from)) {
            return (false, ReasonCodes.FROM_FROZEN);
        }
        if (complianceRegistry.isFrozen(to)) {
            return (false, ReasonCodes.TO_FROZEN);
        }

        // Check compliance allowed status
        if (!complianceRegistry.isAllowed(from)) {
            return (false, ReasonCodes.FROM_NOT_COMPLIANT);
        }
        if (!complianceRegistry.isAllowed(to)) {
            return (false, ReasonCodes.TO_NOT_COMPLIANT);
        }

        // Check bridgeOnly mode
        if (config.bridgeOnly) {
            if (from != config.bridge && to != config.bridge) {
                return (false, ReasonCodes.BRIDGE_ONLY);
            }
        }

        return (true, ReasonCodes.OK);
    }

    /**
     * @notice Sets the paused state for a token
     * @dev Requires POLICY_OPERATOR_ROLE. When paused, all transfers are blocked.
     * @param token Token address to configure
     * @param paused true to pause, false to unpause
     */
    function setPaused(address token, bool paused) external override onlyRole(POLICY_OPERATOR_ROLE) {
        _tokenConfigs[token].paused = paused;
        emit TokenPaused(token, paused);
    }

    /**
     * @notice Sets bridge-only mode for a token
     * @dev Requires POLICY_OPERATOR_ROLE. When enabled, only transfers to/from the bridge address are allowed.
     * @param token Token address to configure
     * @param enabled true to enable bridge-only mode, false to disable
     */
    function setBridgeOnly(address token, bool enabled) external override onlyRole(POLICY_OPERATOR_ROLE) {
        _tokenConfigs[token].bridgeOnly = enabled;
        emit BridgeOnlySet(token, enabled);
    }

    /**
     * @notice Sets the bridge address for a token
     * @dev Requires POLICY_OPERATOR_ROLE. Used in bridge-only mode.
     * @param token Token address to configure
     * @param bridgeAddr Address of the bridge contract
     */
    function setBridge(address token, address bridgeAddr) external override onlyRole(POLICY_OPERATOR_ROLE) {
        _tokenConfigs[token].bridge = bridgeAddr;
        emit BridgeSet(token, bridgeAddr);
    }

    /**
     * @notice Sets the lien mode for a token
     * @dev Requires POLICY_OPERATOR_ROLE. Valid modes: 0 = off, 1 = hard freeze, 2 = encumbered.
     * @param token Token address to configure
     * @param mode Lien mode (0, 1, or 2)
     */
    function setLienMode(address token, uint8 mode) external override onlyRole(POLICY_OPERATOR_ROLE) {
        if (mode > 2) revert PolicyInvalidLienMode(mode);

        TokenConfig storage config = _tokenConfigs[token];
        bool isNewToken = config.lienMode == 0 && mode != 0 && !config.paused && !config.bridgeOnly && config.bridge == address(0);

        config.lienMode = mode;

        if (isNewToken) {
            emit TokenConfigured(token, config.paused, config.bridgeOnly, config.bridge, mode);
        }

        emit LienModeSet(token, mode);
    }

    /**
     * @notice Freezes or unfreezes an account for a specific token
     * @dev Requires POLICY_OPERATOR_ROLE. Per-token freeze (in addition to global compliance freezes).
     * @param token Token address
     * @param account Address to freeze/unfreeze
     * @param frozen true to freeze, false to unfreeze
     */
    function freeze(address token, address account, bool frozen) external override onlyRole(POLICY_OPERATOR_ROLE) {
        _tokenFreezes[token][account] = frozen;
        emit TokenFreeze(token, account, frozen);
    }
}