/**
 * Elevated-permission helpers — the set of moderation/admin permissions worth
 * auditing, plus predicates (`hasElevatedPermissions`, `isElevatedRole`) used
 * when diffing Discord permission changes into the connector's audit events.
 */
import type { IAgentRuntime } from "@elizaos/core";
import type {
	AuditLogEvent,
	Guild,
	GuildMember,
	PermissionOverwrites,
	Role,
} from "discord.js";
import type { AuditInfo, PermissionDiff, PermissionState } from "./types";

/**
 * Permissions that indicate moderation/admin capabilities.
 * Changes to these permissions are considered elevated and worth tracking.
 */
export const ELEVATED_PERMISSIONS = [
	"Administrator",
	"ManageGuild",
	"ManageChannels",
	"ManageRoles",
	"KickMembers",
	"BanMembers",
	"ModerateMembers",
	"ManageMessages",
	"ManageWebhooks",
	"ManageNicknames",
	"MuteMembers",
	"DeafenMembers",
	"MoveMembers",
	"ManageEvents",
	"ManageThreads",
] as const;

/**
 * Check if a role has any elevated (moderation/admin) permissions
 */
export function isElevatedRole(role: Role): boolean {
	return ELEVATED_PERMISSIONS.some((p) => role.permissions.has(p));
}

/**
 * Check if an array of permission names contains any elevated permissions
 */
export function hasElevatedPermissions(permissions: string[]): boolean {
	return permissions.some((p) =>
		ELEVATED_PERMISSIONS.includes(p as (typeof ELEVATED_PERMISSIONS)[number]),
	);
}

/**
 * Fetch the most recent matching audit log entry for an action.
 * Matches by target ID and filters to entries within 10 seconds.
 * Returns null gracefully on errors (rate limits, missing permissions, etc.)
 */
export async function fetchAuditEntry(
	guild: Guild,
	actionType: AuditLogEvent,
	target: string,
	runtime: IAgentRuntime,
): Promise<AuditInfo | null> {
	try {
		const logs = await guild.fetchAuditLogs({ type: actionType, limit: 5 });
		const now = Date.now();

		for (const entry of logs.entries.values()) {
			// Match by target and ensure entry is recent (within 10 seconds)
			// Type guard: entry.target can be various types, not all have 'id'
			const targetId =
				entry.target && "id" in entry.target ? entry.target.id : undefined;
			if (targetId === target && now - entry.createdTimestamp < 10000) {
				return {
					executorId: entry.executor?.id ?? "unknown",
					executorTag: entry.executor?.tag ?? "Unknown",
					reason: entry.reason,
				};
			}
		}
	} catch (err) {
		// Graceful degradation - rate limits, missing permissions, etc.
		runtime.logger.debug(`Audit log fetch failed (non-critical): ${err}`);
	}
	return null;
}

/**
 * Get the permission state from allow/deny arrays
 */
function getState(
	perm: string,
	allow: string[],
	deny: string[],
): PermissionState {
	if (allow.includes(perm)) {
		return "ALLOW";
	}
	if (deny.includes(perm)) {
		return "DENY";
	}
	return "NEUTRAL";
}

/**
 * Convert an overwrite to a list of changes (used for CREATE/DELETE)
 * For CREATE: from NEUTRAL to the actual state (ALLOW/DENY)
 * For DELETE: from the actual state (ALLOW/DENY) to NEUTRAL
 */
function overwriteToChanges(
	ow: PermissionOverwrites,
	isDelete: boolean = false,
): PermissionDiff[] {
	const changes: PermissionDiff[] = [];
	for (const p of ow.allow.toArray()) {
		changes.push({
			permission: p,
			oldState: isDelete ? "ALLOW" : "NEUTRAL",
			newState: isDelete ? "NEUTRAL" : "ALLOW",
		});
	}
	for (const p of ow.deny.toArray()) {
		changes.push({
			permission: p,
			oldState: isDelete ? "DENY" : "NEUTRAL",
			newState: isDelete ? "NEUTRAL" : "DENY",
		});
	}
	return changes;
}

/**
 * Diff two permission overwrites and determine what changed.
 * Returns the list of changes and the action type (CREATE/UPDATE/DELETE).
 */
export function diffOverwrites(
	oldOw: PermissionOverwrites | undefined | null,
	newOw: PermissionOverwrites | undefined | null,
): { changes: PermissionDiff[]; action: "CREATE" | "UPDATE" | "DELETE" } {
	// Both null - no change
	if (!oldOw && !newOw) {
		return { changes: [], action: "UPDATE" };
	}

	// Created new overwrite
	if (!oldOw && newOw) {
		return { changes: overwriteToChanges(newOw, false), action: "CREATE" };
	}

	// Deleted overwrite
	if (oldOw && !newOw) {
		return { changes: overwriteToChanges(oldOw, true), action: "DELETE" };
	}

	// Updated overwrite - compare old and new
	const changes: PermissionDiff[] = [];
	const oldAllow = oldOw?.allow.toArray() ?? [];
	const oldDeny = oldOw?.deny.toArray() ?? [];
	const newAllow = newOw?.allow.toArray() ?? [];
	const newDeny = newOw?.deny.toArray() ?? [];

	// Get all permissions that exist in either old or new
	const allPerms = new Set([...oldAllow, ...oldDeny, ...newAllow, ...newDeny]);

	for (const perm of allPerms) {
		const oldState = getState(perm, oldAllow, oldDeny);
		const newState = getState(perm, newAllow, newDeny);
		if (oldState !== newState) {
			changes.push({ permission: perm, oldState, newState });
		}
	}

	return { changes, action: "UPDATE" };
}

/**
 * Diff two role permission sets and return what changed.
 */
export function diffRolePermissions(
	oldRole: Role,
	newRole: Role,
): PermissionDiff[] {
	const oldPerms = oldRole.permissions.toArray();
	const newPerms = newRole.permissions.toArray();
	const changes: PermissionDiff[] = [];

	// Find added permissions
	for (const p of newPerms) {
		if (!oldPerms.includes(p)) {
			changes.push({ permission: p, oldState: "NEUTRAL", newState: "ALLOW" });
		}
	}

	// Find removed permissions
	for (const p of oldPerms) {
		if (!newPerms.includes(p)) {
			changes.push({ permission: p, oldState: "ALLOW", newState: "NEUTRAL" });
		}
	}

	return changes;
}

/**
 * Diff member roles to find added and removed roles.
 */
export function diffMemberRoles(
	oldMember: GuildMember,
	newMember: GuildMember,
): { added: Role[]; removed: Role[] } {
	const oldRoles = oldMember.roles.cache;
	const newRoles = newMember.roles.cache;

	return {
		added: [...newRoles.filter((r) => !oldRoles.has(r.id)).values()],
		removed: [...oldRoles.filter((r) => !newRoles.has(r.id)).values()],
	};
}