/**
 * CRDT Token Service — server-side token management via Automerge.
 *
 * Manages token ledger documents: minting, balance queries, and seeding.
 */

import * as Automerge from '@automerge/automerge';
import type { SyncServer } from './local-first/sync-server';
import { tokenLedgerSchema, tokenDocId } from './token-schemas';
import type { TokenLedgerDoc, LedgerEntry } from './token-schemas';

let _syncServer: SyncServer | null = null;

export function initTokenService(syncServer: SyncServer) {
	_syncServer = syncServer;
}

/** Create a token doc if it doesn't exist yet. */
function ensureTokenDoc(tokenId: string): TokenLedgerDoc {
	const docId = tokenDocId(tokenId);
	let doc = _syncServer!.getDoc<TokenLedgerDoc>(docId);
	if (!doc) {
		doc = Automerge.change(Automerge.init<TokenLedgerDoc>(), 'init token ledger', (d) => {
			const init = tokenLedgerSchema.init();
			Object.assign(d, init);
		});
		_syncServer!.setDoc(docId, doc);
	}
	return doc;
}

/** Sum all entry amounts for a given DID holder. */
export function getBalance(doc: TokenLedgerDoc, did: string): number {
	let balance = 0;
	for (const entry of Object.values(doc.entries)) {
		if (entry.type === 'mint' && entry.to === did) {
			balance += entry.amount;
		} else if (entry.type === 'transfer') {
			if (entry.to === did) balance += entry.amount;
			if (entry.from === did) balance -= entry.amount;
		} else if (entry.type === 'burn' && entry.from === did) {
			balance -= entry.amount;
		}
	}
	return balance;
}

/** Aggregate balances for all holders. */
export function getAllBalances(doc: TokenLedgerDoc): Record<string, { did: string; label: string; balance: number }> {
	const holders: Record<string, { did: string; label: string; balance: number }> = {};

	for (const entry of Object.values(doc.entries)) {
		if (entry.type === 'mint') {
			if (!holders[entry.to]) holders[entry.to] = { did: entry.to, label: entry.toLabel, balance: 0 };
			holders[entry.to].balance += entry.amount;
			if (entry.toLabel) holders[entry.to].label = entry.toLabel;
		} else if (entry.type === 'transfer') {
			if (!holders[entry.to]) holders[entry.to] = { did: entry.to, label: entry.toLabel, balance: 0 };
			if (!holders[entry.from]) holders[entry.from] = { did: entry.from, label: '', balance: 0 };
			holders[entry.to].balance += entry.amount;
			holders[entry.from].balance -= entry.amount;
		} else if (entry.type === 'burn') {
			if (!holders[entry.from]) holders[entry.from] = { did: entry.from, label: '', balance: 0 };
			holders[entry.from].balance -= entry.amount;
		}
	}

	// Remove zero-balance holders
	for (const [k, v] of Object.entries(holders)) {
		if (v.balance <= 0) delete holders[k];
	}
	return holders;
}

/** Mint tokens to a DID. */
export function mintTokens(
	tokenId: string,
	toDid: string,
	toLabel: string,
	amount: number,
	memo: string,
	issuedBy: string,
): boolean {
	const docId = tokenDocId(tokenId);
	ensureTokenDoc(tokenId);

	const entryId = `mint-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`;
	const result = _syncServer!.changeDoc<TokenLedgerDoc>(docId, `mint ${amount} to ${toLabel}`, (d) => {
		d.entries[entryId] = {
			id: entryId,
			to: toDid,
			toLabel,
			amount,
			memo,
			type: 'mint',
			from: '',
			timestamp: Date.now(),
			issuedBy,
		};
		d.token.totalSupply = (d.token.totalSupply || 0) + amount;
	});
	return result !== null;
}

/** List all token doc IDs. */
export function listTokenDocs(): string[] {
	return _syncServer!.listDocs().filter((id) => id.startsWith('global:tokens:ledgers:'));
}

/** Get a token doc by ID. */
export function getTokenDoc(tokenId: string): TokenLedgerDoc | undefined {
	return _syncServer!.getDoc<TokenLedgerDoc>(tokenDocId(tokenId));
}

/** Seed the cUSDC token with 5 cUSDC minted to jeff. */
export async function seedCUSDC() {
	const tokenId = 'cusdc';
	const doc = ensureTokenDoc(tokenId);

	// Skip if already fully seeded (has entries)
	if (doc.token.name && Object.keys(doc.entries).length > 0) {
		console.log('[TokenService] cUSDC already seeded, skipping');
		return;
	}

	// Set up token definition (idempotent — only writes if not yet defined)
	const docId = tokenDocId(tokenId);
	if (!doc.token.name) {
	_syncServer!.changeDoc<TokenLedgerDoc>(docId, 'define cUSDC token', (d) => {
		d.token.id = 'cusdc';
		d.token.name = 'CRDT USDC';
		d.token.symbol = 'cUSDC';
		d.token.decimals = 6;
		d.token.description = 'CRDT-native stablecoin pegged to USDC, stored as an Automerge document';
		d.token.icon = '💵';
		d.token.color = '#2775ca';
		d.token.createdAt = Date.now();
		d.token.createdBy = 'system';
	});
	}

	// Resolve jeff's DID — use known DID with env override support
	const jeffDid = process.env.SEED_JEFF_DID || 'did:key:jAV6y4tg8UbKJEkN0npvX8CTdJkSCGpU';

	// Mint 5 cUSDC (5 × 10^6 base units)
	const success = mintTokens(tokenId, jeffDid, 'jeff', 5_000_000, 'Initial seed mint', 'system');
	if (success) {
		console.log(`[TokenService] cUSDC seeded: 5 cUSDC minted to jeff (${jeffDid})`);
	} else {
		console.error('[TokenService] Failed to mint cUSDC to jeff');
	}
}