import { readdirSync, readFileSync, writeFileSync } from "node:fs";
import { join } from "node:path";

// Usage: node scripts/generate-bestiary-index.mjs <path-to-5etools-src>
//
// Requires a local clone/checkout of https://github.com/5etools-mirror-3/5etools-src
// with at least data/bestiary/, data/books.json, and data/adventures.json.
//
// Example:
//   git clone --depth 1 --sparse https://github.com/5etools-mirror-3/5etools-src.git /tmp/5etools
//   cd /tmp/5etools && git sparse-checkout set data/bestiary data
//   node scripts/generate-bestiary-index.mjs /tmp/5etools

const TOOLS_ROOT = process.argv[2];
if (!TOOLS_ROOT) {
	console.error(
		"Usage: node scripts/generate-bestiary-index.mjs <5etools-src-path>",
	);
	process.exit(1);
}

const PROJECT_ROOT = join(import.meta.dirname, "..");
const BESTIARY_DIR = join(TOOLS_ROOT, "data/bestiary");
const BOOKS_PATH = join(TOOLS_ROOT, "data/books.json");
const ADVENTURES_PATH = join(TOOLS_ROOT, "data/adventures.json");
const OUTPUT_PATH = join(PROJECT_ROOT, "data/bestiary/index.json");

// --- Build source display name map from books.json + adventures.json ---

function buildSourceMap() {
	const map = {};

	const books = JSON.parse(readFileSync(BOOKS_PATH, "utf-8"));
	for (const book of books.book ?? []) {
		if (book.source && book.name) {
			map[book.source] = book.name;
		}
		// Some books use "id" instead of "source"
		if (book.id && book.name && !map[book.id]) {
			map[book.id] = book.name;
		}
	}

	const adventures = JSON.parse(readFileSync(ADVENTURES_PATH, "utf-8"));
	for (const adv of adventures.adventure ?? []) {
		if (adv.source && adv.name) {
			map[adv.source] = adv.name;
		}
		if (adv.id && adv.name && !map[adv.id]) {
			map[adv.id] = adv.name;
		}
	}

	// Manual additions for sources missing from books.json / adventures.json
	const manual = {
		ESK: "Essentials Kit",
		MCV1SC: "Monstrous Compendium Volume 1: Spelljammer Creatures",
		MCV2DC: "Monstrous Compendium Volume 2: Dragonlance Creatures",
		MCV3MC: "Monstrous Compendium Volume 3: Minecraft Creatures",
		MCV4EC: "Monstrous Compendium Volume 4: Eldraine Creatures",
		MFF: "Mordenkainen's Fiendish Folio",
		MisMV1: "Misplaced Monsters: Volume 1",
		SADS: "Sapphire Anniversary Dice Set",
		TftYP: "Tales from the Yawning Portal",
		VD: "Vecna Dossier",
	};
	for (const [k, v] of Object.entries(manual)) {
		if (!map[k]) map[k] = v;
	}

	return map;
}

// --- Extract type string from raw type field ---

function extractType(type) {
	if (typeof type === "string") return type;
	if (typeof type?.type === "string") return type.type;
	if (typeof type?.type === "object" && Array.isArray(type.type.choose)) {
		return type.type.choose.join("/");
	}
	return "unknown";
}

// --- Extract AC from raw ac field ---

function extractAc(ac) {
	if (!Array.isArray(ac) || ac.length === 0) return 0;
	const first = ac[0];
	if (typeof first === "number") return first;
	if (typeof first === "object" && typeof first.ac === "number")
		return first.ac;
	return 0;
}

// --- Extract CR from raw cr field ---

function extractCr(cr) {
	if (typeof cr === "string") return cr;
	if (typeof cr === "object" && typeof cr.cr === "string") return cr.cr;
	return "0";
}

// --- Main ---

const sourceMap = buildSourceMap();
const files = readdirSync(BESTIARY_DIR).filter(
	(f) => f.startsWith("bestiary-") && f.endsWith(".json"),
);

const creatures = [];
const unmappedSources = new Set();

for (const file of files.sort()) {
	const raw = JSON.parse(readFileSync(join(BESTIARY_DIR, file), "utf-8"));
	const monsters = raw.monster ?? [];

	for (const m of monsters) {
		// Skip creatures that are copies/references (no actual stats)
		if (m._copy || m.hp == null || m.ac == null) continue;

		const source = m.source ?? "";
		if (source && !sourceMap[source]) {
			unmappedSources.add(source);
		}

		creatures.push({
			n: m.name,
			s: source,
			ac: extractAc(m.ac),
			hp: m.hp.average ?? 0,
			dx: m.dex ?? 10,
			cr: extractCr(m.cr),
			ip: m.initiative?.proficiency ?? 0,
			sz: Array.isArray(m.size) ? m.size[0] : (m.size ?? "M"),
			tp: extractType(m.type),
		});
	}
}

// Sort by name then source for stable output
creatures.sort((a, b) => a.n.localeCompare(b.n) || a.s.localeCompare(b.s));

// Filter sourceMap to only include sources that appear in the index
const usedSources = new Set(creatures.map((c) => c.s));
const filteredSourceMap = {};
for (const [key, value] of Object.entries(sourceMap)) {
	if (usedSources.has(key)) {
		filteredSourceMap[key] = value;
	}
}

const output = {
	sources: filteredSourceMap,
	creatures,
};

writeFileSync(OUTPUT_PATH, JSON.stringify(output));

// Stats
const rawSize = Buffer.byteLength(JSON.stringify(output));
console.log(`Sources: ${Object.keys(filteredSourceMap).length}`);
console.log(`Creatures: ${creatures.length}`);
console.log(`Output size: ${(rawSize / 1024).toFixed(1)} KB`);
if (unmappedSources.size > 0) {
	console.log(`Unmapped sources: ${[...unmappedSources].sort().join(", ")}`);
}