// deno task check-mods
// validates every mod in mods/: manifests, data files, textures, references between them, and typechecks scripts
import {
	BlockJson,
	FORMAT_VERSION,
	ItemJson,
	RecipeJson,
	validate_block,
	validate_item,
	validate_manifest,
	validate_recipe,
} from "$/common/mod_data.ts";

export interface ModReport {
	id: string;
	errors: string[];
	warnings: string[];
}

interface LoadedMod {
	id: string;
	dir: string;
	report: ModReport;
	manifest?: Record<string, unknown>;
	blocks: { file: string; json: BlockJson }[];
	items: { file: string; json: ItemJson }[];
	recipes: { file: string; json: RecipeJson }[];
	textures: string[];
}

// the base game's textures are still built from assets/ until the loader exists (phase 1 in MODS.md),
// and the build names all of them bworld:<file>
const BASE_TEXTURE_DIR = "assets/sprites/textures";

export async function check_mods(mods_dir = "mods", options = { typecheck: true }): Promise<ModReport[]> {
	const mods: LoadedMod[] = [];
	for (const entry of safe_read_dir(mods_dir)) {
		if (entry.isDirectory && !entry.name.startsWith(".") && !entry.name.startsWith("_")) {
			mods.push(load_mod(mods_dir, entry.name));
		}
	}

	check_references(mods);

	if (options.typecheck) {
		for (const mod of mods) {
			await typecheck_scripts(mod);
		}
	}

	return mods.map((mod) => mod.report);
}

function load_mod(mods_dir: string, id: string): LoadedMod {
	const dir = `${mods_dir}/${id}`;
	const mod: LoadedMod = {
		id,
		dir,
		report: { id, errors: [], warnings: [] },
		blocks: [],
		items: [],
		recipes: [],
		textures: [],
	};
	const error = (message: string) => mod.report.errors.push(message);

	const manifest = read_json(`${dir}/manifest.json`, error);
	if (manifest !== undefined) {
		for (const problem of validate_manifest(manifest, id)) error(`manifest.json: ${problem}`);
		mod.manifest = manifest as Record<string, unknown>;
	}
	if (id === "engine") {
		error(`"engine" is reserved for the engine itself`);
	}

	const scripts = (mod.manifest?.scripts ?? {}) as Record<string, string>;
	for (const [side, path] of Object.entries(scripts)) {
		if (typeof path === "string" && !exists(`${dir}/${path}`)) {
			error(`manifest.json: scripts.${side} ${path} doesn't exist`);
		}
	}
	const credits = mod.manifest?.credits;
	if (typeof credits === "string" && !exists(`${dir}/${credits}`)) {
		error(`manifest.json: credits ${credits} doesn't exist`);
	}

	const load_data = <T>(
		folder: string,
		key: string,
		validate: (json: unknown) => string[],
		into: { file: string; json: T }[],
	) => {
		for (const file of walk(`${dir}/${folder}`, ".json")) {
			const path = `${folder}/${file}`;
			const wrapper = read_json(`${dir}/${path}`, (m) => error(`${path}: ${m}`));
			if (wrapper === undefined) continue;
			if (!is_object(wrapper) || wrapper.format_version !== FORMAT_VERSION || !(key in wrapper)) {
				error(`${path}: must be { "format_version": ${FORMAT_VERSION}, "${key}": { ... } }`);
				continue;
			}
			const problems = validate(wrapper[key]);
			for (const problem of problems) error(`${path}: ${problem}`);
			if (problems.length === 0) into.push({ file: path, json: wrapper[key] as T });
		}
	};
	load_data("blocks", "block", validate_block, mod.blocks);
	load_data("items", "item", validate_item, mod.items);
	load_data("recipes", "recipe", validate_recipe, mod.recipes);

	// a mod only registers ids in its own namespace
	for (const { file, json } of [...mod.blocks, ...mod.items]) {
		if (json.id.split(":")[0] !== id) error(`${file}: ${json.id} isn't in this mod's namespace "${id}"`);
	}

	for (const file of walk(`${dir}/textures`, ".png")) {
		const texture_id = `${id}:${file.replace(/\.png$/, "").replaceAll("/", "_")}`;
		mod.textures.push(texture_id);
		const size = png_size(`${dir}/textures/${file}`);
		if (!size) {
			error(`textures/${file}: isn't a png`);
		} else if (size.width !== 16 || size.height !== 16) {
			error(`textures/${file}: is ${size.width}×${size.height}, textures must be 16×16`);
		}
	}

	return mod;
}

function check_references(mods: LoadedMod[]) {
	const block_owners = new Map<string, string[]>();
	const item_owners = new Map<string, string[]>();
	const add = (map: Map<string, string[]>, id: string, mod: string) => map.set(id, [...(map.get(id) ?? []), mod]);

	const textures = new Set<string>();
	for (const file of walk(BASE_TEXTURE_DIR, ".png")) {
		textures.add(`bworld:${file.replace(/\.png$/, "")}`);
	}

	for (const mod of mods) {
		for (const { json } of mod.blocks) {
			add(block_owners, json.id, mod.id);
			if (json.item !== false) add(item_owners, json.id, mod.id);
		}
		for (const { json } of mod.items) add(item_owners, json.id, mod.id);
		for (const texture of mod.textures) textures.add(texture);
	}

	const mod_ids = new Set(mods.map((mod) => mod.id));

	for (const mod of mods) {
		const { errors, warnings } = mod.report;
		const dependencies = new Set(
			((mod.manifest?.dependencies ?? []) as { id: string }[]).map((dep) => dep.id),
		);
		for (const dep of dependencies) {
			if (!mod_ids.has(dep)) errors.push(`manifest.json: depends on "${dep}", which isn't installed`);
		}

		const uses = (file: string, id: string, what: "block" | "item" | "texture") => {
			const namespace = id.split(":")[0];
			if (namespace !== mod.id && namespace !== "engine" && !dependencies.has(namespace)) {
				warnings.push(`${file}: uses ${id} but doesn't list "${namespace}" in dependencies`);
			}
			if (what === "texture") {
				if (!textures.has(id)) warnings.push(`${file}: texture ${id} doesn't exist, it will show as missing`);
			} else if (!(what === "block" ? block_owners : item_owners).has(id)) {
				errors.push(`${file}: ${what} ${id} doesn't exist`);
			}
		};

		for (const { file, json } of mod.blocks) {
			if ((block_owners.get(json.id)?.length ?? 0) > 1) {
				errors.push(`${file}: block ${json.id} is also defined by ${block_owners.get(json.id)!.join(", ")}`);
			}
			const texture_ids = typeof json.textures === "string" ? [json.textures] : Object.values(json.textures);
			for (const texture of texture_ids) uses(file, texture, "texture");
			if (json.drops) uses(file, json.drops, "item");
		}
		for (const { file, json } of mod.items) {
			if ((item_owners.get(json.id)?.length ?? 0) > 1) {
				errors.push(`${file}: item ${json.id} is also defined by ${item_owners.get(json.id)!.join(", ")}`);
			}
			uses(file, json.texture, "texture");
			if (json.places) uses(file, json.places, "block");
		}
		for (const { file, json } of mod.recipes) {
			switch (json.type) {
				case "shaped":
					for (const id of Object.values(json.key)) uses(file, id, "item");
					uses(file, json.result.id, "item");
					break;
				case "furnace":
					uses(file, json.input, "item");
					uses(file, json.output.id, "item");
					break;
				case "fuel":
					uses(file, json.item, "item");
					break;
			}
		}
	}
}

async function typecheck_scripts(mod: LoadedMod) {
	const scripts = Object.values((mod.manifest?.scripts ?? {}) as Record<string, string>)
		.filter((path) => typeof path === "string" && exists(`${mod.dir}/${path}`))
		.map((path) => `${mod.dir}/${path}`);
	if (scripts.length === 0) return;

	const output = await new Deno.Command(Deno.execPath(), {
		args: ["check", "--config", "deno.json", ...scripts],
		stdout: "piped",
		stderr: "piped",
		env: { NO_COLOR: "1" },
	}).output();
	if (!output.success) {
		const text = new TextDecoder().decode(output.stderr).trim();
		mod.report.errors.push(`scripts don't typecheck:\n${text}`);
	}
}

// helpers

function read_json(path: string, error: (message: string) => void): unknown {
	let text: string;
	try {
		text = Deno.readTextFileSync(path);
	} catch {
		error(`${path.split("/").pop()} is missing`);
		return undefined;
	}
	try {
		return JSON.parse(text);
	} catch (e) {
		error(`isn't valid json: ${(e as Error).message}`);
		return undefined;
	}
}

// relative paths of files ending in `extension`, in subfolders too
function walk(dir: string, extension: string, prefix = ""): string[] {
	const files: string[] = [];
	for (const entry of safe_read_dir(dir)) {
		if (entry.isDirectory) {
			files.push(...walk(`${dir}/${entry.name}`, extension, `${prefix}${entry.name}/`));
		} else if (entry.name.endsWith(extension)) {
			files.push(`${prefix}${entry.name}`);
		}
	}
	return files.sort();
}

function safe_read_dir(dir: string): Deno.DirEntry[] {
	try {
		return [...Deno.readDirSync(dir)].sort((a, b) => a.name.localeCompare(b.name));
	} catch {
		return [];
	}
}

function exists(path: string) {
	try {
		Deno.statSync(path);
		return true;
	} catch {
		return false;
	}
}

// reads the size out of the png header instead of decoding the image
function png_size(path: string): { width: number; height: number } | undefined {
	const bytes = Deno.readFileSync(path);
	const signature = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
	if (bytes.length < 24 || !signature.every((b, i) => bytes[i] === b)) return undefined;
	const view = new DataView(bytes.buffer, bytes.byteOffset);
	return { width: view.getUint32(16), height: view.getUint32(20) };
}

function is_object(value: unknown): value is Record<string, unknown> {
	return typeof value === "object" && value !== null && !Array.isArray(value);
}

if (import.meta.main) {
	const reports = await check_mods();
	let errors = 0;
	for (const report of reports) {
		const status = report.errors.length ? "✗" : "✓";
		console.log(`${status} ${report.id}`);
		for (const error of report.errors) console.log(`  error: ${error.replaceAll("\n", "\n    ")}`);
		for (const warning of report.warnings) console.log(`  warning: ${warning}`);
		errors += report.errors.length;
	}
	if (reports.length === 0) console.log("No mods in mods/");
	Deno.exit(errors ? 1 : 0);
}