import { existsSync } from "node:fs";
import { resolve } from "node:path";
import { parse } from "vue-docgen-api";
import type { Plugin } from "vite";
import { COMPONENT_LIST } from "../components";
import {
	createEmptyApi,
	type ApiEventRow,
	type ApiExposeRow,
	type ApiPropRow,
	type ApiSlotRow,
	type ComponentApi,
	type ComponentApiMap
} from "../api-types";

/** 虚拟模块的引用标识，业务代码与类型声明共用。 */
export const API_MODULE_ID = "virtual:timi-api";

/** Vite 内部使用的解析后标识，前置 `\0` 避免被其他插件处理。 */
const RESOLVED_ID = `\0${API_MODULE_ID}`;

/**
 * 把 vue-docgen-api 的联合类型描述压平成可读文本。
 * 不同版本对 `defineEmits` 的产出结构不一致，这里统一兜底。
 */
function normalizeType(type: unknown): string {
	if (!type || typeof type !== "object") {
		return "-";
	}
	const candidate = type as { name?: unknown; names?: unknown };
	if (Array.isArray(candidate.names)) {
		return candidate.names.length > 0 ? candidate.names.join(" | ") : "-";
	}
	if (typeof candidate.name === "string" && candidate.name.length > 0) {
		return candidate.name;
	}
	return "-";
}

/** 转换 prop 描述符。 */
function toPropRow(descriptor: any): ApiPropRow {
	return {
		name: String(descriptor.name ?? ""),
		type: normalizeType(descriptor.type),
		defaultValue: descriptor.defaultValue?.value === undefined ? "-" : String(descriptor.defaultValue.value),
		required: descriptor.required === true,
		description: String(descriptor.description ?? "")
	};
}

/** 转换事件描述符。 */
function toEventRow(descriptor: any): ApiEventRow {
	return {
		name: String(descriptor.name ?? ""),
		type: normalizeType(descriptor.type),
		description: String(descriptor.description ?? "")
	};
}

/** 转换插槽描述符，把作用域参数并入说明列。 */
function toSlotRow(descriptor: any): ApiSlotRow {
	const bindings = Array.isArray(descriptor.bindings)
		? descriptor.bindings.map((item: any) => String(item.name ?? "")).filter(Boolean)
		: [];
	const description = String(descriptor.description ?? "");
	const scope = bindings.length > 0 ? `作用域参数：${bindings.join("、")}` : "";
	return {
		name: String(descriptor.name ?? ""),
		description: [description, scope].filter(Boolean).join("；")
	};
}

/** 转换暴露描述符。 */
function toExposeRow(descriptor: any): ApiExposeRow {
	return {
		name: String(descriptor.name ?? ""),
		type: normalizeType(descriptor.type),
		description: String(descriptor.description ?? "")
	};
}

/** 把单个组件文档规范化为纯数据。 */
function toComponentApi(name: string, doc: any): ComponentApi {
	return {
		name,
		description: String(doc?.description ?? ""),
		parsed: true,
		props: Array.isArray(doc?.props) ? doc.props.map(toPropRow) : [],
		events: Array.isArray(doc?.events) ? doc.events.map(toEventRow) : [],
		slots: Array.isArray(doc?.slots) ? doc.slots.map(toSlotRow) : [],
		exposes: Array.isArray(doc?.expose) ? doc.expose.map(toExposeRow) : []
	};
}

/**
 * 逐个解析组件源码。
 * 单个组件解析失败只降级为空 API，不让整个文档站因一处语法而无法构建。
 */
async function parseAll(repoRoot: string): Promise<ComponentApiMap> {
	const result: ComponentApiMap = {};

	for (const meta of COMPONENT_LIST) {
		const filePath = resolve(repoRoot, meta.entry);
		if (!existsSync(filePath)) {
			console.warn(`[timi-docgen] 未找到组件入口，已跳过：${meta.entry}`);
			result[meta.name] = createEmptyApi(meta.name);
			continue;
		}
		try {
			const doc = await parse(filePath);
			result[meta.name] = toComponentApi(meta.name, doc);
		} catch (error) {
			console.warn(`[timi-docgen] 解析 ${meta.name} 失败，已降级为空 API：`, error);
			result[meta.name] = createEmptyApi(meta.name);
		}
	}

	return result;
}

/**
 * 提供 `virtual:timi-api` 虚拟模块，内容为全部组件的 API 数据。
 *
 * 解析结果按需缓存，仅在组件源码变更时失效，避免每次页面请求都重复解析。
 * @param repoRoot 仓库根目录的绝对路径
 */
export function docgenPlugin(repoRoot: string): Plugin {
	const entryPathSet = new Set(COMPONENT_LIST.map(meta => resolve(repoRoot, meta.entry)));
	let cache: ComponentApiMap | null = null;

	return {
		name: "timi-docgen",

		resolveId(id: string) {
			return id === API_MODULE_ID ? RESOLVED_ID : null;
		},

		async load(id: string) {
			if (id !== RESOLVED_ID) {
				return null;
			}
			if (cache === null) {
				cache = await parseAll(repoRoot);
			}
			return `export default ${JSON.stringify(cache)};`;
		},

		handleHotUpdate({ file, server }) {
			if (!entryPathSet.has(file)) {
				return;
			}
			cache = null;
			const invalidated = server.moduleGraph.getModuleById(RESOLVED_ID);
			if (invalidated) {
				server.moduleGraph.invalidateModule(invalidated);
				server.ws.send({ type: "full-reload" });
			}
		}
	};
}