import { NextResponse } from "next/server";
import {
	ok,
	noContent,
	withErrorHandling,
	parseJsonBody,
	ApiError,
} from "@/lib/api/response";
import { updatePostSchema } from "@/lib/validation/post";
import {
	getPostBySlug,
	getPostBySlugIncludingDrafts,
	updatePost,
	deletePost,
	assertSlugAvailable,
} from "@/lib/posts/repository";

/**
 * /api/posts/[slug] —— 单篇文章的读取、更新与删除
 *
 * 注意：GET 默认只返回已发布文章；传入 ?includeDrafts=true 可读到草稿，
 * 供后续接入后台管理时使用（v0.1 尚无鉴权，接入后台前应加上权限校验）。
 */

type RouteContext = { params: Promise<{ slug: string }> };

/** GET /api/posts/[slug] —— 读取单篇文章（含正文） */
export const GET = withErrorHandling(
	async (request: Request, context: RouteContext) => {
		const { slug } = await context.params;
		const { searchParams } = new URL(request.url);
		const includeDrafts = searchParams.get("includeDrafts") === "true";

		const post = includeDrafts
			? await getPostBySlugIncludingDrafts(slug)
			: await getPostBySlug(slug);

		if (!post) {
			throw ApiError.notFound(`文章 "${slug}" 不存在或尚未发布`);
		}

		return ok(post);
	},
);

/**
 * PATCH /api/posts/[slug] —— 更新文章（部分更新）
 *
 * 支持更新 slug 本身；此时会校验新 slug 未被占用。
 */
export const PATCH = withErrorHandling(
	async (request: Request, context: RouteContext) => {
		const { slug } = await context.params;
		const body = await parseJsonBody(request);
		const input = updatePostSchema.parse(body);

		// 目标文章必须存在（含草稿，便于把草稿改为已发布）
		const existing = await getPostBySlugIncludingDrafts(slug);
		if (!existing) {
			throw ApiError.notFound(`文章 "${slug}" 不存在`);
		}

		// 改 slug 时需要判重（排除自身）
		if (input.slug && input.slug !== slug) {
			await assertSlugAvailable(input.slug, slug);
		}

		const updated = await updatePost(slug, input);
		if (!updated) {
			throw ApiError.notFound(`文章 "${slug}" 不存在`);
		}

		return ok(updated);
	},
);

/** PUT 与 PATCH 同义，便于不支持 PATCH 的客户端使用 */
export const PUT = PATCH;

/** DELETE /api/posts/[slug] —— 删除文章 */
export const DELETE = withErrorHandling(
	async (_request: Request, context: RouteContext) => {
		const { slug } = await context.params;

		const removed = await deletePost(slug);
		if (!removed) {
			throw ApiError.notFound(`文章 "${slug}" 不存在`);
		}

		// 204 No Content：删除成功且无响应体
		return noContent();
	},
);

/** 列出该资源支持的方法 */
export function OPTIONS() {
	return new NextResponse(null, {
		status: 204,
		headers: { Allow: "GET, PATCH, PUT, DELETE, OPTIONS" },
	});
}