import type { ResumeData } from "@reactive-resume/schema/resume/data";
import { flattenError, ZodError } from "zod";
import { resumeDataSchema, sectionTypeSchema } from "@reactive-resume/schema/resume/data";

const BUILT_IN_LAYOUT_SECTION_IDS = sectionTypeSchema.options.filter((section) => section !== "cover-letter");

function normalizeBuiltInSectionsInLayout(data: ResumeData): ResumeData {
	const pages = data.metadata.layout.pages;

	// Some exported resumes can arrive without any persisted layout pages.
	if (pages.length === 0) {
		return {
			...data,
			metadata: {
				...data.metadata,
				layout: {
					...data.metadata.layout,
					pages: [
						{
							fullWidth: false,
							main: [...BUILT_IN_LAYOUT_SECTION_IDS],
							sidebar: [],
						},
					],
				},
			},
		};
	}

	const existingSectionIds = new Set<string>();

	// Preserve the imported layout and only compute which built-in IDs are missing entirely.
	for (const page of pages) {
		for (const sectionId of page.main) existingSectionIds.add(sectionId);
		for (const sectionId of page.sidebar) existingSectionIds.add(sectionId);
	}

	const missingSectionIds = BUILT_IN_LAYOUT_SECTION_IDS.filter((sectionId) => !existingSectionIds.has(sectionId));

	if (missingSectionIds.length === 0) return data;

	const [firstPage, ...restPages] = pages;
	if (!firstPage) return data;

	return {
		...data,
		metadata: {
			...data.metadata,
			layout: {
				...data.metadata.layout,
				pages: [
					{
						fullWidth: firstPage.fullWidth ?? false,
						sidebar: firstPage.sidebar ?? [],
						// Recover missing built-in sections without reordering the imported layout.
						main: [...firstPage.main, ...missingSectionIds],
					},
					...restPages,
				],
			},
		},
	};
}

export class ReactiveResumeJSONImporter {
	parse(json: string): ResumeData {
		try {
			const parsed = resumeDataSchema.parse(JSON.parse(json));
			return resumeDataSchema.parse(normalizeBuiltInSectionsInLayout(parsed));
		} catch (error) {
			if (error instanceof ZodError) {
				const errors = flattenError(error);
				throw new Error(JSON.stringify(errors));
			}

			throw error;
		}
	}
}