/**
 * The supported document formats, in one table.
 *
 * The tool handler, the config defaults, the `formats` merge, and the
 * unsupported-file error all derive from `FORMATS`, so adding a format is a
 * local change: one extractor module plus one entry here. See the README's
 * "Adding a format" section.
 */

import { extname } from "node:path";
import type { DocExtractor } from "./extract/file.ts";
import { extractDocText } from "./extract/doc.ts";
import { extractDocxText } from "./extract/docx.ts";
import { extractOdtText } from "./extract/odt.ts";
import { extractPdfText } from "./extract/pdf.ts";
import { extractRtfText } from "./extract/rtf.ts";
import { extractXlsxText } from "./extract/xlsx.ts";

export interface DocumentFormat {
	/** Stable id, also the `document.formats` key in `bytefly.json` and the output `format`. */
	id: "pdf" | "docx" | "doc" | "odt" | "rtf" | "xlsx";
	/** Human label for messages. */
	label: string;
	/** Lower-case extensions, with the dot, that select this format. */
	extensions: readonly string[];
	/** Enabled unless `document.formats[id]` in `bytefly.json` says otherwise. */
	defaultEnabled: boolean;
	/** Extractor; runs the format's parser and throws a readable error when it fails. */
	extract: DocExtractor;
}

export const FORMATS = [
	{ id: "pdf", label: "PDF", extensions: [".pdf"], defaultEnabled: true, extract: extractPdfText },
	{ id: "docx", label: "DOCX", extensions: [".docx"], defaultEnabled: true, extract: extractDocxText },
	{ id: "doc", label: "DOC", extensions: [".doc"], defaultEnabled: true, extract: extractDocText },
	{ id: "odt", label: "ODT", extensions: [".odt"], defaultEnabled: true, extract: extractOdtText },
	{ id: "rtf", label: "RTF", extensions: [".rtf"], defaultEnabled: true, extract: extractRtfText },
	{ id: "xlsx", label: "XLSX", extensions: [".xlsx"], defaultEnabled: true, extract: extractXlsxText },
] as const satisfies readonly DocumentFormat[];

export type FormatId = (typeof FORMATS)[number]["id"];

/** Every supported extension, e.g. `[".pdf", ".docx"]`. */
export function supportedExtensions(): string[] {
	return FORMATS.flatMap((format) => [...format.extensions]);
}

/** The format selected by a path's extension, or undefined when unsupported. */
export function detectFormat(path: string): DocumentFormat | undefined {
	const ext = extname(path).toLowerCase();
	return FORMATS.find((format) => (format.extensions as readonly string[]).includes(ext));
}

/** A targeted hint for a known-but-unsupported extension, or undefined. */
export function unsupportedHint(path: string): string | undefined {
	const ext = extname(path).toLowerCase();
	if (ext === ".xls") return "Legacy .xls is not supported; convert it to .xlsx first.";
	return undefined;
}