import { HUB_URL } from "../consts";
import { createApiError } from "../error";
import type { CredentialsParams, RepoDesignation } from "../types/public";
import { checkCredentials } from "../utils/checkCredentials";
import { toRepoId } from "../utils/toRepoId";

/**
 * @returns null when the file doesn't exist
 */
export async function downloadFile(
	params: {
		repo: RepoDesignation;
		path: string;
		/**
		 * If true, will download the raw git file.
		 *
		 * For example, when calling on a file stored with Git LFS, the pointer file will be downloaded instead.
		 */
		raw?: boolean;
		/**
		 * An optional Git revision id which can be a branch name, a tag, or a commit hash.
		 *
		 * @default "main"
		 */
		revision?: string;
		/**
		 * Fetch only a specific part of the file
		 */
		range?: [number, number];
		hubUrl?: string;
		/**
		 * Custom fetch function to use instead of the default one, for example to use a proxy or edit headers.
		 */
		fetch?: typeof fetch;
	} & Partial<CredentialsParams>
): Promise<Response | null> {
	const accessToken = checkCredentials(params);
	const repoId = toRepoId(params.repo);
	const url = `${params.hubUrl ?? HUB_URL}/${repoId.type === "model" ? "" : `${repoId.type}s/`}${repoId.name}/${
		params.raw ? "raw" : "resolve"
	}/${encodeURIComponent(params.revision ?? "main")}/${params.path}`;

	const resp = await (params.fetch ?? fetch)(url, {
		headers: {
			...(accessToken
				? {
						Authorization: `Bearer ${accessToken}`,
				  }
				: {}),
			...(params.range
				? {
						Range: `bytes=${params.range[0]}-${params.range[1]}`,
				  }
				: {}),
		},
	});

	if (resp.status === 404 && resp.headers.get("X-Error-Code") === "EntryNotFound") {
		return null;
	} else if (!resp.ok) {
		throw await createApiError(resp);
	}

	return resp;
}