import type { Fetch, PostgrestSingleResponse } from "./types";

export default abstract class PostgrestBuilder<Result>
	implements PromiseLike<PostgrestSingleResponse<Result>>
{
	protected method: "GET" | "HEAD" | "POST" | "PATCH" | "DELETE";
	protected url: URL;
	protected headers: Record<string, string>;
	protected schema?: string;
	protected body?: unknown;
	protected shouldThrowOnError = false;
	protected signal?: AbortSignal;
	protected fetch: Fetch = fetch;
	protected allowEmpty: boolean;

	constructor(builder: PostgrestBuilder<Result>) {
		this.method = builder.method;
		this.url = builder.url;
		this.headers = builder.headers;
		this.schema = builder.schema;
		this.body = builder.body;
		this.shouldThrowOnError = builder.shouldThrowOnError;
		this.signal = builder.signal;
		this.allowEmpty = builder.allowEmpty;
	}

	/**
	 * If there's an error with the query, throwOnError will reject the promise by
	 * throwing the error instead of returning it as part of a successful response.
	 *
	 * {@link https://github.com/supabase/supabase-js/issues/92}
	 */
	throwOnError(): this {
		this.shouldThrowOnError = true;
		return this;
	}

	then<TResult1 = PostgrestSingleResponse<Result>, TResult2 = never>(
		onfulfilled?:
			| ((
					value: PostgrestSingleResponse<Result>,
			  ) => TResult1 | PromiseLike<TResult1>)
			| undefined
			| null,
		onrejected?:
			| ((reason: any) => TResult2 | PromiseLike<TResult2>)
			| undefined
			| null,
	): PromiseLike<TResult1 | TResult2> {
		// https://postgrest.org/en/stable/api.html#switching-schemas
		if (this.schema === undefined) {
			// skip
		} else if (["GET", "HEAD"].includes(this.method)) {
			this.headers["Accept-Profile"] = this.schema;
		} else {
			this.headers["Content-Profile"] = this.schema;
		}
		if (this.method !== "GET" && this.method !== "HEAD") {
			this.headers["Content-Type"] = "application/json";
		}

		// NOTE: Invoke w/o `this` to avoid illegal invocation error.
		// https://github.com/supabase/postgrest-js/pull/247
		const _fetch = this.fetch;
		let res = _fetch(this.url.toString(), {
			method: this.method,
			headers: this.headers,
			body: JSON.stringify(this.body),
			signal: this.signal,
		}).then(async (res) => {
			let error = null;
			let data = null;
			let count: number | null = null;
			let status = res.status;
			let statusText = res.statusText;

			if (res.ok) {
				if (this.method !== "HEAD") {
					const body = await res.text();
					if (body === "") {
						// Prefer: return=minimal
					} else if (this.headers["Accept"] === "text/csv") {
						data = body;
					} else if (
						this.headers["Accept"]?.includes("application/vnd.pgrst.plan+text")
					) {
						data = body;
					} else {
						data = JSON.parse(body);
					}
				}

				const countHeader = this.headers["Prefer"]?.match(
					/count=(exact|planned|estimated)/,
				);
				const contentRange = res.headers.get("content-range")?.split("/");
				if (countHeader && contentRange && contentRange.length > 1) {
					count = parseInt(contentRange[1]);
				}
			} else {
				const body = await res.text();

				try {
					error = JSON.parse(body);

					// Workaround for https://github.com/supabase/postgrest-js/issues/295
					if (Array.isArray(error) && res.status === 404) {
						data = [];
						error = null;
						status = 200;
						statusText = "OK";
					}
				} catch {
					// Workaround for https://github.com/supabase/postgrest-js/issues/295
					if (res.status === 404 && body === "") {
						status = 204;
						statusText = "No Content";
					} else {
						error = {
							message: body,
						};
					}
				}

				if (
					error &&
					this.allowEmpty &&
					error?.details?.includes("Results contain 0 rows")
				) {
					error = null;
					status = 200;
					statusText = "OK";
				}

				if (error && this.shouldThrowOnError) {
					throw error;
				}
			}

			const postgrestResponse = {
				error,
				data,
				count,
				status,
				statusText,
			};

			return postgrestResponse;
		});
		if (!this.shouldThrowOnError) {
			res = res.catch((fetchError) => ({
				error: {
					message: `FetchError: ${fetchError.message}`,
					details: "",
					hint: "",
					code: fetchError.code || "",
				},
				data: null,
				count: null,
				status: 0,
				statusText: "",
			}));
		}

		return res.then(onfulfilled, onrejected);
	}
}