import {z} from 'zod'

export type GetApiCoursesArgs = {sort?: string | undefined, page?: number | undefined, per_page?: number | undefined, semester?: string | undefined, credits?: string | undefined, dept_id?: string | undefined, gen_ed?: string | undefined};

export type GetApiCoursesOptions = {baseUrl?: string | undefined, fetch?: typeof fetch | undefined};

export const meeting = z.object({days: z.string().optional(), room: z.string().optional(), building: z.string().optional(), classtype: z.string().optional(), start_time: z.string().optional(), end_time: z.string().optional()});

export const section = z.object({course: z.string().optional(), section_id: z.string().optional(), semester: z.number().optional(), number: z.string().optional(), seats: z.string().optional(), meetings: z.array(meeting).optional(), open_seats: z.string().optional(), waitlist: z.string().optional(), instructors: z.array(z.string()).optional()});

export const course = z.object({course_id: z.string().optional(), semester: z.number().optional(), name: z.string().optional(), dept_id: z.string().optional(), department: z.string().optional(), credits: z.string().optional(), description: z.string().optional(), grading_method: z.array(z.string()).optional(), gen_ed: z.array(z.array(z.string())).optional(), core: z.array(z.string()).optional(), relationships: z.object({coreqs: z.string().nullable().optional(), prereqs: z.string().nullable().optional(), formerly: z.string().nullable().optional(), restrictions: z.string().nullable().optional(), additional_info: z.string().nullable().optional(), also_offered_as: z.string().nullable().optional(), credit_granted_for: z.string().nullable().optional()}).optional(), sections: z.array(z.union([z.string(), section])).optional()});

export const getApiCoursesResponse = z.array(course);

export const validateResponse = async <Output>(
  schema: {
    readonly '~standard': {
      readonly validate: (value: unknown) => ({ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }) | Promise<{ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }>
    }
  },
  value: unknown
): Promise<Output> => {
  const result = await schema['~standard'].validate(value)

  if (result.issues !== undefined) {
    const detail = result.issues
      .map(({ message, path }) =>
        path?.length
          ? `${path.map((segment) => String(typeof segment === 'object' ? segment.key : segment)).join('.')}: ${message}`
          : message
      )
      .join('; ')

    throw new Error(`Response does not match the schema: ${detail}`, { cause: { issues: result.issues } })
  }

  return result.value
};

/**
 * List of courses
 * 
 * GET /courses
 */
export const getApiCourses = async (args: GetApiCoursesArgs, options?: GetApiCoursesOptions) => {
const {baseUrl = "https://api.umd.io/v1", fetch: fetchFn = fetch} = options ?? {}

const query = new URLSearchParams()
const headers = new Headers()
headers.set('accept', "application/json")

if (args.sort != null) query.append("sort", String(args.sort))
if (args.page != null) query.append("page", String(args.page))
if (args.per_page != null) query.append("per_page", String(args.per_page))
if (args.semester != null) query.append("semester", String(args.semester))
if (args.credits != null) query.append("credits", String(args.credits))
if (args.dept_id != null) query.append("dept_id", String(args.dept_id))
if (args.gen_ed != null) query.append("gen_ed", String(args.gen_ed))

const url = `${baseUrl.replace(/\/+$/, '')}/courses${query.size > 0 ? `?${query}` : ''}`

const res = await fetchFn(url, {method: "GET", headers})

if (!res.ok) throw new Error(`Request failed with status ${res.status}`, {cause: {status: res.status, body: await res.text()}})

return validateResponse(getApiCoursesResponse, await res.json())
};