package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
)

/*
func get_courses(token string, link string, client http.Client) []CanvasCourse {
	resp, err := client.Get(link)
	if err != nil {
		fmt.Println("Error performing GET request to get courses.")
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)

	if err != nil {
		fmt.Println("Error trying to read html body for courses.")
	}

	var canvas_courses []CanvasCourse
	err2 := json.Unmarshal(body, &canvas_courses)
	if err2 != nil {
		fmt.Println(err2)
		return nil
	}

	return canvas_courses
}

// Need to change this to grab both ID and name, return as pairs.
func get_course_id_name_pair(canvas_courses []CanvasCourse) []uint64 {
	var courses []uint64

	for _, course := range canvas_courses {
		courses = append(courses, course.ID%10000)
	}
	return courses
}

func select_course() int {
	// course selection by user happens below
	//favorites := fmt.Sprintf("%s/users/self/favorites/courses?access_token=%s&per_page=100", base_link, token)
	//all_courses := fmt.Sprintf("%s/courses?access_token=%s&per_page=100", base_link,token)
	// var canvas_courses []CanvasCourse
	//canvas_courses = get_courses(token, favorites, client)
	//var course_ids []uint64
	//course_ids = get_course_ids(canvas_courses)
	//selected := 1 // course_ids[selected]
	// course selection by user happens above
	return 0
}
*/

func get_aplus(token string, link string, client http.Client) string {
	resp, err := client.Get(link)

	if err != nil {
		fmt.Println("Error performing GET request to initial link.")
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)

	if err != nil {
		fmt.Println("Error reading body of initial aplus html response " +
			"which is supposed to contain a one-time link for getting the form.")
	}

	var aplus Aplus
	json.Unmarshal(body, &aplus)

	return aplus.URL
}

func get_form_from_request_body(req_body []byte) string {
	body_str := string(req_body)
	form_start := strings.Index(body_str, "<form")
	form_end := strings.Index(body_str, "</form>") + 7
	form_html := req_body[form_start:form_end]

	return string(form_html)
}

// parse_form extracts form fields and values from the given HTML form string.
func parse_form(form_html string) url.Values {
	form_values := make(url.Values)
	inputs := strings.Split(form_html, "<input")

	for _, input := range inputs {
		// Extract field name and value
		name := extract_attribute(input, "name")
		value := extract_attribute(input, "value")

		if name != "" {
			form_values.Add(name, value)
		}
	}

	return form_values
}

func extract_attribute(input string, attribute string) string {
	start := strings.Index(input, attribute+"=\"")
	if start == -1 {
		start = strings.Index(input, attribute+"='")
	}

	if start == -1 {
		return ""
	}

	start += len(attribute) + 2

	end := strings.Index(input[start:], "\"")
	if end == -1 {
		end = strings.Index(input[start:], "'")
	}

	if end == -1 {
		return ""
	}

	return input[start : start+end]
}