package main

import (
	"context"
	"crypto/md5"
	"encoding/xml"
	"fmt"
	"io"
	"net/http"
	"net/http/cgi"
	"strings"

	"faculty_media_report/api"
	"faculty_media_report/dbi"
	"faculty_media_report/pages"
)

const cas_url = "https://idp.login.iu.edu/idp/profile/cas/login?service=https://app.law.indiana.edu/faculty/activity/cas"

const validation_url_template = "https://idp.login.iu.edu/idp/profile/cas/serviceValidate?ticket=%s&service=https://app.law.indiana.edu/faculty/activity/cas"

var xml_declaration = `<?xml version="1.0" encoding="UTF-8"?>`

type CASAuthenticationSuccess struct {
	XMLName xml.Name `xml:"authenticationSuccess"`
	User string `xml:"user"`
}

type CASResponse struct {
	XMLName xml.Name `xml:"serviceResponse"`
	AuthenticationSuccess CASAuthenticationSuccess `xml:"authenticationSuccess"`
}

func parse_username(response_body []byte) string {
	var cas_response CASResponse

	xmlstring := string(response_body)
	xmlstring = strings.Replace(xmlstring, xml_declaration, "", 1)
	xmlstring = strings.TrimSpace(xmlstring)
	raw_xml_data := []byte(xmlstring)
	e := xml.Unmarshal(raw_xml_data, &cas_response)
	if e != nil {
		return ""
	}
	return cas_response.AuthenticationSuccess.User

}

func validate_cas(cas_ticket string) (string, error) {
	validation_url := fmt.Sprintf(validation_url_template, cas_ticket)
	username := ""
	response, e := http.Get(validation_url)
	if e == nil {
		response_body, er := io.ReadAll(response.Body)
		if er != nil {
			e = er
			// return error below
		} else {
			username = parse_username(response_body)
			if er != nil {
				e = er
			}
			//if username == "" {
			//	log_to_file(string(response_body))
			//}
		}
		defer response.Body.Close()
	}
	if username != "" {
		return username, nil
	}
	return username, e
}

func getCas(w http.ResponseWriter, r *http.Request){

	fail := func(err_message string) {
		content := fmt.Sprintf(pages.ErrorPage, err_message)
		writeHTML(w, content)
	}

	cas_ticket := r.URL.Query().Get("ticket")
	if cas_ticket != "" { // Validate CAS Ticket (and display page if valid)
		username, e := validate_cas(cas_ticket)
		username = strings.ToLower(username)
		if e != nil {

			content := fmt.Sprintf("CAS validation error: %s", e)
			fail(content)
			return

		} else if username == "" {

			fail("CAS ERROR - user not found")
			return

		} else {

			db, err := dbi.GetDbConn()
			if err != nil {
				fail("Database error")
				return
			}
			defer db.Close()

			conn, err := db.Conn(context.Background())
			if err != nil {
				fail("Database error")
				return
			}
			defer conn.Close()

			user, e := dbi.GetUser(conn, username)
			if e != nil {
				login_error_message := fmt.Sprintf("User error for user %s: %s", username, e)
				fail(login_error_message)
				return
			}

			token, e := dbi.GenJWT(user)
			if e != nil {
				jwt_error_message := fmt.Sprintf("Login token failure for user %s: %s", username, e)
				fail(jwt_error_message)
				return
			}

			if user.Status == "admin" {

				items, e := dbi.GetReportedItems(conn)
				if e != nil {
					items_error_message := fmt.Sprintf("Error fetching items: %s", e)
					fail(items_error_message)
					return
				}
				html, e := pages.DashboardPage(token, items)
				if e != nil {
					content := fmt.Sprintf("Error loading dashboard: %s", e)
					fail(content)
					return
				}
				writeHTML(w, html)
				return

			} else if user.Status == "faculty" {

				writeHTML(w, pages.MainFormPage(token))
				return

			} else {

				fail("User has invalid status")
				return

			}

		}

	} else { //No CAS Ticket - validate user

		http.Redirect(w, r, cas_url, http.StatusFound)

	}

}

func writeHTML(w http.ResponseWriter, html string) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	fmt.Fprint(w, html)
}

func handleCas(w http.ResponseWriter, r *http.Request) {
}

func handleLoginGet(w http.ResponseWriter, r *http.Request) {
	writeHTML(w, pages.LoginPage(""))
}

func handleLoginPost(w http.ResponseWriter, r *http.Request) {
	username := r.FormValue("username")
	password := r.FormValue("password")

	fail := func() {
		writeHTML(w, pages.LoginPage("Username or Password is incorrect."))
	}

	if username == "" || password == "" {
		fail()
		return
	}

	db, err := dbi.GetDbConn()
	if err != nil {
		fail()
		return
	}
	defer db.Close()

	conn, err := db.Conn(context.Background())
	if err != nil {
		fail()
		return
	}
	defer conn.Close()

	user, err := dbi.GetUser(conn, username)
	if err != nil {
		fail()
		return
	}

	hash := md5.Sum([]byte(password))
	if fmt.Sprintf("%x", hash) != user.Password {
		fail()
		return
	}

	if user.Status == "admin" {
		token, err := dbi.GenJWT(user)
		if err != nil {
			fail()
			return
		}
		items, err := dbi.GetReportedItems(conn)
		if err != nil {
			fail()
			return
		}
		html, err := pages.DashboardPage(token, items)
		if err != nil {
			fail()
			return
		}
		writeHTML(w, html)
		return
	}

	token, err := dbi.GenJWT(user)
	if err != nil {
		fail()
		return
	}

	writeHTML(w, pages.MainFormPage(token))
}

func getPortal(w http.ResponseWriter, r *http.Request) {
	_, e := w.Write([]byte(pages.LandingPage))
	if e != nil {
		content := fmt.Sprintf(pages.ErrorPage, "Unable to display landing page")
		writeHTML(w, content)
	}
}

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /faculty/activity/cas", getCas)
	mux.HandleFunc("GET /faculty/activity/portal", getPortal)
	mux.HandleFunc("GET /faculty/activity/login", handleLoginGet)
	mux.HandleFunc("POST /faculty/activity/login", handleLoginPost)
	mux.HandleFunc("POST /faculty/activity/api", api.HandleAPI)
	cgi.Serve(mux)
}