package sync

import (
	"bytes"
	"crypto/tls"
	"fmt"
	"log"
	"strings"

	"github.com/remogatto/slicediff"
	"github.com/sethvargo/go-password/password"

	gomail "gopkg.in/gomail.v2"
	ldap "gopkg.in/ldap.v2"

	"text/template"

	karmen_client "gogs.carducci-dante.gov.it/karmen/client"
	"gogs.carducci-dante.gov.it/karmen/core/config"
	"gogs.carducci-dante.gov.it/karmen/core/orm"
	karmen_ldap "gogs.carducci-dante.gov.it/karmen/ldap"

	tpl_util "gogs.carducci-dante.gov.it/karmen/util/template"
)

type TeachersDsts []*ldap.Entry
type TeachersSrcs []*orm.Teacher

type TeachersMLSrcs []*orm.Teacher

func (d TeachersDsts) Strings() (result []string) {
	for _, entry := range d {
		result = append(
			result,
			entry.DN,
		)
	}
	return
}

func (s TeachersSrcs) Strings() (result []string) {
	for _, teacher := range s {
		result = append(
			result,
			fmt.Sprintf("cn=%s %s,%s", teacher.Name, teacher.Surname, "ou=Docenti,ou=Persone,dc=carducci-dante,dc=gov,dc=it"),
		)
	}
	return
}

type TeachersGroupDsts []string
type TeachersGroupSrcs []*orm.Teacher

func (d TeachersGroupDsts) Strings() (result []string) {
	return d
}

func (s TeachersGroupSrcs) Strings() (result []string) {
	for _, teacher := range s {
		result = append(
			result,
			teacher.Username(),
		)
	}
	return
}

type TeachersMLDsts []*orm.Teacher

func (s TeachersMLDsts) Strings() (result []string) {
	for _, teacher := range s {
		result = append(
			result,
			fmt.Sprintf("cn=%s %s,%s", teacher.Name, teacher.Surname, "ou=Docenti,ou=Persone,dc=carducci-dante,dc=gov,dc=it"),
		)
	}
	return
}

type SyncJob struct {
	conf *config.ConfigT
}

func NewSyncJob(conf *config.ConfigT) *SyncJob {
	return &SyncJob{conf}
}

func (syncJob *SyncJob) sendMail(teacher *orm.Teacher, tpl *template.Template) error {
	var buf bytes.Buffer

	err := tpl.Execute(&buf, teacher)
	if err != nil {
		return err
	}

	if !syncJob.conf.Sync.SafeRun {
		log.Printf("Invio le credenziali a %s", teacher.AltEmail)
		m := gomail.NewMessage()
		m.SetHeader("From", syncJob.conf.Smtp.From)
		m.SetHeader("To", teacher.AltEmail)
		m.SetHeader("Cc", syncJob.conf.Smtp.Cc)
		m.SetHeader("Subject", fmt.Sprintf("Attivazione dell'utenza %s per l'accesso ai servizi informatici del Liceo \"Carducci-Dante\" di Trieste", teacher.CompleteName()))
		m.SetBody("text/plain", buf.String())

		d := gomail.NewDialer(syncJob.conf.Smtp.Host, syncJob.conf.Smtp.Port, syncJob.conf.Smtp.Username, syncJob.conf.Smtp.Password)
		d.TLSConfig = &tls.Config{InsecureSkipVerify: true}

		if err := d.DialAndSend(m); err != nil {
			return err
		}
	} else {
		log.Printf("Credentials would be sent to %s, new password is %s", teacher.AltEmail, teacher.PlainPassword)
	}

	return nil
}

func (syncJob *SyncJob) syncTeachers(ldapClient *karmen_ldap.Client, karmenClient *karmen_client.Client, entries []*ldap.Entry, teachers []*orm.Teacher) error {

	mailTpl, err := tpl_util.LoadTextTemplate("cron/sync/mail.tpl")
	if err != nil {
		log.Println(err)
	}

	actions := slicediff.Diff(TeachersDsts(entries), TeachersSrcs(teachers))

	toBeAdded := make([]*orm.Teacher, 0)
	toBeRemoved := make([]string, 0)
	toBeUpdated := make([]*orm.Teacher, 0)

	for _, a := range actions {
		switch a.Type {
		case slicediff.Remove:
			toBeRemoved = append(toBeRemoved, entries[a.Id].DN)

		case slicediff.Add:
			teacher := teachers[a.Id]
			if !teacher.Exclude {
				toBeAdded = append(toBeAdded, teacher)
			}

		case slicediff.Update:
			teacher := teachers[a.Id]
			if !teacher.Exclude && teacher.Regenerate {
				toBeUpdated = append(toBeUpdated, teacher)
			}

		}
	}

	// Add

	if !syncJob.conf.Sync.SafeRun {
		log.Printf("ADDING %d users", len(toBeAdded))
		for _, teacher := range toBeAdded {
			password, err := password.Generate(8, 2, 0, false, true)
			if err != nil {
				return err
			}

			teacher.PlainPassword = password

			err = ldapClient.AddTeacher(teacher)
			if err != nil {
				return err
			}

			log.Printf("ADD teacher %s", teacher.CompleteName())

			if teacher.Regenerate {
				err = syncJob.sendMail(teacher, mailTpl)
				if err != nil {
					return err
				}

				teacher.Regenerate = false

				err = karmenClient.UpdateTeacher(teacher)
				if err != nil {
					return err
				}

			}

		}
	} else {
		if len(toBeAdded) == 0 {
			log.Println("No users WOULD BE added.")
		} else {
			log.Printf("%d users WOULD BE added...", len(toBeAdded))
			for _, teacher := range toBeAdded {
				log.Println(teacher.CompleteName())
				if teacher.Regenerate {
					password, err := password.Generate(8, 2, 0, false, true)
					if err != nil {
						return err
					}

					teacher.PlainPassword = password
					err = syncJob.sendMail(teacher, mailTpl)
					if err != nil {
						return err
					}
				}

			}
		}
	}

	// Remove

	if !syncJob.conf.Sync.SafeRun {
		if len(toBeRemoved) > 0 {
			log.Printf("%d will be REMOVED...", len(toBeRemoved))
		}
		for _, entry := range toBeRemoved {
			err := ldapClient.DeleteByDN(entry)
			if err != nil {
				return err
			}
			log.Printf("REMOVE %s", entry)
		}
	} else {
		if len(toBeRemoved) > 0 {
			log.Printf("%d users WOULD BE removed", len(toBeRemoved))
		}
		for _, entry := range toBeRemoved {
			log.Println(entry)
		}
	}

	// Update

	if !syncJob.conf.Sync.SafeRun {
		if len(toBeUpdated) > 0 {
			log.Printf("UPDATING %d users", len(toBeUpdated))
		}
		for _, teacher := range toBeUpdated {
			if teacher.Regenerate {
				password, err := password.Generate(8, 2, 0, false, true)
				if err != nil {
					return err
				}

				teacher.PlainPassword = password
				err = syncJob.sendMail(teacher, mailTpl)
				if err != nil {
					return err
				}

				teacher.Regenerate = false

				err = karmenClient.UpdateTeacher(teacher)
				if err != nil {
					return err
				}
				err = ldapClient.UpdateTeacherPassword(teacher, teacher.PlainPassword)
				if err != nil {
					return err

				}
			}
		}

	} else {
		if len(toBeRemoved) > 0 {
			log.Printf("%d users WOULD BE updated...", len(toBeUpdated))
		}
		for _, teacher := range toBeUpdated {
			log.Println(teacher.CompleteName())
		}
	}

	return nil
}

func (syncJob *SyncJob) syncGroup(ldapClient *karmen_ldap.Client, groupDN string, teachers []*orm.Teacher) error {
	actions := make(map[string]*slicediff.Action)
	entries, err := ldapClient.GroupMembers(groupDN)
	if err != nil {
		return err
	}

	values := entries[0].Attributes[0].Values

	if strings.Contains(groupDN, "Mailing Lists") {
		actions = slicediff.Diff(TeachersGroupDsts(values), TeachersMLDsts(teachers))
	} else {
		actions = slicediff.Diff(TeachersGroupDsts(values), TeachersGroupSrcs(teachers))
	}

	toBeAdded := make([]*orm.Teacher, 0)
	toBeRemoved := make([]string, 0)

	for _, a := range actions {
		switch a.Type {
		case slicediff.Remove:
			toBeRemoved = append(toBeRemoved, values[a.Id])

		case slicediff.Add:
			teacher := teachers[a.Id]
			if !teacher.Exclude {
				toBeAdded = append(toBeAdded, teacher)
			}

		}
	}

	if !syncJob.conf.Sync.SafeRun {
		if len(toBeAdded) > 0 {
			log.Printf("ADDING %d teachers to %s group", len(toBeAdded), groupDN)
		}
		for _, teacher := range toBeAdded {
			log.Println(teacher.CompleteName())
			err = ldapClient.AddTeacherToGroup(teacher, groupDN)
			if err != nil {
				return err
			}
		}
	} else {
		if len(toBeAdded) > 0 {
			log.Printf("%d users WOULD BE ADDED to %s group", len(toBeAdded), groupDN)
		}
		for _, teacher := range toBeAdded {
			log.Println(teacher.CompleteName())
		}
	}

	if !syncJob.conf.Sync.SafeRun {
		if len(toBeRemoved) > 0 {
			log.Printf("REMOVING %d users from %s group...", len(toBeRemoved), groupDN)
		}
		for _, value := range toBeRemoved {
			log.Printf("REMOVE %s from %s group.", value, groupDN)
			ldapClient.RemoveTeacherFromGroupByMemberValue(value, groupDN)
		}
	} else {
		if len(toBeRemoved) > 0 {
			log.Printf("%d users WOULD BE REMOVED FROM %s group", len(toBeRemoved), groupDN)
		}
		for _, entry := range toBeRemoved {
			log.Println(entry)
		}
	}

	return nil
}

func (syncJob *SyncJob) Run() {
	if syncJob.conf.Sync.SafeRun {
		log.Println("Running in SAFE MODE...")
	}

	log.Printf("Connecting to karmen at %s...", syncJob.conf.Url)
	karmenClient, err := karmen_client.Dial(syncJob.conf.Url, syncJob.conf.Admin.Username, syncJob.conf.Admin.Password)
	if err != nil {
		log.Println(err)
	}

	teachers, err := karmenClient.GetTeachers()
	if err != nil {
		log.Println(err)
	}

	log.Printf("Connecting to LDAP at %s...", syncJob.conf.Ldap.Host)
	ldapClient, err := karmen_ldap.NewClient(syncJob.conf.Ldap.Host, syncJob.conf)
	if err != nil {
		log.Println(err)
	}

	log.Println("Retrieving teachers from LDAP...")
	entries, err := ldapClient.Teachers()
	if err != nil {
		log.Println(err)
	}

	log.Println("Retrieving Departments...")
	departments, err := karmenClient.GetDepartments()
	if err != nil {
		log.Println(err)
	}

	log.Println("Sync teachers...")
	if err := syncJob.syncTeachers(ldapClient, karmenClient, entries, teachers); err != nil {
		panic(err)
	}

	log.Println("Sync 'Docenti' group...")
	if err := syncJob.syncGroup(ldapClient, "cn=Docenti", teachers); err != nil {
		panic(err)
	}

	log.Println("Sync 'Tutti i docenti' ML...")
	if err := syncJob.syncGroup(ldapClient, "cn=Tutti i docenti,ou=Mailing Lists", teachers); err != nil {
		panic(err)
	}

	log.Println("Sync Departments and MLs...")
	for _, department := range departments {
		group := fmt.Sprintf("cn=%s,ou=Mailing Lists", department.Name)
		err = syncJob.syncGroup(ldapClient, group, department.Teachers)
		if err != nil {
			panic(err)
		}
		group = fmt.Sprintf("cn=%s,ou=Dipartimenti", department.Name)
		err = syncJob.syncGroup(ldapClient, group, department.Teachers)
		if err != nil {
			panic(err)
		}

	}
}