package api

import (
	"encoding/json"
	"fmt"
	"html/template"
	"io/ioutil"
	"net/http"
	"sort"
	"strings"

	"github.com/gorilla/mux"
	"github.com/gorilla/schema"
	"gogs.carducci-dante.gov.it/karmen/core/orm"
	"gogs.carducci-dante.gov.it/karmen/core/renderer"
	"gogs.carducci-dante.gov.it/karmen/datasource/edt"
)

var (
	selectUniqueTeacherClasses = `
SELECT DISTINCT classes.* FROM activities 
INNER JOIN classes on classes.id=activities.class_id 
WHERE teacher_id=?`

	selectUniqueTeacherSubjects = `
SELECT DISTINCT subjects.* FROM activities 
INNER JOIN subjects on subjects.id=activities.subject_id 
WHERE activities.teacher_id=?`
)

func teachersHandler() http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		var teachers []*orm.Teacher
		if err := orm.DB().Find(&teachers).Error; err != nil {
			panic(err)
		}
		for _, teacher := range teachers {
			orm.DB().Raw(selectUniqueTeacherClasses, teacher.ID).Scan(&teacher.Classes)
			orm.DB().Raw(selectUniqueTeacherSubjects, teacher.ID).Scan(&teacher.Subjects)
		}
		sort.Slice(teachers, func(i, j int) bool {
			return strings.ToLower(teachers[i].Surname) < strings.ToLower(teachers[j].Surname)
		})
		if err := renderer.Render(w, "base", "teachers", teachers); err != nil {
			panic(err)
		}
	}
	return http.HandlerFunc(fn)
}

func teacherShowHandler() http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		var teacher orm.Teacher

		if err := orm.DB().First(&teacher, mux.Vars(r)["id"]).Error; err != nil {
			panic(err)
		}

		orm.DB().Raw(selectUniqueTeacherClasses, mux.Vars(r)["id"]).Scan(&teacher.Classes)

		sort.Slice(teacher.Classes, func(i, j int) bool {
			return strings.ToLower(teacher.Classes[i].Name) < strings.ToLower(teacher.Classes[j].Name)
		})

		orm.DB().Raw(selectUniqueTeacherSubjects, mux.Vars(r)["id"]).Scan(&teacher.Subjects)

		sort.Slice(teacher.Subjects, func(i, j int) bool {
			return strings.ToLower(teacher.Subjects[i].Name) < strings.ToLower(teacher.Subjects[j].Name)
		})

		orm.DB().Table("activities").Select("*").Where("teacher_id = ?", mux.Vars(r)["id"]).Scan(&teacher.Activities)

		sort.Slice(teacher.Activities, func(i, j int) bool {
			return teacher.Activities[i].Hours < teacher.Activities[j].Hours
		})

		if err := renderer.Render(w, "base", "teachers_show", teacher); err != nil {
			panic(err)
		}
	}
	return http.HandlerFunc(fn)
}

func teachersAddHandler() http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		if r.Method == "GET" {
			var data struct {
				Update    bool
				SubmitUrl template.URL
			}
			data.SubmitUrl = template.URL(fmt.Sprintf("/teachers/add"))
			if err := renderer.Render(w, "base", "teachers_add_update", data); err != nil {
				panic(err)
			}
		} else if r.Method == "POST" {
			var teacher orm.Teacher
			if err := r.ParseForm(); err != nil {
				panic(err)
			}

			decoder := schema.NewDecoder()
			if err := decoder.Decode(&teacher, r.PostForm); err != nil {
				panic(err)
			}

			// Generate username and initial password

			teacher.Username = teacher.GenerateUsername()
			teacher.Password = teacher.GenerateSaltedPassword(teacher.Username)

			orm.DB().NewRecord(teacher)

			if err := orm.DB().Create(&teacher).Error; err != nil {
				panic(err)
			}

			http.Redirect(w, r, fmt.Sprintf("/teachers/%d", teacher.ID), http.StatusSeeOther)
		}

	}
	return http.HandlerFunc(fn)
}

func teachersDeleteHandler() http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		var teacher orm.Teacher
		if err := orm.DB().First(&teacher, mux.Vars(r)["id"]).Error; err != nil {
			panic(err)
		}

		if err := orm.DB().Delete(&teacher).Error; err != nil {
			panic(err)
		}

		var data struct {
			RedirectUrl string `json:"redirect_url"`
		}

		data.RedirectUrl = "/teachers"

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(data)
	}
	return http.HandlerFunc(fn)
}

func teacherUpdateHandler() http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		if r.Method == "GET" {
			var data struct {
				Update    bool
				SubmitUrl template.URL
				Teacher   orm.Teacher
			}

			if err := orm.DB().First(&data.Teacher, mux.Vars(r)["id"]).Error; err != nil {
				panic(err)
			}
			data.Update = true
			data.SubmitUrl = template.URL(fmt.Sprintf("/teachers/%d/update", data.Teacher.ID))
			if err := renderer.Render(w, "base", "teachers_add_update", data); err != nil {
				panic(err)
			}
		} else if r.Method == "POST" {
			var (
				teacher     orm.Teacher
				oldPassword string
			)
			if err := orm.DB().First(&teacher, mux.Vars(r)["id"]).Error; err != nil {
				panic(err)
			}

			oldPassword = teacher.Password

			if err := r.ParseForm(); err != nil {
				panic(err)
			}

			decoder := schema.NewDecoder()
			if err := decoder.Decode(&teacher, r.PostForm); err != nil {
				panic(err)
			}

			if oldPassword != teacher.Password {
				teacher.Password = teacher.GenerateSaltedPassword(teacher.Password)
			}

			if err := orm.DB().Save(&teacher).Error; err != nil {
				panic(err)
			}

			var data struct {
				Teachers []orm.Teacher
			}

			data.Teachers = make([]orm.Teacher, 0)
			if err := orm.DB().Find(&data.Teachers).Error; err != nil {
				panic(err)
			}

			http.Redirect(w, r, fmt.Sprintf("/teachers/%d", teacher.ID), http.StatusSeeOther)
		}

	}
	return http.HandlerFunc(fn)
}

func teachersCheckUsernameHandler() http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		var teacher orm.Teacher
		var data struct {
			Exists bool `json:"exists"`
		}

		if orm.DB().Where("username = ?", mux.Vars(r)["username"]).Find(&teacher).RecordNotFound() {
			data.Exists = false
		} else {
			data.Exists = true
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(data)

	}
	return http.HandlerFunc(fn)
}

func teachersImportHandler() http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		r.ParseMultipartForm(32 << 20)
		file, _, err := r.FormFile("teachers_import")
		if err != nil {
			panic(err)
		}
		defer file.Close()
		data, err := ioutil.ReadAll(file)
		if err != nil {
			panic(err)
		}
		if importer, err := edt.NewImporter(
			string(data),
			map[string]string{
				"COGNOME": "surname",
				"NOME":    "name",
			},
		); err != nil {
			panic(err)
		} else {
			if err := orm.Import(&orm.Teacher{}, importer); err != nil {
				panic(err)
			}
			http.Redirect(w, r, "/teachers", http.StatusSeeOther)
		}
	}
	return http.HandlerFunc(fn)
}