/*
Copyright 2017-2022 CAcert Inc.
SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/julienschmidt/httprouter"

	"git.cacert.org/cacert-boardvoting/internal/forms"

	"git.cacert.org/cacert-boardvoting/internal/models"
)

func checkRole(v *models.User, roles ...models.RoleName) (bool, error) {
	hasRole, err := v.HasRole(roles...)
	if err != nil {
		return false, fmt.Errorf("could not determine user roles: %w", err)
	}

	return hasRole, nil
}

type topLevelNavItem string
type subLevelNavItem string

const (
	topLevelNavMotions topLevelNavItem = "motions"
	topLevelNavUsers   topLevelNavItem = "users"

	subLevelNavMotionsAll     subLevelNavItem = "all-motions"
	subLevelNavMotionsUnvoted subLevelNavItem = "unvoted-motions"
	subLevelNavUsers          subLevelNavItem = "users"
)

func (m *templateData) motionPaginationOptions(limit int, first, last *time.Time) error {
	motions := m.Motions

	if len(motions) == limit && first.Before(motions[len(motions)-1].Proposed) {
		marshalled, err := motions[len(motions)-1].Proposed.MarshalText()
		if err != nil {
			return fmt.Errorf("could not serialize timestamp: %w", err)
		}

		m.NextPage = string(marshalled)
	}

	if len(motions) > 0 && last.After(motions[0].Proposed) {
		marshalled, err := motions[0].Proposed.MarshalText()
		if err != nil {
			return fmt.Errorf("could not serialize timestamp: %w", err)
		}

		m.PrevPage = string(marshalled)
	}

	return nil
}

func (app *application) motionList(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/motions/" {
		app.notFound(w)

		return
	}

	var (
		listOptions *models.MotionListOptions
		err         error
	)

	listOptions, err = app.calculateMotionListOptions(r)
	if err != nil {
		app.clientError(w, http.StatusBadRequest)

		return
	}

	ctx := r.Context()

	motions, err := app.motions.List(ctx, listOptions)
	if err != nil {
		app.serverError(w, err)

		return
	}

	first, last, err := app.motions.TimestampRange(ctx, listOptions)
	if err != nil {
		app.serverError(w, err)

		return
	}

	templateData := app.newTemplateData(r, "motions", "all-motions")

	if listOptions.UnvotedOnly {
		templateData.ActiveSubNav = subLevelNavMotionsUnvoted
	}

	templateData.Motions = motions

	err = templateData.motionPaginationOptions(listOptions.Limit, first, last)
	if err != nil {
		app.serverError(w, err)

		return
	}

	app.render(w, http.StatusOK, "motions.html", templateData)
}

func (app *application) calculateMotionListOptions(r *http.Request) (*models.MotionListOptions, error) {
	const (
		queryParamBefore  = "before"
		queryParamAfter   = "after"
		queryParamUnvoted = "unvoted"
		motionsPerPage    = 10
	)

	listOptions := &models.MotionListOptions{Limit: motionsPerPage}

	if r.URL.Query().Has(queryParamAfter) {
		var after time.Time

		err := after.UnmarshalText([]byte(r.URL.Query().Get(queryParamAfter)))
		if err != nil {
			return nil, fmt.Errorf("could not unmarshal timestamp: %w", err)
		}

		listOptions.After = &after
	} else if r.URL.Query().Has(queryParamBefore) {
		var before time.Time

		err := before.UnmarshalText([]byte(r.URL.Query().Get(queryParamBefore)))
		if err != nil {
			return nil, fmt.Errorf("could not unmarshal timestamp: %w", err)
		}

		listOptions.Before = &before
	}

	if r.URL.Query().Has(queryParamUnvoted) {
		listOptions.UnvotedOnly = true

		voter, err := app.GetUser(r)
		if err != nil {
			return nil, fmt.Errorf("could not get voter: %w", err)
		}

		if voter != nil {
			listOptions.VoterID = voter.ID
		}
	}

	return listOptions, nil
}

func (app *application) motionDetails(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		return
	}

	data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)

	data.Motion = motion

	app.render(w, http.StatusOK, "motion.html", data)
}

func (app *application) newMotionForm(w http.ResponseWriter, r *http.Request) {
	data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)
	data.Form = &forms.EditMotionForm{
		Type: models.VoteTypeMotion,
	}

	app.render(w, http.StatusOK, "create_motion.html", data)
}

const hoursInDay = 24

func (app *application) newMotionSubmit(w http.ResponseWriter, r *http.Request) {
	var form forms.EditMotionForm

	err := app.decodePostForm(r, &form)
	if err != nil {
		app.clientError(w, http.StatusBadRequest)

		return
	}

	form.Validate()

	if !form.Valid() {
		data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)
		data.Form = form

		app.render(w, http.StatusUnprocessableEntity, "create_motion.html", data)

		return
	}

	user, err := app.GetUser(r)
	if err != nil {
		app.clientError(w, http.StatusUnauthorized)

		return
	}

	now := time.Now().UTC()
	dueDuration := time.Duration(form.Due) * hoursInDay * time.Hour

	decisionID, err := app.motions.Create(
		r.Context(),
		user,
		form.Type,
		form.Title,
		form.Content,
		now,
		now.Add(dueDuration),
	)
	if err != nil {
		app.serverError(w, err)

		return
	}

	decision, err := app.motions.ByID(r.Context(), decisionID)
	if err != nil {
		app.serverError(w, err)

		return
	}

	app.mailNotifier.Notify(&NewDecisionNotification{
		Decision: decision,
		Proposer: user,
	})

	app.jobScheduler.Reschedule(JobIDCloseDecisions, JobIDRemindVoters)

	app.addFlash(r, &FlashMessage{
		Variant: flashSuccess,
		Title:   "New motion started",
		Message: fmt.Sprintf("Started new motion %s: %s", decision.Tag, decision.Title),
	})

	http.Redirect(w, r, "/motions/", http.StatusSeeOther)
}

func (app *application) editMotionForm(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		return
	}

	data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)

	data.Motion = motion

	data.Form = &forms.EditMotionForm{
		Title:   motion.Title,
		Content: motion.Content,
		Type:    motion.Type,
	}

	app.render(w, http.StatusOK, "edit_motion.html", data)
}

func (app *application) editMotionSubmit(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		return
	}

	var form forms.EditMotionForm

	err := app.decodePostForm(r, &form)
	if err != nil {
		app.clientError(w, http.StatusBadRequest)

		return
	}

	form.Validate()

	if !form.Valid() {
		data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)
		data.Form = form

		app.render(w, http.StatusUnprocessableEntity, "edit_motion.html", data)

		return
	}

	form.Normalize()

	user, err := app.GetUser(r)
	if err != nil {
		app.clientError(w, http.StatusUnauthorized)

		return
	}

	now := time.Now().UTC()
	dueDuration := time.Duration(form.Due) * hoursInDay * time.Hour

	err = app.motions.Update(
		r.Context(),
		motion.ID,
		func(m *models.Motion) {
			m.Type = form.Type
			m.Title = strings.TrimSpace(form.Title)
			m.Content = strings.TrimSpace(form.Content)
			m.Due = now.Add(dueDuration)
		},
	)
	if err != nil {
		app.serverError(w, err)

		return
	}

	decision, err := app.motions.ByID(r.Context(), motion.ID)
	if err != nil {
		app.serverError(w, err)

		return
	}

	app.mailNotifier.Notify(&UpdateDecisionNotification{
		Decision: decision,
		User:     user,
	})

	app.jobScheduler.Reschedule(JobIDCloseDecisions, JobIDRemindVoters)

	app.addFlash(r, &FlashMessage{
		Variant: flashInfo,
		Title:   "Motion modified",
		Message: fmt.Sprintf("The motion %s has been modified!", decision.Tag),
	})

	http.Redirect(w, r, "/motions/", http.StatusSeeOther)
}

func (app *application) withdrawMotionForm(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		app.notFound(w)

		return
	}

	data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)

	data.Motion = motion

	app.render(w, http.StatusOK, "withdraw_motion.html", data)
}

func (app *application) withdrawMotionSubmit(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		app.notFound(w)

		return
	}

	user, err := app.GetUser(r)
	if err != nil {
		app.clientError(w, http.StatusUnauthorized)

		return
	}

	err = app.motions.Withdraw(r.Context(), motion.ID)

	if err != nil {
		app.serverError(w, err)

		return
	}

	app.mailNotifier.Notify(&WithDrawMotionNotification{motion, user})

	app.jobScheduler.Reschedule(JobIDCloseDecisions, JobIDRemindVoters)

	app.addFlash(r, &FlashMessage{
		Variant: flashWarning,
		Title:   "Motion withdrawn",
		Message: fmt.Sprintf("The motion %s has been withdrawn!", motion.Tag),
	})

	http.Redirect(w, r, "/motions/", http.StatusSeeOther)
}

func (app *application) voteForm(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		app.notFound(w)

		return
	}

	choice := app.choiceFromRequestParam(w, params)
	if choice == nil {
		app.notFound(w)

		return
	}

	data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)

	data.Motion = motion

	data.Form = &forms.DirectVoteForm{
		Choice: choice,
	}

	app.render(w, http.StatusOK, "direct_vote.html", data)
}

func (app *application) voteSubmit(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		return
	}

	choice := app.choiceFromRequestParam(w, params)
	if choice == nil {
		return
	}

	user, err := app.GetUser(r)
	if err != nil {
		app.clientError(w, http.StatusUnauthorized)

		return
	}

	clientCert, err := getPEMClientCert(r)
	if err != nil {
		app.serverError(w, err)

		return
	}

	if err := app.motions.UpdateVote(r.Context(), user.ID, motion.ID, func(v *models.Vote) {
		v.Vote = choice
		v.Voted = time.Now().UTC()
		v.Notes = fmt.Sprintf("Direct Vote\n\n%s", clientCert)
	}); err != nil {
		app.serverError(w, err)

		return
	}

	app.mailNotifier.Notify(&DirectVoteNotification{
		Decision: motion, User: user, Choice: choice,
	})

	app.addFlash(r, &FlashMessage{
		Variant: flashSuccess,
		Title:   "Vote registered",
		Message: fmt.Sprintf("Your vote for motion %s has been registered.", motion.Tag),
	})

	http.Redirect(w, r, "/motions/", http.StatusSeeOther)
}

func (app *application) proxyVoteForm(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		return
	}

	data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)

	data.Motion = motion

	potentialVoters, err := app.users.Voters(r.Context())
	if err != nil {
		app.serverError(w, err)

		return
	}

	data.Form = &forms.ProxyVoteForm{
		Voters: potentialVoters,
	}

	app.render(w, http.StatusOK, "proxy_vote.html", data)
}

func (app *application) proxyVoteSubmit(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	motion := app.motionFromRequestParam(w, r, params)
	if motion == nil {
		return
	}

	var form forms.ProxyVoteForm

	err := app.decodePostForm(r, &form)
	if err != nil {
		app.clientError(w, http.StatusBadRequest)

		return
	}

	form.Validate()

	if !form.Valid() {
		data := app.newTemplateData(r, topLevelNavMotions, subLevelNavMotionsAll)
		data.Motion = motion

		potentialVoters, err := app.users.Voters(r.Context())
		if err != nil {
			app.serverError(w, err)

			return
		}

		form.Voters = potentialVoters
		data.Form = form

		app.render(w, http.StatusUnprocessableEntity, "proxy_vote.html", data)

		return
	}

	form.Normalize()

	user, err := app.GetUser(r)
	if err != nil {
		app.clientError(w, http.StatusUnauthorized)

		return
	}

	clientCert, err := getPEMClientCert(r)
	if err != nil {
		app.serverError(w, err)

		return
	}

	voter := app.getVoter(w, r, form.Voter.ID)
	if voter == nil {
		return
	}

	if err := app.motions.UpdateVote(r.Context(), form.Voter.ID, motion.ID, func(v *models.Vote) {
		v.Vote = form.Choice
		v.Voted = time.Now().UTC()
		v.Notes = fmt.Sprintf("Proxy-Vote by %s\n\n%s\n\n%s", user.Name, form.Justification, clientCert)
	}); err != nil {
		app.serverError(w, err)

		return
	}

	app.mailNotifier.Notify(&ProxyVoteNotification{
		Decision: motion, User: user, Voter: voter, Choice: form.Choice, Justification: form.Justification,
	})

	app.addFlash(r, &FlashMessage{
		Variant: flashSuccess,
		Title:   "Proxy vote registered",
		Message: fmt.Sprintf(
			"Your proxy vote for %s for motion %s has been registered.",
			voter.Name,
			motion.Tag,
		),
	})

	http.Redirect(w, r, "/motions/", http.StatusSeeOther)
}

func (app *application) userList(w http.ResponseWriter, r *http.Request) {
	data := app.newTemplateData(r, topLevelNavUsers, subLevelNavUsers)

	users, err := app.users.List(
		r.Context(),
		app.users.WithRoles(),
		app.users.CanDelete(),
	)
	if err != nil {
		app.serverError(w, err)

		return
	}

	data.Users = users

	app.render(w, http.StatusOK, "users.html", data)
}

func (app *application) editUserForm(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	userToEdit := app.userFromRequestParam(w, r, params, app.users.WithRoles(), app.users.WithEmailAddresses())
	if userToEdit == nil {
		return
	}

	roles, err := userToEdit.Roles()
	if err != nil {
		app.serverError(w, err)

		return
	}

	emailAddresses, err := userToEdit.EmailAddresses()
	if err != nil {
		app.serverError(w, err)

		return
	}

	roleNames := make([]string, len(roles))
	for i := range roles {
		roleNames[i] = roles[i].Name
	}

	data := app.newTemplateData(r, topLevelNavUsers, subLevelNavUsers)

	data.Form = &forms.EditUserForm{
		User:          userToEdit,
		Name:          userToEdit.Name,
		MailAddresses: emailAddresses,
		AllRoles:      models.AllRoles,
		ReminderMail:  userToEdit.Reminder.String,
		Roles:         roleNames,
	}

	app.render(w, http.StatusOK, "edit_user.html", data)
}

func (app *application) editUserSubmit(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	userToEdit := app.userFromRequestParam(w, r, params, app.users.WithRoles(), app.users.WithEmailAddresses())
	if userToEdit == nil {
		app.notFound(w)

		return
	}

	var form forms.EditUserForm

	if err := app.decodePostForm(r, &form); err != nil {
		app.clientError(w, http.StatusBadRequest)

		return
	}

	form.User = userToEdit
	form.AllRoles = models.AllRoles

	if err := form.Validate(); err != nil {
		app.serverError(w, err)

		return
	}

	data := app.newTemplateData(r, topLevelNavUsers, subLevelNavUsers)

	if !form.Valid() {
		roles, err := userToEdit.Roles()
		if err != nil {
			app.serverError(w, err)

			return
		}

		emailAddresses, err := userToEdit.EmailAddresses()
		if err != nil {
			app.serverError(w, err)

			return
		}

		roleNames := make([]string, len(roles))
		for i := range roles {
			roleNames[i] = roles[i].Name
		}

		form.MailAddresses = emailAddresses
		form.Roles = roleNames

		data.Form = &form

		app.render(w, http.StatusUnprocessableEntity, "edit_user.html", data)

		return
	}

	form.Normalize()
	form.UpdateUser(userToEdit)

	if err := app.users.EditUser(r.Context(), userToEdit, data.User, form.Roles, form.Reasoning); err != nil {
		app.serverError(w, err)

		return
	}

	app.addFlash(r, &FlashMessage{
		Variant: flashInfo,
		Title:   "User modified",
		Message: fmt.Sprintf("User %s has been modified.", userToEdit.Name),
	})

	http.Redirect(w, r, "/users/", http.StatusSeeOther)
}

func (app *application) userAddEmailForm(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	userToEdit := app.userFromRequestParam(w, r, params, app.users.WithEmailAddresses())
	if userToEdit == nil {
		app.notFound(w)

		return
	}

	emailAddresses, err := userToEdit.EmailAddresses()
	if err != nil {
		app.serverError(w, err)

		return
	}

	data := app.newTemplateData(r, topLevelNavUsers, subLevelNavUsers)

	data.Form = &forms.AddEmailForm{
		User:           userToEdit,
		EmailAddresses: emailAddresses,
	}

	app.render(w, http.StatusOK, "add_email.html", data)
}

func (app *application) userAddEmailSubmit(w http.ResponseWriter, r *http.Request) {
	params := httprouter.ParamsFromContext(r.Context())

	userToEdit := app.userFromRequestParam(w, r, params, app.users.WithEmailAddresses())
	if userToEdit == nil {
		app.notFound(w)

		return
	}

	var form forms.AddEmailForm

	if err := app.decodePostForm(r, &form); err != nil {
		app.clientError(w, http.StatusBadRequest)

		return
	}

	form.User = userToEdit

	form.Validate()

	data := app.newTemplateData(r, topLevelNavUsers, subLevelNavUsers)

	if form.Valid() {
		emailExists, err := app.users.EmailExists(r.Context(), form.EmailAddress)
		if err != nil {
			app.serverError(w, err)

			return
		}

		if emailExists {
			form.FieldErrors = map[string]string{
				"email_address": "Email address must be unique",
			}
		}
	}

	if !form.Valid() {
		emailAddresses, err := userToEdit.EmailAddresses()
		if err != nil {
			app.serverError(w, err)

			return
		}

		form.EmailAddresses = emailAddresses

		data.Form = &form

		app.render(w, http.StatusUnprocessableEntity, "add_email.html", data)

		return
	}

	form.Normalize()

	if err := app.users.AddEmail(r.Context(), userToEdit, data.User, form.EmailAddress, form.Reasoning); err != nil {
		app.serverError(w, err)

		return
	}

	app.addFlash(r, &FlashMessage{
		Variant: flashSuccess,
		Title:   "Email address added",
		Message: fmt.Sprintf(
			"Added email address %s for user %s",
			form.EmailAddress,
			userToEdit.Name,
		),
	})

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

func (app *application) userDeleteEmailForm(_ http.ResponseWriter, _ *http.Request) {
	// TODO: implement userDeleteEmailForm
	panic("not implemented")
}

func (app *application) userDeleteEmailSubmit(_ http.ResponseWriter, _ *http.Request) {
	// TODO: implement userDeleteEmailSubmit
	panic("not implemented")
}

func (app *application) newUserForm(_ http.ResponseWriter, _ *http.Request) {
	// TODO: implement newUserForm
	panic("not implemented")
}

func (app *application) newUserSubmit(_ http.ResponseWriter, _ *http.Request) {
	// TODO: implement newUserSubmit
	panic("not implemented")
}

func (app *application) deleteUserForm(w http.ResponseWriter, r *http.Request) {
	userToDelete := app.userFromRequestParam(w, r, httprouter.ParamsFromContext(r.Context()), app.users.CanDelete())
	if userToDelete == nil {
		return
	}

	if !userToDelete.CanDelete() {
		app.notFound(w)

		return
	}

	data := app.newTemplateData(r, topLevelNavUsers, subLevelNavUsers)

	data.Form = &forms.DeleteUserForm{
		User: userToDelete,
	}

	app.render(w, http.StatusOK, "delete_user.html", data)
}

func (app *application) deleteUserSubmit(w http.ResponseWriter, r *http.Request) {
	userToDelete := app.userFromRequestParam(w, r, httprouter.ParamsFromContext(r.Context()), app.users.CanDelete())
	if userToDelete == nil {
		return
	}

	if !userToDelete.CanDelete() {
		app.notFound(w)

		return
	}

	var form forms.DeleteUserForm

	err := app.decodePostForm(r, &form)
	if err != nil {
		app.clientError(w, http.StatusBadRequest)

		return
	}

	form.User = userToDelete

	form.Validate()

	data := app.newTemplateData(r, topLevelNavUsers, subLevelNavUsers)

	if !form.Valid() {
		data.Form = &form

		app.render(w, http.StatusUnprocessableEntity, "delete_user.html", data)

		return
	}

	form.Normalize()

	if err = app.users.DeleteUser(r.Context(), userToDelete, data.User, form.Reasoning); err != nil {
		app.serverError(w, err)

		return
	}

	app.addFlash(r, &FlashMessage{
		Variant: flashWarning,
		Title:   "User deleted",
		Message: fmt.Sprintf("User %s has been deleted.", userToDelete.Name),
	})

	http.Redirect(w, r, "/users/", http.StatusSeeOther)
}

func (app *application) healthCheck(w http.ResponseWriter, _ *http.Request) {
	const (
		ok     = "OK"
		failed = "FAILED"
	)

	response := struct {
		DB   string `json:"database"`
		Mail string `json:"mail"`
	}{DB: ok, Mail: ok}

	enc := json.NewEncoder(w)

	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Refresh", "10")
	w.Header().Add("Cache-Control", "no-store")

	var (
		err       error
		hasErrors = false
	)

	if err = app.mailNotifier.Ping(); err != nil {
		hasErrors = true

		response.Mail = failed
	}

	if err = app.motions.DB.Ping(); err != nil {
		hasErrors = true

		response.DB = failed
	}

	if hasErrors {
		w.WriteHeader(http.StatusInternalServerError)
	} else {
		w.WriteHeader(http.StatusOK)
	}

	_ = enc.Encode(response)
}