package routing

import (
	"encoding/json"
	"net/http"
	"slices"

	"lishwist/db"
	"lishwist/error"
	"lishwist/templates"
)

type GroupProps struct {
	Group           *db.Group
	CurrentUsername string
}

func (ctx *Context) GroupPage(currentUser *db.User, w http.ResponseWriter, r *http.Request) {
	groupReference := r.PathValue("groupReference")
	group, err := currentUser.GetGroupByReference(groupReference)
	if err != nil {
		error.Page(w, "An error occurred while fetching this group :(", http.StatusInternalServerError, err)
		return
	}
	if group == nil {
		error.Page(w, "Group not found. (It might be because you're not a member)", http.StatusNotFound, nil)
		return
	}
	index := group.MemberIndex(currentUser.Id)
	group.Members = slices.Delete(group.Members, index, index+1)
	p := GroupProps{
		Group:           group,
		CurrentUsername: currentUser.Name,
	}
	templates.Execute(w, "group_page.gotmpl", p)
}

func (ctx *Context) PublicGroupPage(w http.ResponseWriter, r *http.Request) {
	groupReference := r.PathValue("groupReference")
	group, err := db.GetGroupByReference(groupReference)
	if err != nil {
		error.Page(w, "An error occurred while fetching this group :(", http.StatusInternalServerError, err)
		return
	}
	p := GroupProps{
		Group: group,
	}
	templates.Execute(w, "public_group_page.gotmpl", p)
}

func (ctx *Context) GroupPost(currentUser *db.User, w http.ResponseWriter, r *http.Request) {
	if !currentUser.IsAdmin {
		NotFoundJson(w, r)
		return
	}
	if err := r.ParseForm(); err != nil {
		writeGeneralErrorJson(w, http.StatusBadRequest, "Failed to parse form: "+err.Error())
		return
	}

	var group *db.Group

	reference := r.PathValue("groupReference")
	name := r.Form.Get("name")
	addUsers := r.Form["addUser"]
	removeUsers := r.Form["removeUser"]

	if name != "" {
		createdGroup, err := db.CreateGroup(name, reference)
		if err != nil {
			writeGeneralErrorJson(w, http.StatusBadRequest, "Failed to create group: "+err.Error())
			return
		}
		group = createdGroup
	} else {
		existingGroup, err := db.GetGroupByReference(reference)
		if err != nil {
			writeGeneralErrorJson(w, http.StatusBadRequest, "Failed to get group: "+err.Error())
			return
		}
		if existingGroup == nil {
			writeGeneralErrorJson(w, http.StatusNotFound, "Group not found")
			return
		}
		group = existingGroup

		for _, userId := range removeUsers {
			index := group.MemberIndex(userId)
			if index == -1 {
				writeGeneralErrorJson(w, http.StatusBadRequest, "Group %q does not contain a user with id %s", reference, userId)
				return
			}
			err = group.RemoveUser(userId)
			if err != nil {
				writeGeneralErrorJson(w, http.StatusBadRequest, "On group %q failed to remove user with id %s: %s", reference, userId, err)
				return
			}
			group.Members = slices.Delete(group.Members, index, index+1)
		}
	}

	for _, userId := range addUsers {
		user, err := db.GetUser(userId)
		if err != nil {
			writeGeneralErrorJson(w, http.StatusBadRequest, "Groups exists, but a user with id %s could not be fetched: %s", userId, err)
			return
		}
		if user == nil {
			writeGeneralErrorJson(w, http.StatusBadRequest, "Groups exists, but a user with id %s does not exist", userId)
			return
		}
		err = group.AddUser(user.Id)
		if err != nil {
			writeGeneralErrorJson(w, http.StatusBadRequest, "Groups exists, but failed to add user with id %s: %s", userId, err)
			return
		}
		group.Members = append(group.Members, *user)
	}

	_ = json.NewEncoder(w).Encode(group)
}

func (ctx *Context) GroupsJson(currentUser *db.User, w http.ResponseWriter, r *http.Request) {
	if !currentUser.IsAdmin {
		NotFoundJson(w, r)
		return
	}

	groups, err := db.GetAllGroups()
	if err != nil {
		writeGeneralErrorJson(w, http.StatusBadRequest, "Failed to get groups: "+err.Error())
		return
	}

	_ = json.NewEncoder(w).Encode(groups)
}

func (ctx *Context) Group(currentUser *db.User, w http.ResponseWriter, r *http.Request) {
	if !currentUser.IsAdmin {
		NotFoundJson(w, r)
		return
	}
	groupReference := r.PathValue("groupReference")
	group, err := db.GetGroupByReference(groupReference)
	if err != nil {
		writeGeneralErrorJson(w, http.StatusBadRequest, "Couldn't get group: %s", err)
		return
	}
	if group == nil {
		writeGeneralErrorJson(w, http.StatusNotFound, "Group not found.")
		return
	}

	_ = json.NewEncoder(w).Encode(group)
}