package gonexapp

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
)

// Groups reads Users and Groups from Provisioning OCS.
type Groups struct {
	Cred   Credentials
	Client *http.Client
	OCS    OCSClient
}

// NewGroups returns a directory reader using cred for AppAPI auth.
func NewGroups(cred Credentials) Groups {
	return Groups{
		Cred: cred,
		OCS:  OCSClient{Cred: cred},
	}
}

func (g Groups) ocsClient() OCSClient {
	c := g.OCS
	if c.Cred.BaseURL == "" {
		c.Cred = g.Cred
	}
	if c.Client == nil {
		c.Client = g.Client
	}
	return c
}

// UserGroups returns the Nextcloud group ids of userID, calling OCS as that user.
func (g Groups) UserGroups(userID string) ([]string, error) {
	ocs := g.ocsClient()
	ocs.Cred = ocs.Cred.WithUser(userID)
	path := "cloud/users/" + url.PathEscape(userID) + "/groups"
	raw, err := ocs.Call(http.MethodGet, path, nil)
	if err != nil {
		return nil, err
	}
	return decodeUserGroups(raw)
}

// GroupMembers returns the user ids in groupID, calling OCS as the Requesting user.
func (g Groups) GroupMembers(groupID string) ([]string, error) {
	ocs := g.ocsClient()
	path := "cloud/groups/" + url.PathEscape(groupID)
	raw, err := ocs.Call(http.MethodGet, path, nil)
	if err != nil {
		return nil, err
	}
	return decodeGroupMembers(raw)
}

func decodeGroupMembers(raw []byte) ([]string, error) {
	var parsed struct {
		OCS struct {
			Data struct {
				Users []string `json:"users"`
			} `json:"data"`
		} `json:"ocs"`
	}
	if err := json.Unmarshal(raw, &parsed); err != nil {
		return nil, fmt.Errorf("group members decode: %w", err)
	}
	return parsed.OCS.Data.Users, nil
}

// ListGroups returns instance group ids, calling OCS as the Requesting user.
func (g Groups) ListGroups() ([]string, error) {
	ocs := g.ocsClient()
	raw, err := ocs.Call(http.MethodGet, "cloud/groups", nil)
	if err != nil {
		return nil, err
	}
	return decodeUserGroups(raw)
}

func decodeUserGroups(raw []byte) ([]string, error) {
	var parsed struct {
		OCS struct {
			Data struct {
				Groups []string `json:"groups"`
			} `json:"data"`
		} `json:"ocs"`
	}
	if err := json.Unmarshal(raw, &parsed); err != nil {
		return nil, fmt.Errorf("user groups decode: %w", err)
	}
	return parsed.OCS.Data.Groups, nil
}