package web

import (
	"context"
	"errors"
	"strconv"
	"time"
)

const (
	AdminUsersPerPage       = 20
	AdminMembersPerPage     = 25
	AdminGroupsPerPage      = 25
	AdminInvitationsPerPage = 25
	AdminListBadges         = 5
	AdminDetailBadges       = 10
)

var ErrAdminNotFound = errors.New("web: no such user, group or invitation")

var (
	ErrAdminConfirmCode  = errors.New("web: the confirmation code does not match")
	ErrAdminConfirmSpent = errors.New("web: too many wrong confirmation codes")
)

type AdminPendingAccount struct {
	Username  string
	Spent     bool
	ExpiresAt time.Time
}

type AdminProblem int

const (
	AdminUsernameGrammar AdminProblem = iota + 1
	AdminUsernameTaken
	AdminDisplayNameInvalid
	AdminGroupNameGrammar
	AdminGroupNameTaken
	AdminDescriptionInvalid
	AdminUnknownUser
	AdminUnknownGroup
	AdminAlreadyMember
	AdminNotMember
	AdminPrimaryGroup
	AdminSelf
	AdminLastAdmin
	AdminReferencedGroup
	AdminInvitationClosed
	AdminGoogleNotLinked
	AdminResetLinkDisabled
	AdminResetLinkPending
	AdminLabelInvalid
	AdminExpiryInvalid
	AdminAdminGroupGrant
	AdminBatchSize
	AdminUserPending
	AdminUnknownBatch
	AdminSSHKeyDisabled
	AdminSSHKeyPending
)

var adminProblemNames = map[AdminProblem]string{
	AdminUsernameGrammar:    "the username does not follow the username grammar",
	AdminUsernameTaken:      "the username is taken",
	AdminDisplayNameInvalid: "the display name is not valid",
	AdminGroupNameGrammar:   "the group name does not follow the group name grammar",
	AdminGroupNameTaken:     "the group name is taken",
	AdminDescriptionInvalid: "the description is not valid",
	AdminUnknownUser:        "no user has that username",
	AdminUnknownGroup:       "no group has that name",
	AdminAlreadyMember:      "the user is already a member of the group",
	AdminNotMember:          "the user is not a member of the group",
	AdminPrimaryGroup:       "the primary group's membership cannot be changed",
	AdminSelf:               "an administrator cannot do this to their own account",
	AdminLastAdmin:          "the admin group would have no enabled member",
	AdminReferencedGroup:    "the group is named in the configuration",
	AdminInvitationClosed:   "the invitation is no longer pending",
	AdminGoogleNotLinked:    "the user has no linked Google account",
	AdminResetLinkDisabled:  "a reset link cannot be issued to a disabled account",
	AdminResetLinkPending:   "a reset link cannot be issued to an account waiting for its confirmation",
	AdminLabelInvalid:       "a label is empty or not valid",
	AdminExpiryInvalid:      "the expiry is not one of the offered choices",
	AdminAdminGroupGrant:    "an invitation cannot grant the admin group",
	AdminBatchSize:          "the batch is empty or larger than the cap",
	AdminUserPending:        "the account is waiting for its confirmation",
	AdminUnknownBatch:       "no invitation batch has that id",
	AdminSSHKeyDisabled:     "a disabled account takes no new SSH key",
	AdminSSHKeyPending:      "an account waiting for its confirmation takes no SSH key",
}

func (p AdminProblem) Error() string {
	if s, ok := adminProblemNames[p]; ok {
		return "web: admin: " + s
	}
	return "web: unknown admin problem " + strconv.Itoa(int(p))
}

type AdminAuditEntry struct {
	At         time.Time
	Actor      string
	Action     string
	Subject    string
	NewSession bool
}

type AdminDashboard struct {
	Users              int
	DisabledUsers      int
	Groups             int
	PendingInvitations int
	LiveSessions       int
	Recent             []AdminAuditEntry
}

type AdminUserRow struct {
	ID          string
	Username    string
	DisplayName string
	Disabled    bool
	Pending     bool
	Groups      []string
	GroupCount  int
}

type AdminUserList struct {
	Users []AdminUserRow
	Total int
}

type AdminGroupRef struct {
	ID      string
	Name    string
	Primary bool
}

type AdminGoogleLink struct {
	LinkedAt time.Time
}

type AdminUser struct {
	ID            string
	Username      string
	DisplayName   string
	UIDNumber     int
	Disabled      bool
	Pending       bool
	Admin         bool
	CreatedAt     time.Time
	LastLoginAt   *time.Time
	Groups        []AdminGroupRef
	GroupCount    int
	Google        *AdminGoogleLink
	Sessions      int
	RefreshTokens int
	Activity      []AdminAuditEntry
	SSHKeys       []SSHKey
}

type AdminMemberships struct {
	Username   string
	Groups     []AdminGroupRef
	Total      int
	Candidates []string
}

type AdminGroupRow struct {
	ID          string
	Name        string
	Description string
	Members     int
}

type AdminGroupList struct {
	Groups []AdminGroupRow
	Total  int
}

type AdminMember struct {
	ID          string
	Username    string
	DisplayName string
	Pending     bool
}

type AdminGroup struct {
	ID            string
	Name          string
	Description   string
	GIDNumber     int
	Primary       bool
	Referenced    bool
	Members       []AdminMember
	Total         int
	Disabled      []AdminMember
	DisabledTotal int
}

type AdminInvitationState int

const (
	AdminInvitationPending AdminInvitationState = iota + 1
	AdminInvitationUsed
	AdminInvitationRevoked
	AdminInvitationExpired
)

type AdminInvitation struct {
	ID            string
	CreatedBy     string
	CreatedAt     time.Time
	ExpiresAt     time.Time
	State         AdminInvitationState
	Label         string
	UsedBy        string
	UsedByID      string
	UsedByPending bool
	UsedByDeleted bool
	Batch         string
	Groups        []AdminInvitationGroup
}

type AdminInvitationGroup struct {
	Name    string
	Deleted bool
}

type AdminInvitationList struct {
	Invitations []AdminInvitation
	Total       int
}

var AdminInvitationExpiries = []time.Duration{24 * time.Hour, 7 * 24 * time.Hour, 30 * 24 * time.Hour}

const AdminInvitationExpiryDefault = 7 * 24 * time.Hour

type AdminNewInvitations struct {
	Labels     []string
	GroupIDs   []string
	GroupNames []string
	Expiry     time.Duration
}

type AdminIssuedInvitation struct {
	Label string
	URL   string
}

type AdminCreatedInvitations struct {
	Invitations []AdminIssuedInvitation
	ExpiresAt   time.Time
	Groups      []string
}

type AdminGroupChoice struct {
	ID   string
	Name string
}

type AdminGroupChoices struct {
	Groups   []AdminGroupChoice
	More     bool
	Defaults []string
}

type AdminNewUser struct {
	Username    string
	DisplayName string
}

type AdminProfile struct {
	DisplayName string
}

type AdminNewGroup struct {
	Name        string
	Description string
}

type AdminBackend interface {
	Dashboard(ctx context.Context) (AdminDashboard, error)
	ListUsers(ctx context.Context, query string, page int) (AdminUserList, error)
	User(ctx context.Context, id string) (AdminUser, error)
	CreateUser(ctx context.Context, actor string, u AdminNewUser) (string, error)
	UpdateProfile(ctx context.Context, actor, id string, p AdminProfile) error
	DisableUser(ctx context.Context, actor, id string) error
	EnableUser(ctx context.Context, actor, id string) error
	RevokeAllSessions(ctx context.Context, actor, id string) error
	UnlinkGoogle(ctx context.Context, actor, id string) error
	DeleteUser(ctx context.Context, actor, id string) error
	Memberships(ctx context.Context, userID string, page int) (AdminMemberships, error)
	AddMembership(ctx context.Context, actor, userID, groupName string) error
	AddMember(ctx context.Context, actor, groupID, username string) error
	RemoveMembership(ctx context.Context, actor, userID, groupID string) error
	ListGroups(ctx context.Context, page int) (AdminGroupList, error)
	Group(ctx context.Context, id string, page int) (AdminGroup, error)
	GroupCandidates(ctx context.Context, groupID, query string) ([]AdminMember, error)
	CreateGroup(ctx context.Context, actor string, g AdminNewGroup) (string, error)
	DescribeGroup(ctx context.Context, actor, id, description string) error
	DeleteGroup(ctx context.Context, actor, id string) error
	ListInvitations(ctx context.Context, page int) (AdminInvitationList, error)
	Invitation(ctx context.Context, id string) (AdminInvitation, error)
	CreateInvitations(ctx context.Context, actor string, n AdminNewInvitations) (AdminCreatedInvitations, error)
	InvitationGroupChoices(ctx context.Context) (AdminGroupChoices, error)
	PendingAccount(ctx context.Context, id string) (AdminPendingAccount, error)
	ConfirmAccount(ctx context.Context, actor, id, code string) error
	RejectAccount(ctx context.Context, actor, id string) error
	RevokeInvitation(ctx context.Context, actor, id string) error
	RevokeInvitationBatch(ctx context.Context, actor, batch string) error
	IssueResetLink(ctx context.Context, actor, id string) (AdminResetLink, error)
	AddSSHKey(ctx context.Context, actor, id, key, label string) (SSHKey, error)
	RemoveSSHKey(ctx context.Context, actor, id, keyID string) (SSHKey, error)
	Audit(ctx context.Context, q AdminAuditQuery) (AdminAuditPage, error)
}