package adminapi

import (
	"errors"
	"net/http"

	"github.com/dariuszjaniak/warp/server/internal/httputil"
	"github.com/dariuszjaniak/warp/server/internal/storage"
	"github.com/dariuszjaniak/warp/server/internal/userapi"
)

// The endpoints about one user, addressed by full user ID.

// userDetail is GET /users/{userID}: the list row and what it takes a
// count to know.
type userDetail struct {
	adminUser

	Devices int `json:"devices"`

	// JoinedRooms is absent on a server without rooms.
	JoinedRooms *int `json:"joined_rooms,omitempty"`

	// Media is absent on a server without a media repository.
	Media *mediaResponse `json:"media,omitempty"`
}

// mediaResponse is a user's uploads against their quota.
type mediaResponse struct {
	Uploads int   `json:"uploads"`
	Bytes   int64 `json:"bytes"`

	// QuotaBytes is the quota in force, 0 for no limit; CustomQuota says
	// whether it was set for this user rather than taken from the config.
	QuotaBytes  int64 `json:"quota_bytes"`
	CustomQuota bool  `json:"custom_quota"`
}

// pathUser reads the {userID} path value: a user of this server.
func (a *AdminAPI) pathUser(r *http.Request) (string, error) {
	raw := r.PathValue("userID")
	localpart, err := a.users.ParseLocalUserID(raw)
	switch {
	case errors.Is(err, userapi.ErrForeignServer):
		return "", httputil.InvalidParam("%s is not a user of this server", raw)
	case err != nil:
		return "", httputil.InvalidParam("%s is not a valid user ID", raw)
	}
	return localpart, nil
}

// pathAccount reads the {userID} path value and the account it names.
func (a *AdminAPI) pathAccount(r *http.Request) (storage.Account, error) {
	localpart, err := a.pathUser(r)
	if err != nil {
		return storage.Account{}, err
	}
	account, err := a.users.Account(r.Context(), localpart)
	switch {
	case errors.Is(err, userapi.ErrNoSuchUser):
		return storage.Account{}, httputil.NotFound("No such user")
	case err != nil:
		return storage.Account{}, err
	}
	return account, nil
}

func (a *AdminAPI) adminUserOf(acc storage.Account) adminUser {
	return adminUser{
		UserID:      a.users.UserID(acc.Localpart),
		DisplayName: acc.DisplayName,
		AvatarURL:   acc.AvatarURL,
		Admin:       acc.Admin,
		Deactivated: acc.Deactivated,
		CreatedAtMS: acc.CreatedAtMS,
	}
}

// handleGetUser implements GET /_warp/admin/v1/users/{userID}.
func (a *AdminAPI) handleGetUser(w http.ResponseWriter, r *http.Request, _ userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	return a.writeUser(w, r, account)
}

// writeUser answers with a user's detail, which is also what every change
// to a user answers with, so the panel can redraw from the response.
func (a *AdminAPI) writeUser(w http.ResponseWriter, r *http.Request, account storage.Account) error {
	devices, err := a.users.Devices(r.Context(), account.Localpart)
	if err != nil {
		return err
	}
	resp := userDetail{adminUser: a.adminUserOf(account), Devices: len(devices)}
	userID := a.users.UserID(account.Localpart)
	if a.rooms != nil {
		joined, err := a.rooms.JoinedRooms(r.Context(), userID)
		if err != nil {
			return err
		}
		n := len(joined)
		resp.JoinedRooms = &n
	}
	if a.media != nil {
		quota, err := a.media.Quota(r.Context(), userID)
		if err != nil {
			return err
		}
		resp.Media = &mediaResponse{
			Uploads: quota.Usage.Count, Bytes: quota.Usage.Bytes,
			QuotaBytes: quota.MaxBytes, CustomQuota: quota.Custom,
		}
	}
	httputil.NoCache(w)
	httputil.WriteJSON(w, http.StatusOK, resp)
	return nil
}

// refuseSelf stops an admin taking their own admin flag or deactivating
// themselves. Both are one click from locking the last admin out of the
// panel, and both are easy to do by accident on a table of users; another
// admin can still do either.
func refuseSelf(auth userapi.Authenticated, localpart, what string) error {
	if auth.Localpart == localpart {
		return httputil.Forbidden("You cannot %s your own account; ask another admin", what)
	}
	return nil
}

// adminFlagRequest is the PUT /users/{userID}/admin body.
type adminFlagRequest struct {
	Admin *bool `json:"admin"`
}

// handlePutUserAdmin implements PUT /_warp/admin/v1/users/{userID}/admin.
func (a *AdminAPI) handlePutUserAdmin(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	var req adminFlagRequest
	if err := httputil.DecodeJSON(w, r, &req); err != nil {
		return err
	}
	if req.Admin == nil {
		return httputil.MissingParam("admin is required")
	}
	if !*req.Admin {
		if err := refuseSelf(auth, account.Localpart, "remove the admin flag from"); err != nil {
			return err
		}
	}
	if account.Admin != *req.Admin {
		if err := a.users.SetAdmin(r.Context(), account.Localpart, *req.Admin); err != nil {
			return err
		}
		account.Admin = *req.Admin
		a.audit(r.Context(), auth, auditUserAdmin, a.users.UserID(account.Localpart),
			map[string]any{"admin": *req.Admin})
	}
	return a.writeUser(w, r, account)
}

// deactivateRequest is the POST /users/{userID}/deactivate body.
type deactivateRequest struct {
	// Erase forgets the profile as well.
	Erase bool `json:"erase"`
}

// handleDeactivateUser implements POST /_warp/admin/v1/users/{userID}/deactivate.
//
// It does what the user's own POST /account/deactivate does: every token
// stops working, the devices and their keys and pushers go, the user
// leaves every room, and with erase the display name and avatar are
// cleared first so the leave events carry neither. The name stays taken.
// Deactivating a deactivated account changes nothing.
func (a *AdminAPI) handleDeactivateUser(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	var req deactivateRequest
	if _, err := httputil.DecodeOptionalJSON(w, r, &req); err != nil {
		return err
	}
	if err := refuseSelf(auth, account.Localpart, "deactivate"); err != nil {
		return err
	}
	if !account.Deactivated {
		if err := a.users.DeactivateAccount(r.Context(), account.Localpart, req.Erase); err != nil {
			return err
		}
		a.audit(r.Context(), auth, auditUserDeactivate, a.users.UserID(account.Localpart),
			map[string]any{"erase": req.Erase})
	}
	if account, err = a.users.Account(r.Context(), account.Localpart); err != nil {
		return err
	}
	return a.writeUser(w, r, account)
}

// handleReactivateUser implements POST /_warp/admin/v1/users/{userID}/reactivate.
//
// The account can log in again, with its old password unless an admin
// sets a new one. Nothing else comes back: the rooms were left and the
// devices are gone.
func (a *AdminAPI) handleReactivateUser(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	if account.Deactivated {
		if err := a.users.ReactivateAccount(r.Context(), account.Localpart); err != nil {
			return err
		}
		account.Deactivated = false
		a.audit(r.Context(), auth, auditUserReactivate, a.users.UserID(account.Localpart), nil)
	}
	return a.writeUser(w, r, account)
}

// resetPasswordRequest is the POST /users/{userID}/password body.
type resetPasswordRequest struct {
	Password string `json:"password"`

	// LogoutDevices defaults to true: an admin resetting a password is
	// usually doing it because somebody else has the account.
	LogoutDevices *bool `json:"logout_devices"`
}

// handleResetPassword implements POST /_warp/admin/v1/users/{userID}/password.
func (a *AdminAPI) handleResetPassword(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	var req resetPasswordRequest
	if err := httputil.DecodeJSON(w, r, &req); err != nil {
		return err
	}
	if req.Password == "" {
		return httputil.MissingParam("password is required")
	}
	if len(req.Password) > userapi.MaxPasswordLength {
		return httputil.NewError(http.StatusBadRequest, httputil.ErrCodeWeakPassword,
			"Password must be at most %d bytes", userapi.MaxPasswordLength)
	}
	logout := req.LogoutDevices == nil || *req.LogoutDevices
	if err := a.users.ChangePassword(r.Context(), account.Localpart, req.Password, logout, ""); err != nil {
		return err
	}
	a.audit(r.Context(), auth, auditUserPassword, a.users.UserID(account.Localpart),
		map[string]any{"logout_devices": logout})
	return a.writeUser(w, r, account)
}

// adminDevice is one device in the device list.
type adminDevice struct {
	DeviceID    string `json:"device_id"`
	DisplayName string `json:"display_name,omitempty"`
	CreatedAtMS int64  `json:"created_at_ms"`
	LastSeenMS  int64  `json:"last_seen_ms"`
	LastSeenIP  string `json:"last_seen_ip,omitempty"`
	UserAgent   string `json:"user_agent,omitempty"`
}

// handleGetUserDevices implements GET /_warp/admin/v1/users/{userID}/devices.
func (a *AdminAPI) handleGetUserDevices(w http.ResponseWriter, r *http.Request, _ userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	devices, err := a.users.Devices(r.Context(), account.Localpart)
	if err != nil {
		return err
	}
	out := make([]adminDevice, 0, len(devices))
	for _, d := range devices {
		out = append(out, adminDevice{
			DeviceID: d.ID, DisplayName: d.DisplayName, CreatedAtMS: d.CreatedAtMS,
			LastSeenMS: d.LastSeenMS, LastSeenIP: d.LastSeenIP, UserAgent: d.UserAgent,
		})
	}
	httputil.NoCache(w)
	httputil.WriteJSON(w, http.StatusOK, map[string]any{"devices": out})
	return nil
}

// handleDeleteUserDevice implements
// DELETE /_warp/admin/v1/users/{userID}/devices/{deviceID}: log one
// session out, taking its keys and pushers with it.
func (a *AdminAPI) handleDeleteUserDevice(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	deviceID := r.PathValue("deviceID")
	if _, err := a.users.Device(r.Context(), account.Localpart, deviceID); errors.Is(err, userapi.ErrNoSuchDevice) {
		return httputil.NotFound("No such device")
	} else if err != nil {
		return err
	}
	if err := a.users.DeleteDevices(r.Context(), account.Localpart, []string{deviceID}); err != nil {
		return err
	}
	a.audit(r.Context(), auth, auditUserDeviceDelete, a.users.UserID(account.Localpart),
		map[string]any{"device_id": deviceID})
	httputil.WriteJSON(w, http.StatusOK, struct{}{})
	return nil
}

// handleDeleteUserDevices implements
// DELETE /_warp/admin/v1/users/{userID}/devices: log every session out.
func (a *AdminAPI) handleDeleteUserDevices(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	if err := a.users.DeleteAllDevices(r.Context(), account.Localpart); err != nil {
		return err
	}
	a.audit(r.Context(), auth, auditUserDeviceDelete, a.users.UserID(account.Localpart),
		map[string]any{"all": true})
	httputil.WriteJSON(w, http.StatusOK, struct{}{})
	return nil
}

// requireMedia refuses the media endpoints on a server without a media
// repository.
func (a *AdminAPI) requireMedia() error {
	if a.media == nil {
		return httputil.NotFound("This server has no media repository")
	}
	return nil
}

// handleGetUserMedia implements GET /_warp/admin/v1/users/{userID}/media.
func (a *AdminAPI) handleGetUserMedia(w http.ResponseWriter, r *http.Request, _ userapi.Authenticated) error {
	if err := a.requireMedia(); err != nil {
		return err
	}
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	return a.writeMedia(w, r, account)
}

func (a *AdminAPI) writeMedia(w http.ResponseWriter, r *http.Request, account storage.Account) error {
	quota, err := a.media.Quota(r.Context(), a.users.UserID(account.Localpart))
	if err != nil {
		return err
	}
	httputil.NoCache(w)
	httputil.WriteJSON(w, http.StatusOK, mediaResponse{
		Uploads: quota.Usage.Count, Bytes: quota.Usage.Bytes,
		QuotaBytes: quota.MaxBytes, CustomQuota: quota.Custom,
	})
	return nil
}

// quotaRequest is the PUT /users/{userID}/media/quota body.
type quotaRequest struct {
	MaxBytes *int64 `json:"max_bytes"`
}

// handlePutMediaQuota implements PUT /_warp/admin/v1/users/{userID}/media/quota.
//
// A quota below what the user already has does not delete anything; it
// stops further uploads until they are back under it.
func (a *AdminAPI) handlePutMediaQuota(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	if err := a.requireMedia(); err != nil {
		return err
	}
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	var req quotaRequest
	if err := httputil.DecodeJSON(w, r, &req); err != nil {
		return err
	}
	if req.MaxBytes == nil {
		return httputil.MissingParam("max_bytes is required (0 for no limit)")
	}
	if *req.MaxBytes < 0 {
		return httputil.InvalidParam("max_bytes must not be negative")
	}
	userID := a.users.UserID(account.Localpart)
	if err := a.media.SetQuota(r.Context(), userID, *req.MaxBytes); err != nil {
		return err
	}
	a.audit(r.Context(), auth, auditUserMediaQuota, userID, map[string]any{"max_bytes": *req.MaxBytes})
	return a.writeMedia(w, r, account)
}

// handleDeleteMediaQuota implements DELETE
// /_warp/admin/v1/users/{userID}/media/quota: back to the configured
// default.
func (a *AdminAPI) handleDeleteMediaQuota(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	if err := a.requireMedia(); err != nil {
		return err
	}
	account, err := a.pathAccount(r)
	if err != nil {
		return err
	}
	userID := a.users.UserID(account.Localpart)
	if err := a.media.ResetQuota(r.Context(), userID); err != nil {
		return err
	}
	a.audit(r.Context(), auth, auditUserMediaQuota, userID, map[string]any{"max_bytes": nil})
	return a.writeMedia(w, r, account)
}