package adminapi

import (
	"errors"
	"net/http"
	"strconv"

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

// adminUser is one row of the user list. It is a flatter shape than the
// Client-Server API's profile object because the panel shows it as a table.
type adminUser struct {
	UserID      string `json:"user_id"`
	DisplayName string `json:"display_name,omitempty"`
	AvatarURL   string `json:"avatar_url,omitempty"`
	Admin       bool   `json:"admin"`
	Deactivated bool   `json:"deactivated"`
	CreatedAtMS int64  `json:"created_at_ms"`
}

type usersResponse struct {
	Users []adminUser `json:"users"`

	// Total is the number of users matching the query, not the number
	// returned, so the panel can page.
	Total int `json:"total"`

	Limit  int `json:"limit"`
	Offset int `json:"offset"`
}

// defaultUserPageLimit is what a request without ?limit= gets.
const defaultUserPageLimit = 50

// handleGetUsers implements GET /_warp/admin/v1/users.
func (a *AdminAPI) handleGetUsers(w http.ResponseWriter, r *http.Request, _ userapi.Authenticated) error {
	query := r.URL.Query()

	limit, err := intParam(query.Get("limit"), defaultUserPageLimit)
	if err != nil {
		return httputil.InvalidParam("limit must be a number")
	}
	offset, err := intParam(query.Get("offset"), 0)
	if err != nil {
		return httputil.InvalidParam("offset must be a number")
	}
	if limit < 0 || offset < 0 {
		return httputil.InvalidParam("limit and offset must not be negative")
	}

	accounts, total, err := a.users.ListAccounts(r.Context(), storage.AccountFilter{
		Search: query.Get("search"),
		Limit:  limit,
		Offset: offset,
	})
	if err != nil {
		return err
	}

	users := make([]adminUser, 0, len(accounts))
	for _, acc := range accounts {
		users = append(users, adminUser{
			UserID:      a.users.UserID(acc.Localpart),
			DisplayName: acc.DisplayName,
			AvatarURL:   acc.AvatarURL,
			Admin:       acc.Admin,
			Deactivated: acc.Deactivated,
			CreatedAtMS: acc.CreatedAtMS,
		})
	}
	httputil.WriteJSON(w, http.StatusOK, usersResponse{
		Users:  users,
		Total:  total,
		Limit:  limit,
		Offset: offset,
	})
	return nil
}

// createUserRequest is the body of POST /_warp/admin/v1/users.
type createUserRequest struct {
	// Username is the localpart; it is normalised like any other.
	Username string `json:"username"`

	Password    string `json:"password"`
	DisplayName string `json:"display_name"`
	Admin       bool   `json:"admin"`
}

// handlePostUsers implements POST /_warp/admin/v1/users.
//
// This is how an operator adds an account on a server with registration
// turned off, so it deliberately ignores the registration switch: it is the
// admin's own action, not a public sign-up. It does require a password —
// unlike `warp create-account`, which may leave one unset — because an
// account created from the panel is meant to be handed to somebody.
func (a *AdminAPI) handlePostUsers(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
	var req createUserRequest
	if err := httputil.DecodeJSON(w, r, &req); err != nil {
		return err
	}
	if req.Username == "" {
		return httputil.MissingParam("username is required")
	}
	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)
	}

	account, err := a.users.CreateAccount(r.Context(), userapi.NewAccountRequest{
		Localpart:   req.Username,
		Password:    req.Password,
		DisplayName: req.DisplayName,
		Admin:       req.Admin,
	})
	switch {
	case errors.Is(err, userapi.ErrUserExists):
		return httputil.UserInUse()
	case errors.Is(err, userapi.ErrInvalidLocalpart):
		return httputil.InvalidUsername("%s", err.Error())
	case err != nil:
		return err
	}

	a.audit(r.Context(), auth, auditUserCreate, a.users.UserID(account.Localpart),
		map[string]any{"admin": account.Admin})

	httputil.WriteJSON(w, http.StatusCreated, adminUser{
		UserID:      a.users.UserID(account.Localpart),
		DisplayName: account.DisplayName,
		Admin:       account.Admin,
		CreatedAtMS: account.CreatedAtMS,
	})
	return nil
}

// intParam parses an optional integer query parameter.
func intParam(raw string, fallback int) (int, error) {
	if raw == "" {
		return fallback, nil
	}
	return strconv.Atoi(raw)
}