package web

import (
	"context"
	"errors"
	"net/http"
	"time"

	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
)

// AccountAdmin is the store half of account administration.
type AccountAdmin interface {
	Users(ctx context.Context, state store.UserState) ([]store.User, error)
	UserByID(ctx context.Context, id string) (store.User, error)
	ApproveUser(ctx context.Context, id, projectID, by string, at time.Time) error
	SetUserState(ctx context.Context, id string, state store.UserState) error
	DeleteUserSessions(ctx context.Context, userID string) error
	AllProjects(ctx context.Context) ([]store.ProjectPath, error)
}

type adminUsersData struct {
	Pending  []store.User
	Active   []store.User
	Projects []store.ProjectPath
	Message  string
	Error    string
	CSRF     string
	Version  string
	Now      string
	// HasMirror keeps the nav from offering a page that was never mounted.
	HasMirror bool
}

// RegisterAdminUsers mounts account administration under /admin/users.
//
// What is here and what is not is the whole design. Approving and suspending
// are the work an operator does constantly and should not need a terminal for.
// Making someone an admin, resetting a password and issuing keys on another
// person's behalf are not here: each of them turns a stolen admin session into
// more than it was — more access, or somebody else's account — and each is rare
// enough that a shell is no hardship.
func (p *AccountPages) RegisterAdminUsers(mux *http.ServeMux, s AccountAdmin) {
	mux.HandleFunc("GET /admin/users", p.adminOnly(func(w http.ResponseWriter, r *http.Request, admin store.User) {
		p.renderUsers(w, r, s, "", "")
	}))

	mux.HandleFunc("POST /admin/users/{id}/approve", p.adminAction(s,
		func(ctx context.Context, admin store.User, id string, r *http.Request) (string, error) {
			project := r.FormValue("project")
			if project == "" {
				return "", errors.New("choose a project for their keys")
			}
			if err := s.ApproveUser(ctx, id, project, admin.Email, time.Now()); err != nil {
				return "", err
			}
			return "approved into " + project, nil
		}))

	mux.HandleFunc("POST /admin/users/{id}/suspend", p.adminAction(s,
		func(ctx context.Context, admin store.User, id string, _ *http.Request) (string, error) {
			if id == admin.ID {
				// Locking yourself out is not a thing an interface should let
				// you do by misclicking.
				return "", errors.New("you cannot suspend your own account")
			}
			if err := s.SetUserState(ctx, id, store.UserSuspended); err != nil {
				return "", err
			}
			// Otherwise they stay signed in and suspension is advisory until
			// their session happens to expire.
			if err := s.DeleteUserSessions(ctx, id); err != nil {
				return "", err
			}
			return "suspended, and signed out everywhere", nil
		}))

	mux.HandleFunc("POST /admin/users/{id}/reinstate", p.adminAction(s,
		func(ctx context.Context, _ store.User, id string, _ *http.Request) (string, error) {
			if err := s.SetUserState(ctx, id, store.UserActive); err != nil {
				return "", err
			}
			return "reinstated", nil
		}))
}

// adminOnly is the guard every page under /admin shares.
func (p *AccountPages) adminOnly(
	next func(w http.ResponseWriter, r *http.Request, admin store.User),
) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		noStore(w)
		_, user, ok := p.session(r)
		if !ok {
			http.Redirect(w, r, "/login", http.StatusSeeOther)
			return
		}
		if !user.IsAdmin {
			// 404 rather than 403: a 403 confirms the page exists.
			http.NotFound(w, r)
			return
		}
		next(w, r, user)
	}
}

// adminAction wraps a state change: admin session, CSRF, audit line, redirect.
func (p *AccountPages) adminAction(s AccountAdmin,
	do func(ctx context.Context, admin store.User, id string, r *http.Request) (string, error),
) http.HandlerFunc {
	return p.adminOnly(func(w http.ResponseWriter, r *http.Request, admin store.User) {
		sess, _, _ := p.session(r)
		if !p.accounts.CheckCSRF(sess, r.FormValue("csrf")) {
			http.Error(w, "bad request", http.StatusBadRequest)
			return
		}
		id := r.PathValue("id")

		subject := id
		if u, err := s.UserByID(r.Context(), id); err == nil {
			subject = u.Email
		}

		msg, err := do(r.Context(), admin, id, r)
		if err != nil {
			// Logged at warn whether it worked or not: a refused administrative
			// action is as worth knowing about as one that went through.
			p.log.Warn("an administrative action was refused",
				"admin", admin.Email, "subject", subject, "err", err)
			p.renderUsers(w, r, s, "", err.Error())
			return
		}
		p.log.Info("an account was changed",
			"admin", admin.Email, "subject", subject, "what", msg)
		p.renderUsers(w, r, s, subject+" "+msg, "")
	})
}

func (p *AccountPages) renderUsers(w http.ResponseWriter, r *http.Request,
	s AccountAdmin, msg, errMsg string,
) {
	d := adminUsersData{
		Message: msg, Error: errMsg,
		CSRF:      csrfFor(r),
		Version:   p.version,
		HasMirror: p.hasMirror,
		Now:       time.Now().UTC().Format(time.RFC3339),
	}

	all, err := s.Users(r.Context(), "")
	if err != nil {
		p.log.Error("could not list accounts", "err", err)
		d.Error = "could not read the accounts"
	}
	for _, u := range all {
		if u.State == store.UserPending {
			d.Pending = append(d.Pending, u)
		} else {
			d.Active = append(d.Active, u)
		}
	}
	if d.Projects, err = s.AllProjects(r.Context()); err != nil {
		p.log.Error("could not list projects", "err", err)
	}
	render(w, "admin_users", d)
}