package main

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"regexp"
	"slices"
	"sort"
	"strings"

	"gitea/internal/forgehttp"
)

// The forge accounts and teams the module made once and declares no more (novox/hq ADR 0605 §5: no build module holds
// a registry's write credential; the npm write token is revoked). The npm pair provisioner, removed when the package
// seats came, made each consumer of npm-package-registry an account under the mesh's derived login
// (mesh_<node>_<consumer>) and put it in the organisation's team packages (read and write) or readers (read only).
// Reads of the packages are anonymous and every write goes through the seats, so both teams go, and each account of
// that form in no team but them goes with them. Only what the provisioner made goes: a team of those names in its
// organisation (RetiredOrg) is the provisioner's when every member of it is an account of the provisioner's form and
// it has one at least, since the provisioner put its own accounts in them alone and nobody else ever made one. A team
// a person makes later under such a name holds no such account (they are gone with the first run), so it stays, and
// so does a team of those names with a person in it or with no member. Nothing else is touched: a team of another
// name or organisation, an account of another form or one still in a team the module does not retire stays as it is.
var RetiredTeams = []string{"packages", "readers"}

// RetiredOrg is the organisation the npm pair provisioner made its teams in (its ORG, the npm registry's owner).
const RetiredOrg = "novox"

// retiredAccount is the login form the npm pair provisioner made its accounts under.
var retiredAccount = regexp.MustCompile(`^mesh_[a-z0-9-]+_[a-z0-9_]+$`)

// Retire removes the retired teams in every organisation, and each account of the pair's form whose only teams they
// are. An account the forge refuses to delete (it owns a repository or an organisation, so a delete would take what
// it owns) has its login prohibited instead, said, so its password no longer reaches anything. Each removal is said
// in one line; a run with nothing left to retire says nothing.
func (s *Syncer) Retire(ctx context.Context, orgs []string) error {
	teamsOf := map[string][]string{} // login -> every team it is in, as org/team
	type retired struct {
		org  string
		team forgeTeam
	}
	var gone []retired
	retiring := map[string]bool{} // org/team
	for _, org := range orgs {
		teams, err := s.teams(ctx, org)
		if err != nil {
			return err
		}
		for _, t := range teams {
			var members []forgeMember
			if err := s.list(ctx, fmt.Sprintf("/api/v1/teams/%d/members", t.ID), &members); err != nil {
				return fmt.Errorf("the members of %s in %s could not be read, so nothing is retired: %w", t.Name, org, err)
			}
			for _, m := range members {
				teamsOf[m.Login] = append(teamsOf[m.Login], org+"/"+t.Name)
			}
			made := len(members) > 0 && !slices.ContainsFunc(members, func(m forgeMember) bool { return !retiredAccount.MatchString(m.Login) })
			if org == RetiredOrg && slices.Contains(RetiredTeams, t.Name) && made {
				gone = append(gone, retired{org, t})
				retiring[org+"/"+t.Name] = true
			}
		}
	}
	isRetired := func(orgTeam string) bool { return retiring[orgTeam] }
	var accounts []string
	for login, in := range teamsOf {
		if retiredAccount.MatchString(login) && slices.ContainsFunc(in, isRetired) && !slices.ContainsFunc(in, func(t string) bool { return !isRetired(t) }) {
			accounts = append(accounts, login)
		}
	}
	sort.Strings(accounts)
	var errs []string
	for _, a := range accounts {
		if err := s.removeAccount(ctx, a); err != nil {
			errs = append(errs, err.Error())
		}
	}
	for _, r := range gone {
		if err := s.Forge.SendJSON(ctx, http.MethodDelete, fmt.Sprintf("/api/v1/teams/%d", r.team.ID), nil, nil); err != nil && !errors.Is(err, forgehttp.ErrNotFound) {
			errs = append(errs, fmt.Sprintf("the retired team %s in %s could not be removed: %v", r.team.Name, r.org, err))
			continue
		}
		s.say("removed the retired team %s in %s (the npm pair's, ADR 0605 §5)", r.team.Name, r.org)
	}
	if len(errs) > 0 {
		return errors.New(strings.Join(errs, "; "))
	}
	return nil
}

// removeAccount deletes a retired account, never purging what it owns; one the forge refuses to delete has its login
// prohibited instead.
func (s *Syncer) removeAccount(ctx context.Context, login string) error {
	err := s.Forge.SendJSON(ctx, http.MethodDelete, "/api/v1/admin/users/"+url.PathEscape(login), nil, nil)
	if err == nil || errors.Is(err, forgehttp.ErrNotFound) {
		s.say("removed the retired account %s (the npm pair's, ADR 0605 §5)", login)
		return nil
	}
	var se *forgehttp.StatusError
	if !errors.As(err, &se) || se.Status != http.StatusUnprocessableEntity {
		return fmt.Errorf("the retired account %s could not be removed: %w", login, err)
	}
	if perr := s.Forge.SendJSON(ctx, http.MethodPatch, "/api/v1/admin/users/"+url.PathEscape(login), map[string]any{
		"login_name": login, "source_id": 0, "prohibit_login": true,
	}, nil); perr != nil {
		return fmt.Errorf("the retired account %s could not be removed (%v) nor its login prohibited: %w", login, err, perr)
	}
	s.say("the retired account %s owns something, so the forge keeps it (%v): its login is prohibited instead", login, err)
	return nil
}