package forge

import (
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"
)

const moderationSchema = `
create table if not exists blocks (
	user integer not null references users(id) on delete cascade,
	blocked integer not null references users(id) on delete cascade,
	created integer not null,
	primary key (user, blocked)
);
create table if not exists reports (
	id integer primary key,
	reporter integer not null references users(id) on delete cascade,
	kind text not null,
	target text not null,
	reason text not null,
	state text not null default 'open',
	handler integer not null default 0,
	created integer not null
);
create index if not exists reports_state on reports(state, created);
create table if not exists guestpushes (
	user integer not null references users(id) on delete cascade,
	created integer not null
);
create index if not exists guestpushes_user on guestpushes(user, created);
`

const (
	guestPushes    = 30
	threadsPerHour = 20
	reportsPerHour = 5
	maxReason      = 2000
)

var reportKinds = map[string]string{"user": "account", "repo": "repository", "issue": "issue", "pull": "pull request"}

type Report struct {
	ID       int64
	Reporter User
	Kind     string
	Target   string
	Reason   string
	State    string
	Created  time.Time
}

func (r Report) Link() string {
	switch r.Kind {
	case "user":
		return "/~" + r.Target
	case "repo":
		return "/~" + r.Target
	case "issue", "pull":
		repo, num, _ := strings.Cut(r.Target, "#")
		section := map[string]string{"issue": "issues", "pull": "pulls"}[r.Kind]
		return "/~" + repo + "/" + section + "/" + num
	}
	return "/"
}

func (r Report) Owner() string {
	name, _, _ := strings.Cut(r.Target, "/")
	name, _, _ = strings.Cut(name, "#")
	return name
}

func (s *Store) IsBanned(id int64) bool {
	var banned bool
	s.db.QueryRow(`select banned from users where id = ?`, id).Scan(&banned)
	return banned
}

func (s *Store) PagesAllowed(id int64) bool {
	var on bool
	s.db.QueryRow(`select pages from users where id = ?`, id).Scan(&on)
	return on
}

func (s *Store) SetPages(name string, on bool) error {
	res, err := s.db.Exec(`update users set pages = ? where name = ?`, on, name)
	if err != nil {
		return err
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return ErrNotFound
	}
	return nil
}

func (s *Store) Blocked(owner, actor int64) bool {
	var n int
	s.db.QueryRow(`select count(*) from blocks where user = ? and blocked = ?`, owner, actor).Scan(&n)
	return n > 0
}

func (s *Store) SetBlock(user, blocked int64, on bool) error {
	if !on {
		_, err := s.db.Exec(`delete from blocks where user = ? and blocked = ?`, user, blocked)
		return err
	}
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	if _, err := tx.Exec(`insert or ignore into blocks(user, blocked, created) values (?, ?, ?)`, user, blocked, time.Now().Unix()); err != nil {
		return err
	}
	if _, err := tx.Exec(`delete from follows where (follower = ?1 and followee = ?2) or (follower = ?2 and followee = ?1)`, blocked, user); err != nil {
		return err
	}
	if _, err := tx.Exec(`delete from stars where user = ? and repo in (select id from repos where owner = ?)`, blocked, user); err != nil {
		return err
	}
	return tx.Commit()
}

func (s *Store) BlockedUsers(user int64) []User {
	rows, err := s.db.Query(`select u.id, u.name, u.created from blocks b join users u on u.id = b.blocked where b.user = ? order by u.name`, user)
	if err != nil {
		return nil
	}
	defer rows.Close()
	var out []User
	for rows.Next() {
		var u User
		var created int64
		if rows.Scan(&u.ID, &u.Name, &created) == nil {
			u.Created = time.Unix(created, 0)
			out = append(out, u)
		}
	}
	return out
}

func (s *Store) ThreadBudget(user int64) bool {
	since := time.Now().Add(-time.Hour).Unix()
	var n int
	s.db.QueryRow(`select (select count(*) from issues where author = ?1 and created > ?2) + (select count(*) from pulls where author = ?1 and created > ?2)`, user, since).Scan(&n)
	return n < threadsPerHour
}

func (s *Store) GuestPushBudget(user int64) bool {
	var n int
	s.db.QueryRow(`select count(*) from guestpushes where user = ? and created > ?`, user, time.Now().Add(-time.Hour).Unix()).Scan(&n)
	return n < guestPushes
}

func (s *Store) GuestPushed(user int64) {
	now := time.Now()
	s.db.Exec(`insert into guestpushes(user, created) values (?, ?)`, user, now.Unix())
	s.db.Exec(`delete from guestpushes where created < ?`, now.Add(-time.Hour).Unix())
}

func (s *Store) AddReport(reporter int64, kind, target, reason string) error {
	if _, ok := reportKinds[kind]; !ok {
		return errors.New("Unknown report type")
	}
	reason = strings.TrimSpace(reason)
	if reason == "" {
		return errors.New("Say what is wrong")
	}
	if len(reason) > maxReason {
		return fmt.Errorf("Keep the report under %d characters", maxReason)
	}
	var recent, dup int
	s.db.QueryRow(`select count(*) from reports where reporter = ? and created > ?`, reporter, time.Now().Add(-time.Hour).Unix()).Scan(&recent)
	if recent >= reportsPerHour {
		return errors.New("Too many reports, try again later")
	}
	s.db.QueryRow(`select count(*) from reports where reporter = ? and kind = ? and target = ? and state = 'open'`, reporter, kind, target).Scan(&dup)
	if dup > 0 {
		return errors.New("You already reported this, an admin will look at it")
	}
	_, err := s.db.Exec(`insert into reports(reporter, kind, target, reason, created) values (?, ?, ?, ?, ?)`, reporter, kind, target, reason, time.Now().Unix())
	return err
}

func (s *Store) Reports(state string) []Report {
	rows, err := s.db.Query(`select r.id, r.kind, r.target, r.reason, r.state, r.created, u.id, u.name from reports r join users u on u.id = r.reporter where r.state = ? order by r.created desc limit 200`, state)
	if err != nil {
		return nil
	}
	defer rows.Close()
	var out []Report
	for rows.Next() {
		var rep Report
		var created int64
		if rows.Scan(&rep.ID, &rep.Kind, &rep.Target, &rep.Reason, &rep.State, &created, &rep.Reporter.ID, &rep.Reporter.Name) == nil {
			rep.Created = time.Unix(created, 0)
			out = append(out, rep)
		}
	}
	return out
}

func (s *Store) Report(id int64) (Report, error) {
	var rep Report
	var created int64
	err := s.db.QueryRow(`select id, kind, target, reason, state, created from reports where id = ?`, id).Scan(&rep.ID, &rep.Kind, &rep.Target, &rep.Reason, &rep.State, &created)
	rep.Created = time.Unix(created, 0)
	return rep, err
}

func (s *Store) CloseReports(kind, target, state string, handler int64) {
	s.db.Exec(`update reports set state = ?, handler = ? where kind = ? and target = ? and state = 'open'`, state, handler, kind, target)
}

func (s *Store) OpenReports() int {
	var n int
	s.db.QueryRow(`select count(*) from reports where state = 'open'`).Scan(&n)
	return n
}

func (s *Server) shunned(repo Repo, u *User) bool {
	return u != nil && s.store.Blocked(repo.Owner.ID, u.ID)
}

func (s *Server) reportTarget(kind, target string, viewer *User) (string, bool) {
	switch kind {
	case "user":
		u, err := s.store.UserByName(target)
		return u.Name, err == nil
	case "repo", "issue", "pull":
		path, num, hasNum := strings.Cut(target, "#")
		owner, name, ok := strings.Cut(path, "/")
		if !ok || hasNum != (kind != "repo") {
			return "", false
		}
		repo, err := s.store.RepoByPath(owner, name)
		if err != nil || (repo.Private && !s.store.CanWrite(repo, viewer)) {
			return "", false
		}
		bare := repo.Owner.Name + "/" + repo.Name
		if kind == "repo" {
			return bare, true
		}
		n, err := strconv.ParseInt(num, 10, 64)
		if err != nil {
			return "", false
		}
		if kind == "issue" {
			_, err = s.store.Issue(repo.ID, n)
		} else {
			_, err = s.store.Pull(repo, n)
		}
		return fmt.Sprintf("%s#%d", bare, n), err == nil
	}
	return "", false
}

func (s *Server) report(w http.ResponseWriter, r *http.Request) {
	u := s.require(w, r)
	if u == nil {
		return
	}
	kind := r.FormValue("kind")
	target, ok := s.reportTarget(kind, strings.TrimPrefix(strings.TrimSpace(r.FormValue("target")), "~"), u)
	if !ok {
		s.fail(w, r, 404, "Nothing to report there")
		return
	}
	data := map[string]any{"Kind": kind, "Noun": reportKinds[kind], "Target": target, "Reason": r.FormValue("reason")}
	if r.Method == "POST" {
		if err := s.store.AddReport(u.ID, kind, target, r.FormValue("reason")); err != nil {
			w.WriteHeader(400)
			s.render(w, r, "report", page{Title: "Report", User: u, Error: err.Error(), Data: data})
			return
		}
		data["Sent"] = true
	}
	s.render(w, r, "report", page{Title: "Report", User: u, Data: data})
}

func (s *Server) block(w http.ResponseWriter, r *http.Request) {
	u := s.require(w, r)
	if u == nil {
		return
	}
	target, err := s.store.UserByName(strings.TrimPrefix(strings.TrimSpace(r.FormValue("name")), "~"))
	if err != nil || target.ID == u.ID || s.store.IsOrg(target.ID) {
		s.fail(w, r, 400, "You cannot block that account")
		return
	}
	on := r.FormValue("action") != "unblock"
	if err := s.store.SetBlock(u.ID, target.ID, on); err != nil {
		s.fail(w, r, 500, err.Error())
		return
	}
	back := "/~" + target.Name
	if r.FormValue("back") == "settings" {
		back = "/settings#blocked"
	}
	http.Redirect(w, r, back, http.StatusSeeOther)
}

func (s *Server) moderate(w http.ResponseWriter, r *http.Request, admin *User, fail func(string)) bool {
	id, _ := strconv.ParseInt(r.FormValue("report"), 10, 64)
	rep, err := s.store.Report(id)
	if err != nil {
		fail("No such report")
		return false
	}
	switch r.FormValue("do") {
	case "dismiss":
		s.store.CloseReports(rep.Kind, rep.Target, "dismissed", admin.ID)
	case "resolve":
		s.store.CloseReports(rep.Kind, rep.Target, "resolved", admin.ID)
	case "ban":
		name := s.reportAuthor(rep)
		if name == "" {
			fail("Could not tell who wrote that")
			return false
		}
		if name == admin.Name {
			fail("You cannot ban yourself")
			return false
		}
		if err := s.store.SetBanned(name, true); err != nil {
			fail("No such account")
			return false
		}
		s.store.CloseReports(rep.Kind, rep.Target, "resolved", admin.ID)
	case "pages":
		if err := s.store.SetPages(rep.Owner(), false); err != nil {
			fail("No such account")
			return false
		}
		s.store.CloseReports(rep.Kind, rep.Target, "resolved", admin.ID)
	case "delete":
		if rep.Kind != "repo" || r.FormValue("confirm") != rep.Target {
			fail("Type the repository path to confirm deletion")
			return false
		}
		owner, name, _ := strings.Cut(rep.Target, "/")
		repo, err := s.store.RepoByPath(owner, name)
		if err != nil {
			fail("That repository is already gone")
			return false
		}
		if err := s.store.DeleteRepo(repo.ID); err != nil {
			fail(err.Error())
			return false
		}
		os.RemoveAll(s.repoDir(repo))
		s.store.CloseReports(rep.Kind, rep.Target, "resolved", admin.ID)
	default:
		fail("Unknown action")
		return false
	}
	return true
}

func (s *Server) reportAuthor(rep Report) string {
	if rep.Kind == "user" || rep.Kind == "repo" {
		return rep.Owner()
	}
	path, num, _ := strings.Cut(rep.Target, "#")
	owner, name, _ := strings.Cut(path, "/")
	repo, err := s.store.RepoByPath(owner, name)
	if err != nil {
		return ""
	}
	n, err := strconv.ParseInt(num, 10, 64)
	if err != nil {
		return ""
	}
	if rep.Kind == "issue" {
		if issue, err := s.store.Issue(repo.ID, n); err == nil {
			return issue.Author.Name
		}
		return ""
	}
	if pull, err := s.store.Pull(repo, n); err == nil {
		return pull.Author.Name
	}
	return ""
}

func reportURL(kind, target string) string {
	return "/report?kind=" + kind + "&target=" + url.QueryEscape(target)
}