package main

import (
	"crypto/rand"
	"encoding/hex"
	"log/slog"
	"net/http"
	"net/url"
	"strconv"
	"time"

	"golang.org/x/crypto/bcrypt"
)

type adminInvite struct {
	ID        int64
	Code      string
	IsValid   bool
	CreatedAt time.Time
	Link      string
}

type adminMember struct {
	ID        int64
	Name      string
	Email     string
	Banned    bool
	CreatedAt time.Time
}

type dashboard struct {
	Invites    []adminInvite
	SpentCount int
	Members    []adminMember
	Songs      []adminSong
	OpenCount  int
}

func (a *app) adminDashboard(w http.ResponseWriter, r *http.Request) {
	var d dashboard

	// Unused invites are the ones with a job to do; spent ones are counted, not listed. Truncating
	// a list silently reads as "that's all of them".
	if err := a.pool.QueryRow(r.Context(),
		`select count(*)::int from invites where not is_valid`).Scan(&d.SpentCount); err != nil {
		adminError(w, "invites", err)
		return
	}
	rows, err := a.pool.Query(r.Context(),
		`select id, code, is_valid, created_at from invites where is_valid order by created_at desc`)
	if err != nil {
		adminError(w, "invites", err)
		return
	}
	for rows.Next() {
		var i adminInvite
		if err := rows.Scan(&i.ID, &i.Code, &i.IsValid, &i.CreatedAt); err != nil {
			adminError(w, "invites", err)
			return
		}
		i.Link = a.inviteLink(i.Code)
		d.Invites = append(d.Invites, i)
	}
	rows.Close()
	if err := rows.Err(); err != nil {
		adminError(w, "invites", err)
		return
	}

	rows, err = a.pool.Query(r.Context(),
		`select id, name, email, banned, created_at from users order by created_at`)
	if err != nil {
		adminError(w, "users", err)
		return
	}
	defer rows.Close()
	for rows.Next() {
		var m adminMember
		if err := rows.Scan(&m.ID, &m.Name, &m.Email, &m.Banned, &m.CreatedAt); err != nil {
			adminError(w, "users", err)
			return
		}
		d.Members = append(d.Members, m)
	}
	if err := rows.Err(); err != nil {
		adminError(w, "users", err)
		return
	}

	if d.Songs, err = a.adminSongs(r.Context()); err != nil {
		adminError(w, "songs", err)
		return
	}
	if err := a.pool.QueryRow(r.Context(),
		`select count(*)::int from reports where resolved_at is null`).Scan(&d.OpenCount); err != nil {
		adminError(w, "reports", err)
		return
	}

	a.render(w, r, http.StatusOK, "admin.html", page{Title: "Ylläpito", Admin: true, Data: d})
}

// 128 bits of entropy. The code is shown once on the dashboard and pasted to whoever is joining.
func inviteCode() string {
	b := make([]byte, 16)
	rand.Read(b)
	return hex.EncodeToString(b)
}

// The link is what actually gets sent to someone: the register form reads ?code= and prefills it,
// so the recipient clicks and fills in their name. PUBLIC_URL unset falls back to a relative path,
// which is enough locally.
func (a *app) inviteLink(code string) string {
	return a.cfg.publicURL + "/register?code=" + url.QueryEscape(code)
}

func (a *app) createInvite(w http.ResponseWriter, r *http.Request) {
	code := inviteCode()
	if _, err := a.pool.Exec(r.Context(), `insert into invites (code) values ($1)`, code); err != nil {
		adminError(w, "invites", err)
		return
	}
	slog.Info("invite minted", "ctx", "invites")
	// The dashboard lists it as a clickable link immediately below, newest first, so the flash
	// doesn't repeat the URL as unclickable text.
	a.flash(w, "Uusi kutsulinkki luotu.")
	http.Redirect(w, r, "/admin", http.StatusSeeOther)
}

// Ban is a reversible toggle. It drops live sessions immediately — checking `banned` only at login
// would leave a banned member browsing until their session expired.
func (a *app) toggleBan(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.Error(w, "not found", http.StatusNotFound)
		return
	}
	var banned bool
	err = a.pool.QueryRow(r.Context(),
		`update users set banned = not banned where id = $1 returning banned`, id).Scan(&banned)
	if err != nil {
		adminError(w, "users", err)
		return
	}
	if banned {
		if _, err := a.pool.Exec(r.Context(), `delete from sessions where user_id = $1`, id); err != nil {
			adminError(w, "users", err)
			return
		}
		a.flash(w, "Jäsen estetty.")
	} else {
		a.flash(w, "Esto poistettu.")
	}
	slog.Info("ban toggled", "ctx", "auth", "user", id, "banned", banned)
	http.Redirect(w, r, "/admin", http.StatusSeeOther)
}

// The admin reset is the only password recovery there is, so it also drops the member's sessions.
func (a *app) resetPassword(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.Error(w, "not found", http.StatusNotFound)
		return
	}
	password := r.FormValue("password")
	if password == "" {
		a.flash(w, "Salasana on pakollinen.")
		http.Redirect(w, r, "/admin", http.StatusSeeOther)
		return
	}
	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		adminError(w, "auth", err)
		return
	}
	if _, err := a.pool.Exec(r.Context(),
		`update users set password_hash = $2 where id = $1`, id, string(hash)); err != nil {
		adminError(w, "auth", err)
		return
	}
	if _, err := a.pool.Exec(r.Context(), `delete from sessions where user_id = $1`, id); err != nil {
		adminError(w, "auth", err)
		return
	}
	slog.Info("password reset by admin", "ctx", "auth", "user", id)
	a.flash(w, "Salasana vaihdettu.")
	http.Redirect(w, r, "/admin", http.StatusSeeOther)
}

func adminError(w http.ResponseWriter, ctx string, err error) {
	slog.Error("admin", "ctx", ctx, "error", err)
	http.Error(w, "virhe", http.StatusInternalServerError)
}