package auth

import (
	"database/sql"
	"errors"
	"net/http"
	"strings"

	"gitea.parodia.dev/drwily/petal/internal/db"
	"gitea.parodia.dev/drwily/petal/internal/httputil"
)

// UserStore provisions and reads accounts. Petal has no signup flow: a row
// appears the first time someone Authentik vouches for signs in, and that is
// the only way one is ever created.
type UserStore struct {
	db *sql.DB
}

// NewUserStore returns a store backed by the given database.
func NewUserStore(sqlDB *sql.DB) *UserStore { return &UserStore{db: sqlDB} }

// Upsert records the account behind an OIDC login, keyed by the issuer's
// subject id.
//
// The subject is the id — not the email, which people change and which
// Authentik does not promise is stable. Email and display name are refreshed on
// every login so a rename upstream shows up here; pair_lang is deliberately not
// touched, because it is Petal's own setting rather than the IdP's.
func (u *UserStore) Upsert(sub, email, displayName string) error {
	if sub == "" {
		return errors.New("oidc: empty subject")
	}
	if displayName == "" {
		displayName = email
	}
	_, err := u.db.Exec(
		`INSERT INTO users (id, email, display_name) VALUES (?, ?, ?)
		 ON CONFLICT(id) DO UPDATE SET
		     email        = excluded.email,
		     display_name = excluded.display_name`,
		sub, email, displayName,
	)
	return err
}

// Get loads one account.
func (u *UserStore) Get(id string) (db.User, error) {
	var user db.User
	err := u.db.QueryRow(
		`SELECT id, email, COALESCE(display_name, ''), created_at, pair_lang
		   FROM users WHERE id = ?`, id,
	).Scan(&user.ID, &user.Email, &user.DisplayName, &user.CreatedAt, &user.PairLang)
	return user, err
}

// MeHandler reports who the caller is. The frontend uses it to namespace
// per-account browser state and to show the signed-in writer; it sits behind
// the auth middleware, so reaching it at all already proves a valid session.
func (u *UserStore) MeHandler() http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		user, err := u.Get(UserID(r.Context()))
		if err != nil {
			httputil.ErrorJSON(w, http.StatusUnauthorized, "not signed in")
			return
		}
		httputil.WriteJSON(w, http.StatusOK, user)
	}
}

// Allowlist decides which of Authentik's users may write in this Petal.
// Authentik fronts several applications; being a valid user there does not mean
// being a user here.
//
// An entry matches a subject id or an email address, case-insensitively. Both
// are accepted on purpose: a subject is an opaque uuid nobody can know before
// that person's first login, so a subject-only list means the operator must let
// someone in, read a log line, and edit config — whereas an email is knowable in
// advance. An empty list allows everyone the IdP authenticates, which is the
// right default for a single-household instance.
type Allowlist map[string]bool

// ParseAllowlist builds an Allowlist from a comma-separated env value.
func ParseAllowlist(raw string) Allowlist {
	list := Allowlist{}
	for _, part := range strings.Split(raw, ",") {
		if p := strings.ToLower(strings.TrimSpace(part)); p != "" {
			list[p] = true
		}
	}
	return list
}

// Permits reports whether this login may proceed.
func (a Allowlist) Permits(sub, email string) bool {
	if len(a) == 0 {
		return true
	}
	return a[strings.ToLower(sub)] || (email != "" && a[strings.ToLower(email)])
}