package classes

import (
	"context"
	"errors"
	"fmt"
	"log/slog"
	"net/http"
	"strconv"
	"strings"
	"time"

	"git.golem15.com/golem15/sm-user-plugin/models"
	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/bouncer"
	"gorm.io/gorm"
)

// sessionCookieNames are the cookies the plugin's "jwt" guard reads after
// the Authorization header, in the same order (plugin.go Boot).
var sessionCookieNames = []string{"token", "auth_token"}

// RequestUser returns the signed-in user of r for handlers that run without
// the jwt.auth middleware and must also serve anonymous requests (an OAuth
// provider's authorize page, for example). The token is read and checked
// exactly as the plugin's "jwt" guard does: the Authorization bearer header
// first, then the token and auth_token cookies; the plugin's JWT secret;
// the published bouncer.BlacklistStore when there is one; and the user's
// tokens_valid_after cutoff. A soft-deleted user is not returned.
//
// An anonymous request, or a token that is invalid, expired, blacklisted or
// names no user, returns (nil, nil). Only an infrastructure failure (no
// database handle, a failing query or blacklist lookup) returns an error.
func RequestUser(ctx context.Context, app *backpack.App, r *http.Request) (*models.User, error) {
	if r == nil {
		return nil, nil
	}
	raw := sessionToken(r)
	if raw == "" {
		return nil, nil
	}
	secret, err := JWTSecret(app)
	if err != nil {
		return nil, err
	}
	sub, iat, _, jti, err := bouncer.VerifyClaims(raw, secret)
	if err != nil {
		return nil, nil
	}
	id, err := strconv.ParseUint(sub, 10, 64)
	if err != nil || id == 0 {
		return nil, nil
	}
	gdb, ok := app.Lookup[*gorm.DB]()
	if !ok || gdb == nil {
		return nil, fmt.Errorf("golem15.user: gorm handle is missing")
	}
	var user models.User
	err = gdb.WithContext(ctx).Where("id = ?", uint(id)).Take(&user).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	if bl, ok := app.Lookup[bouncer.BlacklistStore](); ok && bl != nil {
		blocked, err := bl.IsBlacklisted(ctx, jti)
		if err != nil {
			return nil, err
		}
		if blocked {
			return nil, nil
		}
	}
	if user.TokensValidAfter != nil && iat.Before(*user.TokensValidAfter) {
		return nil, nil
	}
	return &user, nil
}

// EndRequestSession signs the request's user out the way Logout does and
// forgets the token cookie. When r carries a valid session JWT its jti is
// added to the published bouncer.BlacklistStore until the token expires;
// the response always gets the forget cookie of
// bouncer.LoadCookieConfig(app.Config), so its Domain and Path match the
// cookie the login wrote. It is best effort, as in the PHP provider: a
// blacklist failure is logged and never returned, and the function writes
// no status or body.
func EndRequestSession(ctx context.Context, app *backpack.App, w http.ResponseWriter, r *http.Request) error {
	if r != nil {
		if raw := sessionToken(r); raw != "" {
			revokeSessionToken(ctx, app, raw)
		}
	}
	if w == nil {
		return nil
	}
	cfg := bouncer.CookieConfig{Name: bouncer.DefaultCookieName, Path: "/", SameSite: http.SameSiteLaxMode}
	if app != nil && app.Config != nil {
		loaded, err := bouncer.LoadCookieConfig(app.Config)
		if err != nil {
			slog.Default().Warn("golem15.user: end session: cookie config", "err", err)
		} else {
			cfg = loaded
		}
	}
	http.SetCookie(w, cfg.ForgetTokenCookie())
	return nil
}

// revokeSessionToken blacklists raw's jti until its expiry (best effort).
func revokeSessionToken(ctx context.Context, app *backpack.App, raw string) {
	if app == nil {
		return
	}
	secret, err := JWTSecret(app)
	if err != nil {
		return
	}
	_, _, exp, jti, err := bouncer.VerifyClaims(raw, secret)
	if err != nil || jti == "" {
		return
	}
	bl, ok := app.Lookup[bouncer.BlacklistStore]()
	if !ok || bl == nil {
		return
	}
	if err := bl.Add(ctx, jti, exp, time.Now()); err != nil {
		slog.Default().Warn("golem15.user: end session: blacklist token", "err", err)
	}
}

// sessionToken extracts the session JWT as the "jwt" guard does: the
// Authorization bearer header, then each session cookie in order.
func sessionToken(r *http.Request) string {
	h := strings.TrimSpace(r.Header.Get("Authorization"))
	if token, ok := strings.CutPrefix(h, "Bearer "); ok {
		if token = strings.TrimSpace(token); token != "" {
			return token
		}
	}
	for _, name := range sessionCookieNames {
		c, err := r.Cookie(name)
		if err != nil {
			continue
		}
		if v := strings.TrimSpace(c.Value); v != "" {
			return v
		}
	}
	return ""
}