package authn

import (
	"fmt"
	"net/http"
	"strconv"
	"time"

	"forge.cadoles.com/Cadoles/go-proxy"
	"forge.cadoles.com/Cadoles/go-proxy/wildcard"
	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
	"forge.cadoles.com/cadoles/bouncer/internal/store"
	"github.com/expr-lang/expr"
	"github.com/gorilla/sessions"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

type Layer struct {
	layerType store.LayerType
	auth      Authenticator
	store     sessions.Store
}

func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
	return func(next http.Handler) http.Handler {
		fn := func(w http.ResponseWriter, r *http.Request) {
			ctx := r.Context()

			options, err := fromStoreOptions(layer.Options)
			if err != nil {
				logger.Error(ctx, "could not parse layer options", logger.E(errors.WithStack(err)))
				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

				return
			}

			sess, err := l.store.Get(r, options.Session.Name)
			if err != nil {
				logger.Error(ctx, "could not retrieve session", logger.E(errors.WithStack(err)))
			}

			if preAuth, ok := l.auth.(PreAuthentication); ok {
				if err := preAuth.PreAuthentication(w, r, layer, sess); err != nil {
					if errors.Is(err, ErrSkipRequest) {
						return
					}

					logger.Error(ctx, "could not execute pre-auth hook", logger.E(errors.WithStack(err)))
					http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

					return
				}
			}

			matches := wildcard.MatchAny(r.URL.String(), options.MatchURLs...)
			if !matches {
				next.ServeHTTP(w, r)

				return
			}

			user, err := l.auth.Authenticate(w, r, layer, sess)
			if err != nil {
				if errors.Is(err, ErrSkipRequest) {
					return
				}

				logger.Error(ctx, "could not authenticate user", logger.E(errors.WithStack(err)))
				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

				return
			}

			if err = l.injectHeaders(r, options, user); err != nil {
				logger.Error(ctx, "could not inject header", logger.E(errors.WithStack(err)))
				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

				return
			}

			if postAuth, ok := l.auth.(PostAuthentication); ok {
				if err := postAuth.PostAuthentication(w, r, layer, sess, user); err != nil {
					if errors.Is(err, ErrSkipRequest) {
						return
					}

					logger.Error(ctx, "could not execute post-auth hook", logger.E(errors.WithStack(err)))
					http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

					return
				}
			}

			next.ServeHTTP(w, r)
		}

		return http.HandlerFunc(fn)
	}
}

func (l *Layer) getRuleOptions(r *http.Request) []expr.Option {
	options := make([]expr.Option, 0)

	setHeader := expr.Function(
		"set_header",
		func(params ...any) (any, error) {
			name := params[0].(string)
			rawValue := params[1]

			var value string
			switch v := rawValue.(type) {
			case time.Time:
				value = strconv.FormatInt(v.UTC().Unix(), 10)
			case time.Duration:
				value = strconv.FormatInt(int64(v.Seconds()), 10)
			default:
				value = fmt.Sprintf("%v", rawValue)
			}

			r.Header.Set(name, value)

			return true, nil
		},
		new(func(string, string) bool),
	)

	options = append(options, setHeader)

	delHeaders := expr.Function(
		"del_headers",
		func(params ...any) (any, error) {
			pattern := params[0].(string)
			deleted := false

			for key := range r.Header {
				if !wildcard.Match(key, pattern) {
					continue
				}

				r.Header.Del(key)
				deleted = true
			}

			return deleted, nil
		},
		new(func(string) bool),
	)

	options = append(options, delHeaders)

	return options
}

func (l *Layer) injectHeaders(r *http.Request, options *LayerOptions, user *User) error {
	rules := options.Headers.Rules
	if len(rules) == 0 {
		return nil
	}

	env := map[string]any{
		"user": user,
	}

	rulesOptions := l.getRuleOptions(r)

	for i, r := range rules {
		program, err := expr.Compile(r, rulesOptions...)
		if err != nil {
			return errors.Wrapf(err, "could not compile header rule #%d", i)
		}

		if _, err := expr.Run(program, env); err != nil {
			return errors.Wrapf(err, "could not execute header rule #%d", i)
		}
	}

	return nil
}

// LayerType implements director.MiddlewareLayer
func (l *Layer) LayerType() store.LayerType {
	return l.layerType
}

func NewLayer(layerType store.LayerType, auth Authenticator, adapter StoreAdapter) *Layer {
	return &Layer{
		layerType: layerType,
		auth:      auth,
		store:     NewStore(adapter),
	}
}

var _ director.MiddlewareLayer = &Layer{}