package authn

import (
	"bytes"
	"html/template"
	"io"
	"net/http"
	"path/filepath"

	"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/proxy/director/layer/util"
	"forge.cadoles.com/cadoles/bouncer/internal/rule"
	ruleHTTP "forge.cadoles.com/cadoles/bouncer/internal/rule/http"
	"forge.cadoles.com/cadoles/bouncer/internal/store"
	"github.com/Masterminds/sprig/v3"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

type Layer struct {
	layerType store.LayerType
	auth      Authenticator
	debug     bool

	ruleEngineCache *util.RuleEngineCache[*Vars, *LayerOptions]

	templateDir string
}

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 {
				director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not parse layer options"))
				return
			}

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

					err = errors.WithStack(err)
					logger.Error(ctx, "could not execute pre-auth hook", logger.CapturedE(err))
					l.renderErrorPage(w, r, layer, options, err)

					return
				}
			}

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

				return
			}

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

				if errors.Is(err, ErrForbidden) {
					l.renderForbiddenPage(w, r, layer, options, user)
					return
				}

				err = errors.WithStack(err)
				logger.Error(ctx, "could not authenticate user", logger.CapturedE(err))
				l.renderErrorPage(w, r, layer, options, err)

				return
			}

			if err := l.applyRules(ctx, r, layer, options, user); err != nil {
				if errors.Is(err, ErrForbidden) {
					l.renderForbiddenPage(w, r, layer, options, user)
					return
				}

				err = errors.WithStack(err)
				logger.Error(ctx, "could not apply rules", logger.CapturedE(err))
				l.renderErrorPage(w, r, layer, options, err)

				return
			}

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

					if errors.Is(err, ErrForbidden) {
						l.renderForbiddenPage(w, r, layer, options, user)
						return
					}

					err = errors.WithStack(err)
					logger.Error(ctx, "could not execute post-auth hook", logger.CapturedE(err))
					l.renderErrorPage(w, r, layer, options, err)

					return
				}
			}

			next.ServeHTTP(w, r)
		}

		return http.HandlerFunc(fn)
	}
}

type baseTemplateData struct {
	Layer   *store.Layer
	Debug   bool
	Request *http.Request
}

func (l *Layer) renderForbiddenPage(w http.ResponseWriter, r *http.Request, layer *store.Layer, options *LayerOptions, user *User) {
	templateData := struct {
		baseTemplateData
		User *User
	}{
		baseTemplateData: baseTemplateData{
			Layer:   layer,
			Debug:   l.debug,
			Request: r,
		},
		User: user,
	}

	w.WriteHeader(http.StatusForbidden)
	l.renderPage(w, r, "forbidden", options.Templates.Forbidden.Block, templateData)
}

func (l *Layer) renderErrorPage(w http.ResponseWriter, r *http.Request, layer *store.Layer, options *LayerOptions, err error) {
	templateData := struct {
		baseTemplateData
		Err error
	}{
		baseTemplateData: baseTemplateData{
			Layer:   layer,
			Debug:   l.debug,
			Request: r,
		},
		Err: err,
	}

	w.WriteHeader(http.StatusInternalServerError)
	l.renderPage(w, r, "error", options.Templates.Error.Block, templateData)
}

func (l *Layer) renderPage(w http.ResponseWriter, r *http.Request, page string, block string, templateData any) {
	ctx := r.Context()

	pattern := filepath.Join(l.templateDir, page+".gohtml")

	logger.Info(ctx, "loading authn templates", logger.F("pattern", pattern))

	tmpl, err := template.New("").Funcs(sprig.FuncMap()).ParseGlob(pattern)
	if err != nil {
		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not load authn templates"))
		return
	}

	w.Header().Add("Cache-Control", "no-cache")

	var buf bytes.Buffer

	if err := tmpl.ExecuteTemplate(w, block, templateData); err != nil {
		director.HandleError(ctx, w, r, http.StatusInternalServerError, errors.Wrap(err, "could not render authn page"))
		return
	}

	if _, err := io.Copy(w, &buf); err != nil {
		logger.Error(ctx, "could not write authn page", logger.CapturedE(errors.WithStack(err)))
	}
}

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

func NewLayer(layerType store.LayerType, auth Authenticator, funcs ...OptionFunc) *Layer {
	opts := NewOptions(funcs...)

	return &Layer{
		ruleEngineCache: util.NewInMemoryRuleEngineCache[*Vars, *LayerOptions](func(options *LayerOptions) (*rule.Engine[*Vars], error) {
			engine, err := rule.NewEngine[*Vars](
				rule.WithRules(options.Rules...),
				rule.WithExpr(getAuthnAPI()...),
				ruleHTTP.WithRequestFuncs(),
			)
			if err != nil {
				return nil, errors.WithStack(err)
			}

			return engine, nil
		}),
		layerType:   layerType,
		auth:        auth,
		templateDir: opts.TemplateDir,
		debug:       opts.Debug,
	}
}

var _ director.MiddlewareLayer = &Layer{}