package hws

import (
	"errors"
	"fmt"
	"net/http"
	"slices"
)

type Route struct {
	Path   string // Absolute path to the requested resource
	Method Method // HTTP Method
	// Methods is an optional slice of Methods to use, if more than one can use the same handler.
	// Will take precedence over the Method field if provided
	Methods []Method
	Handler http.Handler // Handler to use for the request
}

type Method string

const (
	MethodGET     Method = "GET"
	MethodPOST    Method = "POST"
	MethodPUT     Method = "PUT"
	MethodHEAD    Method = "HEAD"
	MethodDELETE  Method = "DELETE"
	MethodCONNECT Method = "CONNECT"
	MethodOPTIONS Method = "OPTIONS"
	MethodTRACE   Method = "TRACE"
	MethodPATCH   Method = "PATCH"
)

// AddRoutes registers the page handlers for the server.
// At least one route must be provided.
// If any route patterns (path + method) are defined multiple times, the first
// instance will be added and any additional conflicts will be discarded.
func (s *Server) AddRoutes(routes ...Route) error {
	if len(routes) == 0 {
		return errors.New("no routes provided")
	}
	patterns := []string{}
	mux := http.NewServeMux()
	mux.HandleFunc("GET /healthz", func(http.ResponseWriter, *http.Request) {})
	for _, route := range routes {
		if len(route.Methods) == 0 {
			route.Methods = []Method{route.Method}
		}
		for _, method := range route.Methods {
			if !validMethod(method) {
				return fmt.Errorf("invalid method %s for path %s", method, route.Path)
			}
			if route.Handler == nil {
				return fmt.Errorf("no handler provided for %s %s", method, route.Path)
			}
			pattern := fmt.Sprintf("%s %s", method, route.Path)
			if slices.Contains(patterns, pattern) {
				continue
			}
			patterns = append(patterns, pattern)
			mux.Handle(pattern, route.Handler)
		}
	}

	s.server.Handler = mux
	s.routes = true

	return nil
}

func validMethod(m Method) bool {
	switch m {
	case MethodGET, MethodPOST, MethodPUT, MethodHEAD,
		MethodDELETE, MethodCONNECT, MethodOPTIONS, MethodTRACE, MethodPATCH:
		return true
	default:
		return false
	}
}