capstan/router_utils.go

package capstan

import (
	"strings"
)

// ParseRoute processes the specified route, processes it, and returns a
// routeProps struct describing the route using go-chi syntax.
//
// Route parsing is somewhat analogous to go-chi but uses a different syntax. In
// particular, route variables are delineated by "<" and ">" rather than "{" and
// "}" as per go-chi. Further, besides regex types, Capstan routes also define
// string, float, float32, float64, int, int32, and int64 types. Route syntax
// is:
//
// String:
//
// /<varname:string>
//
// Integer types:
//
// /<varname:int32>
//
// Regular expressions:
//
// /<varname:regex>
func (r *Router) ParseRoute(route string) *routeProps {
	props := &routeProps{
		params: make(map[string]string),
	}

	if route == "" {
		route = "/"
	}

	if route == "/" {
		props.route = "/"
		props.baseRoute = "/"
		props.slashIsDefault = true
		props.optionalSlash = true
		return props
	}

	if route[len(route)-1:] == "/" {
		props.mandatorySlash = true
	} else if strings.HasSuffix(route, "?") {
		props.optionalSlash = true
		if len(route) >= 2 && route[len(route)-2:] == "/?" {
			props.slashIsDefault = true
		}
		route = route[:len(route)-1]
	} else if strings.HasSuffix(route, "!") {
		props.mandatoryNoSlash = true
		if len(route) >= 2 && route[len(route)-2:] != "/!" {
			route = route[:len(route)-1] + "/"
		} else {
			route = route[:len(route)-1]
		}
	} else if strings.HasSuffix(route, "+") {
		props.mandatorySlash = true
		// Accept routes with just a + suffix, e.g. "/route+".
		if len(route) >= 2 && route[len(route)-2:] != "/+" {
			route = route[:len(route)-1] + "/"
		} else {
			route = route[:len(route)-1]
		}
	} else {
		props.optionalSlash = true
	}

	open := 0
	param := ""
	paramType := ""
	colon := false
	base := true
	for _, c := range route {
		if open == 0 && c == '/' {
			props.route += string(c)
			if base {
				props.baseRoute += string(c)
			}
			continue
		}

		if c == '<' {
			base = false
			open++
			if open == 1 {
				props.route += "{"
				continue
			}
		} else if c == '>' {
			open--
			if open == 0 {
				props.params[param] = paramType
				switch paramType {
				case "string":
				case "float":
				case "float32":
				case "float64":
				case "int":
				case "int32":
				case "int64":
				case "integer":
				default:
					// Most likely a regex type.
					props.route += ":" + paramType
				}
				props.route += "}"

				colon = false
				param = ""
				paramType = ""
				continue
			}
		} else {
			if open == 0 && c != '?' {
				props.route += string(c)
			}
		}

		if open == 1 && c == ':' {
			colon = true
			continue
		}

		if open == 1 {
			if !colon {
				param += string(c)
				props.route += string(c)
			} else {
				paramType += string(c)
			}
		}

		if open > 1 {
			paramType += string(c)
		}

		if base {
			props.baseRoute += string(c)
		}
	}

	if open >= 1 {
		// TODO: Handle error.
	}

	return props
}