/*
Package echo implements high performance, minimalist Go web framework.

Example:

	package main

	import (
	  "net/http"

	  "github.com/labstack/echo/v4"
	  "github.com/labstack/echo/v4/middleware"
	)

	// Handler
	func hello(c echo.Context) error {
	  return c.String(http.StatusOK, "Hello, World!")
	}

	func main() {
	  // Echo instance
	  e := echo.New()

	  // Middleware
	  e.Use(middleware.Logger())
	  e.Use(middleware.Recover())

	  // Routes
	  e.GET("/", hello)

	  // Start server
	  e.Logger.Fatal(e.Start(":1323"))
	}

Learn more at https://echo.labstack.com
*/
package echo

import (
	stdContext "context"
	"crypto/tls"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	stdLog "log"
	"net"
	"net/http"
	"os"
	"reflect"
	"runtime"
	"sync"
	"time"

	"github.com/labstack/gommon/color"
	"github.com/labstack/gommon/log"
	"golang.org/x/crypto/acme"
	"golang.org/x/crypto/acme/autocert"
	"golang.org/x/net/http2"
	"golang.org/x/net/http2/h2c"
)

type (
	// Echo is the top-level framework instance.
	//
	// Goroutine safety: Do not mutate Echo instance fields after server has started. Accessing these
	// fields from handlers/middlewares and changing field values at the same time leads to data-races.
	// Adding new routes after the server has been started is also not safe!
	Echo struct {
		filesystem
		common
		// startupMutex is mutex to lock Echo instance access during server configuration and startup. Useful for to get
		// listener address info (on which interface/port was listener binded) without having data races.
		startupMutex sync.RWMutex
		colorer      *color.Color

		// premiddleware are middlewares that are run before routing is done. In case a pre-middleware returns
		// an error the router is not executed and the request will end up in the global error handler.
		premiddleware []MiddlewareFunc
		middleware    []MiddlewareFunc
		maxParam      *int
		router        *Router
		routers       map[string]*Router
		pool          sync.Pool

		StdLogger        *stdLog.Logger
		Server           *http.Server
		TLSServer        *http.Server
		Listener         net.Listener
		TLSListener      net.Listener
		AutoTLSManager   autocert.Manager
		DisableHTTP2     bool
		Debug            bool
		HideBanner       bool
		HidePort         bool
		HTTPErrorHandler HTTPErrorHandler
		Binder           Binder
		JSONSerializer   JSONSerializer
		Validator        Validator
		Renderer         Renderer
		Logger           Logger
		IPExtractor      IPExtractor
		ListenerNetwork  string

		// OnAddRouteHandler is called when Echo adds new route to specific host router.
		OnAddRouteHandler func(host string, route Route, handler HandlerFunc, middleware []MiddlewareFunc)
	}

	// Route contains a handler and information for matching against requests.
	Route struct {
		Method string `json:"method"`
		Path   string `json:"path"`
		Name   string `json:"name"`
	}

	// HTTPError represents an error that occurred while handling a request.
	HTTPError struct {
		Code     int         `json:"-"`
		Message  interface{} `json:"message"`
		Internal error       `json:"-"` // Stores the error returned by an external dependency
	}

	// MiddlewareFunc defines a function to process middleware.
	MiddlewareFunc func(next HandlerFunc) HandlerFunc

	// HandlerFunc defines a function to serve HTTP requests.
	HandlerFunc func(c Context) error

	// HTTPErrorHandler is a centralized HTTP error handler.
	HTTPErrorHandler func(err error, c Context)

	// Validator is the interface that wraps the Validate function.
	Validator interface {
		Validate(i interface{}) error
	}

	// JSONSerializer is the interface that encodes and decodes JSON to and from interfaces.
	JSONSerializer interface {
		Serialize(c Context, i interface{}, indent string) error
		Deserialize(c Context, i interface{}) error
	}

	// Renderer is the interface that wraps the Render function.
	Renderer interface {
		Render(io.Writer, string, interface{}, Context) error
	}

	// Map defines a generic map of type `map[string]interface{}`.
	Map map[string]interface{}

	// Common struct for Echo & Group.
	common struct{}
)

// HTTP methods
// NOTE: Deprecated, please use the stdlib constants directly instead.
const (
	CONNECT = http.MethodConnect
	DELETE  = http.MethodDelete
	GET     = http.MethodGet
	HEAD    = http.MethodHead
	OPTIONS = http.MethodOptions
	PATCH   = http.MethodPatch
	POST    = http.MethodPost
	// PROPFIND = "PROPFIND"
	PUT   = http.MethodPut
	TRACE = http.MethodTrace
)

// MIME types
const (
	MIMEApplicationJSON                  = "application/json"
	MIMEApplicationJSONCharsetUTF8       = MIMEApplicationJSON + "; " + charsetUTF8
	MIMEApplicationJavaScript            = "application/javascript"
	MIMEApplicationJavaScriptCharsetUTF8 = MIMEApplicationJavaScript + "; " + charsetUTF8
	MIMEApplicationXML                   = "application/xml"
	MIMEApplicationXMLCharsetUTF8        = MIMEApplicationXML + "; " + charsetUTF8
	MIMETextXML                          = "text/xml"
	MIMETextXMLCharsetUTF8               = MIMETextXML + "; " + charsetUTF8
	MIMEApplicationForm                  = "application/x-www-form-urlencoded"
	MIMEApplicationProtobuf              = "application/protobuf"
	MIMEApplicationMsgpack               = "application/msgpack"
	MIMETextHTML                         = "text/html"
	MIMETextHTMLCharsetUTF8              = MIMETextHTML + "; " + charsetUTF8
	MIMETextPlain                        = "text/plain"
	MIMETextPlainCharsetUTF8             = MIMETextPlain + "; " + charsetUTF8
	MIMEMultipartForm                    = "multipart/form-data"
	MIMEOctetStream                      = "application/octet-stream"
)

const (
	charsetUTF8 = "charset=UTF-8"
	// PROPFIND Method can be used on collection and property resources.
	PROPFIND = "PROPFIND"
	// REPORT Method can be used to get information about a resource, see rfc 3253
	REPORT = "REPORT"
	// RouteNotFound is special method type for routes handling "route not found" (404) cases
	RouteNotFound = "echo_route_not_found"
)

// Headers
const (
	HeaderAccept         = "Accept"
	HeaderAcceptEncoding = "Accept-Encoding"
	// HeaderAllow is the name of the "Allow" header field used to list the set of methods
	// advertised as supported by the target resource. Returning an Allow header is mandatory
	// for status 405 (method not found) and useful for the OPTIONS method in responses.
	// See RFC 7231: https://datatracker.ietf.org/doc/html/rfc7231#section-7.4.1
	HeaderAllow               = "Allow"
	HeaderAuthorization       = "Authorization"
	HeaderContentDisposition  = "Content-Disposition"
	HeaderContentEncoding     = "Content-Encoding"
	HeaderContentLength       = "Content-Length"
	HeaderContentType         = "Content-Type"
	HeaderCookie              = "Cookie"
	HeaderSetCookie           = "Set-Cookie"
	HeaderIfModifiedSince     = "If-Modified-Since"
	HeaderLastModified        = "Last-Modified"
	HeaderLocation            = "Location"
	HeaderRetryAfter          = "Retry-After"
	HeaderUpgrade             = "Upgrade"
	HeaderVary                = "Vary"
	HeaderWWWAuthenticate     = "WWW-Authenticate"
	HeaderXForwardedFor       = "X-Forwarded-For"
	HeaderXForwardedProto     = "X-Forwarded-Proto"
	HeaderXForwardedProtocol  = "X-Forwarded-Protocol"
	HeaderXForwardedSsl       = "X-Forwarded-Ssl"
	HeaderXUrlScheme          = "X-Url-Scheme"
	HeaderXHTTPMethodOverride = "X-HTTP-Method-Override"
	HeaderXRealIP             = "X-Real-Ip"
	HeaderXRequestID          = "X-Request-Id"
	HeaderXCorrelationID      = "X-Correlation-Id"
	HeaderXRequestedWith      = "X-Requested-With"
	HeaderServer              = "Server"
	HeaderOrigin              = "Origin"
	HeaderCacheControl        = "Cache-Control"
	HeaderConnection          = "Connection"

	// Access control
	HeaderAccessControlRequestMethod    = "Access-Control-Request-Method"
	HeaderAccessControlRequestHeaders   = "Access-Control-Request-Headers"
	HeaderAccessControlAllowOrigin      = "Access-Control-Allow-Origin"
	HeaderAccessControlAllowMethods     = "Access-Control-Allow-Methods"
	HeaderAccessControlAllowHeaders     = "Access-Control-Allow-Headers"
	HeaderAccessControlAllowCredentials = "Access-Control-Allow-Credentials"
	HeaderAccessControlExposeHeaders    = "Access-Control-Expose-Headers"
	HeaderAccessControlMaxAge           = "Access-Control-Max-Age"

	// Security
	HeaderStrictTransportSecurity         = "Strict-Transport-Security"
	HeaderXContentTypeOptions             = "X-Content-Type-Options"
	HeaderXXSSProtection                  = "X-XSS-Protection"
	HeaderXFrameOptions                   = "X-Frame-Options"
	HeaderContentSecurityPolicy           = "Content-Security-Policy"
	HeaderContentSecurityPolicyReportOnly = "Content-Security-Policy-Report-Only"
	HeaderXCSRFToken                      = "X-CSRF-Token"
	HeaderReferrerPolicy                  = "Referrer-Policy"
)

const (
	// Version of Echo
	Version = "4.11.1"
	website = "https://echo.labstack.com"
	// http://patorjk.com/software/taag/#p=display&f=Small%20Slant&t=Echo
	banner = `
   ____    __
  / __/___/ /  ___
 / _// __/ _ \/ _ \
/___/\__/_//_/\___/ %s
High performance, minimalist Go web framework
%s
____________________________________O/_______
                                    O\
`
)

var (
	methods = [...]string{
		http.MethodConnect,
		http.MethodDelete,
		http.MethodGet,
		http.MethodHead,
		http.MethodOptions,
		http.MethodPatch,
		http.MethodPost,
		PROPFIND,
		http.MethodPut,
		http.MethodTrace,
		REPORT,
	}
)

// Errors
var (
	ErrBadRequest                    = NewHTTPError(http.StatusBadRequest)                    // HTTP 400 Bad Request
	ErrUnauthorized                  = NewHTTPError(http.StatusUnauthorized)                  // HTTP 401 Unauthorized
	ErrPaymentRequired               = NewHTTPError(http.StatusPaymentRequired)               // HTTP 402 Payment Required
	ErrForbidden                     = NewHTTPError(http.StatusForbidden)                     // HTTP 403 Forbidden
	ErrNotFound                      = NewHTTPError(http.StatusNotFound)                      // HTTP 404 Not Found
	ErrMethodNotAllowed              = NewHTTPError(http.StatusMethodNotAllowed)              // HTTP 405 Method Not Allowed
	ErrNotAcceptable                 = NewHTTPError(http.StatusNotAcceptable)                 // HTTP 406 Not Acceptable
	ErrProxyAuthRequired             = NewHTTPError(http.StatusProxyAuthRequired)             // HTTP 407 Proxy AuthRequired
	ErrRequestTimeout                = NewHTTPError(http.StatusRequestTimeout)                // HTTP 408 Request Timeout
	ErrConflict                      = NewHTTPError(http.StatusConflict)                      // HTTP 409 Conflict
	ErrGone                          = NewHTTPError(http.StatusGone)                          // HTTP 410 Gone
	ErrLengthRequired                = NewHTTPError(http.StatusLengthRequired)                // HTTP 411 Length Required
	ErrPreconditionFailed            = NewHTTPError(http.StatusPreconditionFailed)            // HTTP 412 Precondition Failed
	ErrStatusRequestEntityTooLarge   = NewHTTPError(http.StatusRequestEntityTooLarge)         // HTTP 413 Payload Too Large
	ErrRequestURITooLong             = NewHTTPError(http.StatusRequestURITooLong)             // HTTP 414 URI Too Long
	ErrUnsupportedMediaType          = NewHTTPError(http.StatusUnsupportedMediaType)          // HTTP 415 Unsupported Media Type
	ErrRequestedRangeNotSatisfiable  = NewHTTPError(http.StatusRequestedRangeNotSatisfiable)  // HTTP 416 Range Not Satisfiable
	ErrExpectationFailed             = NewHTTPError(http.StatusExpectationFailed)             // HTTP 417 Expectation Failed
	ErrTeapot                        = NewHTTPError(http.StatusTeapot)                        // HTTP 418 I'm a teapot
	ErrMisdirectedRequest            = NewHTTPError(http.StatusMisdirectedRequest)            // HTTP 421 Misdirected Request
	ErrUnprocessableEntity           = NewHTTPError(http.StatusUnprocessableEntity)           // HTTP 422 Unprocessable Entity
	ErrLocked                        = NewHTTPError(http.StatusLocked)                        // HTTP 423 Locked
	ErrFailedDependency              = NewHTTPError(http.StatusFailedDependency)              // HTTP 424 Failed Dependency
	ErrTooEarly                      = NewHTTPError(http.StatusTooEarly)                      // HTTP 425 Too Early
	ErrUpgradeRequired               = NewHTTPError(http.StatusUpgradeRequired)               // HTTP 426 Upgrade Required
	ErrPreconditionRequired          = NewHTTPError(http.StatusPreconditionRequired)          // HTTP 428 Precondition Required
	ErrTooManyRequests               = NewHTTPError(http.StatusTooManyRequests)               // HTTP 429 Too Many Requests
	ErrRequestHeaderFieldsTooLarge   = NewHTTPError(http.StatusRequestHeaderFieldsTooLarge)   // HTTP 431 Request Header Fields Too Large
	ErrUnavailableForLegalReasons    = NewHTTPError(http.StatusUnavailableForLegalReasons)    // HTTP 451 Unavailable For Legal Reasons
	ErrInternalServerError           = NewHTTPError(http.StatusInternalServerError)           // HTTP 500 Internal Server Error
	ErrNotImplemented                = NewHTTPError(http.StatusNotImplemented)                // HTTP 501 Not Implemented
	ErrBadGateway                    = NewHTTPError(http.StatusBadGateway)                    // HTTP 502 Bad Gateway
	ErrServiceUnavailable            = NewHTTPError(http.StatusServiceUnavailable)            // HTTP 503 Service Unavailable
	ErrGatewayTimeout                = NewHTTPError(http.StatusGatewayTimeout)                // HTTP 504 Gateway Timeout
	ErrHTTPVersionNotSupported       = NewHTTPError(http.StatusHTTPVersionNotSupported)       // HTTP 505 HTTP Version Not Supported
	ErrVariantAlsoNegotiates         = NewHTTPError(http.StatusVariantAlsoNegotiates)         // HTTP 506 Variant Also Negotiates
	ErrInsufficientStorage           = NewHTTPError(http.StatusInsufficientStorage)           // HTTP 507 Insufficient Storage
	ErrLoopDetected                  = NewHTTPError(http.StatusLoopDetected)                  // HTTP 508 Loop Detected
	ErrNotExtended                   = NewHTTPError(http.StatusNotExtended)                   // HTTP 510 Not Extended
	ErrNetworkAuthenticationRequired = NewHTTPError(http.StatusNetworkAuthenticationRequired) // HTTP 511 Network Authentication Required

	ErrValidatorNotRegistered = errors.New("validator not registered")
	ErrRendererNotRegistered  = errors.New("renderer not registered")
	ErrInvalidRedirectCode    = errors.New("invalid redirect status code")
	ErrCookieNotFound         = errors.New("cookie not found")
	ErrInvalidCertOrKeyType   = errors.New("invalid cert or key type, must be string or []byte")
	ErrInvalidListenerNetwork = errors.New("invalid listener network")
)

// Error handlers
var (
	NotFoundHandler = func(c Context) error {
		return ErrNotFound
	}

	MethodNotAllowedHandler = func(c Context) error {
		// See RFC 7231 section 7.4.1: An origin server MUST generate an Allow field in a 405 (Method Not Allowed)
		// response and MAY do so in any other response. For disabled resources an empty Allow header may be returned
		routerAllowMethods, ok := c.Get(ContextKeyHeaderAllow).(string)
		if ok && routerAllowMethods != "" {
			c.Response().Header().Set(HeaderAllow, routerAllowMethods)
		}
		return ErrMethodNotAllowed
	}
)

// New creates an instance of Echo.
func New() (e *Echo) {
	e = &Echo{
		filesystem: createFilesystem(),
		Server:     new(http.Server),
		TLSServer:  new(http.Server),
		AutoTLSManager: autocert.Manager{
			Prompt: autocert.AcceptTOS,
		},
		Logger:          log.New("echo"),
		colorer:         color.New(),
		maxParam:        new(int),
		ListenerNetwork: "tcp",
	}
	e.Server.Handler = e
	e.TLSServer.Handler = e
	e.HTTPErrorHandler = e.DefaultHTTPErrorHandler
	e.Binder = &DefaultBinder{}
	e.JSONSerializer = &DefaultJSONSerializer{}
	e.Logger.SetLevel(log.ERROR)
	e.StdLogger = stdLog.New(e.Logger.Output(), e.Logger.Prefix()+": ", 0)
	e.pool.New = func() interface{} {
		return e.NewContext(nil, nil)
	}
	e.router = NewRouter(e)
	e.routers = map[string]*Router{}
	return
}

// NewContext returns a Context instance.
func (e *Echo) NewContext(r *http.Request, w http.ResponseWriter) Context {
	return &context{
		request:  r,
		response: NewResponse(w, e),
		store:    make(Map),
		echo:     e,
		pvalues:  make([]string, *e.maxParam),
		handler:  NotFoundHandler,
	}
}

// Router returns the default router.
func (e *Echo) Router() *Router {
	return e.router
}

// Routers returns the map of host => router.
func (e *Echo) Routers() map[string]*Router {
	return e.routers
}

// DefaultHTTPErrorHandler is the default HTTP error handler. It sends a JSON response
// with status code.
//
// NOTE: In case errors happens in middleware call-chain that is returning from handler (which did not return an error).
// When handler has already sent response (ala c.JSON()) and there is error in middleware that is returning from
// handler. Then the error that global error handler received will be ignored because we have already "commited" the
// response and status code header has been sent to the client.
func (e *Echo) DefaultHTTPErrorHandler(err error, c Context) {

	if c.Response().Committed {
		return
	}

	he, ok := err.(*HTTPError)
	if ok {
		if he.Internal != nil {
			if herr, ok := he.Internal.(*HTTPError); ok {
				he = herr
			}
		}
	} else {
		he = &HTTPError{
			Code:    http.StatusInternalServerError,
			Message: http.StatusText(http.StatusInternalServerError),
		}
	}

	// Issue #1426
	code := he.Code
	message := he.Message

	switch m := he.Message.(type) {
	case string:
		if e.Debug {
			message = Map{"message": m, "error": err.Error()}
		} else {
			message = Map{"message": m}
		}
	case json.Marshaler:
		// do nothing - this type knows how to format itself to JSON
	case error:
		message = Map{"message": m.Error()}
	}

	// Send response
	if c.Request().Method == http.MethodHead { // Issue #608
		err = c.NoContent(he.Code)
	} else {
		err = c.JSON(code, message)
	}
	if err != nil {
		e.Logger.Error(err)
	}
}

// Pre adds middleware to the chain which is run before router.
func (e *Echo) Pre(middleware ...MiddlewareFunc) {
	e.premiddleware = append(e.premiddleware, middleware...)
}

// Use adds middleware to the chain which is run after router.
func (e *Echo) Use(middleware ...MiddlewareFunc) {
	e.middleware = append(e.middleware, middleware...)
}

// CONNECT registers a new CONNECT route for a path with matching handler in the
// router with optional route-level middleware.
func (e *Echo) CONNECT(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodConnect, path, h, m...)
}

// DELETE registers a new DELETE route for a path with matching handler in the router
// with optional route-level middleware.
func (e *Echo) DELETE(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodDelete, path, h, m...)
}

// GET registers a new GET route for a path with matching handler in the router
// with optional route-level middleware.
func (e *Echo) GET(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodGet, path, h, m...)
}

// HEAD registers a new HEAD route for a path with matching handler in the
// router with optional route-level middleware.
func (e *Echo) HEAD(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodHead, path, h, m...)
}

// OPTIONS registers a new OPTIONS route for a path with matching handler in the
// router with optional route-level middleware.
func (e *Echo) OPTIONS(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodOptions, path, h, m...)
}

// PATCH registers a new PATCH route for a path with matching handler in the
// router with optional route-level middleware.
func (e *Echo) PATCH(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodPatch, path, h, m...)
}

// POST registers a new POST route for a path with matching handler in the
// router with optional route-level middleware.
func (e *Echo) POST(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodPost, path, h, m...)
}

// PUT registers a new PUT route for a path with matching handler in the
// router with optional route-level middleware.
func (e *Echo) PUT(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodPut, path, h, m...)
}

// TRACE registers a new TRACE route for a path with matching handler in the
// router with optional route-level middleware.
func (e *Echo) TRACE(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(http.MethodTrace, path, h, m...)
}

// RouteNotFound registers a special-case route which is executed when no other route is found (i.e. HTTP 404 cases)
// for current request URL.
// Path supports static and named/any parameters just like other http method is defined. Generally path is ended with
// wildcard/match-any character (`/*`, `/download/*` etc).
//
// Example: `e.RouteNotFound("/*", func(c echo.Context) error { return c.NoContent(http.StatusNotFound) })`
func (e *Echo) RouteNotFound(path string, h HandlerFunc, m ...MiddlewareFunc) *Route {
	return e.Add(RouteNotFound, path, h, m...)
}

// Any registers a new route for all HTTP methods (supported by Echo) and path with matching handler
// in the router with optional route-level middleware.
//
// Note: this method only adds specific set of supported HTTP methods as handler and is not true
// "catch-any-arbitrary-method" way of matching requests.
func (e *Echo) Any(path string, handler HandlerFunc, middleware ...MiddlewareFunc) []*Route {
	routes := make([]*Route, len(methods))
	for i, m := range methods {
		routes[i] = e.Add(m, path, handler, middleware...)
	}
	return routes
}

// Match registers a new route for multiple HTTP methods and path with matching
// handler in the router with optional route-level middleware.
func (e *Echo) Match(methods []string, path string, handler HandlerFunc, middleware ...MiddlewareFunc) []*Route {
	routes := make([]*Route, len(methods))
	for i, m := range methods {
		routes[i] = e.Add(m, path, handler, middleware...)
	}
	return routes
}

func (common) file(path, file string, get func(string, HandlerFunc, ...MiddlewareFunc) *Route,
	m ...MiddlewareFunc) *Route {
	return get(path, func(c Context) error {
		return c.File(file)
	}, m...)
}

// File registers a new route with path to serve a static file with optional route-level middleware.
func (e *Echo) File(path, file string, m ...MiddlewareFunc) *Route {
	return e.file(path, file, e.GET, m...)
}

func (e *Echo) add(host, method, path string, handler HandlerFunc, middlewares ...MiddlewareFunc) *Route {
	router := e.findRouter(host)
	//FIXME: when handler+middleware are both nil ... make it behave like handler removal
	name := handlerName(handler)
	route := router.add(method, path, name, func(c Context) error {
		h := applyMiddleware(handler, middlewares...)
		return h(c)
	})

	if e.OnAddRouteHandler != nil {
		e.OnAddRouteHandler(host, *route, handler, middlewares)
	}

	return route
}

// Add registers a new route for an HTTP method and path with matching handler
// in the router with optional route-level middleware.
func (e *Echo) Add(method, path string, handler HandlerFunc, middleware ...MiddlewareFunc) *Route {
	return e.add("", method, path, handler, middleware...)
}

// Host creates a new router group for the provided host and optional host-level middleware.
func (e *Echo) Host(name string, m ...MiddlewareFunc) (g *Group) {
	e.routers[name] = NewRouter(e)
	g = &Group{host: name, echo: e}
	g.Use(m...)
	return
}

// Group creates a new router group with prefix and optional group-level middleware.
func (e *Echo) Group(prefix string, m ...MiddlewareFunc) (g *Group) {
	g = &Group{prefix: prefix, echo: e}
	g.Use(m...)
	return
}

// URI generates an URI from handler.
func (e *Echo) URI(handler HandlerFunc, params ...interface{}) string {
	name := handlerName(handler)
	return e.Reverse(name, params...)
}

// URL is an alias for `URI` function.
func (e *Echo) URL(h HandlerFunc, params ...interface{}) string {
	return e.URI(h, params...)
}

// Reverse generates a URL from route name and provided parameters.
func (e *Echo) Reverse(name string, params ...interface{}) string {
	return e.router.Reverse(name, params...)
}

// Routes returns the registered routes for default router.
// In case when Echo serves multiple hosts/domains use `e.Routers()["domain2.site"].Routes()` to get specific host routes.
func (e *Echo) Routes() []*Route {
	return e.router.Routes()
}

// AcquireContext returns an empty `Context` instance from the pool.
// You must return the context by calling `ReleaseContext()`.
func (e *Echo) AcquireContext() Context {
	return e.pool.Get().(Context)
}

// ReleaseContext returns the `Context` instance back to the pool.
// You must call it after `AcquireContext()`.
func (e *Echo) ReleaseContext(c Context) {
	e.pool.Put(c)
}

// ServeHTTP implements `http.Handler` interface, which serves HTTP requests.
func (e *Echo) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// Acquire context
	c := e.pool.Get().(*context)
	c.Reset(r, w)
	var h HandlerFunc

	if e.premiddleware == nil {
		e.findRouter(r.Host).Find(r.Method, GetPath(r), c)
		h = c.Handler()
		h = applyMiddleware(h, e.middleware...)
	} else {
		h = func(c Context) error {
			e.findRouter(r.Host).Find(r.Method, GetPath(r), c)
			h := c.Handler()
			h = applyMiddleware(h, e.middleware...)
			return h(c)
		}
		h = applyMiddleware(h, e.premiddleware...)
	}

	// Execute chain
	if err := h(c); err != nil {
		e.HTTPErrorHandler(err, c)
	}

	// Release context
	e.pool.Put(c)
}

// Start starts an HTTP server.
func (e *Echo) Start(address string) error {
	e.startupMutex.Lock()
	e.Server.Addr = address
	if err := e.configureServer(e.Server); err != nil {
		e.startupMutex.Unlock()
		return err
	}
	e.startupMutex.Unlock()
	return e.Server.Serve(e.Listener)
}

// StartTLS starts an HTTPS server.
// If `certFile` or `keyFile` is `string` the values are treated as file paths.
// If `certFile` or `keyFile` is `[]byte` the values are treated as the certificate or key as-is.
func (e *Echo) StartTLS(address string, certFile, keyFile interface{}) (err error) {
	e.startupMutex.Lock()
	var cert []byte
	if cert, err = filepathOrContent(certFile); err != nil {
		e.startupMutex.Unlock()
		return
	}

	var key []byte
	if key, err = filepathOrContent(keyFile); err != nil {
		e.startupMutex.Unlock()
		return
	}

	s := e.TLSServer
	s.TLSConfig = new(tls.Config)
	s.TLSConfig.Certificates = make([]tls.Certificate, 1)
	if s.TLSConfig.Certificates[0], err = tls.X509KeyPair(cert, key); err != nil {
		e.startupMutex.Unlock()
		return
	}

	e.configureTLS(address)
	if err := e.configureServer(s); err != nil {
		e.startupMutex.Unlock()
		return err
	}
	e.startupMutex.Unlock()
	return s.Serve(e.TLSListener)
}

func filepathOrContent(fileOrContent interface{}) (content []byte, err error) {
	switch v := fileOrContent.(type) {
	case string:
		return os.ReadFile(v)
	case []byte:
		return v, nil
	default:
		return nil, ErrInvalidCertOrKeyType
	}
}

// StartAutoTLS starts an HTTPS server using certificates automatically installed from https://letsencrypt.org.
func (e *Echo) StartAutoTLS(address string) error {
	e.startupMutex.Lock()
	s := e.TLSServer
	s.TLSConfig = new(tls.Config)
	s.TLSConfig.GetCertificate = e.AutoTLSManager.GetCertificate
	s.TLSConfig.NextProtos = append(s.TLSConfig.NextProtos, acme.ALPNProto)

	e.configureTLS(address)
	if err := e.configureServer(s); err != nil {
		e.startupMutex.Unlock()
		return err
	}
	e.startupMutex.Unlock()
	return s.Serve(e.TLSListener)
}

func (e *Echo) configureTLS(address string) {
	s := e.TLSServer
	s.Addr = address
	if !e.DisableHTTP2 {
		s.TLSConfig.NextProtos = append(s.TLSConfig.NextProtos, "h2")
	}
}

// StartServer starts a custom http server.
func (e *Echo) StartServer(s *http.Server) (err error) {
	e.startupMutex.Lock()
	if err := e.configureServer(s); err != nil {
		e.startupMutex.Unlock()
		return err
	}
	if s.TLSConfig != nil {
		e.startupMutex.Unlock()
		return s.Serve(e.TLSListener)
	}
	e.startupMutex.Unlock()
	return s.Serve(e.Listener)
}

func (e *Echo) configureServer(s *http.Server) error {
	// Setup
	e.colorer.SetOutput(e.Logger.Output())
	s.ErrorLog = e.StdLogger
	s.Handler = e
	if e.Debug {
		e.Logger.SetLevel(log.DEBUG)
	}

	if !e.HideBanner {
		e.colorer.Printf(banner, e.colorer.Red("v"+Version), e.colorer.Blue(website))
	}

	if s.TLSConfig == nil {
		if e.Listener == nil {
			l, err := newListener(s.Addr, e.ListenerNetwork)
			if err != nil {
				return err
			}
			e.Listener = l
		}
		if !e.HidePort {
			e.colorer.Printf("⇨ http server started on %s\n", e.colorer.Green(e.Listener.Addr()))
		}
		return nil
	}
	if e.TLSListener == nil {
		l, err := newListener(s.Addr, e.ListenerNetwork)
		if err != nil {
			return err
		}
		e.TLSListener = tls.NewListener(l, s.TLSConfig)
	}
	if !e.HidePort {
		e.colorer.Printf("⇨ https server started on %s\n", e.colorer.Green(e.TLSListener.Addr()))
	}
	return nil
}

// ListenerAddr returns net.Addr for Listener
func (e *Echo) ListenerAddr() net.Addr {
	e.startupMutex.RLock()
	defer e.startupMutex.RUnlock()
	if e.Listener == nil {
		return nil
	}
	return e.Listener.Addr()
}

// TLSListenerAddr returns net.Addr for TLSListener
func (e *Echo) TLSListenerAddr() net.Addr {
	e.startupMutex.RLock()
	defer e.startupMutex.RUnlock()
	if e.TLSListener == nil {
		return nil
	}
	return e.TLSListener.Addr()
}

// StartH2CServer starts a custom http/2 server with h2c (HTTP/2 Cleartext).
func (e *Echo) StartH2CServer(address string, h2s *http2.Server) error {
	e.startupMutex.Lock()
	// Setup
	s := e.Server
	s.Addr = address
	e.colorer.SetOutput(e.Logger.Output())
	s.ErrorLog = e.StdLogger
	s.Handler = h2c.NewHandler(e, h2s)
	if e.Debug {
		e.Logger.SetLevel(log.DEBUG)
	}

	if !e.HideBanner {
		e.colorer.Printf(banner, e.colorer.Red("v"+Version), e.colorer.Blue(website))
	}

	if e.Listener == nil {
		l, err := newListener(s.Addr, e.ListenerNetwork)
		if err != nil {
			e.startupMutex.Unlock()
			return err
		}
		e.Listener = l
	}
	if !e.HidePort {
		e.colorer.Printf("⇨ http server started on %s\n", e.colorer.Green(e.Listener.Addr()))
	}
	e.startupMutex.Unlock()
	return s.Serve(e.Listener)
}

// Close immediately stops the server.
// It internally calls `http.Server#Close()`.
func (e *Echo) Close() error {
	e.startupMutex.Lock()
	defer e.startupMutex.Unlock()
	if err := e.TLSServer.Close(); err != nil {
		return err
	}
	return e.Server.Close()
}

// Shutdown stops the server gracefully.
// It internally calls `http.Server#Shutdown()`.
func (e *Echo) Shutdown(ctx stdContext.Context) error {
	e.startupMutex.Lock()
	defer e.startupMutex.Unlock()
	if err := e.TLSServer.Shutdown(ctx); err != nil {
		return err
	}
	return e.Server.Shutdown(ctx)
}

// NewHTTPError creates a new HTTPError instance.
func NewHTTPError(code int, message ...interface{}) *HTTPError {
	he := &HTTPError{Code: code, Message: http.StatusText(code)}
	if len(message) > 0 {
		he.Message = message[0]
	}
	return he
}

// Error makes it compatible with `error` interface.
func (he *HTTPError) Error() string {
	if he.Internal == nil {
		return fmt.Sprintf("code=%d, message=%v", he.Code, he.Message)
	}
	return fmt.Sprintf("code=%d, message=%v, internal=%v", he.Code, he.Message, he.Internal)
}

// SetInternal sets error to HTTPError.Internal
func (he *HTTPError) SetInternal(err error) *HTTPError {
	he.Internal = err
	return he
}

// WithInternal returns clone of HTTPError with err set to HTTPError.Internal field
func (he *HTTPError) WithInternal(err error) *HTTPError {
	return &HTTPError{
		Code:     he.Code,
		Message:  he.Message,
		Internal: err,
	}
}

// Unwrap satisfies the Go 1.13 error wrapper interface.
func (he *HTTPError) Unwrap() error {
	return he.Internal
}

// WrapHandler wraps `http.Handler` into `echo.HandlerFunc`.
func WrapHandler(h http.Handler) HandlerFunc {
	return func(c Context) error {
		h.ServeHTTP(c.Response(), c.Request())
		return nil
	}
}

// WrapMiddleware wraps `func(http.Handler) http.Handler` into `echo.MiddlewareFunc`
func WrapMiddleware(m func(http.Handler) http.Handler) MiddlewareFunc {
	return func(next HandlerFunc) HandlerFunc {
		return func(c Context) (err error) {
			m(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				c.SetRequest(r)
				c.SetResponse(NewResponse(w, c.Echo()))
				err = next(c)
			})).ServeHTTP(c.Response(), c.Request())
			return
		}
	}
}

// GetPath returns RawPath, if it's empty returns Path from URL
// Difference between RawPath and Path is:
//   - Path is where request path is stored. Value is stored in decoded form: /%47%6f%2f becomes /Go/.
//   - RawPath is an optional field which only gets set if the default encoding is different from Path.
func GetPath(r *http.Request) string {
	path := r.URL.RawPath
	if path == "" {
		path = r.URL.Path
	}
	return path
}

func (e *Echo) findRouter(host string) *Router {
	if len(e.routers) > 0 {
		if r, ok := e.routers[host]; ok {
			return r
		}
	}
	return e.router
}

func handlerName(h HandlerFunc) string {
	t := reflect.ValueOf(h).Type()
	if t.Kind() == reflect.Func {
		return runtime.FuncForPC(reflect.ValueOf(h).Pointer()).Name()
	}
	return t.String()
}

// // PathUnescape is wraps `url.PathUnescape`
// func PathUnescape(s string) (string, error) {
// 	return url.PathUnescape(s)
// }

// tcpKeepAliveListener sets TCP keep-alive timeouts on accepted
// connections. It's used by ListenAndServe and ListenAndServeTLS so
// dead TCP connections (e.g. closing laptop mid-download) eventually
// go away.
type tcpKeepAliveListener struct {
	*net.TCPListener
}

func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
	if c, err = ln.AcceptTCP(); err != nil {
		return
	} else if err = c.(*net.TCPConn).SetKeepAlive(true); err != nil {
		return
	}
	// Ignore error from setting the KeepAlivePeriod as some systems, such as
	// OpenBSD, do not support setting TCP_USER_TIMEOUT on IPPROTO_TCP
	_ = c.(*net.TCPConn).SetKeepAlivePeriod(3 * time.Minute)
	return
}

func newListener(address, network string) (*tcpKeepAliveListener, error) {
	if network != "tcp" && network != "tcp4" && network != "tcp6" {
		return nil, ErrInvalidListenerNetwork
	}
	l, err := net.Listen(network, address)
	if err != nil {
		return nil, err
	}
	return &tcpKeepAliveListener{l.(*net.TCPListener)}, nil
}

func applyMiddleware(h HandlerFunc, middleware ...MiddlewareFunc) HandlerFunc {
	for i := len(middleware) - 1; i >= 0; i-- {
		h = middleware[i](h)
	}
	return h
}